Abstract
Ultrawide-bandgap (UWBG) semiconductor technology is presently going through a renaissance exemplified by advances in material-level understanding, extensions of known concepts to new materials, novel device concepts, and new applications. This focus issue presents a timely selection of papers spanning the current state of the art in UWBG materials and applications, including both experimental results and theoretical developments. It covers broad research subtopics on UWBG bulk crystals and substrate technologies, UWBG defect science and doping, UWBG epitaxy, UWBG electronic and optoelectronic properties, and UWBG power devices and emitters. In this overview article, we consolidate the fundamentals and background of key UWBG semiconductors including aluminum gallium nitride alloys (AlxGa1–xN), boron nitride (BN), diamond, β-phase gallium oxide (β-Ga2O3), and a number of other UWBG binary and ternary oxides.
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Ultrawide-bandgap (UWBG) semiconductors, with bandgap energies much greater than the 3.4 eV of GaN or 3.2 eV of SiC, represent an emerging new area of intensive research covering a wide spectrum of materials, physics, devices, and applications [1]. As the critical electric field of avalanche breakdown increases super-linearly with increasing bandgap energy (detailed analysis discussed in a recent study led by Sandia and MIT Lincoln Lab [2]), UWBG semiconductors can tolerate high fields to enable high-power electronic devices for telecommunications, motor drives, power grid, electric vehicles, industrial and locomotive traction control, and various other applications. In addition, light emission from UWBG materials occurs in the deep ultraviolet (UV) part of the electromagnetic spectrum, which is attractive for extending the working wavelengths of photonic devices beyond the UV–visible (UV–vis) spectrum to enable potential applications in deep-UV optoelectronics, quantum information science, and bio-chemical sensing. This new class of semiconductors is also being explored for device applications in harsh environments by taking advantage of their thermal stability and radiation hardness. Compared to the development of GaN and SiC, all UWBG materials are relatively immature and still at a nascent stage. Most research efforts in UWBG focus on aluminum gallium nitride alloys (AlxGa1–xN), boron nitride (BN), diamond, and a large family of binary (typified by β-phase gallium oxide (β-Ga2O3)) and ternary oxide semiconductors. The extensive research activities on these materials are motivated by their reliable dopability and high carrier mobilities, the availability of substrates for thin-film growth, and successful demonstrations of devices. In this article, we provide an overview of the aforementioned different types of UWBG semiconductors, whose recent developments and state of the art in materials and applications are featured in this focus issue.
AlGaN
AlxGa1–xN is an alloyed UWBG semiconductor that typically possesses a hexagonal wurtzite structure. Its bandgap can be tuned from 3.4 eV (GaN at x = 0) to over 6 eV (AlN at x = 1) by varying the aluminum composition x in the material [1]. This tunability permits the ready formation of heterostructures [3], which allows great flexibility in the types of electronic devices that can be realized. Additionally, because it is a direct-gap semiconductor, it is suitable for the fabrication of UV emitters. Visible- and solar-blind photodetectors have also been demonstrated [4]. AlxGa1–xN can be doped n-type by incorporating Si, which is a shallow impurity up to a composition x of 80–85% [5]. Mg is used as a p-type dopant, although it is somewhat deep in the gap for GaN (~ 160 meV) and becomes deeper as the Al composition x is increased [6]. In addition to impurity doping, a great advantage of AlxGa1–xN is the presence of spontaneous and piezoelectric polarization [7], which aids in doping of the material through the formation of two-dimensional electron gases (2DEGs) as well as three-dimensional electron slabs [8]. Additionally, this approach of polarization-induced doping overcomes the large thermal activation energy of Mg and enables efficient p-type doping by field-ionizing the acceptors [9]. Growth of AlxGa1–xN is typically done by metal–organic chemical vapor deposition (MOCVD), but other growth techniques have also been employed, such as plasma-assisted molecular beam epitaxy (MBE) [10]. AlxGa1–xN may also be grown on a variety of substrates including sapphire, although growth on AlN substrates is becoming more common and has been instrumental for electronic devices [11] as well as UV optoelectronics. Growth on GaN [12] and even Si [13] substrates is also possible. While AlxGa1–xN is typically grown in the polar c-orientation, growth of semi-polar AlxGa1–xN has also been reported [14]. The physics of deep levels in AlxGa1–xN is likewise a very rich topic, with sensitivity to growth conditions and Al composition documented [15]. Deep levels are critical not only because they can compensate intentional impurity dopants [16], but also because they can impact electronic device performance due to carrier trapping and de-trapping and optical device performance due to absorption and non-radiative recombination. AlxGa1–xN may also potentially be used in photonic integrated circuits with applications in positioning, navigation, and timing [17].
Numerous electronic and optoelectronic devices have been demonstrated by groups around the world. The breakdown electric field is expected to increase approximately quadratically with the AlxGa1–xN bandgap [18], and this has enabled power switching devices based both on lateral-transport AlxGa1–xN/AlyGa1–yN heterostructures [19] and on vertical-transport devices with thick drift layers such as pn diodes [20] and Schottky diodes [21]. Moreover, the high breakdown electric field coupled with the favorable carrier velocity saturation properties of AlxGa1–xN [22] has permitted the demonstration of radio-frequency devices with encouraging performance [23]. One challenge with electronic devices is alloy scattering, which impacts not only the low-field mobility [24] but also the thermal conductivity. An additional major challenge is the formation of ohmic contacts, and various approaches not only to achieve linear contacts but also to reduce the specific contact resistivity have been demonstrated, including compositional grading [25]. Similarly, the integration of dielectrics on AlxGa1–xN is a topic of current research, which is especially challenging due to the large bandgap of the semiconductor and the resulting small conduction-band offset with the dielectric [26]. Regarding optoelectronics, the ultrawide direct bandgap of AlxGa1–xN has permitted the realization of UV emitters including light-emitting diodes [27] and lasers [28], with applications such as water purification in mind, and such devices are now commercially available. Several representative figures from a review paper on AlxGa1–xN-based UV optoelectronics by Kirste et al. [29] are reproduced below and are intended to convey key aspects of AlxGa1–xN, notably the high quality of epitaxy in Fig. 1 and exemplary device performance in Fig. 2.
BN
BN is a compound isoelectronic with carbon. Like carbon, BN can possess sp2- and sp3-bonded phases [30], which are the analogs of graphite and diamond, respectively. The thermodynamically stable phase under standard temperature and pressure is sp2-bonded hexagonal BN (h-BN), whose wide bandgap of ~ 6 eV and ability to form single layers make it especially attractive for two-dimensional (opto)electronics or as an interlayer for heteroepitaxy [31,32,33,34,35]. The physics of high-temperature chemical vapor deposition (CVD) of h-BN using carbon-free precursors has been studied by Bansal et al. [36].
In its tetrahedrally coordinated sp3-bonded structure, BN can occur in multiple polymorphs. The wurtzite structure (w-BN) can potentially be alloyed with III-nitrides and grown lattice-matched on GaN template substrates to achieve wider bandgaps, which are useful for charge confinement in high-power electronic devices or quantum barriers in UV–vis optoelectronic devices [37, 38], However, BN is very dissimilar to the III-nitrides in terms of lattice parameters and stable crystalline phase; therefore, random alloys of B-III-N with more than a few percent of boron are difficult to attain [39,40,41,42]. In their review, Sarker and Mazumder summarize the developments of B-III-N alloys and provide insights into the microstructures of B-III-N films as demonstrated by local microstructural and atomic-scale chemical analyses [43].
Another sp3-bonded polymorph of BN is zinc-blende cubic (c-BN). This structure has a very large bandgap energy (~ 6.4 eV) [44], boasts an extremely high thermal conductivity second only to diamond [45], possesses arguably the highest breakdown field in the UWBG family, and can be doped either n-type or p-type [46,47,48,49,50,51], thereby making it a strong competitor for future high-power, high-frequency, and high-temperature electronics. To date, however, it has remained difficult to achieve device-quality c-BN using conventional MBE or MOCVD techniques since the cubic structure is metastable under ambient conditions. In general, it is believed that the nucleation of c-BN requires energetic bombardment of the growing surface with charged or neutral ions, regardless of the synthesis approach [52]. A multitude of factors, including degree of ion bombardment, strain, impurity concentration, and growth temperature, is important in determining the quality of the c-BN films [53,54,55,56,57].
Diamond
Recent progress on large wafers and device processing technologies has propelled diamond, which has a bandgap of 5.5 eV, onto the stage of high-power and high-frequency electronics [58]. The figures of merit of diamond devices are extremely high because of high carrier mobility (4500 cm2/V s for electrons, 3800 cm2/V s for holes) [59], large breakdown field (> 10 MV/cm), and high thermal conductivity (2200 W/m K) [60].
CVD is widely adopted for the growth of both substrates and epitaxial layers of diamond. Two promising techniques for realizing large wafers at low production cost are the direct wafer method (lift-off) and hetereoepitaxial growth. The former technique involves implanting carbon ions into the subsurface region of a diamond seed crystal to create a defective layer, followed by homoepitaxial growth on the seed crystal by CVD that simultaneously turns the defective layer into graphite. The grown film, a so-called clone-plate, is lifted off by etching the graphitized layer electrochemically [61]. Heteroepitaxial growth of diamond can be performed on Si, 3C-SiC, Pt, and Ir with lattice mismatches of 52%, 22%, 10%, and 7.6%, respectively [58]. Thanks to the small misfit presented by Ir, freestanding diamond wafers larger than 90 mm in diameter [62] and wafers with excellent structural quality [63] have been realized.
High-power capability of diamond devices was first confirmed on Schottky barrier diodes (SBDs) with boron-doped p-type layers [64]. The breakdown field of diamond SBDs reaches > 7 MV/cm without edge termination [65]. Diamond SBDs also show low leakage current and short turn-off transient with small reverse recovery time and charges even at elevated temperatures [58]. However, their specific on-resistance is high at room temperature and decreases only when the ambient/junction temperature exceeds 200 °C to increase the activation of the relatively deep boron acceptors (ionization energy ~ 370 meV [66]). To solve this problem, a new structure known as the Schottky pn-junction diode (SPND) has been proposed [67]. By precisely controlling the donor concentration in the SPND, holes injected from the impurity band of a p+ anode drift across a depleted n-type layer with high velocity even under forward-bias conditions to realize extremely low on-resistance with high forward current density > 20 kA/cm2 at room temperature. The SPND is expected to be useful for high-power radio-frequency applications because of its low capacitance, specific on-resistance, and forward voltage drop [68].
For switching devices, high-voltage or high-breakdown-field operation has been reported for metal–semiconductor field-effect transistors (MESFETs) [69], junction FETs (JFETs) [70], and deep-depletion diamond metal–oxide–semiconductor FETs (D3MOSFETs) [71]. Those FET devices use a bulk boron-doped p-type layer as the conducting channel, which leads to low current density at room temperature and increasing current density at elevated temperatures, similarly to the SBDs. Current controllability at room temperature can be dramatically enhanced using a two-dimensional hole gas (2DHG) channel [72,73,74], formed using surface-transfer doping when the diamond surface is terminated by hydrogen [75]. Hydrogen termination lowers the ionization energy of diamond, driving electron transfer from the valence band at the diamond surface into an acceptor layer consisting of molecular adsorbates or a transition metal oxide such as MoO3 [76]. This gives rise to p-type surface conductivity, with holes confined to a thin subsurface layer useful for reducing short-channel effects in high-frequency devices [73]. Output current densities of 2DHG channels reach 1.3 A/mm and 12 kA/cm2 for lateral [77] and vertical [78] configurations, respectively. Inversion p-type channel has also been confirmed on MOSFETs fabricated on phosphorous-doped n-type diamond [79], which realizes normally off operation and opens the door for practical applications. Reduction of interface-state density, which can be accomplished by using a 2D material free of dangling bonds as the gate insulator, is key to the improvement of channel mobility and current capability of the devices [80], as shown in Fig. 3. Recently, a hydrogen-terminated diamond FET with high channel mobility of 680 cm2/V s using a h-BN/diamond heterostructure was reported [81]. It is predicted that a strain-mediated rippled structure developed in the h-BN layer can enhance charge transfer across the h-BN/diamond interface [82].
Oxides
Oxides present a fascinating range of tunable physical properties, including conductivities ranging from insulating through semiconducting to superconducting, magnetism, and piezo-/ferro-/antiferro-electricity. This versatility makes oxides a materials class with high potential for new generations of electronic devices. Applications in power electronics and solar-blind UV detection can particularly benefit from UWBG semiconducting oxides. Compared to the widely explored III-nitrides, these oxides are still in their infancy, except for β-Ga2O3 which has been intensely studied over the last decade.
Like the quest to engineer GaN, harnessing oxides for (opto)electronic devices requires high-quality growth of bulk crystals and epitaxial layers with well-defined doping. A broad understanding of device-relevant physical properties is also essential. Bulk oxide crystals provide not only workhorse materials for the extraction of material properties, such as the mobility of electrons as discussed by Galazka et al. [83], but also substrates for homoepitaxy of thin films to achieve the highest structural quality. A versatile tool proven to pioneer novel oxide thin-film systems with highest quality is MBE, as discussed in a review by Nunn et al. [84].
In the following, we briefly review a selection of promising UWBG oxide materials ranging from binary oxides to ternary spinel and complex oxides, whose key materials properties are summarized in Table 1. A common feature of most UWBG oxides is that they can only be doped n-type with maximum Hall electron mobilities on the order of 100 to 300 cm2/V s [83], which limits their application space to unipolar devices unless hetero-pn-junctions are used. Often, the bandgaps of oxides were measured by the optical absorption of thin films. As a consequence, only direct transitions with large absorption coefficient or dipole momentum (e.g., from conduction band minimum to a lower-lying valence band at the Gamma point) were identified, resulting in a wider apparent “optical” bandgap than the fundamental indirect or direct but dipole-forbidden bandgap with weak optical absorption. Table 1 lists both types of bandgaps since the optical bandgap is relevant to optoelectronics applications (UV detectors, transparent conductors) and the fundamental bandgap determines the breakdown electric field for power electronics applications.
Binary oxides
β-Ga2O3
The most mature, benchmark binary UWBG oxide is β-Ga2O3, whose monoclinic β-gallia crystal structure is the most thermodynamically stable polymorph of Ga2O3 [85]. This material has attracted significant attention for power electronics applications because of a large 4.8-eV bandgap, controllable n-type doping with Si/Sn/Ge, and relatively high electron mobility of ~ 200 cm2/V s [86,87,88,89]. With a critical field strength approximately three times that of SiC and GaN, β-Ga2O3 offers greater intrinsic power conversion efficiencies and further expansion of the operating-voltage–switching-frequency power electronics application space. Melt-grown native substrates are available for β-Ga2O3, with 4-inch substrates already commercially available, indicating a path to commercially viable Ga2O3 devices [90]. Due to its wide bandgap, broadband transparency, low cost, and high thermal/chemical stability, β-Ga2O3 has also emerged as a new platform for UV–vis nonlinear optics and integrated photonics such as waveguides and solar-blind photodetectors [91, 92]. Successful development of processing techniques, such as ohmic contacts [93] and etching [94, 95] (Fig. 4), enables complex device structures to be fabricated. The monoclinic lattice of β-Ga2O3 leads to pronounced anisotropy in optical, dielectric, and thermal properties [96,97,98,99,100,101,102,103,104], yet surprisingly maintains near-isotropic electrical conductivity [105]. Lack of p-type doping [106,107,108] and low thermal conductivity [103, 104, 109] pose fundamental limitations to the design of β-Ga2O3 devices.
Epitaxial growth techniques developed for β-Ga2O3 include MBE [110,111,112], halide vapor phase epitaxy (HVPE) [113], MOCVD [114], pulsed laser deposition (PLD) [115], and low-pressure chemical vapor deposition (LPCVD) [116]. In the early stages of development, epitaxy of β-Ga2O3 was mostly explored by MBE, with typical growth rates of 1–5 nm/min for oxygen-plasma-assisted growths and about 2× higher for ozone-assisted growths. While MBE is suitable for the epitaxy of lateral β-Ga2O3 devices, HVPE has been a popular technique for growing vertical devices owing to its capabilities of achieving much higher growth rates (> 10 μm/h) and low background electron densities (< 1013 cm–3) [117], which are desirable attributes for obtaining thick, lightly doped drift layers required for high breakdown. As a strong competitor of HVPE, MOCVD has also been adopted for growing homoepitaxial Ga2O3 films with smooth morphology, controllable n-type doping, and fast growth rates up to about 10 μm/h [118]. High-purity epitaxial films demonstrating superior electronic qualities, including a room-temperature carrier concentration of low 1014 cm–3 [119], a compensating acceptor concentration as low as 2 × 1013 cm–3 (< 0.1% donor compensation) [120], and a low-temperature electron mobility exceeding 104 cm2/V s, have been reported [121].
Alloys between Ga2O3 and Al2O3 present a rich material space with unique properties that make them attractive candidates as UWBG semiconductors. Modulation-doped field-effect transistors (MODFETs) that utilize β-(AlxGa1–x)2O3/Ga2O3 heterostructures can offer advantages of high sheet-charge density and excellent electron mobility from a 2DEG localized at the heterointerface [122,123,124,125,126,127]. However, alloying within the (AlxGa1–x)2O3 system is complicated by the variety of structures and local coordination environments that can be adopted by both parent compounds Ga2O3 and Al2O3 (Fig. 5) whose ground-state crystal structures are the monoclinic β phase and the corundum α phase, respectively. The Al composition of most epitaxially grown β-(AlxGa1–x)2O3 has been limited to about 30%, with higher incorporation tending to drive structural degradation, phase segregation, and the formation of γ-phase inclusions [128,129,130,131,132]. The highest Al content of 52% in β-(AlxGa1–x)2O3 is achieved by MOCVD in (100)-oriented films [133, 134]. The thermodynamics of Al incorporation in Ga2O3, and the resulting effects on crystal structure and the optical and electronic properties of (AlxGa1–x)2O3 alloys, are reviewed by Varley [135].
α-Ga2O3
Lately, there is increasing interest in the metastable polymorphs of Ga2O3, among which α-Ga2O3 possesses the largest bandgap of about 5.3 eV [136, 137]. α-Ga2O3 can be grown heteroepitaxially with high quality on the c-, m-, a-, or r- planes of isostructural α-Al2O3 substrates (sapphire) by mist-CVD [136, 138,139,140], MBE [141,142,143], MOCVD [144, 145], or PLD [146, 147], enabling the full compositional range of α-(AlxGa1–x)2O3 from Ga2O3 to Al2O3 to be covered without miscibility gaps to allow bandgap engineering for α-Ga2O3-based heterostructures from 5.3 to 8.8 eV [138, 142, 145, 147]. Strain relaxation of α-(AlxGa1–x)2O3 on sapphire is anisotropic and its mechanisms have been investigated [148, 149].
Rutile GeO2
A series of recent publications predicts rutile GeO2 (r-GeO2) to be an UWBG semiconductor that can outperform Ga2O3 in terms of device efficiency [150,151,152,153]. r-GeO2 has a bandgap (~ 4.7 eV [150, 154]) similar to that of Ga2O3. Its dielectric constant, predicted electron and hole mobilities [152], and thermal conductivity [151] are, however, higher than those of Ga2O3, thus bringing beneficial consequences for power-device efficiency. In addition, the predicted prospects for p-type conductivity in GeO2 [150, 155] is extremely attractive as it would enable the realization of r-GeO2 pn-junctions, thereby dramatically widening the device application space to bipolar devices, including pn-junction field management for high-voltage devices. Sb and Al are theoretically predicted to be viable donor and acceptor dopants, respectively [150]. The feasibility of bulk growth by solution top-seeding [156] and from the flux [155], as well as of epitaxial growth by MBE [157] (yet at a low growth rate of 10 nm/h) and mist-CVD [158] (at much higher growth rates of up to 1.7 µm/h), has already been experimentally demonstrated. Definitive understandings of doping and charge carrier transport properties are yet to be developed.
Rutile SnO2
A relatively narrow bandgap of about 3.7 eV does not qualify the classical binary oxide rutile SnO2 as a true UWBG semiconductor. Nonetheless, this material’s combination of significantly higher thermal conductivity and higher electron mobility than most UWBG oxides are appealing for device applications, not to mention the potential for bandgap engineering when alloyed with r-GeO2.
Ternary oxides
Spinels
The ternary spinel oxides ZnGa2O4 and MgGa2O4 provide bandgaps similar to that of β-Ga2O3. Their lower electron mobilities [83] and structure-related propensity for antisite defects [84] that carry detrimental implications on the control of carrier concentrations may, however, explain the fact that these oxides are so far only investigated for applications in photodetectors [159] or as phosphors [160, 161] rather than for power electronic devices.
Complex oxides
Ternary complex oxides of general stoichiometry ABO3 (with cations A and B) provide, based on the choice of A and B as well as strain state, a wealth of (emergent) physical phenomena resulting in a fully tunable spectrum of conductivities as well as magnetic and dielectric properties [84]. At the same time, their common cubic (or pseudocubic orthorhombic) perovskite crystal structure provides the basis for monolithic integration of those properties in epitaxial, multifunctional heterostructures for novel devices. While the prototypical wide-bandgap semiconducting complex oxide SrTiO3 suffers from a low electron mobility (< 10 cm2/V s) at room temperature, the stannates have been demonstrated to alleviate this issue. To this end, BaSnO3 has recently been demonstrated to exhibit the highest room-temperature electron mobility (> 200 cm2/V s) among the complex oxides [83, 84], and SrSnO3 has already been made into a demonstrator MESFET device [162] since it offers reasonable electron mobilities in combination with a large bandgap.
p-type oxides
UWBG p-type oxides are rare, largely unexplored, and typically suffer from ultra-low hole mobilities (< 1 cm2/V s). A review by Zhang et al. [163] on p-type transparent conducting oxides indicates that p-type oxides with optical bandgaps above 4 eV, such as the delafossite CuBO2 (with exceptionally high hole mobility of 100 cm2/V s) or perovskite Sr-doped LaCrO3 (with low hole mobility of 0.03 cm2/V s), exhibit fundamental bandgaps (either dipole-forbidden direct or indirect) around 2 eV. A potential exception is the double perovskite oxide Ba2BiTaO6 [164] with an optical bandgap > 4.5 eV (fundamental bandgap yet to be experimentally explored) and hole mobility of 30 cm2/V s, albeit at low achievable hole concentrations on the order of 1014 cm–3. Kaneko and Fujita have demonstrated how alloying a p-type oxide α-Ir2O3 (bandgap 2.6 eV) with α-Ga2O3 results in a true p-type UWBG semiconducting α-(Ir,Ga)2O3 [165].
Summary
This focus issue provides an opportunity for the reader to get a glimpse of the recent advancements in UWBG materials, physics, and related technologies. Despite being in its early years, tremendous progress has been made in this research field in exploiting the fascinating properties of UWBG semiconductors. Fundamental materials-level work in AlxGa1–xN, diamond, β-Ga2O3, and other emerging UWBG materials has begun to produce device results commensurate with the fundamental advantages that these materials promise. Open questions remain in UWBG semiconductor research while new ones continuously evolve, to which first-principles computation techniques working in tandem with experimental studies have proven indispensable for improving device performance, discovering new materials with targeted functionalities, and stimulating new research directions [174].
Data availability
Data sharing not applicable to this article as no datasets were generated or analyzed during the current study.
References
J.Y. Tsao, S. Chowdhury, M.A. Hollis, D. Jena, N.M. Johnson, K.A. Jones, R.J. Kaplar, S. Rajan, C.G. Van de Walle, E. Bellotti, C.L. Chua, R. Collazo, M.E. Coltrin, J.A. Cooper, K.R. Evans, S. Graham, T.A. Grotjohn, E.R. Heller, M. Higashiwaki, M.S. Islam, P.W. Juodawlkis, M.A. Khan, A.D. Koehler, J.H. Leach, U.K. Mishra, R.J. Nemanich, R.C.N. Pilawa-Podgurski, J.B. Shealy, Z. Sitar, M.J. Tadjer, A.F. Witulski, M. Wraback, J.A. Simmons, Ultrawide-bandgap semiconductors: research opportunities and challenges. Adv. Electron. Mater. 4, 1600501 (2018). https://doi.org/10.1002/aelm.201600501
O. Slobodyan, J. Flicker, J. Dickerson, J. Shoemaker, A. Binder, T. Smith, S. Goodnick, R. Kaplar, M. Hollis, Analysis of the dependence of critical electric field on semiconductor bandgap. J. Mater. Res. (2021). https://doi.org/10.1557/s43578-021-00465-2
A.G. Baca, A.M. Armstrong, A.A. Allerman, E.A. Douglas, C.A. Sanchez, M.P. King, M.E. Coltrin, T.R. Fortune, R.J. Kaplar, An AlN/Al0.85Ga0.15N high electron mobility transistor. Appl. Phys. Lett. 109, 033509 (2016). https://doi.org/10.1063/1.4959179
A.M. Armstrong, B. Klein, A.A. Allerman, E.A. Douglas, A.G. Baca, M.H. Crawford, G.W. Pickrell, C.A. Sanchez, Visible-blind and solar-blind detection induced by defects in AlGaN high electron mobility transistors. J. Appl. Phys. 123, 114502 (2018). https://doi.org/10.1063/1.4997605
P. Pampili, P.J. Parbrook, Doping of III-nitride materials. Mater. Sci. Semi. Proc. 62, 180 (2017). https://doi.org/10.1016/j.mssp.2016.11.006
Y.-H. Liang, E. Towe, Progress in efficient doping of high aluminum-containing group-III nitrides. Appl. Phys. Rev. 5, 011107 (2018). https://doi.org/10.1063/1.5009349
F. Bernardini, V. Fiorentini, D. Vanderbilt, Spontaneous polarization and piezoelectric constants of III-V nitrides. Phys. Rev. B 56, R10024(R) (1997). https://doi.org/10.1103/PhysRevB.56.R10024
D. Jena, S. Heikman, D. Green, D. Buttari, R. Coffie, H. Xing, S. Keller, S. DenBaars, J.S. Speck, U.K. Mishra, Realization of wide electron slabs by polarization bulk doping in graded III-V nitride semiconductor alloys. Appl. Phys. Lett. 81, 4395 (2002). https://doi.org/10.1063/1.1526161
J. Simon, V. Protasenko, C. Lian, H. Xing, D. Jena, Polarization-induced hole doping in wide–band-gap uniaxial semiconductor heterostructures. Science 327, 60 (2010). https://doi.org/10.1126/science.1183226
E. Iliopoulos, T.D. Moustakas, Growth kinetics of AlGaN films by plasma-assisted molecular-beam epitaxy. Appl. Phys. Lett. 81, 295 (2002). https://doi.org/10.1063/1.1492853
H. Tokuda, M. Hatano, N. Yafune, S. Hashimoto, K. Akita, Y. Yamamoto, M. Kuzuhara, High Al composition AlGaN-channel high-electron-mobility transistor on AlN substrate. Appl. Phys. Express 3, 121003 (2010). https://doi.org/10.1143/APEX.3.121003
S.S. Pasayat, N. Hatui, W. Li, C. Gupta, S. Nakamura, S.P. DenBaars, S. Keller, U.K. Mishra, Method of growing elastically relaxed crack-free AlGaN on GaN as substrates for ultra-wide bandgap devices using porous GaN. Appl. Phys. Lett. 117, 062102 (2020). https://doi.org/10.1063/5.0017948
A. Kaminska, K. Koronski, P. Strak, A. Wierzbicka, M. Sobanska, K. Klosek, D.V. Nechaev, V. Pankratov, K. Chernenko, S. Krukowski, Z.R. Zytkiewicz, Defect-related photoluminescence and photoluminescence excitation as a method to study the excitonic bandgap of AlN epitaxial layers: Experimental and ab initio analysis. Appl. Phys. Lett. 117, 232101 (2020). https://doi.org/10.1063/5.0027743
H.M. Foronda, D.A. Hunter, M. Pietsch, L. Sulmoni, A. Muhin, S. Graupeter, N. Susilo, M. Schilling, J. Enslin, K. Irmscher, R.W. Martin, T. Wernicke, M. Kneissl, Electrical properties of (11–22) Si:AlGaN layers at high Al contents by metal-organic vapor phase epitaxy. Appl. Phys. Lett. 117, 221101 (2020). https://doi.org/10.1063/5.0031468
A.M. Armstrong, A.A. Allerman, Evolution of AlGaN deep level defects as a function of alloying and compositional grading and resultant impact on electrical conductivity. Appl. Phys. Lett. 111, 042103 (2017). https://doi.org/10.1063/1.4996237
J.S. Harris, J.N. Baker, B.E. Gaddy, I. Bryan, Z. Bryan, K.J. Mirrielees, P. Reddy, R. Collazo, Z. Sitar, D.L. Irving, On compensation in Si-doped AlN. Appl. Phys. Lett. 112, 152101 (2018). https://doi.org/10.1063/1.5022794
M. Soltani, R. Soref, T. Palacios, D. Englund, AlGaN/AlN integrated photonics platform for the ultraviolet and visible spectral range. Opt. Express 24, 25415 (2016). https://doi.org/10.1364/OE.24.025415
T.P. Chow, R. Tyagi, Wide bandgap compound semiconductors for superior high-voltage unipolar power devices. IEEE Trans. Electron Devices 41, 1481 (1994). https://doi.org/10.1109/16.297751
S. Muhtadi, S.M. Hwang, A. Coleman, F. Asif, G. Simin, M.V.S. Chandrashekhar, A. Khan, High electron mobility transistors with Al0.65Ga0.35N channel layers on thick AlN/sapphire templates. IEEE Electron Device Lett. 38, 914 (2017). https://doi.org/10.1109/LED.2017.2701651
A.A. Allerman, A.M. Armstrong, A.J. Fischer, J.R. Dickerson, M.H. Crawford, M.P. King, M.W. Moseley, J.J. Wierer, R.J. Kaplar, Al0.3Ga0.7N PN diode with breakdown Voltage >1600 V. Electron. Lett. 52, 1319 (2016). https://doi.org/10.1049/el.2016.1280
J. Xie, S. Mia, R. Dalmau, R. Collazo, A. Rice, J. Tweedie, Z. Sitar, Ni/Au Schottky diodes on AlxGa1–xN (0.7<x<1) grown on AlN single crystal substrates. Phys. Status Solidi C 8, 2407 (2011). https://doi.org/10.1002/pssc.201001009
M. Farahmand, C. Garetto, E. Bellotti, K. F. Brennan, M. Goano, E. Ghillino, G. Ghione, J. D. Albrecht, P. P. Ruden, Monte Carlo simulation of electron transport in the III-nitride wurtzite phase materials system: Binaries and ternaries. IEEE Trans. Electron Devices 48, 535 (2001). https://doi.org/10.1109/16.906448
H. Xue, C.H. Lee, K. Hussian, T. Razzak, M. Abdullah, Z. Xia, S.H. Sohel, A. Khan, S. Rajan, W. Lu, Al0.75Ga0.25N/Al0.60Ga0.40N heterojunction field effect transistor with fT of 40 GHz. Appl. Phys. Express 12, 066502 (2019). https://doi.org/10.7567/1882-0786/ab1cf9
M.E. Coltrin, R.J. Kaplar, Transport and breakdown analysis for improved figure-of-merit for AlGaN power devices. J. Appl. Phys. 121, 055706 (2017). https://doi.org/10.1063/1.4975346
S. Bajaj, F. Akyol, S. Krishnamoorthy, Y. Zhang, S. Rajan, AlGaN channel field effect transistors with graded heterostructure ohmic contacts. Appl. Phys. Lett. 109, 133508 (2016). https://doi.org/10.1063/1.4963860
E.A. Paisley, M. Brumbach, A.A. Allerman, S. Atcitty, A.G. Baca, A.M. Armstrong, R.J. Kaplar, J.F. Ihlefeld, Spectroscopic investigations of band offsets of MgO|AlxGa1–xN epitaxial heterostructures with varying Al content. Appl. Phys. Lett. 107, 102101 (2015). https://doi.org/10.1063/1.4930309
A. Yoshikawa, R. Hasegawa, T. Morishita, K. Nagase, S. Yamada, J. Grandusky, J. Mann, A. Miller, L.J. Schowalter, Improved efficiency and long lifetime UVC LEDs with wavelengths between 230 and 237 nm. Appl. Phys. Express. 13, 022001 (2020). https://doi.org/10.35848/1882-0786/ab65fb
Z. Zhang, M. Kushimoto, T. Sakai, N. Sugiyama, L.J. Schowalter, C. Sasaoka, H. Amano, A 271.8 nm deep-ultraviolet laser diode for room temperature operation. Appl. Phys. Express 12, 124003 (2019). https://doi.org/10.7567/1882-0786/ab50e0
R. Kirste, B. Sarkar, P. Reddy, Q. Guo, R. Collazo, Z. Sitar, Status of the growth and fabrication of AlGaN-based UV laser diodes for near and mid-UV wavelength. J. Mater. Res. (2021). https://doi.org/10.1557/s43578-021-00443-8
C. Cazorla, T. Gould, Polymorphism of bulk boron nitride. Sci. Adv. 5, eaau5832 (2019). https://doi.org/10.1126/sciadv.aau5832
K. Watanabe, T. Taniguchi, H. Kanda, Direct-bandgap properties and evidence for ultraviolet lasing of hexagonal boron nitride single crystal. Nature Mater. 3, 404 (2004). https://doi.org/10.1038/nmat1134
K. Watanabe, T. Taniguchi, T. Niiyama, K. Miya, M. Taniguchi, Far-ultraviolet plane-emission handheld device based on hexagonal boron nitride. Nature Photon. 3, 591 (2009). https://doi.org/10.1038/nphoton.2009.167
R. Bourrellier, S. Meuret, A. Tararan, O. Stéphan, M. Kociak, L.H.G. Tizei, A. Zobelli, Bright UV single photon emission at point defects in h-BN. Nano Lett. 16, 4317 (2016). https://doi.org/10.1021/acs.nanolett.6b01368
T.Q.P. Vuong, G. Cassabois, P. Valvin, E. Rousseau, A. Summerfield, C.J. Mellor, Y. Cho, T.S. Cheng, J.D. Albar, L. Eaves, C.T. Foxon, P.H. Beton, S.V. Novikov, B. Gil, Deep ultraviolet emission in hexagonal boron nitride grown by high-temperature molecular beam epitaxy. 2D Mater. 4, 021023 (2017). https://doi.org/10.1088/2053-1583/aa604a
Y. Kobayashi, K. Kumakura, T. Akasaka, T. Makimoto, Layered boron nitride as a release layer for mechanical transfer of GaN-based devices. Nature 484, 223 (2012). https://doi.org/10.1038/nature10970
A. Bansal, X. Zhang, J.M. Redwing, Gas source chemical vapor deposition of hexagonal boron nitride on C-plane sapphire using B2H6 and NH3. J. Mater. Res. (2021). https://doi.org/10.1557/s43578-021-00446-5
L. Williams, E. Kioupakis, BAlGaN alloys nearly lattice-matched to AlN for efficient UV LEDs. Appl. Phys. Lett. 115, 231103 (2019). https://doi.org/10.1063/1.5129387
S. Sakai, Y. Ueta, Y. Terauchi, Band gap energy and band lineup of III–V alloy semiconductors incorporating nitrogen and boron. Jpn. J. Appl. Phys., Part 1 32, 4413 (1993). https://doi.org/10.1143/JJAP.32.4413
V. Vezin, S. Yatagai, H. Shiraki, S. Uda, Growth of Ga1–xBxN by molecular beam epitaxy. Jpn. J. Appl. Phys., Part 2 36, L1483 (1997). https://doi.org/10.1143/JJAP.36.L1483
L. Escalanti, G.L.W. Hart, Boron alloying in GaN. Appl. Phys. Lett. 84, 705 (2004). https://doi.org/10.1063/1.1644910
A. Ougazzaden, S. Gautier, C. Sartel, N. Maloufi, J. Martin, F. Jomard, BGaN materials on GaN/sapphire substrate by MOVPE using N2 carrier gas. J. Cryst. Growth 289, 316 (2007). https://doi.org/10.1016/j.jcrysgro.2006.10.072
J.-X. Shen, M.E. Turiansky, D. Wickramaratne, C.G. Van de Walle, Thermodynamics of boron incorporation in BGaN. Phys. Rev. Mater. 5, L030401 (2021). https://doi.org/10.1103/PhysRevMaterials.5.L030401
J. Sarker, B. Mazumder, A comprehensive review on the effects of local microstructures and nanoscale chemical features on B-III-nitride films. J. Mater. Res. (2021). https://doi.org/10.1557/s43578-021-00340-0
R.M. Chrenko, Ultraviolet and infrared spectra of cubic boron nitride. Solid State Commun. 14, 511 (1974). https://doi.org/10.1016/0038-1098(74)90978-8
K. Chen, B. Song, N.K. Ravichandran, Q. Zheng, X. Chen, H. Lee, H. Sun, S. Li, G.A.G.U. Gamage, F. Tian, Z. Ding, Q. Song, A. Rai, H. Wu, P. Koirala, A.J. Schmidt, K. Watanabe, B. Lv, Z. Ren, L. Shi, D.G. Cahill, T. Taniguchi, D. Broido, G. Chen, Ultrahigh thermal conductivity in isotope-enriched cubic boron nitride. Science 367, 555 (2020). https://doi.org/10.1126/science.aaz6149
T. Taniguchi, T. Teraji, S. Koizumi, K. Watanabe, S. Yamaoka, Appearance of n-type semiconducting properties of cBN single crystals grown at high pressure. Jpn. J. Appl. Phys., Part 2 41, L109 (2002). https://doi.org/10.1143/JJAP.41.L109
C.-X. Wang, G.-W. Yang, T.-C. Zhang, H.-W. Liu, Y.-H. Han, J.-F. Luo, C.-X. Gao, G.-T. Zou, High-quality heterojunction between p-type diamond single-crystal film and n-type cubic boron nitride bulk single crystal. Appl. Phys. Lett. 83, 4854 (2003). https://doi.org/10.1063/1.1631059
K. Hirama, Y. Taniyasu, H. Yamamoto, K. Kumakura, Control of n-type electrical conductivity for cubic boron nitride (c-BN) epitaxial layers by Si doping. Appl. Phys. Lett. 116, 162104 (2020). https://doi.org/10.1063/1.5143791
M.E. Turiansky, D. Wickramaratne, J.L. Lyons, C.G. Van de Walle, Prospects for n-type conductivity in cubic boron nitride. Appl. Phys. Lett. 119, 162105 (2021). https://doi.org/10.1063/5.0069970
D. Litvinov, C.A. Taylor II., R. Clarke, Semiconducting cubic boron nitride. Diam. Relat. Mater. 7, 360 (1998). https://doi.org/10.1016/S0925-9635(97)00216-1
T. Taniguchi, S. Koizumi, K. Watanabe, I. Sakaguchi, T. Sekiguchi, S. Yamaoka, High pressure synthesis of UV-light emitting cubic boron nitride single crystals. Diam. Relat. Mater. 12, 1098 (2003). https://doi.org/10.1016/S0925-9635(02)00330-8
K. Hirama, Y. Taniyasu, S. Karimoto, H. Yamamoto, K. Kumakura, Heteroepitaxial growth of single-domain cubic boron nitride films by ion-beam-assisted MBE. Appl. Phys. Express 10, 035501 (2017). https://doi.org/10.7567/APEX.10.035501
T. Yoshida, Vapor phase deposition of cubic boron nitride. Diam. Relat. Mater. 5, 501 (1996). https://doi.org/10.1016/0925-9635(96)80068-9
P.B. Mirkarimi, K.F. McCarty, D.L. Medlin, Review of advances in cubic boron nitride film synthesis. Mater. Sci. Eng. R 21, 47 (1997). https://doi.org/10.1016/S0927-796X(97)00009-0
C.B. Samantaray, R.N. Singh, Review of synthesis and properties of cubic boron nitride (c-BN) thin films. Int. Mater. Rev. 50, 313 (2005). https://doi.org/10.1179/174328005X67160
W.J. Zhang, Y.M. Chong, I. Bello, S.T. Lee, Nucleation, growth and characterization of cubic boron nitride (cBN) films. J. Phys. D: Appl. Phys. 40, 6159 (2007). https://doi.org/10.1088/0022-3727/40/20/S03
X.W. Zhang, Doping and electrical properties of cubic boron nitride thin films: A critical review. Thin Solid Films 544, 2 (2013). https://doi.org/10.1016/j.tsf.2013.07.001
S. Koizumi, H. Umezawa, J. Pernot, M. Suzuki (eds.), Power Electronics Device Applications of Diamond Semiconductors (Woodhead Publishing, Duxford, 2018). https://doi.org/10.1016/C2016-0-03999-2
J. Isberg, J. Hammersberg, E. Johansson, T. Wikström, D.J. Twitchen, A.J. Whitehead, S.E. Coe, G.A. Scarsbrook, High carrier mobility in single-crystal plasma-deposited diamond. Science 297, 1670 (2002). https://doi.org/10.1126/science.1074374
H. Umezawa, Recent advances in diamond power semiconductor devices. Mater. Sci. Semicond. Process. 78, 147 (2018). https://doi.org/10.1016/j.mssp.2018.01.007
H. Yamada, A. Chayahara, Y. Mokuno, Y. Kato, S. Shikata, A 2-in. mosaic wafer made of a single-crystal diamond. Appl. Phys. Lett. 104, 102110 (2014). https://doi.org/10.1063/1.4868720
M. Schreck, S. Gsell, R. Brescia, M. Fischer, Ion bombardment induced buried lateral growth: the key mechanism for the synthesis of single crystal diamond wafers. Sci. Rep. 7, 44462 (2017). https://doi.org/10.1038/srep44462
S.-W. Kim, R. Takaya, S. Hirano, M. Kasu, Two-inch high-quality (001) diamond heteroepitaxial growth on sapphire (\(11\bar{2}0\)) misoriented substrate by step-flow mode. Appl. Phys. Express 14, 115501 (2021). https://doi.org/10.35848/1882-0786/ac28e7
D.J. Twitchen, A.J. Whitehead, S.E. Coe, J. Isberg, J. Hammersberg, T. Wikström, E. Johansson, High-voltage single-crystal diamond diodes. IEEE Trans. Electron Devices 51, 826 (2004). https://doi.org/10.1109/TED.2004.826867
A. Traoré, P. Muret, A. Fiori, D. Eon, E. Gheeraert, J. Pernot, Zr/oxidized diamond interface for high power Schottky diodes. Appl. Phys. Lett. 104, 052105 (2014). https://doi.org/10.1063/1.4864060
K. Thonke, The boron acceptor in diamond. Semicond. Sci. Technol. 18, S20 (2003). https://doi.org/10.1088/0268-1242/18/3/303
T. Makino, S. Tanimoto, Y. Hayashi, H. Kato, N. Tokuda, M. Ogura, D. Takeuchi, K. Oyama, H. Ohashi, H. Okushi, S. Yamasaki, Diamond Schottky-pn diode with high forward current density and fast switching operation. Appl. Phys. Lett. 94, 262101 (2009). https://doi.org/10.1063/1.3159837
V. Jha, H. Surdi, M.F. Ahmad, F. Koeck, R.J. Nemanich, S. Goodnick, T.J. Thornton, Diamond Schottky p-i-n diodes for high power RF receiver protectors. Solid-State Electron. 186, 108154 (2021). https://doi.org/10.1016/j.sse.2021.108154
H. Umezawa, T. Matsumoto, S. Shikata, Diamond metal–semiconductor field-effect transistor with breakdown voltage over 1.5 kV. IEEE Electron Device Lett. 35, 1112 (2014). https://doi.org/10.1109/LED.2014.2356191
T. Iwasaki, J. Yaita, H. Kato, T. Makino, M. Ogura, D. Takeuchi, H. Okushi, S. Yamasaki, M. Hatano, 600 V diamond junction field-effect transistors operated at 200 °C. IEEE Electron Device Lett. 35, 241 (2014). https://doi.org/10.1109/LED.2013.2294969
C. Masante, N. Rouger, J. Pernot, Recent progresses in deep-depletion diamond metal–oxide–semiconductor field-effect transistors. J. Phys. D: Appl. Phys. 54, 233002 (2021). https://doi.org/10.1088/1361-6463/abe8fe
H. Kawarada, T. Yamada, D. Xu, H. Tsuboi, Y. Kitabayashi, D. Matsumura, M. Shibata, T. Kudo, M. Inaba, A. Hiraiwa, Durability-enhanced two-dimensional hole gas of C-H diamond surface for complementary power inverter applications. Sci. Rep. 7, 42368 (2017). https://doi.org/10.1038/srep42368
X. Yu, J. Zhou, C. Qi, Z. Cao, Y. Kong, T. Chen, A high frequency hydrogen-terminated diamond MISFET with fT/fmax of 70/80 GHz. IEEE Electron Device Lett. 39, 1373 (2018). https://doi.org/10.1109/LED.2018.2862158
M. Kasu, N.C. Saha, T. Oishi, S.-W. Kim, Fabrication of diamond modulation-doped FETs by NO2 delta doping in an Al2O3 gate layer. Appl. Phys. Express 14, 051004 (2021). https://doi.org/10.35848/1882-0786/abf445
C.I. Pakes, J.A. Garrido, H. Kawarada, Diamond surface conductivity: Properties, devices, and sensors. MRS Bull. 39, 542 (2014). https://doi.org/10.1557/mrs.2014.95
M.R. Neupane, J. Cruz, J.D. Weil, M.N. Groves, Neural network-based study of structural, chemical and electronic properties of doped MoO3. J. Mater. Res. (2021). https://doi.org/10.1557/s43578-021-00396-y
K. Hirama, H. Sato, Y. Harada, H. Yamamoto, M. Kasu, Diamond field-effect transistors with 1.3 A/mm drain current density by Al2O3 passivation layer. Jpn. J. Appl. Phys. 51, 090112 (2012). https://doi.org/10.1143/JJAP.51.090112
M. Iwataki, N. Oi, K. Horikawa, S. Amano, J. Nishimura, T. Kageura, M. Inaba, A. Hiraiwa, H. Kawarada, Over 12000 A/cm2 and 3.2 mΩcm2 miniaturized vertical-type two-dimensional hole gas diamond MOSFET. IEEE Electron Device Lett. 41, 111 (2020). https://doi.org/10.1109/LED.2019.2953693
X. Zhang, T. Matsumoto, S. Yamasaki, C.E. Nebel, T. Inokuma, N. Tokuda, Inversion-type p-channel diamond MOSFET issues. J. Mater. Res. (2021). https://doi.org/10.1557/s43578-021-00317-z
T. Matsumoto, H. Kato, T. Makino, M. Ogura, D. Takeuchi, S. Yamasaki, T. Inokuma, N. Tokuda, Inversion channel mobility and interface state density of diamond MOSFET using N-type body with various phosphorus concentrations. Appl. Phys. Lett. 114, 242101 (2019). https://doi.org/10.1063/1.5100328
Y. Sasama, T. Kageura, M. Imura, K. Watanabe, T. Taniguchi, T. Uchihashi, Y. Takahide, High-mobility p-channel wide bandgap transistors based on h-BN/diamond heterostructures. arXiv:2102.05982v2 [cond-mat.mtrl-sci] (2021).
P.S. Mirabedini, M.R. Neupane, P.A. Greaney, Ab initio study of the effect of 2D layer rippling on the electronic properties of 2D/H-terminated diamond (100) heterostructures. J. Mater. Res. (2021). https://doi.org/10.1557/s43578-021-00330-2
Z. Galazka, K. Irmscher, M. Pietsch, S. Ganschow, D. Schulz, D. Klimm, I.M. Hanke, T. Schroeder, M. Bickermann, Experimental Hall electron mobility of bulk single crystals of transparent semiconducting oxides. J. Mater. Res. (2021). https://doi.org/10.1557/s43578-021-00353-9
W. Nunn, T.K. Truttmann, B. Jalan, A review of molecular-beam epitaxy of wide bandgap complex oxide semiconductors. J. Mater. Res. (2021). https://doi.org/10.1557/s43578-021-00377-1
A. Hassa, M. Grundmann, H. von Wenckstern, Progression of group-III sesquioxides: epitaxy, solubility and desorption. J. Phys. D: Appl. Phys. 54, 223001 (2021). https://doi.org/10.1088/1361-6463/abd4a4
M. Higashiwaki, G.H. Jessen, Guest Editorial: The dawn of gallium oxide microelectronics. Appl. Phys. Lett. 112, 060401 (2018). https://doi.org/10.1063/1.5017845
K.D. Chabak, K.D. Leedy, A.J. Green, S. Mou, A.T. Neal, T. Asel, E.R. Heller, N.S. Hendricks, K. Liddy, A. Crespo, N.C. Miller, M.T. Lindquist, N.A. Moser, R.C. Fitch Jr., D.E. Walker Jr., D.L. Dorsey, G.H. Jessen, Lateral β-Ga2O3 field effect transistors. Semicond. Sci. Technol. 35, 013002 (2020). https://doi.org/10.1088/1361-6641/ab55fe
M.H. Wong, M. Higashiwaki, Vertical β-Ga2O3 power transistors: A review. IEEE Trans. Electron Devices 67, 3925 (2020). https://doi.org/10.1109/TED.2020.3016609
N. Ma, N. Tanen, A. Verma, Z. Guo, T. Luo, H.G. Xing, D. Jena, Intrinsic electron mobility limits in β-Ga2O3. Appl. Phys. Lett. 109, 212101 (2016). https://doi.org/10.1063/1.4968550
S.B. Reese, T. Remo, J. Green, A. Zakutayev, How much will gallium oxide power electronics cost? Joule 3, 903 (2019). https://doi.org/10.1016/j.joule.2019.01.011
X. Hou, Y. Zou, M. Ding, Y. Qin, Z. Zhang, X. Ma, P. Tan, S. Yu, X. Zhou, X. Zhao, G. Xu, H. Sun, S. Long, Review of polymorphous Ga2O3 materials and their solar-blind photodetector applications. J. Phys. D: Appl. Phys. 54, 043001 (2021). https://doi.org/10.1088/1361-6463/abbb45
J. Zhou, H. Chen, K. Fu, Y. Zhao, Gallium oxide-based optical nonlinear effects and photonics devices. J. Mater. Res. (2021). https://doi.org/10.1557/s43578-021-00397-x
M.-H. Lee, R.L. Peterson, Process and characterization of ohmic contacts for beta-phase gallium oxide. J. Mater. Res. (2021). https://doi.org/10.1557/s43578-021-00334-y
H.-C. Huang, M. Kim, X. Zhan, K. Chabak, J.D. Kim, A. Kvit, D. Liu, Z. Ma, J.-M. Zuo, X. Li, High aspect ratio β-Ga2O3 fin arrays with low-interface charge density by inverse metal-assisted chemical etching. ACS Nano 13, 8784 (2019). https://doi.org/10.1021/acsnano.9b01709
H.-C. Huang, Z. Ren, C. Chan, X. Li, Wet etch, dry etch, and MacEtch of β-Ga2O3: A review of characteristics and mechanism. J. Mater. Res. (2021). https://doi.org/10.1557/s43578-021-00413-0
N. Ueda, H. Hosono, R. Waseda, H. Kawazoe, Anisotropy of electrical and optical properties in β-Ga2O3 single crystals. Appl. Phys. Lett. 71, 933 (1997). https://doi.org/10.1063/1.119693
T. Matsumoto, M. Aoki, A. Kinoshita, T. Aono, Absorption and reflection of vapor grown single crystal platelets of β-Ga2O3. Jpn. J. Appl. Phys. 13, 1578 (1974). https://doi.org/10.1143/JJAP.13.1578
C. Sturm, J. Furthmüller, F. Bechstedt, R. Schmidt-Grund, M. Grundmann, Dielectric tensor of monoclinic Ga2O3 single crystals in the spectral range 0.5–8.5 eV. APL Mater. 3, 106106 (2015). https://doi.org/10.1063/1.4934705
T. Onuma, S. Saito, K. Sasaki, T. Masui, T. Yamaguchi, T. Honda, M. Higashiwaki, Valence band ordering in β-Ga2O3 studied by polarized transmittance and reflectance spectroscopy. Jpn. J. Appl. Phys. 54, 112601 (2015). https://doi.org/10.7567/JJAP.54.112601
F. Ricci, F. Boschi, A. Baraldi, A. Filippetti, M. Higashiwaki, A. Kuramata, V. Fiorentini, R. Fornari, Theoretical and experimental investigation of optical absorption anisotropy in β-Ga2O3. J. Phys: Condens. Matter 28, 224005 (2016). https://doi.org/10.1088/0953-8984/28/22/224005
A. Mock, R. Korlacki, C. Briley, V. Darakchieva, B. Monemar, Y. Kumagai, K. Goto, M. Higashiwaki, M. Schubert, Band-to-band transitions, selection rules, effective mass, and excitonic contributions in monoclinic β-Ga2O3. Phys. Rev. B 96, 245205 (2017). https://doi.org/10.1103/PhysRevB.96.245205
M. Schubert, R. Korlacki, S. Knight, T. Hofmann, S. Schöche, V. Darakchieva, E. Janzén, B. Monemar, D. Gogova, Q.-T. Thieu, R. Togashi, H. Murakami, Y. Kumagai, K. Goto, A. Kuramata, S. Yamakoshi, M. Higashiwaki, Anisotropy, phonon modes, and free charge carrier parameters in monoclinic β-gallium oxide single crystals. Phys. Rev. B 93, 125209 (2016). https://doi.org/10.1103/PhysRevB.93.125209
Z. Guo, A. Verma, X. Wu, F. Sun, A. Hickman, T. Masui, A. Kuramata, M. Higashiwaki, D. Jena, T. Luo, Anisotropic thermal conductivity in single crystal β-gallium oxide. Appl. Phys. Lett. 106, 111909 (2015). https://doi.org/10.1063/1.4916078
M. Handwerg, R. Mitdank, Z. Galazka, S.F. Fischer, Temperature-dependent thermal conductivity and diffusivity of a Mg-doped insulating β-Ga2O3 single crystal along [100], [010] and [001]. Semicond. Sci. Technol. 31, 125006 (2016). https://doi.org/10.1088/0268-1242/31/12/125006
C. Golz, Z. Galazka, J. Lähnemann, V. Hortelano, F. Hatami, W.T. Masselink, O. Bierwagen, Electrical conductivity tensor of β-Ga2O3 analyzed by van der Pauw measurements: Inherent anisotropy, off-diagonal element, and the impact of grain boundaries. Phys. Rev. Mater. 3, 124604 (2019). https://doi.org/10.1103/PhysRevMaterials.3.124604
J.B. Varley, A. Janotti, C. Franchini, C.G. Van de Walle, Role of self-trapping in luminescence and p-type conductivity of wide-band-gap oxides. Phys. Rev. B 85, 081109(R) (2012). https://doi.org/10.1103/PhysRevB.85.081109
A. Kyrtsos, M. Matsubara, E. Bellotti, On the feasibility of p-type Ga2O3. Appl. Phys. Lett. 112, 032108 (2018). https://doi.org/10.1063/1.5009423
T. Gake, Y. Kumagai, F. Oba, First-principles study of self-trapped holes and acceptor impurities in Ga2O3 polymorphs. Phys. Rev. Mater. 3, 044603 (2019). https://doi.org/10.1103/PhysRevMaterials.3.044603
Y. Song, P. Ranga, Y. Zhang, Z. Feng, H.-L. Huang, M.D. Santia, S.C. Badescu, C.U. Gonzalez-Valle, C. Perez, K. Ferri, R.M. Lavelle, D.W. Snyder, B.A. Klein, J. Deitz, A.G. Baca, J.-P. Maria, B. Ramos-Alvarado, J. Hwang, H. Zhao, X. Wang, S. Krishnamoorthy, B.M. Foley, S. Choi, Thermal conductivity of β-phase Ga2O3 and (AlxGa1–x)2O3 heteroepitaxial thin films. ACS Appl. Mater. Interfaces 13, 38477 (2021). https://doi.org/10.1021/acsami.1c08506
A. Mauze, J. Speck, Plasma-assisted molecular beam epitaxy 1—Growth, doping, and heterostructures. Chapter 5 in Gallium Oxide: Material Properties, Crystal Growth, and Devices. Springer Series in Materials Science, vol. 293, ed. by M. Higashiwaki, S. Fujita (Springer, Cham, 2020). https://doi.org/10.1007/978-3-030-37153-1_5
O. Bierwagen, P. Vogt, P. Mazzolini, Plasma-assisted molecular beam epitaxy 2—Fundamentals of suboxide-related growth kinetics, thermodynamics, catalysis, polymorphs, and faceting. Chapter 6 in Gallium Oxide: Material Properties, Crystal Growth, and Devices. Springer Series in Materials Science, vol. 293, ed. by M. Higashiwaki, S. Fujita (Springer, Cham, 2020). https://doi.org/10.1007/978-3-030-37153-1_6
K. Sasaki, S. Yamakoshi, A. Kuramata, Ozone-enhanced molecular beam epitaxy. Chapter 7 in Gallium Oxide: Material Properties, Crystal Growth, and Devices. Springer Series in Materials Science, vol. 293, ed. by M. Higashiwaki, S. Fujita (Springer, Cham, 2020). https://doi.org/10.1007/978-3-030-37153-1_7
Y. Kumagai, K. Konishi, K. Goto, H. Murakami, B. Monemar, Halide vapor phase epitaxy 1—Homoepitaxial growth of β-Ga2O3 on β-Ga2O3 substrates. Chapter 10 in Gallium Oxide: Material Properties, Crystal Growth, and Devices. Springer Series in Materials Science, vol. 293, ed. by M. Higashiwaki, S. Fujita (Springer, Cham, 2020). https://doi.org/10.1007/978-3-030-37153-1_10
F. Alema, A. Osinsky, Metalorganic chemical vapor deposition 1—Homoepitaxial and heteroepitaxial growth of Ga2O3 and related alloys. Chapter 8 in Gallium Oxide: Material Properties, Crystal Growth, and Devices. Springer Series in Materials Science, vol. 293, ed. by M. Higashiwaki, S. Fujita (Springer, Cham, 2020). https://doi.org/10.1007/978-3-030-37153-1_8
K.D. Leedy, Pulsed laser deposition 1—Homoepitaxial growth of β-Ga2O3 on β-Ga2O3 substrates. Chapter 14 in Gallium Oxide: Material Properties, Crystal Growth, and Devices. Springer Series in Materials Science, vol. 293, ed. by M. Higashiwaki, S. Fujita (Springer, Cham, 2020). https://doi.org/10.1007/978-3-030-37153-1_14
H. Zhao, Low-pressure chemical vapor deposition. Chapter 16 in Gallium Oxide: Material Properties, Crystal Growth, and Devices. Springer Series in Materials Science, vol. 293, ed. by M. Higashiwaki, S. Fujita (Springer, Cham, 2020). https://doi.org/10.1007/978-3-030-37153-1_16
H. Murakami, K. Nomura, K. Goto, K. Sasaki, K. Kawara, Q.T. Thieu, R. Togashi, Y. Kumagai, M. Higashiwaki, A. Kuramata, Homoepitaxial growth of β-Ga2O3 layers by halide vapor phase epitaxy. Appl. Phys. Express 8, 015503 (2015). https://doi.org/10.7567/APEX.8.015503
F. Alema, B. Hertog, A. Osinsky, P. Mukhopadhyay, M. Toporkov, W.V. Schoenfeld, Fast growth rate of epitaxial β-Ga2O3 by close coupled showerhead MOCVD. J. Cryst. Growth 475, 77 (2017). https://doi.org/10.1016/j.jcrysgro.2017.06.001
F. Alema, Y. Zhang, A. Osinsky, N. Orishchin, N. Valente, A. Mauze, J.S. Speck, Low 1014 cm−3 free carrier concentration in epitaxial β-Ga2O3 grown by MOCVD. APL Mater. 8, 021110 (2020). https://doi.org/10.1063/1.5132752
G. Seryogin, F. Alema, N. Valente, H. Fu, E. Steinbrunner, A.T. Neal, S. Mou, A. Fine, A. Osinsky, MOCVD growth of high purity Ga2O3 epitaxial films using trimethylgallium precursor. Appl. Phys. Lett. 117, 262101 (2020). https://doi.org/10.1063/5.0031484
F. Alema, Y. Zhang, A. Osinsky, N. Valente, A. Mauze, T. Itoh, J.S. Speck, Low temperature electron mobility exceeding 104 cm2/Vs in MOCVD grown β-Ga2O3. APL Mater. 7, 121110 (2019). https://doi.org/10.1063/1.5132954
A. Kumar, K. Ghosh, U. Singisetti, Low field transport calculation of 2-dimensional electron gas in β-(AlxGa1–x)2O3/Ga2O3 heterostructures. J. Appl. Phys. 128, 105703 (2020). https://doi.org/10.1063/5.0008578
S. Krishnamoorthy, Z. Xia, C. Joishi, Y. Zhang, J. McGlone, J. Johnson, M. Brenner, A.R. Arehart, J. Hwang, S. Lodha, S. Rajan, Modulation-doped β-(Al0.2Ga0.8)2O3/Ga2O3 field-effect transistor. Appl. Phys. Lett. 111, 023502 (2017). https://doi.org/10.1063/1.4993569
Y. Zhang, A. Neal, Z. Xia, C. Joishi, J.M. Johnson, Y. Zheng, S. Bajaj, M. Brenner, D. Dorsey, K. Chabak, G. Jessen, J. Hwang, S. Mou, J.P. Heremans, S. Rajan, Demonstration of high mobility and quantum transport in modulation-doped β-(AlxGa1–x)2O3/Ga2O3 heterostructures. Appl. Phys. Lett. 112, 173502 (2018). https://doi.org/10.1063/1.5025704
N.K. Kalarickal, Z. Xia, H.-L. Huang, W. Moore, Y. Liu, M. Brenner, J. Hwang, S. Rajan, β-(Al0.18Ga0.82)2O3/Ga2O3 double heterojunction transistor with average field of 5.5 MV/cm. IEEE Electron Device Lett. 42, 899 (2021). https://doi.org/10.1109/LED.2021.3072052
P. Ranga, A. Bhattacharyya, A. Chmielewski, S. Roy, R. Sun, M.A. Scarpulla, N. Alem, S. Krishnamoorthy, Growth and characterization of metalorganic vapor-phase epitaxy-grown β-(AlxGa1–x)2O3/Ga2O3 heterostructure channels. Appl. Phys. Express 14, 025501 (2021). https://doi.org/10.35848/1882-0786/abd675
A. Vaidya, C.N. Saha, U. Singisetti, Enhancement mode β-(AlxGa1–x)2O3/Ga2O3 heterostructure FET (HFET) with high transconductance and cutoff frequency. IEEE Electron Device Lett. 42, 1444 (2021). https://doi.org/10.1109/LED.2021.3104256
A.F.M.A.U. Bhuiyan, Z. Feng, J.M. Johnson, H.-L. Huang, J. Sarker, M. Zhu, M.R. Karim, B. Mazumder, J. Hwang, H. Zhao, Phase transformation in MOCVD growth of (AlxGa1–x)2O3 thin films. APL Mater. 8, 031104 (2020). https://doi.org/10.1063/1.5140345
C.S. Chang, N. Tanen, V. Protasenko, T.J. Asel, S. Mou, H.G. Xing, D. Jena, D.A. Muller, γ-phase inclusions as common structural defects in alloyed β-(AlxGa1–x)2O3 and doped β-Ga2O3 films. APL Mater. 9, 051119 (2021). https://doi.org/10.1063/5.0038861
J.M. Johnson, H.-L. Huang, M. Wang, S. Mu, J.B. Varley, A.F.M.A.U. Bhuiyan, Z. Feng, N.K. Kalarickal, S. Rajan, H. Zhao, C.G. Van de Walle, J. Hwang, Atomic scale investigation of aluminum incorporation, defects, and phase stability in β-(AlxGa1–x)2O3 films. APL. Mater. 9, 051103 (2021). https://doi.org/10.1063/5.0039769
B. Mazumder, J. Sarker, Probing structural and chemical evolution in (AlxGa1–x)2O3 using atom probe tomography: A review. J. Mater. Res. 36, 52 (2021). https://doi.org/10.1557/s43578-020-00072-7
A.F.M.A.U. Bhuiyan, Z. Feng, L. Meng, H. Zhao, MOCVD growth of (010) β-(AlxGa1–x)2O3 thin films. J. Mater. Res. (2021). https://doi.org/10.1557/s43578-021-00354-8
A.F.M.A.U. Bhuiyan, Z. Feng, J.M. Johnson, H.-L. Huang, J. Hwang, H. Zhao, MOCVD epitaxy of ultrawide bandgap β-(AlxGa1–x)2O3 with high-Al composition on (100) β-Ga2O3 substrates. Cryst. Growth Des. 20, 6722 (2020). https://doi.org/10.1021/acs.cgd.0c00864
A.F.M.A.U. Bhuiyan, Z. Feng, J.M. Johnson, H.-L. Huang, J. Hwang, H. Zhao, Band offsets of (100) β-(AlxGa1–x)2O3/β-Ga2O3 heterointerfaces grown via MOCVD. Appl. Phys. Lett. 117, 252105 (2020). https://doi.org/10.1063/5.0031584
J. Varley, First-principles calculations of structural, electrical, and optical properties of ultra-wide bandgap (AlxGa1–x)2O3 alloys. J. Mater. Res. (2021). https://doi.org/10.1557/s43578-021-00371-7
D. Shinohara, S. Fujita, Heteroepitaxy of corundum-structured α-Ga2O3 thin films on α-Al2O3 substrates by ultrasonic mist chemical vapor deposition. Jpn. J. Appl. Phys. 47, 7311 (2008). https://doi.org/10.1143/JJAP.47.7311
H. Peelaers, J.B. Varley, J.S. Speck, C.G. Van de Walle, Structural and electronic properties of Ga2O3–Al2O3 alloys. Appl. Phys. Lett. 112, 242101 (2018). https://doi.org/10.1063/1.5036991
K. Kaneko, K. Suzuki, Y. Ito, S. Fujita, Growth characteristics of corundum-structured α-(AlxGa1–x)2O3/Ga2O3 heterostructures on sapphire substrates. J. Cryst. Growth 436, 150 (2016). https://doi.org/10.1016/j.jcrysgro.2015.12.013
S. Fujita, M. Oda, K. Kaneko, T. Hitora, Evolution of corundum-structured III-oxide semiconductors: Growth, properties, and devices. Jpn. J. Appl. Phys. 55, 1202A3 (2016). https://doi.org/10.7567/JJAP.55.1202A3
R. Jinno, N. Yoshimura, K. Kaneko, S. Fujita, Enhancement of epitaxial lateral overgrowth in the mist chemical vapor deposition of α-Ga2O3 by using a-plane sapphire substrate. Jpn. J. Appl. Phys. 58, 120912 (2019). https://doi.org/10.7567/1347-4065/ab55c6
Z. Cheng, M. Hanke, P. Vogt, O. Bierwagen, A. Trampert, Phase transformation and strain relaxation of Ga2O3 on c-plane and a-plane sapphire substrates as studied by synchrotron-based x-ray diffraction. Appl. Phys. Lett. 111, 162104 (2017). https://doi.org/10.1063/1.4998804
R. Jinno, C.S. Chang, T. Onuma, Y. Cho, S.-T. Ho, D. Rowe, M.C. Cao, K. Lee, V. Protasenko, D.G. Schlom, D.A. Muller, H.G. Xing, D. Jena, Crystal orientation dictated epitaxy of ultrawide-bandgap 5.4- to 8.6-eV α-(AlGa)2O3 on m-plane sapphire. Sci. Adv. 7, edbd5891 (2021). https://doi.org/10.1126/sciadv.abd5891
J.P. McCandless, C.S. Chang, N. Nomoto, J. Casamento, V. Protasenko, P. Vogt, D. Rowe, K. Gann, S.T. Ho, W. Li, R. Jinno, Y. Cho, A.J. Green, K.D. Chabak, D.G. Schlom, M.O. Thompson, D.A. Muller, H.G. Xing, D. Jena, Thermal stability of epitaxial α-Ga2O3 and (Al,Ga)2O3 layers on m-plane sapphire. Appl. Phys. Lett. 119, 062102 (2021). https://doi.org/10.1063/5.0064278
V. Gottschalch, S. Merker, S. Blaurock, M. Kneiβ, U. Teschner, M. Grundmann, H. Krautscheid, Heteroepitaxial growth of α-, β-, γ- and κ-Ga2O3 phases by metalorganic vapor phase epitaxy. J. Cryst. Growth 510, 76 (2019). https://doi.org/10.1016/j.jcrysgro.2019.01.018
A.F.M.A.U. Bhuiyan, Z. Feng, H.-L. Huang, L. Meng, J. Hwang, H. Zhao, Metalorganic chemical vapor deposition of α-Ga2O3 and α-(AlxGa1–x)2O3 thin films on m-plane sapphire substrates. APL Mater. 9, 101109 (2021). https://doi.org/10.1063/5.0065087
M. Grundmann, T. Stralka, M. Lorenz, Epitaxial growth and strain relaxation of corundum-phase (Al,Ga)2O3 thin films from pulsed laser deposition at 1000°C on r-plane Al2O3. Appl. Phys. Lett. 117, 242102 (2020). https://doi.org/10.1063/5.0030675
A. Hassa, P. Storm, M. Kneiβ, D. Splith, H. von Wenckstern, M. Lorenz, M. Grundmann, Structural and elastic properties of α-(AlxGa1–x)2O3 thin films on (11.0) Al2O3 substrates for the entire composition range. Phys. Status Solidi B 258, 2000394 (2021). https://doi.org/10.1002/pssb.202000394
M. Grundmann, M. Lorenz, Anisotropic strain relaxation through prismatic and basal slip in α-(Al,Ga)2O3 on R-plane Al2O3. APL Mater. 8, 021108 (2020). https://doi.org/10.1063/1.5144744
M. Kneiβ, D. Splith, H. von Wenckstern, M. Lorenz, T. Schultz, N. Koch, M. Grundmann, Strain states and relaxation for α-(AlxGa1–x)2O3 thin films on prismatic planes of α-Al2O3 in the full composition range: Fundamental difference of a- and m-epitaxial planes in the manifestation of shear strain and lattice tilt. J. Mater Res. (2021). https://doi.org/10.1557/s43578-021-00375-3
S. Chae, J. Lee, K.A. Mengle, J.T. Heron, E. Kioupakis, Rutile GeO2: An ultrawide-band-gap semiconductor with ambipolar doping. Appl. Phys. Lett. 114, 102104 (2019). https://doi.org/10.1063/1.5088370
S. Chae, K.A. Mengle, R. Lu, A. Olvera, N. Sanders, J. Lee, P.F.P. Poudeu, J.T. Heron, E. Kioupakis, Thermal conductivity of rutile germanium dioxide. Appl. Phys. Lett. 117, 102106 (2020). https://doi.org/10.1063/5.0011358
K. Bushick, K.A. Mengle, S. Chae, E. Kioupakis, Electron and hole mobility of rutile GeO2 from first principles: An ultrawide-bandgap semiconductor for power electronics. Appl. Phys. Lett. 117, 182104 (2020). https://doi.org/10.1063/5.0033284
K.A. Mengle, S. Chae, E. Kioupakis, Quasiparticle band structure and optical properties of rutile GeO2, an ultra-wide-band-gap semiconductor. J. Appl. Phys. 126, 085703 (2019). https://doi.org/10.1063/1.5111318
M. Stapelbroek, B.D. Evans, Exciton structure in the u.v.-absorption edge of tetragonal GeO2. Solid State Commun. 25, 959 (1978). https://doi.org/10.1016/0038-1098(78)90311-3
C.A. Niedermeier, K. Ide, T. Katase, H. Hosono, T. Kamiya, Shallow valence band of rutile GeO2 and p-type doping. J. Phys. Chem. C 124, 25721 (2020). https://doi.org/10.1021/acs.jpcc.0c07757
J.W. Goodrum, Solution top-seeding: Growth of GeO2 polymorphs. J. Cryst. Growth 13–14, 604 (1972). https://doi.org/10.1016/0022-0248(72)90527-1
S. Chae, H. Paik, N.M. Vu, E. Kioupakis, J.T. Heron, Epitaxial stabilization of rutile germanium oxide thin film by molecular beam epitaxy. Appl. Phys. Lett. 117, 072105 (2020). https://doi.org/10.1063/5.0018031
H. Takane, K. Kaneko, Establishment of a growth route of crystallized rutile GeO2 thin film (≥1 μm/h) and its structural properties. Appl. Phys. Lett. 119, 062104 (2021). https://doi.org/10.1063/5.0060785
R.-H. Horng, P.-H. Huang, Y.-S. Li, F.-G. Tarntair, C. S. Tan, Reliability study on deep-ultraviolet photodetectors based on ZnGa2O4 epilayers grown by MOCVD. Appl. Surf. Sci. 555, 149657 (2021). https://doi.org/10.1016/j.apsusc.2021.149657
A. Bessière, S. Jacquart, K. Priolkar, A. Lecointre, B. Viana, D. Gourier, ZnGa2O4:Cr3+: a new red long-lasting phosphor with high brightness. Opt. Express 19, 10131 (2011). https://doi.org/10.1364/OE.19.010131
N. Basavaraju, S. Sharma, A. Bessière, B. Viana, D. Gourier, K.R. Priolkar, Red persistent luminescence in MgGa2O4: Cr3+; a new phosphor for in vivo imaging. J. Phys. D: Appl. Phys. 46, 375401 (2013). https://doi.org/10.1088/0022-3727/46/37/375401
V.R.S.K. Chaganti, A. Prakash, J. Yue, B. Jalan, S.J. Koester, Demonstration of a depletion-mode SrSnO3 n-channel MESFET. IEEE Electron Device Lett. 39, 1381 (2018). https://doi.org/10.1109/LED.2018.2861320
K.H.L. Zhang, K. Xi, M.G. Blamire, R.G. Egdell, P-type transparent conducting oxides. J. Phys. 28, 383002 (2016). https://doi.org/10.1088/0953-8984/28/38/383002
A. Bhatia, G. Hautier, T. Nilgianskul, A. Miglio, J. Sun, H.J. Kim, K.H. Kim, S. Chen, G.-M. Rignanese, X. Gonze, J. Suntivich, High-mobility bismuth-based transparent p-type oxide from high-throughput material screening. Chem. Mater. 28, 30 (2016). https://doi.org/10.1021/acs.chemmater.5b03794
K. Kaneko, S. Fujita, Novel p-type oxides with corundum-structure for gallium oxide electronics. J. Mater. Res. (2021). https://doi.org/10.1557/s43578-021-00439-4
H. Peelaers, C.G. Van de Walle, Brillouin zone and band structure of β-Ga2O3. Phys. Status Solidi B 252, 828 (2015). https://doi.org/10.1002/pssb.201451551
P. Turkes, C. Pluntke, R. Helbig, Thermal conductivity of SnO2 single crystals. J. Phys. C: Solid State Phys. 13, 4941 (1980). https://doi.org/10.1088/0022-3719/13/26/015
Z. Galazka, S. Ganschow, R. Schewski, K. Irmscher, D. Klimm, A. Kwasniewski, M. Pietsch, A. Fiedler, I. Schulze-Jonack, M. Albrecht, T. Schröder, M. Bickermann, Ultra-wide bandgap, conductive, high mobility, and high quality melt-grown bulk ZnGa2O4 single crystals. APL Mater. 7, 022512 (2019). https://doi.org/10.1063/1.5053867
Z. Galazka, Transparent Semiconducting Oxides: Bulk Crystal Growth and Fundamental Properties (Jenny Stanford Publishing, New York, 2020). https://doi.org/10.1201/9781003045205
H.J. Kim, U. Kim, H.M. Kim, T.H. Kim, H.S. Mun, B.-G. Jeon, K.T. Hong, W.-J. Lee, C. Ju, K.H. Kim, K. Char, High mobility in a stable transparent perovskite oxide. Appl. Phys. Express 5, 061102 (2012). https://doi.org/10.1143/APEX.5.061102
H.J. Kim, T.H. Kim, W.-J. Lee, Y. Chai, J.W. Kim, Y.J. Jwa, S. Chung, S.J. Kim, E. Sohn, S.M. Lee, K.-Y. Choi, K.H. Kim, Determination of temperature-dependent thermal conductivity of a BaSnO3−δ single crystal by using the 3ω method. Thermochim. Acta 585, 16 (2014). https://doi.org/10.1016/j.tca.2014.03.036
M. Wei, A.V. Sanchela, B. Feng, Y. Ikuhara, H.J. Cho, H. Ohta, High electrical conducting deep-ultraviolet-transparent oxide semiconductor La-doped SrSnO3 exceeding ∼3000 S cm−1. Appl. Phys. Lett. 116, 022103 (2020). https://doi.org/10.1063/1.5128410
K.H.L. Zhang, Y. Du, A. Papadogianni, O. Bierwagen, S. Sallis, L.F.J. Piper, M.E. Bowden, V. Shutthanandan, P.V. Sushko, S.A. Chambers, Perovskite Sr-doped LaCrO3 as a new p-type transparent conducting oxide. Adv. Mater. 27, 5191 (2015). https://doi.org/10.1002/adma.201501959
E. Kioupakis, S. Chae, K. Bushick, N. Pant, X. Zhang, W. Lee, Theoretical characterization and computational discovery of ultra-wide-band-gap semiconductors with predictive atomistic calculations. J. Mater. Res. (2021). https://doi.org/10.1557/s43578-021-00437-6
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Sandia National Laboratories is a multi-mission laboratory managed and operated by National Technology and Engineering Solutions of Sandia, LLC, a wholly owned subsidiary of Honeywell International Inc., for the US Department of Energy’s National Nuclear Security Administration under contract DE-NA0003525. This paper describes objective technical results and analysis. Any subjective views or opinions that might be expressed in the paper do not necessarily represent the views of the US Department of Energy or the United States Government.
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Wong, M.H., Bierwagen, O., Kaplar, R.J. et al. Ultrawide-bandgap semiconductors: An overview. Journal of Materials Research 36, 4601–4615 (2021). https://doi.org/10.1557/s43578-021-00458-1
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DOI: https://doi.org/10.1557/s43578-021-00458-1