Carrier Transport in an Inversion Channel

Abstract

In the previous two chapters, we directed our attention to basic questions of carrier transport in bulk material. We derived the Boltzmann equation in Chapter 1 and in Chapter 2 studied its consequences for low- and high-field transport in an electron-impurity-phonon system. We did not consider the influence of a finite domain containing interfaces on the transport properties. Interfaces are essential in device operation. Every contact is related to an interface problem. Neither ohmic nor Schottky contacts have hitherto been described self-consistently within the framework of the drift-diffusion approximation. Modeling efforts are based on heuristic arguments and more or less do the job. We will not go into the details of how to formulate a suitable theory for current-carrying contacts. In Chapter 1, we mentioned that a self-consistent incorporation of tunneling in the transport problem is the key feature of such a theory and that Eqs. (1.151) or (1.163) are a possible starting point. Tunneling is a quantum-mechanical phenomenon and is therefore not included in the drift-diffusion approximation.