Effect of random potential on two-dimensional electronic states

Abstract It has been observed that the subthreshold coefficients of MOSFETs saturate at cryogenic temperatures. One model that explains this phenomenon is one that assumes an exponential tail in the density of states (DOS) of a two-dimensional electron gas (2DEG). In this study, the effect of a random potential on 2DEG states has been investigated by calculating the DOS within the effective mass approximation. It is shown that the spatially averaged DOS has exponential tail states in lower energy regions below an onset energy. The dependence of the tail width and the onset energy on the strength and the correlation length of the potential fluctuation is presented.