Hot carrier transport in modulation doped Si/SiGe and Ge/SiGe heterostructures

Abstract

In this paper we report studies carried out on 2D electrons in strained silicon and 2D holes in strained germanium channel modulation doped heterostructures, to understand their high field transport properties. Geometric magnetoresistance technique was used to measure the mobility as a function of the applied field up to 300 V/cm and for lattice temperatures from 10 to 160 K. We observe that at high fields the mobility decreases at a faster rate in the germanium channels compared with silicon channels. Empirical relations were fitted to the data. Theoretical calculations using Boltzmann transport theory and Green's function for non-linear transport at high fields are also presented. We find that the Green's function approach is better suited to explain the hot carrier mobility degradation in these high mobility samples.