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

In this paper we report studies carried out on 2D electrons in strained sil icon and 2D holes in strained germanium channel modulation doped heterostru ctures, to understand their high field transport properties. Geometric magn etoresistance technique was used to measure the mobility as a function of t he applied field up to 300 V/cm and fbr 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 relatio ns were fitted to the data. Theoretical calculations using Boltzmann transp ort 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 suite d to explain the hot carrier mobility degradation in these high mobility sa mples. (C) 2000 Elsevier Science S.A. All rights reserved.