Abstract
Electron transport in relaxed InxGa1-x As grown on GaAs by MBE and doped with Si to a carrier density of approximately 1016cm-3 has been investigated as a function of temperature (4.2 - 300K) and pressure (0-8 kbar) for a wide range alloy compositions. A dramatic decrease in both the mobility and carrier concentration in a limited alloy composition range, x=0.30-0.60, has been observed. The results, analyzed using an Iterative Solution of Boltzmann equation (ISBE) based on the usual scattering mechanisms, indicate that in general very good agreement can be obtained at high temperatures for the alloy compositions where the electron scattering from deep centres is unimportant. Both the measured temperature and pressure dependence of mobility and carrier concentration together with the ISBE calculations indicate that the deep levels are responsible for the sharp decrease both in the mobility and carrier concentration in the alloy composition range, x=0.30-0.60. For the x=0.51 and 0.60 layers an additional scattering mechanism having temperature dependence ~T2.6 has been observed, which is attributed to electron scattering from the deep levels generated in association with layer relaxation. The resistivity analysis at low temperatures shows that the Mott transition occurs in the limited alloy composition range x=0.30-0.50 at these doping densities. The temperature and pressure dependence of the low temperature resistivity can be well described in terms of the thermally-activated hopping conduction law for alloy compositions x0.72.