Impurity conduction in $In_xGa_{1-x}As$

Özet

Resistivity measurements on $In_xGa_{1-x}As$ grown on semi-insulating GaAs by MBE and doped with Si to a carrier density of approximately $10^{16}$ $cm^{-3}$ were made as a function of temperature (4.2-50 K) and pressure (0-8 kbar) for a wide range of alloy compositions. The resistivity analysis at low temperatures shows that the Mott transition occurs in the limited alloy composition range x = 0.30 — 0.60 at these doping densities. For alloy compositions x $\leq$ 0.20, the temperature and pressure dependence of the low temperature resistivity can be well explained by the thermally-activated hopping conduction law. At higher In compositions (x > 0.60), the conduction in the impurity band is of a metallic character instead of thermally-activated hopping conduction.