Influence of delta doping profile and interface roughness on the transport properties of pseudomorphic heterostructures.

Thickness effects of the InGaAs channel on photoluminescence and transport properties of delta-doped Al0.3Ga0.7As/In0.3Ga0.7As heterostructures are investigated. The spreading of the Si delta-doping layer is deduced from a comparison of the measured charge with self-consistent calculations assuming a Gaussian Si distribution profile and a definite ionization probability of the Si-related DX centers. With decreasing channel thickness below 80 Angström, the effect of the spreading on the sheet carrier concentration increases and the low temperature mobility decreases due to roughness scattering at the In0.3Ga0.7As/GaAs interface. In channels thicker than 80 Angström the thickness-independent alloy scattering process dominates.