Reduced Mobility and PPC in In.20Ga.80As/Al.23Ga.77 as Hemt Structure

Abstract

ABSTRACTTransport properties of a pseudomorphic In .20Ga.80As/Al.23Ga.77As HEMT structure have been measured by Hall and SdH techniques. Two samples of identical structures but different doping levels were compared. Low temperature mobility measurements as a function of concentration shows a sharp peak at a Hall concentration of 1.9.1012/cm2. This concentration coincides with the onset of second subband occupancy, indicating that the decrease in mobility is due to intersubband scattering. In spite of the low Al content (23%) large PPC was observed in the highly doped sample only, showing a direct correlation between the PPC and doping concentration of the barrier layer.