Characteristics of indium-doped GaAs layers grown by liquid phase epitaxy with indium content in the range (0.3–7)×1019 cm−3

Abstract

GaAs layers grown by liquid phase epitaxy and doped with indium in the concentration range of (0.3–7)×1019 cm−3 are studied by etch pit density (EPD), Hall, capacitance-voltage and current-voltage measurement techniques. Layers doped with indium in the range (0.5–5)×1019 cm−3 show about 10%–15% increase in mobility and a corresponding decrease in the background impurity concentrations. In the same range, EPD is found to fall below 102 cm−2. Above 5×1019 cm−3 In doping, mobility decreases drastically, and the dislocation density measured by EPD count goes above 103 cm−2. This result, together with a comparison of free carrier concentrations measured by Hall and capacitance-voltage techniques indicate that dislocation-related scatterings are effective in lowering the mobility for high indium content layers. Reverse current-voltage characteristics of gold Schottky diodes fabricated on the layers do not show any dependence of breakdown voltages on In doping. Simple theoretical calculations give evidence to the fact that the reverse breakdown process in the diodes are, in fact, controlled by the normal avalanching mechanisms dependent on the electrically active background impurities.