Dopant and As4/Ga Flux Ratio Influence on the Electrical and Structural Properties of LT GaAs

Abstract

ABSTRACTDouble crystal x-ray diffraction and Hall effect measurements have been performed on GaAs layers grown by molecular beam epitaxy at low substrate temperature (200-250°C). The concentration of excess As incorporated in undoped material is found to be a strong function of growth temperature but not of As4/Ga beam equivalent pressure ratio at a given temperature. Doping with Si or Be at concentrations of 1019cm−3 or greater has resulted in significant reduction of excess As concentration in layers grown at 250'C. This effect is seen to diminish with reducing substrate temperature. The effect is not seen when Se is used as the doping source. Reducing As overpressure in the presence of such a high doping concentrations has led to highly electrically active n- and p-type layers grown at 250'C.