Critical V/III dependence of formation of high density GaSb/GaAs quantum dots grown by AP-MOVPE

The effect of AP-MOVPE growth parameters on the formation of GaSb QD structures on GaAs with TMSb and TEGa as Sb and Ga sources has been studied. Formation of small, coherent GaSb dots on GaAs improved with decreasing V/III ratios which were controlled through changing either TMSb/TEGa at a constant temperature or changing growth temperature at constant TMSb/TEGa ratio. A summary of required source vapour V/III ratios for dot growth at various temperatures is also presented. The maximum effective V/III ratio for dot formation was 0.175. Dot density was more sensitive to growth time as time determines the amount of deposited dot material. Dot density increased with increasing growth time. The shape and size was more sensitive to source vapour mole fraction which controls the growth rate. Lower mole fraction gave smaller sized dots with more uniform distribution compared to higher mole fraction.