Growth of GaSb and AlSb quantum dots on high-index GaAs substrates

We investigate the growth of GaSb and AlSb quantum dots (QDs) on high-index GaAs substrates at various substrate temperatures (Ts). The GaSb QD density on GaAs(311)A is about 1.5?2 times larger than that on GaAs(100) substrates. Small and dense AlSb QDs are formed by AlSb deposition on GaAs(311)A substrates at relatively high temperatures (Ts ? 430 ?C) with QD densities as high as 29 ? 1010 cm?2. In contrast, no QDs are observed for low-temperature AlSb deposition (Ts ? 410 ?C). In contrast to InAs QDs, GaSb and AlSb QDs are easily formed even on GaAs(111)A surfaces. We use a rate equation to analyze the experimental data and discuss QD density and size and their Ts dependences.