Effects of Ga deposition rate and antimony flux on morphology of GaSb quantum dots formed on GaAs

We investigate the effects of Ga deposition rate (R) and antimony flux (P) on the morphology of GaSb quantum dots (QDs). GaSb QDs are formed on GaAs at 420 °C by Stranski-Krastanov (SK) mode under various conditions of R (0.13 ∼ 0.73 monolayer (ML)/s) and P (1.0 ∼ 4.2 × 10
⁻⁷
Torr). An atomic microscope study shows that the density n of GaSb QDs is markedly affected by P and R; no (or few) QDs are formed at high R (∼ 0.73 ML/s) and at low P (≤ 1.2 × 10
⁻⁷
Torr). As R (P) increases, n first increases and then decreases. n reaches its maximum ( 1 × 10
¹¹
cm
⁻²
), when the V–III ratio is about 3.6. We also analyze the experimental data by using a rate equation model and discuss the dependences of n on R and P.