Nucleation of GaSb on GaAs (001) by low pressure metal-organic chemical vapor deposition

The initial growth stage of GaSb on GaAs (001) by low pressure metal-organic chemical vapor deposition (MOCVD) is investigated. The dependence of the nucleation on growth temperature, growth pressure, and vapor V/Ⅲ ratio is studied by means of atomic force microscopy. The nucleation characteristics include the island density, size, and size uniformity distribution. The nucleation mechanism is discussed by the effects of growth temperature, growth pressure, and vapor V/Ⅲ ratio on the density, size, and size uniformity of GaSb islands. With the growth temperature increasing from 500 ℃ to 610 ℃ and the growth pressure increasing from 50 mbar to 1000 mbar (1 mbar = 10⁵ Pa), the island density first increases and then decreases; with the V/Ⅲ ratio increasing from 0.5 to 3, the trend is contrary.