Metalorganic chemical vapour deposition of GaSb quantum dots on germanium

Metalorganic chemical vapour deposition (MOCVD) was used to study the growth of GaSb islands on (100)Ge. For the first time formation GaSb islands on Ge with dimensions of 250 nm wide by 100 nm high were observed using atomic force microscopy. The average density of these islands across the surface was 4 × 10⁸ cm^-2 for 30 s or 60 monolayers of deposition. For longer growth times, these islands coalesced as three-dimensional growth became dominant. The existence of GaSb islands for 60 monolayers of growth suggests that nucleation of islands in the GaSb/Ge system is slower compared to previously reported island growth in the GaSb/GaAs system. The size of the GaSb islands observed here is compatible with the onset of size quantisation.