Observations on RHEED intensity oscillations during the growth of GaSb and InAs by MOMBE

Abstract

Reflection high-energy electron diffraction (RHEED) intensity oscillations are studied during the growth of GaSb and InAs on GaSb substrates by metalorganic molecular beam epitaxy (MOMBE) using triethylgallium (TEGa) and trimethylindium (TMIn), respectively. For the GaSb growth, the temperature dependence of the growth rate shows a monotonic increase up to 590°C, which is different from the GaAs growth. The Sb overpressure induces a drastic decrease of the growth rate at all temperatures. This behavior is explained by a lower surface site catalytic effect of GaSb surface than GaAs and by the effect of group V kinetics where excessive Sb molecules reduce the possibility for TEGa to move to proper site for bond-breaking, assuming that the rate limiting step during the GaSb growth is the first bond-breaking of TEGa. For the InAs growth, a hysteresis is observed in the phase transition for the surface reconstructions between As-stabilized (2 × 4) and In-stabilized (4 × 2). The growth rate variation with temperature shows a transport limited region above 400°C under the As-stabilized (2 × 4) conditions. Under the (4 × 2) conditions, a remarkable decrease of the growth rate is observed, which is thought to be associated with the decrease of the surface site catalytic effect.