Growth rate enhancement of III–V antimonides on high-index substrates in metalorganic molecular beam epitaxy

Abstract

Metalorganic molecular beam epitaxy growth of GaSb, InSb and AlSb on ( N 1 1) high-index substrates is studied. The growth rates of antimonides on (1 0 0) substrates are generally low because the decomposition of group III species is suppressed by the excessively adsorbed antimony atoms on the surface, i.e. the site-blocking effect. However, in the growth of GaSb using triethylgallium (TEGa) and elemental antimony, growth rates are enhanced on (3 1 1), (4 1 1) and (5 1 1) substrates. This substrate orientation dependence is also observed in the InSb growth using trimethylindium (TMIn) at low substrate temperatures, although with increasing substrate temperature, the growth rate becomes independent of substrate orientation due to the complete thermal decomposition of TMIn. These results imply that the decomposition of TEGa and TMIn is enhanced at atomic steps consisting of (1 0 0) and (1 1 1) planes and that the growth on high-index substrates is effective for the low-temperature growth of GaSb and InSb. On the other hand, the growth rate of AlSb using trimethylamine alane (TMAAl) is independent of substrate orientation because of low-temperature (∼ 100°C) decomposition of TMAAl.