Reflection High-Energy Electron Diffraction Study of Arsenic Incorporation in Metalorganic Molecular Beam Epitaxy of GaAs

ABSTRACTMetalorganic molecular beam epitaxy (MOMBE) of GaAs using triethylgallium (TEGa) and As4 has been studied by reflection high-energy electron diffraction (RHEED). The effect of varying the group-Ill flow rates and group-V beam flux on the growth rate has been investigated over a wide range of substrate temperatures. For a given arsenic flux, the GaAs growth rate first increases linearly as the TEGa flow rate increases. This linear relation extends up to a certain TEGa flow rate, where the growth rate reaches its maximum value. When the TEGa flow rate is increased above this critical value, the growth rate decreases and reaches a stabilized value. From a study of both group-Ill and group-V induced RHEED intensity oscillations, we find that the V/Ill incorporation ratio is unity at the transition point. Compared to conventional molecular beam epitaxy (MBE), MOMBE behaves differently when the V/Ill incorporation ratio is less than unity. The transition region between V/III>I and V/III<1 is gradual and no excess gallium accumulates on the surface during growth. The arseniccontrolled growth rate obtained from conventional group-V induced oscillations where excess Ga atoms are present is greater than the growth rate in the stabilization region where V/IIl<1.