Selective growth of GaAs and GaAlAs by Cl-assisted OMVPE at atmospheric pressure

Abstract

Selective epitaxy of GaAs is generally obtained at low pressure, when the diffusion length of the active species over the dielectric mask is large enough. Another way is to use an organochloride as a precursor, which suppresses the deposition over the dielectric. This method is also used at reduced pressure. In this work, we have obtained selective area epitaxy of GaAs and GaAIAs for a wide range of aluminium composition by adding a controlled flow of AsCl3 during a conventional OMVPE growth at atmospheric pressure. This method is called Cl-assisted OMVPE. When no AsCl3 is used, a finely structured polycrystal is deposited on the mask. When AsCl3 is introduced into the reactor, with otherwise the same growth conditions, complete selectivity was obtained over a 100μm wide Si3N4 mask. We have studied the influence of the growth temperature, the TMG/ AsCl3 and the AsH3/TMG ratios on the growth selectivity. We have also studied the evolution of the limiting planes of the selectively grown ridges with different growth conditions. Finally, on a selectively grown GaAs/GaAlAs double heterostructure, room temperature photoluminescence topography was performed.