In situ thermal oxidation for surface cleaning and mask generation prior to selective area epitaxy

Dry thermal oxidation of GaAs and AlAs has been carried out in an organometallic chemical vapor deposition system. This in situ process performed either before or after an epitaxial growth serves the purposes of surface cleaning and mask generation for selective area epitaxy of various III-V semiconductors. AlAs oxidized immediately after growth and patterned for the next regrowth provides better oxide-semiconductor interfaces and minimizes wafer handling. Pre-epitaxy oxidation at 435°C on a patterned wafer with AlAs/GaAs areas resulted in a selective oxide mask. Since thermal oxides of GaAs sublime at temperatures >600°C, a 700°C pregrowth annealing thus thermally cleans the oxidized GaAs areas while the oxides of AlAs remain as a mask for the following regrowth. Photoluminescence results indicate that high quality regrown interfaces have been obtained.