Selective area epitaxy of GaAs using tri-isopropylgallium

Abstract

We have studied the selective area epitaxy of GaAs by chemical beam epitaxy, using tri-isopropylgallium as the Ga source. The results show that GaAs can be selectively grown at a rate of up to ∼0.36 µm/h on patterned GaAs substrates at temperatures as low as 380°C. A low selective growth temperature allows us to utilize deep-ultraviolet radiation to modify the GaAs surface oxides for use as the masking material. We found that excess AsH₃ over-pressure degrades the selectivity significantly, and the maximum selective growth thickness is limited by a critical total adatom coverage on the mask. In addition, the low selective growth temperature does not result in a very high C background concentration. Initial Hall measurements indicate that unintentional C doping levels are at least two orders of magnitude lower than those in GaAs layers grown under comparable conditions using trimethylgallium.