SELECTIVE-AREA EPITAXY OF GAAS USING TRI-ISOPROPYLGALLIUM

We have studied the selective area epitaxy of GaAs by chemical beam ep itaxy, using tri-isopropylgallium as the Ga source. The results show t hat GaAs can be selectively grown at a rate of up to similar to 0.36 m u m/h on patterned GaAs substrates at temperatures as low as 380 degre es C. A low selective growth temperature allows us to utilize deep-ult raviolet radiation to modify the GaAs surface oxides for use as the ma sking material. We found that excess AsH3 over-pressure degrades the s electivity significantly, and the maximum selective growth thickness i s 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 un intentional C doping levels are at least two orders of magnitude lower than those in GaAs layers grown under comparable conditions using tri methylgallium.