Effect of Hydrogen Radicals on the Reduction of Carbon Incorporation into GaAs Grown by Using Trimethylgallium

概要

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Carbon incorporation into GaAs grown under an ultra-high vacuum (UHV) environment was investigated in a trimethylgallium (TMGa)-As_4 or AsH_3 (cracked at 850℃) system with hydrogen molecules (H_2) or hydrogen radicals (H・). The residual carbon concentrations in GaAs layers grown at a substrate temperature of 490℃ were measured by secondary ton mass spectrometry (SIMS). In the case of GaAs growth by simultaneous source supply, the introduction of H・reduced the residual carbon concentrations in epitaxial layers from 8×10^<19> to 7×10^<18> cm^<-3> for TMGa-As_4, and from 4×10^<19> to 5×10^<18> cm^<-3> for TMGa-AsH_3. In the case of an alternating source supply of TMGa and AsH_3 without hydrogen, a higher level of carbon concentrations (1-2×10^<20> cm^<-3>) than that of the simultaneous source supply case was observed irrespective of the purge duration (10-250 s) of TMGa in UHV. The residual carbon concentrations were reduced to 6×10^<18> cm^<-3> by the injection of H・after TMGa-exposure in an alternating supply cycle, although H_2 did not affect the carbon incorporation. This result indicates that the adsorbed carbon-containing species derived from TMGa, which has a residence time of more than 600 s on GaAs surfaces, can be desorbed by a reaction with H・.
社団法人応用物理学会の論文
1994-07-15