Effect of hydrogen radicals on the reduction of carbon incorporation into GaAs grown by using trimethylgallium

• Published in: Japanese Journal of Applied Physics 1994-07, Vol.33 (7A), p.3825-3829
• Main Authors: GOTO, S, NOMURA, Y, MORISHITA, Y, KATAYAMA, Y, OHNO, H
• Format: Article
• Language: English
• Subjects: Condensed matter: structure, mechanical and thermal properties; Defects and impurities: doping, implantation, distribution, concentration, etc; Exact sciences and technology; Physics; Surfaces and interfaces; thin films and whiskers (structure and nonelectronic properties); Thin film structure and morphology
• ISSN: 0021-4922; 1347-4065
• DOI: 10.1143/jjap.33.3825

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° C) system with hydrogen molecules ( H 2 ) or hydrogen radicals ( H•). The residual carbon concentrations in GaAs layers grown at a substrate temperature of 490° C were measured by secondary ion 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 sup- ply 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• .