Journal of Crystal Growth, Vol.271, No.3-4, 376-384, 2004
Parameter study of intrinsic carbon doping of AlxGa1-xAs by MOCVD
Intrinsic carbon doping of metalorganic chemical vapor deposition-grown (MOCVD-grown) AlxGa1-xAs was investigated under variation of the growth parameters aluminum fraction, growth temperature and V/III ratio. Growth was performed on 2degrees misoriented GaAs substrates, as commonly applied in industry. A linear increase of the hole concentration with increasing aluminum fraction was found. The dependence of the doping level on the V/III ratio showed an approximately constant level up to a V/III ratio of 2 and a decrease at higher V/III ratios. The trends observed were attributed to a decrease of hydrogenation by lower temperatures and by lower V/III ratios and the higher bond strength of Al-C compared to the Ga-C bond strength. A maximum hole concentration up to 1.25 x 10(20) cm(-3) was found at a growth temperature of 530degreesC and a V/III ratio of 1. For the first time hole concentrations as high as 7.5 x 10(19) cm(-3) were obtained at a normal growth temperature of 650degreesC. The last result shows that structures containing high intrinsically p-type doped AlxGa1-xAs layers can be grown at 650degreesC without the need for temperature variations. (C) 2004 Elsevier B.V. All rights reserved.
Keywords:doping;metalorganic chemical vapor deposition;carbon;gallium compounds;semiconducting III-V materials