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 2° 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 1.25×1020cm-3 was found at a growth temperature of 530°C and a V/III ratio of 1. For the first time hole concentrations as high as 7.5×1019cm-3 were obtained at a normal growth temperature of 650°C. The last result shows that structures containing high intrinsically p-type doped AlxGa1-xAs layers can be grown at 650°C without the need for temperature variations. [Copyright &y& Elsevier]