CARBON-DOPED GAAS AND ALGAAS GROWN BY OMVPE - DOPING PROPERTIES, OXYGEN INCORPORATION, AND HYDROGEN PASSIVATION

The carbon-doping behavior of GaAs and AlGaAs grown by organometallic vapor phase epitaxy was examined using AsH3 or tertiarybutylarsine (TBAs) as the arsenic precursors. Carbon tetrachloride was utilized as the carbon dopant precursor for GaAs and AlGaAs. In addition, the intrinsic carbon doping of AlGaAs was also examined for these two As sources. The use of TBAs led to a significant reduction in carbon incorporation, by approximately a factor of 5-10 per mole of As precursor, both with respect to extrinsic and intrinsic carbon incorporation. For the GaAs:C layers grown at temperatures less-than-or-equal-to 550-degrees-C, significant concentrations (1.0-6 x 10(19) cm-3) of hydrogen were detected. Approximately 25-55% of the carbon acceptors were passivated by the hydrogen, based on Hall measurements and infrared absorption measurements. The CCl4 source introduced oxygen into the AlGaAs layers. TBAs was more effective in reducing oxygen incorporation compared to AsH3 and the concentration of oxygen was reduced with either increasing TBAs or AsH3 flow rate.