CARBON-DOPED GAAS GROWN BY ORGANOMETALLIC VAPOR-PHASE EPITAXY USING TRIS-DIMETHYLAMINOARSENIC AND CCL4

Carbon-doped GaAs epitaxial layers were grown by low-pressure (30 Torr) organometallic vapor phase epitaxy using tris-dimethylaminoarsenic (DMAA) as the As precursor and carbon tetrachloride as the doping source. The epilayers were characterized by Hall measurements, secondary ion mass spectrometry, and infrared absorption. Hole concentrations exceeding 10(20) cm(-3) were obtained at a growth temperature of 550 degrees C while still maintaining a featureless surface morphology. Typically 25-50% of the carbon accepters were passivated by hydrogen despite the absence of an As-H bond in the DMAA precursor molecule. Rapid thermal annealing of the GaAs:C epilayers at 550 degrees C for 90 s effectively removes the hydrogen and increases the hole concentration. Subsequent annealing of these layers under an ambient of DMAA in helium at 550 degrees C for 120 s reintroduced the hydrogen at comparable concentrations to the as-grown layers, suggesting that the DMAA is probably the major source of hydrogen.