Carbon Doped GaAs Grown in Low Pressure-Metalorganic Vapor Phase Epitaxy Using Carbon Tetrabromide

摘要

Carbon tetrabromide was used as carbon source for heavily p-doped GaAs in low pressure metalorganic vapor phase epitaxy (MOVPE). The efficiency of carbon incorporation was investigated at temperatures between 550 and 670℃, at Ⅴ/Ⅲ ratios from 1 to 50 and carbon tetrabromide partial pressures from 0.01 to 0.03 Pa. Hole concentrations from 8 x 10~(17) to 5 x 10~(19) cm~(-3) in as-grown layers were obtained. After annealing in nitrogen atmosphere at 450℃, a maximum hole concentration of 9 x 10~(19) cm~(-3) and a mobility of 87 cm~2/Vs was found. At growth temperatures below 600℃, traces of bromine were detected in the layers. Photoluminescence mapping revealed an excellent doping homogeneity. Thus, CBr_4 is found to be a suitable carbon dopant source in MOVPE.