Sulfur diffussion into Ga1−xAlxAs with various Al content

This communication describes the diffusion of sulfur into Ga1−xAlxAs layers having various amounts of Al content. GaS and As in a weight ratio of 2:1 were used as the diffusion source. The GaS diffusion source was carefully selected via x-ray diffraction analysis. Sulfur diffusion was carried out in a sealed quartz ampoule at a temperature of 820 °C and in ambient arsenic at a vapor pressure of 1 atm. Ga1−xAlxAs layers of various x values were grown by liquid phase epitaxy. The Al content indicated by x was in the range of 0–0.3. For x values of 0, 0.08, 0.2, and 0.3, the surface concentrations and diffusion coefficients were found to be 1.0×1018, 3.8×1017, 2.0×1017, and 1.4×1011 cm−3, and 3.5×10−13, 2.0×10−12, 3.5×10−12, and 5.5×10−12 cm2/s, respectively. The carrier concentration profiles from the experimental results agree well with the theoretical profiles, which were calculated with the complementary error function solution. The activation energies of the diffusion coefficient in GaAs and Ga0.7Al0.3A...