Effect of Heat Treatment on Photoluminescence of Zn-Doped GaAs

Abstract

Comparisons of photoluminescence at 20°, 77° and 300°K are made for Zn-doped GaAs before and after heat treatment. It is found that the intensity of the Zn acceptor band I (hvZn) increases after heat treatment at 800°C for acceptor concentrations NA up to approximately 7×1018 cm−3. For NA > 7×1018 cm−3, I (hvZn) remains unchanged by heat treatment. These results can be attributed to lattice defects which dominate the nonradiative processes and are annealed out by heat treatment. Isochronal annealing of a lightly doped crystal in the temperature range 600°–1100°C shows that 800°C is the optimum heat-treatment temperature for maximum luminescence intensity. This result can be rationalized by considering the temperature dependence of the total defect concentration. The broad band at 1.37 eV commonly seen in p-type GaAs photoluminescence is found to practically disappear after heat treatment at temperatures greater than 600°C.