Effect of thermal annealing on the band-edge absorption spectrum of arsenic-ion-implanted GaAs

摘要

Abstract: We report the effect of annealing temperature on the near bandgap transmittance, absorption coefficient, as well as the evolution of shallow-level defects of arsenic-ion-implanted GaAs (referred as GaAs:As$+$PLU$/) by using Fourier transform infrared spectroscopy. By either fitting the absorption curve with A(hv-E$-g$/)$+$HLF$/ or extrapolating the ($alpha@hv)$+2$/ curve to the abscissa, the blue shift of bandgap energy of RTA-annealed GaAs:As$+$PLU$/ samples was found to increase from 1.35 eV (T$-a$/ equals 300 degrees Celsius) to 1.41 eV (T$-a$/ equals 800 degrees Celsius). The slightly perturbed absorption spectra at near bandgap region interpret that there are still a large amount of near-bandedge defects continuously distributed in the RTA-annealed GaAs:As$+$PLU$/ samples. The diminishing of shallow-level defects with at higher annealing temperatures was also observed via the derivative absorption spectra. !23