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 + ) by using Fourier transform infrared spectroscopy. By either firing the absorption curve with A(hV-E g ) 1/2 or extrapolating the (αhν) 2 curve to the abscissa, the blue shift of bandgap energy of RTA-annealed GaAs:As + samples was found to increase from 1.35 eV (T a = 300 °C) to 1.41 eV (T a = 800 °C). 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 + samples. The diminishing of shallow-level defects with at higher annealing temperatures was also observed via the derivative absorption spectra.