Refractive index of ion-implanted GaAs

Room-temperature near-infrared reflection and transmission measurements on GaAs ion implanted at 2.7 MeV with a fluence of 6.4×1016 P+/cm2 showed amplitude-modulated interference fringes. The reflection fringes were analyzed by using a simple model in which the implanted material is approximated by two partially absorbing layers on a nonabsorbing substrate. The analysis results indicate that the effective layer thicknesses are comparable with those predicted by the projected ion range and the width of the Gaussian ion distribution. The implantation-induced damage produces an increase in the refractive indices. The observed increase in the absorption is similar to that previously reported for GaAs which has been implanted at lower energy.