Photoreflectance and electrical characterization of Si-implanted GaAs

Si-implanted semi-insulating GaAs was studied by the photoreflectance (PR) technique and electrical analysis. Different energies and doses were used for Si implantation in two groups of samples. Subsequently, different rapid thermal annealing (RTA) conditions were utilized for one group of samples to optimize the damage removal and impurity activation. A significant annealing temperature dependence of the electrical activation and damage removal was observed. The 120 keV Si implantation introduced two impurity-like transitions in the PR spectra at photon energies about 40 meV and 100 meV from the band-edge. The 180 keV implantation introduced two impurity-like signals with energies about 50 meV and 65 meV from the band-edge which could be removed by RTA. Particularly, the 950‡ C, 10s RTA can totally remove the 65 meV signal caused by the 180 keV implantation. Samples exhibiting good PR signal also produced diodes from which electrical data was superior to the other cases.