Pulse Laser Annealing Effects in Si-Implanted GaAs

The effects of pulsed ruby and Nd:Glass laser irradiation on the electrical properties of Si-mplanted GaAs were investigated to reveal the reason for the lack of activity in low-dose-implanted samples after pulsed-laser annealing. High electrical activity was observed in a sample implanted at a dose of 1015/cm2, while no activity was observed in a sample implanted at a dose of less than 1014/cm2 after the same pulsed laser annealing process. It was found that the ruby laser irradiation of a thermally-annealed sample greatly reduces the carrier concentration and mobility near the surface, while Nd: Glass laser irradiation does not. It is suggested that the surface melting and recrystallization that takes place at a high rate of cooling in pulsed annealing induces defects, giving rise to the lack of activity and low mobility in laser-annealed GaAs.