CONTACTLESS CHARACTERIZATION OF THE SI+ ION-IMPLANTED SEMIINSULATING GAAS

Si+ ion-implanted semi-insulating GaAs substrates have been characterized by the contactless measurement of the optically injected carrier concentration using the reflectance microwave probe method. The signal intensity decreases with dosage because of implantation damage. After rapid thermal annealing (RTA), the signal intensity becomes larger than those of the as-implanted samples. However, the signal intensity decreases with dosage even after RTA. From observation of the dosage dependence, it is found that the implantation damage is not fully annealed after RTA. The measurement with the He-Ne laser is sensitive enough to evaluate the implantation damage because most excess carriers are injected near the surface. It is found that this method is effective in evaluating the condition of the ion-implanted GaAs substrates.