RAMAN AND ION CHANNELING ANALYSIS OF DAMAGE IN ION-IMPLANTED GAAS - DEPENDENCE ON ION DOSE AND DOSE-RATE

Raman scattering and ion channeling techniques were used to investigate the damage in GaAs implanted at room temperature with 100-keV Si+ ions. The ion-induced damage was analyzed for different ion doses and dose rates (current densities). The development of different damage components was monitored by comparing a Raman signal which is specific to amorphization in GaAs to ion channeling results which are sensitive to small-volume crystalline defects, as well as to amorphous regions. Raman analysis showed that the rate of growth of the amorphous fraction with implant dose was comparable to the growth rate of the total damage as determined by ion channeling. However, while Raman analysis indicated a weak dependence of damage on dose rate, the ion channeling results showed a substantially stronger dependence. These results demonstrate that the damage morphology in GaAs is dependent upon both dose and dose rate, and that the dose-rate-dependent component of the total damage consists primarily of crystalline defects.