MeV ion implantation in GaAs is known to cause amorphization of the region at the end of the ion range. The near-surface region, however, is still crystalline albeit heavily compensated. We have carried out deep level transient spectroscopy (DLTS) studies of the defect levels in the near—surface region of n—GaAs samples implanted with different doses of 2.0 MeV 16O+ ions.
A comparison between the defect structures in the original and the implanted samples shows that implantation produced a broad range of defect levels ranging from 0.58 to 0.3 eV from the conduction band edge. This broad range of defects has an unusually large capture cross—section. The intensities of the DLTS peaks increase with the dose of 160+ ions. The presence of EL2, which was present in the original samples, was not observed in the implanted samples.
Results from measurements made on samples that have been implanted at 200°C and on implanted samples subjected to rapid thermal annealing will also be discussed.