Optical and channeling studies of ion-bombarded GaP

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Abstract
Below‐gap optical absorption, above‐gap reflectivity, photoluminescence, and He ion channeling backscattering measurements are reported for ion‐bombarded GaP. Each of the four experiments provides a measure of disorder. A one‐to‐one correspondence exists between the absorption, reflectivity, and backscattering measurements, and all three exhibit comparable sensitivity to damage. Photoluminescence is ∼ 100 times more sensitive. The absorption results suggest that every implanted ion species produces amorphous regions associated with each projectile and that these regions have properties very much like those of cold‐deposited amorphous films. The results are interpreted in terms of a model which ascribes these amorphous regions to localized melting followed by rapid quenching to a glassy (amorphous) state in which short‐range tetrahedral order remains intact. The damaged volume per bombarding ion as determined from absorption data is ∼6 times larger than that determined from channeling measurements. Although the annealing experiments show considerable scatter, the damage‐induced changes in absorption and reflectivity can be largely removed by annealing at ∼600°C for 30 min. Some anomalies are observed in the photoluminescence annealing results.