Photoluminescence Study of Laser Interaction with GaAs.

A study was made on the effect of scanned CW laser radiation on the photoluminescence of virgin, VPE and ion-implanted GaAs. The samples were scanned at room temperature using an argon laser with a beam spot size of 25 microns and a beam dwell time of 1 msec. A flowing cover gas was found to be essential during scanning for beam powers near the damage threshold. The damage threshold was primarily a function of laser power and spot size dwell time was of secondary importance. Photoluminescence data was taken at 5 deg K using argon laser excitation. Spectra from virgin samples scanned below the damage threshold was similar to that from unscanned samples. For VPE samples implanted at room temperature with Ge at a fluence of 1 times 10 to the 14 per cubic centimeter, approximately 5 of virgin material luminescence was recovered after laser annealing of both capped and uncapped samples. This is approximately the same percentage achieved after thermal annealing. However, no sign of Ge activation was seen in the laser annealed samples, even though activation was achieved using thermal annealing. Ellipsometry measurements showed that the laser annealed samples had the same index of refraction as found in unimplanted material. Author