Photoluminescence from annealed semi-insulating GaAs crystals - The 1.360 eV band.

We investigated the near band edge photoluminescence from semi-insulating GaAs crystals after they were annealed either in wafer form or in bulk form. Our results with respect to the improvements in uniformity achieved after annealing are in agreement with previous studies. The 1.360 eV emission band which is seen in the annealed crystals and which has been taken to imply a V sub (As) related rapid diffusion process as the mechanism responsible for the annealing induced uniformity, is shown not to be connected with it. We also cite evidences which question the involvement of V sub (As) in the band. From data in the literature we estimate the diffusion coefficient of V sub (As) and find it to be too low to bring about bulk equilibrium and uniformity via vacancy diffusion from the surface at the annealing temperatures used. We conclude that the local rearrangement of defects and impurities is still a viable mechanism for producing uniformity during post-growth annealing.