Positron Annihilation Study Of The Diffusion Of Oxygen In Annealed Silicon-Doped Gallium Arsenide

Positron annihilation spectroscopy has been applied to silicon-doped GaAs grown by molecular-beam epitaxy. Annealing SiO2 capped samples at 930degreesC causes the Si-Ga-V-Ga vacancies to become positively charged. The SiO2 caps cause oxygen to diffuse beneath the surface and the spectroscopy leads to the first measurement of the oxygen diffusion coefficient in GaAs. The application of a new analysis program ROYPROF reveals the creation of internal electric fields.