Diffusion of implanted beryllium in gallium arsenide as a function of anneal temperature and dose

The diffusion of implanted Be in GaAs was studied by annealing samples of GaAs implanted with low and high doses of Be. The high-dose (1×1014 cm−2) samples show an increase in diffusion with increasing anneal temperature from 700 to 900 °C. However, the low-dose (2×1013 cm−2) samples show a decrease in diffusion as the temperature is increased. The temperature dependence of the low-dose case can be reversed by coimplantation of 1×1014 cm−2 boron. This behavior is explained in terms of the substitutional-interstitial diffusion mechanism and the relative concentrations of Be interstitials and Be substitutionals for the different cases.