Positron annihilation spectroscopy was applied to observe the spontaneous formation of vacancy-type defects by annealing of heavily Zn-doped InP at 500 to 700K. The defect was identified as the VP-Zn pair by detecting the annihilation of positrons with core electrons. It was concluded that the defect was formed through a diffusion process; a P vacancy migrates until trapped by a Zn impurity and forms a negatively charged VP-Zn pair. The kinetics of the diffusion process was investigated by measuring the average positron lifetime as a function of annealing time and by fitting a diffusion model to the experimental results. A migration energy of 1.8eV was deduced for the P vacancy. The results explained both the presence of native VP-Zn pairs in Zn-doped InP and their disappearance during post-growth annealing.

Formation of Vacancy-Impurity Complexes in Heavily Zn-Doped InP. J.Slotte, K.Saarinen, A.Salmi, S.Simula, R.Aavikko, P.Hautojärvi: Physical Review B, 2003, 67[11], 115209