The effects of strain upon the diffusion of Sn were studied by using laser Raman and photoluminescence spectroscopy. It was found that an increase in compressive strain produced an increase in the carrier concentration, while a decrease in compressive strain or an increase in tensile strain led to a decrease in the carrier concentration at the surface. This behavior was attributed to a decrease in the diffusion coefficient of Sn with compressive strain, and an increase with tensile strain (figure 3). The photoluminescence data showed that the peak which was due to Ga antisite defects increased with increasing compressive stress. This indicated a decrease, in the Ga vacancy concentration, from the equilibrium concentration in an unstressed sample. Photoluminescence data for tensile-stressed samples revealed an increase in Ga vacancy concentration with respect to the equilibrium concentration in an unstressed sample. It was concluded that the change in diffusion coefficient with strain was related to Ga vacancies. It was found that the diffusion coefficient decreased exponentially with the compressive strain, and increased exponentially with tensile strain. The activation energy for Sn diffusion therefore varied linearly as a function of strain.

A.B.M.Harun-ur Rashid, T.Katoda: Journal of Applied Physics, 1997, 81[4], 1661-9