Diffusion of Electrically and Optically Active Defect Centers in II-VI Compounds

Abstract

The diffusion of Cu into doped and undoped ZnSe and ZnS has been studied by radiotracer techniques, accompanied by luminescence and electrical measurements. Both luminescence and radiotracer measurements have shown that the diffusion coefficient of Cu in undoped and Cl-doped ZnSe in the temperature range of 300-570°C obeys the relationship $D=1.7\mathrm{}\times {10}^{-5\mathrm{}}\exp (-0.56\mathrm{} \mathrm{eV}/kT)$. A strong retarding influence on the diffusion of Cu by the presence of Al in the crystals has been interpreted in terms of ion pairing between Al and the in-diffusing Cu. The same effect has also been observed in ZnS. The diffusion of Al into ZnSe has been found to be accompanied by a codiffusion of Zn vacancies. The luminescence patterns, the electrical characteristics and the radiotracer data in partially diffused crystals have been used to correlate the electrical and optical activity of the in-diffused defect centers.