Self‐diffusion of Zn and Se in ZnSe

Abstract

The high‐temperature defect equilibria of ZnSe have been studied by self‐diffusion measurements on single crystals as a function of temperature, component partial pressure, and added impurity content. The self‐diffusion of Zn was found to be independent of component partial pressure and is expressed as D_zn = 9.8 exp (3.0 eV/kT) cm² s⁻¹, for the temperature range 760 to 1150 °C. Doping with Cu or A1 enhanced the self‐diffusion of Zn under Zn saturation at lower temperatures. The self‐diffusion of Se was found to be D_se = 0.13 × exp (2.6 eV/kT) cm² s⁻¹, for Se‐saturated crystals in the temperature range of 860 to 1020 °C, and decreased with decreasing pressure of Se₂. Doubly‐ionized Frenkel defects are proposed as the dominant mobile defect on the Zn sublattice and a combination of neutral Se interstitials and doubly‐ionized Se vacancies on the Se sublattice. A tentative defect equilibrium isotherm for ZnSe is given.