Deep level defects in heteroepitaxial zinc selenide

Deep level defects in epitaxially grown high-conductivity zinc selenide were investigated using transient capacitance spectroscopy. A total of seven electron traps was observed in Au/ZnSe Schottky diodes and ZnSe/GaAs n-p heterojunctions, having activation energies of 0.24, 0.33, 0.35, 0.42, 0.54, 0.71, and 0.86 eV, respectively. The emission rate, capture cross-section prefactor, and concentration of each trap are reported in this paper. Trap concentrations ranged from 10¹¹ to 10¹⁴ cm^-3 depending upon the epitaxial growth conditions. A defect model involving selenium vacancies and divacancies as well as deep donor impurities satisfactorily describes the variation of electron trap concentration with zinc/selenium ratio in the vapor phase.