Resonant donor defect as a cause of compensation in p-type ZnSe: Photoluminescence studies under hydrostatic pressure

We report the presence, in heavily doped and compensated ZnSe:N, of a resonant donor defect having an activation energy of ȼ=120–160 meV. The donor-acceptor pair photoluminescence observed in these materials is quenched at pressures higher than 25 kbar. We attribute this quenching to the shift of a resonant defect level into the band gap. A split N-N interstitial on a Se site is proposed as a strong candidate for the observed defect. We further propose that this species is the dominant donor defect at high p-doping levels and, consequently, is responsible for the potential fluctuations observed in this material. Moreover, a very important point shown by the present ZnSe:N data is that different compensating species will dominate in different ranges of N concentrations.