The calculated low-energy side of the luminescence spectrum in zinc selenide

In this paper we consider electron-hole recombination in wide gap semiconductor ZnSe (Zinc Selenide) under electric fields. The calculated low energy side of the luminescence spectrum displays the so-called Urbach's tail, which is characterized as resulting from the presence of side bands in the form of replicas of the main band, corresponding to recombination with accompanying emission of one, two, three, etc., lo-phonons. Through the numerical solution of associate quantum transport equations based on the Non Equilibrium Statistical Operator Method, the carrier drift velocity and the nonequilibrium temperatures of electrons and phonons were obtained and the dependence on the electric field strength was determined. The influence of the applied electric field on the luminescence spectrum is evidenced. Our results for electric fields intensities of 5-25 kV/cm points to 15.7-19.7 meV Urbach tail widths in ZnSe.