Low Threshold DC Electroluminescence in ZnSe: Mn Films Deposited onn-GaAs Single Crystal

Bright electroluminescence (EL) with a low threshold voltage less than 60 V in the dc mode is observed in an Al/ZnSe: Mn/ n -GaAs system. It is shown that a heterojunction contact between n -GaAs and ZnSe acts as an efficient electron injector which lowers the threshold voltage of electroluminescence remarkably. Two processes may exist for the electron injection. One is the electron injection from n -GaAs to ZnSe over the heterojunction barrier, and the other is an internal field emission of electrons via the interface states at the heterojunction, Experimental results on the voltage dependence of the brightness and emission spectrum imply that the emission mechanism is based upon the direct impact excitation by collision of energetic electrons with the Mn centers. These phenomena are clarified by the analyses of the brightness wave form and its variations with injection level.