FREE EXCITON EMISSION IN II-VI COMPOUND MIS DIODES

The author gives a review on free exciton emission in MIS diodes with wide band gap II-VI compounds in forward bias. The research work includes as follows: Free exciton emission and its longitudinal optical (LO) phonon replicas in ZnSe and CdS MIS diodes have been identified in terms of Gross's theory. Pure green, blue, blue-violet and violet electroluminescence(EL) at room temperature(RT) have been obtained in II-VI compound MIS diodes, respectively. The origin of two blue EL bands at RT in ZnSe MIS diodes is attributed to emission related to free exciton. The homogeneity of blue EL in ZnSe MIS diodes has been improved by using a suitable insulating layer. Finally a new P band, which is ascribed to exciton-exciton(E_x-E_y) interaction has been found in ZnSe MIS diodes with high pulse current density.