n-CdSe/p-ZnTe based wide band-gap light emitters: Numerical simulation and design

Abstract

The only II-VI/II-VI wide band-gap heterojunction to provide both good lattice match and p- and n-type dopability is CdSe/ZnTe. We have carried out numerical simulations of several light emitter designs incorporating CdSe, ZnTe, and Mg alloys. In the simulations, Poisson's equation is solved in conjunction with the hole and electron current and continuity equations. Radiative and nonradiative recombination in bulk material and at interfaces are included in the model. Simulation results show that an n-CdSe/p-ZnTe heterostructure is unfavorable for efficient wide band-gap light emission due to recombination in the CdSe and at the CdSe/ZnTe interface. An n-CdSe/MgxCd 1-xSe/p-ZnTe heterostructure significantly reduces interfacial recombination and facilitates electron injection into the p-ZnTe layer. The addition of a MgyZn1-yTe electron confining layer further improves the efficiency of light emission. Finally, an n-CdSe/Mg xCd1-xSe/MgyZn1-yTe/p-ZnTe design allows tunability of the wavelength of light emission from green into the blue wavelength regime.