N-CDSE P-ZNTE BASED WIDE BAND-GAP LIGHT EMITTERS - NUMERICAL-SIMULATION AND DESIGN/

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 carr ied out numerical simulations of several light emitter designs incorpo rating CdSe, ZnTe, and Mg alloys. In the simulations, Poisson's equati on is solved in conjunction with the hole and electron current and con tinuity equations. Radiative and nonradiative recombination in bulk ma terial and at interfaces are included in the model. Simulation results -show that an n-CdSe/p-ZnTe heterostructure is unfavorable for efficie nt wide band-gap light emission due to recombination in the CdSe and a t the CdSe/ZnTe interface. An n-CdSe/MgxCd1-xSe/p-ZnTe heterostructure significantly reduces interfacial recombination and facilitates elect ron injection into the p-ZnTe layer. The addition of a MgyZn1-y electr on confining layer further improves the efficiency ot' light emission. Finally, an n-CdSe/MgxCd1-xSe/MgyZn1-yTe/p-ZnTe design allows tunabil ity of the wavelength of light emission from green into the blue wavel ength regime.