Light up-conversion mechanism of ZnSe–ZnTe superlattices

The specially designed ZnSe–ZnTe superlattice (SL), type-II SL, has the light up-conversion effect that SL emits a photoluminescence (PL) peak under the irradiation of the excitation light with the lower energy than the PL peak. The excitation intensity dependence of the energy of up-converted PL peak obeys the characteristic of type-II SL. The PL peak intensity has the super-linear dependence on the excitation intensity. The five kinds of samples in this work showed these phenomena. The model to explain these situations has been proposed.