Enhancement of Type-I Emission in Type-II Zn0.97Mn0.03Se/ZnSe0.8Te0.2 Quantum Wells under Applied Electric Field

In this study, multiple quantum well (QW) structures were formed by the diluted magnetic semiconductor, Zn0.97Mn0.03Se, and ZnSe0.8Te0.2 using molecular beam epitaxy. The thickness of ZnSe0.8Te0.2 layer was changed from l, 2, 3, and 4 nm for sample l, 2, 3 and 4, respectively. However, the thickness of Zn0.97Mn0.03Se was fixed at 20 nm. The Zn0.97Mn0.03Se/ZnSe0.8Te0.2 QW is a type-II band alignment. Nevertheless, when the thickness of ZnSeTe was decreased to I nm, the type-I emission come from ZnMnSe layer dominated the spectrum. Under applied electric field to 6 KV/cm, the photoluminescence (PL) spectrum of sample 4 showed a strong red energy shift from 2.110 eV to 2.070 eV. However, the PL spectra of sample 1 and sample 2 did not change. It seems the electric field increases the chance of hole, which was confined in ZnSeTe layer, to transfer to ZnMnSe layer. Therefore, under applied electric field, the emission of Zn0.97Mn0.03Se/ZnSe0.8Te0.2 MQW changed from type-II to type-I.