Photoluminescence Characterization of Type-Ⅱ Zn_(0.97)Mn_(0.03)Se/ZnSe_(0.92)Te_(0.08) Multiple-Quantum-Well Structures

摘要

The optical characterization of type-Ⅱ Zn_(0.97)Mn_(0.03)Se/ZnSe_(0.92)Te_(0.08) multiple-quantum-well structures has been studied using photoluminescence (PL), temperature-dependent PL, and power-dependent PL. The PL data reveal that the band alignment of the ZnMnSe/ZnSeTe multiple quantum wells (MQWs) is type Ⅱ. In comparison with the theoretical calculation based on solving the Schrodinger equation of a square potential well, the valence band offset is estimated to be 0.6 eV. From the power-dependent PL spectra, it is observed that the peak position of PL spectra shows a blue shift on increasing the excitation power. The blue shift can be interpreted in terms of the band-bending effect due to spatially separated carriers in a type-Ⅱ alignment and the band filling effect. The thermal activation energy (E_A) for quenching the PL intensity was determined from temperature-dependent PL spectra. The thermal activation energy was found to decrease as the thickness of ZnMnSe or ZnSeTe layers decreased.