Room temperature blue LED based on p-ZnO/(CdZnO/ZnO) MQWs/ n-ZnO

Abstract

Blue multiple quantum well light-emitting diodes comprising of p-ZnO/(Cd0.12Zn0.88O/ZnO) multiple quantum wells/n-ZnO were grown on n-Si substrates using dual ion-beam sputtering deposition technique. X-ray diffraction of individual thin films revealed growth preferentially in c-axis direction perpendicular to the substrate. Photoluminescence studies indicated blue emission ~ 440nm from CdZnO and UV emission ~384nm arising from ZnO thin films. The LED showed a rectifying current–voltage behavior with a turn-on voltage of ~4.69V at room temperature. It emanated a room-temperature electroluminescence peak centered at 442nm, along with shoulder peak at 380nm in ultra-violet region associated with the recombination in ZnO layers of structure. It was found that with the increase in injection current the blue EL intensity increased and UV emission decreased, leading to improvement in successful radiative recombination in quantum wells. The results indicate prospects of fabrication of ZnO-based blue multiple quantum well LEDs.