ZnCdO/ZnO coaxial multiple quantum well nanowire heterostructures and optical properties

Abstract

High quality vertical-aligned arrays of ZnCdO/ZnO coaxial multiple-quantum-well (MQW) nanowire heterostructures are fabricated for the first time by combining a simple chemical vapor deposition (CVD) and pulsed laser deposition (PLD) method. The ZnO nanowire core enables epitaxial and dislocation-free growth of uniform ZnCdO/ZnO quantum wells. Both steady-state and time-resolved photoluminescence measurements of the MQW nanowires are performed in the temperature range of 10-300 K. Strong quantum confinement and carrier localization effect are verified. In addition, an S-shaped temperature dependence is observed for both the exciton emission energy (Ep) and their lifetime in ZnCdO MQWs, which has not previously been reported in ZnMgO MQWs. A simple phenomenological model was introduced to explain this anomalous behavior. Such ZnCdO/ZnO coaxial MQW nanowires might find applications in nanoscale laser sources and other oxide-based quantum devices. © 2010 American Chemical Society.