Temperature dependent photoluminescence from ZnO nanowires and nanosheets on brass substrate

The temperature-dependent optical properties of ZnO nanosheets and nanowires fabricated on conductive brass substrates with different surface-to-volume ratios and morphologies are investigated. The near band edge and deep-level emission mechanisms are studied. The blueshifted donor bound exciton D 0X peak and enhanced deep-level emission in the low-temperature photoluminescence spectrum of the nanosheets are due to the large surface-to-volume ratios. Although D 0X is the dominant emission from both the nanowires and nanosheets at low temperature, the room-temperature spectra are dominated by D 0X (nanowires) and first order longitudinal optical phonon replica of free exciton (nanosheets). The decay in the D 0X peak intensity stems from the thermal dissociation of D 0X to free exciton.