Effects of calcination temperature on the UV light emission of CaO-decorated ZnO nanorods

There have been numerous efforts to cap or decorate ZnO one-dimensional (1D) nanostructures with various materials including metal oxide semiconductors, metals, and polymers, to obtain intense ultraviolet (UV) emission. The UV emission intensity depends strongly on the calcination temperature conducted after the decoration of ZnO 1D nanostructures with other oxide, but it has hardly been reported yet. In this paper, we report on optimal calcination temperature for the most intense UV emission from CaO-decorated ZnO nanorods. The optimal calcination temperature was found to be 400 °C. The intensity of the UV emission from CaO-decorated ZnO nanorods was enhanced and the deep-level visible (vis) emission was suppressed completely with calcination at 400 °C in an oxidizing atmosphere. In contrast, higher temperature calcination resulted in a decrease in UV emission intensity. The underlying mechanism for the enhancement of the UV emission and the complete suppression of the vis emission from the CaO-decorated ZnO nanorods by calcination at 400 °C is discussed in detail.