Producing ZnO films that exhibited near-infrared (NIR) luminescence with a templated design procedure

Abstract

ZnO thin films with near-infrared emission (NIR) were fabricated with pulsed laser deposition (PLD) under vacuum conditions. No additional background gas, or other implantation method (such as nitrogen- or electron-implantation) was required to achieve NIR radiation from the fabricated ZnO thin films. This was done with the aid of a transmission electron microscope (TEM) copper grid, used as a mask on top of the substrate. It is hypothesized that high energy particles impact on the surface of the sample and this causes defects in the ZnO film due to the configuration of the laser-target-sample positions. This leads to the observed NIR emission. Furthermore, the thin films were characterized with scanning electron microscopy (SEM), and energy dispersive X-ray spectroscopy (EDS), photoluminescence (PL). The thin films displayed unique optical properties. Their PL spectra had three broad emissions located across the ultraviolet (UV), visible and NIR regions. The NIR emission was produced despite the samples being prepared in a vacuum, unlike previous work where such emission has only been reported for ZnO nanostructures grown by thermal evaporation in an oxygen or argon atmosphere.