Enhanced UV Light-Emission of Zinc-Phosphate-Hydrate Hydrothermally-Grown on Cu Metal Substrates for Opto-Electronic Applications

Abstract

In the present study, polycrystalline films of layered zinc phosphate hydrate are produced by a facile, low-temperature single-step hydrothermal fabrication method on top of Cu metal substrates. Despite containing structural water, the as-grown films remain crystalline, chemically stable, and electrically conductive. The photoluminescence spectrum obtained at room-temperature reveals the presence of a spectrally narrow, high-intensity ultraviolet band that consists of two Gaussian peaks at ≈377 and 383 nm and a UV-to-visible peak emission intensity ratio of ≈5.3. The electrical charge-transport properties remain Ohmic for electric fields of up to ≈2 kV m−1 and temperature (T) range of ≈223–368 K. The electrical conductivity is further found to vary exponentially with the inverse temperature, and the thermal activation energy, Ea is 285 ± 8 meV. A moderate UV-vis photoconduction effect is registered and assigned to light-assisted electronic transitions that involve near-band edge defect states. This study can potentially open a door to the engineering and deployment of water-based compounds with advanced, semiconducting-like attributes in short-wavelength opto-electronic devices.