An optimal thermal evaporation synthesis of c-axis oriented ZnO nanowires with excellent UV sensing and emission characteristics

Abstract

Well-aligned (c-axis oriented) ZnO nanowire arrays were successfully synthesized on Si (100) substrates through an optimized self-seeding thermal evaporation method. An open-ended chemical vapor deposition (CVD) setup was used in the experiment, with argon and purified air as reaction gases. Epitaxial growth of c-axis oriented ZnO nanowires was observed for 5sccm flow rate of purified air, whereas Zn/Zn suboxide layers and multiple polycrystalline layers of ZnO were obtained for absence and excess of purified air, respectively. Ultraviolet (UV) sensing and emission properties of the as-grown ZnO nanostructures were investigated through the current–voltage (I–V) characteristics of the nanowires under UV (λ=365nm) illumination of 8mW/cm2 and using photoluminescence spectra. Nanowires grown under optimum flow of air emitted four times higher intensity of 380nm UV light as well as exhibited 34 times higher UV radiation sensitivity compared to that of other nanostructures synthesized in this study.