The effects of thermal power and deposition time on the structural characteristics of ZnO nanorods and their optical properties for photovoltaic applications

Abstract

In this study, zinc oxide nanowires are elaborated by the hydrothermal method using a microwave furnace, which varies power and deposition times. The growth of nanowires is done on a buffer layer deposited on glass substrates using the sol–gel method associated with spin-coating. The X-Ray Diffraction (XRD) spectrums indicate that the obtained nanowires are well oriented in (002) plane according to the hexagonal wurtzite phase. The density and length of these nanowires increase while their diameter decreases with the deposition time and the microwave power. For high powers and longer deposition times, the ZnO nanowires adopt a pyramidal shape due to the low concentration of OH− hydroxides in the deposition solution. The elaborated nanowires have an optical transmittance level in the visible region of about 90% with a red shift of the optical gap as the deposition time increases qualifying them for photovoltaic and other optoelectronic applications. A correlation between the diameter of the nanowires and their optical gap has been found which illustrates the narrow relationship between the structural, electronic, and optical aspects of these nanowires.