Synthesis of ZnO nanowires on steel alloy substrate by thermal evaporation: Growth mechanism and structural and optical properties

ZnO nanowires having a diameter in the range of 15–40 nm and several tens of micrometers in length were grown on steel alloy substrates by the thermal evaporation technique without the use of any catalyst or additives. A detailed structural analysis revealed that the as-grown ZnO nanowires are single crystalline with wurtzite hexagonal structures and preferentially oriented in the c-axis direction. Origination of a strong and sharp Raman-active E2 mode at 436.6 cm-1 indicated that the grown ZnO nanowires have good crystal quality with the hexagonal wurtzite phase. Photoluminescence spectra also exhibited a sharp and strong peak in UV and a suppressed and weak band in the visible region, confirming the good optical properties and less structural defects for the deposited products. Additionally, a systematic growth mechanism is also proposed in detail to acquire a better understanding for the growth of nanowires on steel alloy substrate.