Growth of high-quality ZnO nanowires without a catalyst

In this study, an efficient method to achieve a wide range of high-quality zinc oxide (ZnO) nanostructures through zinc powder evaporation at lower temperatures is developed. ZnO nanowires could be synthesized on n-type silicon substrates by a simple thermal-evaporation technique without a catalyst at 550, 600, and 650 deg. C. Samples are annealed in wet oxygen and ambient argon gases. Surface morphology, crystallinity, and optical properties of the ZnO nanowires are examined by scanning electron microscopy, X-ray diffraction, and photoluminescence measurement. The optimum temperature for synthesizing high-density, long ZnO nanowires was determined as 650 deg. C. The possible growth mechanism of ZnO nanowires is also proposed.