Zinc oxide (ZnO), a wide direct band gap (3.37 eV) II-VI semiconductor, is a fascinating technological material capable of exhibiting both semiconducting and piezoelectric characteristics and distinguished performance in photonics and optoelectronics. We report the synthesis of ZnO thin films composed of randomly oriented, 1-dimensional (1-D) and multipod (tripod and tetrapod)-like nanostructures of varying diameters by thermal evaporation technique. ZnO films of 150 nm thickness were grown for various deposition rates on room temperature Si and pyrex substrates by evaporating catalyst-free ZnO powder. X-ray diffraction (XRD) analysis of the films confirmed polycrystalline nature of wurtzite ZnO nanostructures with lattice constants of a = b = 3.24 Å and c = 5.2 Å. Field emission scanning electron microscopy (FESEM) and high-resolution transmission electron microscopy (HRTEM) analysis revealed a strong influence of film deposition rate on the morphology of nanostructures. For a typical deposition rate of 0.04 nm/sec, aligned 1-D vertically oriented ZnO nanowires of 50–60 nm diameter having lattice spacing of 5.2 Å with [0001] facet were grown. Energy-dispersive x-ray spectroscopy (EDS) has confirmed spatially uniform high quality ZnO nanostructures growth. Micro-Raman spectra of the films confirmed appearance of characteristic longitudinal optical (LO) and transverse optical (TO) modes of wurtzite ZnO dependent on the deposition rate. The nanostructure formation is via a multiphase polytypic growth process depending on precursor growth to deposition ratio, thus promoting a particular growth facet by the crystal growth kinetics under those conditions.

氧化锌 (ZnO) 是一种宽直接带隙 (3.37 eV) II-VI 半导体，是一种迷人的技术材料，能够同时表现出半导体和压电特性以及光子学和光电子学方面的卓越性能。我们报告了通过热蒸发技术合成由随机取向、一维 (1-D) 和多脚架（三脚架和四脚架）状纳米结构组成的不同直径的 ZnO 薄膜。通过蒸发无催化剂的 ZnO 粉末，在室温 Si 和耐热玻璃基板上以不同的沉积速率生长 150 nm 厚的 ZnO 膜。薄膜的 X 射线衍射 (XRD) 分析证实了纤锌矿 ZnO 纳米结构的多晶性质，晶格常数为a  =  b  = 3.24 Å 和c = 5.2 埃。场发射扫描电子显微镜 (FESEM) 和高分辨率透射电子显微镜 (HRTEM) 分析揭示了薄膜沉积速率对纳米结构形态的强烈影响。对于 0.04 nm/sec 的典型沉积速率，生长出直径为 50-60 nm、晶格间距为 5.2 Å 且具有 [0001] 面的排列的 1-D 垂直取向 ZnO 纳米线。能量色散 X 射线光谱 (EDS) 已证实空间均匀的高质量 ZnO 纳米结构生长。薄膜的微拉曼光谱证实了纤锌矿 ZnO 依赖于沉积速率的特征纵向光学 (LO) 和横向光学 (TO) 模式的出现。纳米结构的形成是通过多相多型生长过程，取决于前体生长与沉积的比率，