Sharif Digital Repository

The ZnO nanowires have been synthesized using vapor-liquid-solid (VLS) process on Au catalyst thin film deposited on different substrates including Si(1 0 0), epi-Si(1 0 0), quartz and alumina. The influence of surface roughness of different substrates and two different environments (Ar + H2 and N2) on formation of ZnO nanostructures was investigated. According to AFM observations, the degree of surface roughness of the different substrates is an important factor to form Au islands for growing ZnO nanostructures (nanowires and nanobelts) with different diameters and lengths. Si substrate (without epi-taxy layer) was found that is the best substrate among Si (with epi-taxy layer), alumina and... 

The field emission properties of MoO2 nanostars grown on a silicon substrate and their emission performance in various vacuum gaps are reported in this article. A new structure of molybdenum oxides, named a nanostar, is grown by thermal vapor deposition with a length of ̃1 μm, a thickness of ̃50 nm, and its width in the range of 500-700 nm. The morphology, structure, composition, and chemical states of the prepared nanostars were characterized by scanning electron microscopy, high-resolution transmission electron microscopy, X-ray diffraction (XRD), and X-ray photoelectron spectroscopy (XPS). According to XRD analysis, the grown nanostructures are composed of both crystalline Mo4O11 and... 

The field-emission properties of molybdenum oxide nanowires grown on a silicon substrate and its emission performance in various vacuum gaps are reported in this article. A new kind of molybdenum oxides named nanowires with nanoscale protrusions on their surfaces were grown by thermal vapor deposition with a length of ~1 μm and an average diameter of ~50 nm. The morphology, structure, composition and chemical states of the prepared nanostructures were characterized by scanning electron microscopy (SEM), high-resolution transmission electron microscopy (HRTEM), X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS). According to XRD, XPS, and TEM analyses, the synthesized samples...