Preparation of p-type NiO thin film and investigation on its optical, electrical and material characteristics

• Main Authors: Ching-Feng Chen, 陳璟鋒
• Other Authors: Jen-Sue Chen
• Format: Others
• Language: zh-TW
• Published: 2004
• Online Access: http://ndltd.ncl.edu.tw/handle/32394049393061528854

碩士 === 國立成功大學 === 材料科學及工程學系碩博士班 === 92 === Abstract 　　Nickel oxide films may be one of the potential candidates for p-type transparent conducting oxide (TCO). Because the optical and electrical properties of the nickel oxide films have not reached the optimal values, it is expected that doping impurities such as N atoms and changing prccess parameters may improve the transparency and conductivity of nickel oxide films. 　　In this study, nickel oxide films were prepared with various gas flow ratios by RF magnetron reactive sputtering from a Ni target. By changing the substrate heating temperatures during sputtering and the annealing　temperatures after depositions, the nickel oxide films would exhibit different properties. Rutherford　backscattering spectrometry (RBS) analysis was used to determine the composition and density of nickel oxide　films. The structure and crystallinity of nickel oxide films were characterized by X-ray diffraction (θ-2θXRD), glancing incident angle X-ray diffraction (GIAXRD), and transmission electron microscope (TEM) diffraction patterns. The morphology of nickel oxide films were observed with scanning electron microscope (SEM), transmission electron microscope (TEM), and atomic force microscopy (AFM). The chemical bondings of nickel oxide films were investigated by Fourier transform infrared spectroscopy (FTIR) and X-ray photoelectron spectroscopy (XPS). The transmittance of nickel oxide films was measured by UV-Vis spectrophotometer. Four-point probe and Hall measurement were used to measure resistivity of nickel oxide films. Besides, carrier concentrations and mobility were obtained from Hall measurement. 　　The exprimental results reveal that O/Ni ratios in the nickel oxide films change with gas flow ratios during sputtering, and all O/Ni ratios are greater than 1. It is found that all nickel oxide films exhibit polycrystalline structures. From XRD results, it is suggested that oxygen interstitials are the dominant factor that results in the non-stoichiometry. After aging at room temperature and annealing treatments, oxygen atoms may evaporate from the nickel oxide films in forms of O2 gas and cause variations in the optical and electrical properties. Resistivity and transparency of the nickel oxide films increase with increasing aging time or annealing temperature. The nickel oxide film with high O/Ni ratio possesses better conductivity due to higher carrier concentrations, but transmittance is poor and the energy gap calculated from the transparency is smaller. The nickel oxide film with low O/Ni ratio exhibits opposite properties. It is found that nitrogen atoms would not be retained in the nickel oxide films during sputtering, and the purposes of doping N atoms and adding carrier concentrations are not achieved. Furthermore, it results in lower O/Ni raitos and inferior conductivity of the nickel oxide films. However, those nickel oxide films have better crystallinity.