| Summary: | 碩士 === 國立中央大學 === 材料科學與工程研究所 === 98 === Hydrogenated amorphous silicon (a-Si:H) thin films were deposited on pre-oxidized Si wafers at low-temperature by electron cyclotron resonance chemical vapor deposition (ECRCVD). The furnace annealing treatment by solid-phase crystallization (SPC) method were applied to the as-grown films in nitrogen or oxygen atmosphere, and the temperature range for variable times was from 612℃ to 675℃.
The crystallization and grain growth behaviors of the annealed films were investigated by Raman spectroscopy and X-ray diffraction (XRD). The crystalline fraction of annealed films can reach ~ 80% , and a grain size up to 17 nm could be obtained from the FA treatment at high temperature. The surface morphologies and microstructure of annealed films were observed by scanning electron microscope (SEM) and transmission electron microscope (TEM).
The evolution of crystallization with nucleation and grain growth process for annealed films was described by classical thermal kinetics. The activation energy of ECRCVD film in incubation time and grain growth were 3.51 0.09 eV and 2.54 0.13 eV, respectively. Moreover, the a-Si:H films were oxidized at lower temperature in oxygen atmosphere. The chemical states of silicon of thermal oxidized films were investigated for by X-ray photoelectron spectroscopy (XPS). The degree of oxidation for annealed films was dependent on annealing temperature and time. The crystalline fraction of annealed films in oxygen atmosphere was higher than in nitrogen atmosphere due to the amorphous phase was oxidized in Raman spectra.
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