| Summary: | 碩士 === 雲林科技大學 === 光學電子工程研究所 === 97 === In this work, polycrystalline silicon and polycrystalline germanium films were formed by metal induced crystallization (MIC) that can be used to improve the performance of the silicon thin film solar cells. First, thermal evaporation was used to evaporate a thin aluminum layer on the ITO glass substrate. Amorphous silicon and germanium layers were then deposited on top of the Al layer. Thermal annealing was then carried out to form the p-type polycrystalline silicon and polycrystalline germanium layers. MIC process has advantages including low-temperature, low-cost, simple, and capable for large-scale production. In this work, the thickness ratio of silicon and germanium to aluminum is 1:1 and the MIC temperature is 550℃. The annealing time has been varied to observe the MIC results. An i-type and an n-type silicon layers were grown on top of the p-type poly-Si and poly-Ge film to form the thin film solar cells. In Si solar cells the sunlight with long wavelength cannot be absorbed by the silicon layers. We proposed that a polycrystalline germanium layer with low bandgap can be incorporated into the thin film Si solar cell to improve the cell efficiency by absorbing the long-wavelength incident light. For MIC of poly-Ge, the optimum anneal condition is 550℃ for 4 hours. For MIC of poly-Si, the optimum anneal condition is 550℃ for 5 hours. Measurements using FE-SEM, XRD, SIMS, and Keithley 2440 have been used to characterize the film properties and the solar cell efficiency.
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