| Summary: | 碩士 === 國立臺灣科技大學 === 材料科學與工程系 === 107 === In recent years, the passivated emitter rear cell (PERC) solar cell has benefits such as easy fabrication and high conversion efficiency which demonstrate a promising cell structure of Si-based solar cells. In general, the alumina oxide was deposited on the emitter region of PERC for passivation purpose. It is well known that the DLC thin films exhibits many advantages such as high hardness, transparency in visible-light and IR-light and high resistivity etc. In this study, the diamond like carbon (DLC) thin films is tried to grow on the p-type Si substrate by combined electron-cyclotron resonance (ECR) plasma and radio-frequency (RF) plasma chemical vapor deposition (CVD), namely hybrid plasma CVD (HPCVD) system. The growth parameters of DLC thin films such as precursors flow ratio of CH4 and H2, working pressure and RF power are optimized in order to find a better passivation result.
The capacitance-voltage (C-V) measurement of samples constructed by metal Al/DLC/p-Si/metal Al are used for studied the fix-charge density, trap-center density and interface defect density of DLC passivation layer by techniques of the flat-band voltage, hysteresis behavior and conductance. The quasi steady state photoconductivity (QSSPC) is also be used for carrier lifetime measurement. In addition, the leakage current of sample structure is studied by the current-voltage (I-V) measurement. Finally, an optimized DLC passivation layer with growth conditions: working pressure of 1 torr, CH4/H2 flow ratio of 10/90 sccm, RF power of 150 W is used for achieving the lowest surface recombination rate (0.23 cm/s), interface defect density (2.25×〖10〗^10 〖eV〗^(-1) 〖cm〗^(-2)). In addition, the carrier lifetime is increased from 2.99 s for p-Si substrate to 9.85 s for DLC passivated p-Si substrate.
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