非晶富矽碳化矽薄膜太陽能電池

Amorphous Si-rich Silicon Carbide Thin-Film Photovoltaic Solar Cells

李喬荻(Chiao-Ti Lee)

指導教授 ： 林恭如

國立臺灣大學/電機資訊學院/光電工程學研究所/碩士(2011年)

https://doi.org/10.6342/NTU.2011.01175

摘要

本論文利用電漿輔助化學氣相沉積成長非晶碳化矽薄膜，首先在成膜過程前，預先以三段式通入氬氣以稀釋腔體內的殘氧量。藉由調整不同的電漿功率從20W到100W在500oC 下沉積，進行碳化矽薄膜的分析。從 SIMS 分析中得知，我們已經成功的藉由預通氬氣的步驟將碳化矽薄膜中的氧含量降至 1.1×105 以下。隨後藉由XPS 分析中呈現，碳化矽薄膜的碳矽比例隨著電漿功率的提高而升高。並且在Si2p3軌域以及 C1s 軌域中發現碳化矽薄膜多半以 Si-C 鍵結存在。另，我們也觀察到 C-Si-O 的鍵結隨著電漿功率的提高而逐漸將低。同時在 FTIR 的分析中可以得知在低電漿功率的情況下，會造成甲烷解離的不完全，因此碳化矽薄膜中會有明顯的 Si-CH3 的訊號。然而在提高電漿功率後，此訊號就漸漸減弱而 Si-C 鍵結的訊號就漸漸增強。從吸收譜中看出在低電漿功率下的碳化矽薄膜明顯對於可見光的吸收較強，同時藉由模擬看出，在此條件下製程的碳化矽薄膜太陽能電池可以貢獻大約 2%的轉換效率。透過改變不同的矽甲烷與甲烷的流量比例，藉此發現在 R=0.5 的比例下，吸收譜在可見光 300 nm 到 500 nm 的波段有些微的提升。再以此條件去參雜磷與硼元素沉積 p 型與 n 型碳化矽薄膜，將薄膜的阻值降低至 0.31Ω∙cm。碳化矽薄膜太陽能電池 ITO/p-SiC/i-SiC/n-SiC/Al 的電壓電流曲線，隨著 i-SiC 薄膜的厚度由 150 nm 將低至 50 nm 下，有效的降低元件中的串連電阻至 150 Ω，並且提高了轉換效率。碳化矽薄膜太陽能電池 ITO/p-SiC/n-SiC/Al 中，隨著 n-SiC 的厚度由 150 nm降低至 50 nm 下，元件的串連電阻可降低至 6 Ω，對轉換效率又有進一步的提升。

關鍵字

電漿輔助化學氣相沉積 ； 非晶碳化矽 ； 碳化矽薄膜太陽能電池

並列摘要

The non-stoichiometric silicon carbide (Si 1-x C x ) film is prepared by plasmas enhanced chemical vapor deposition with different RF plasmas power from 20 to 100W
and fixed substrate temperature at 500oC. According to SIMS analysis, we effectively decrease the oxygen concentration to 1.1×105 by using three processes Ar purged. However, the carbon content is increased by enhancing the RF plasmas power to 100 W in XPS analysis. Besides, the Si-C signal is significantly observed than others in Si 2p3 and C 1s core level. The C-Si-O signal is decreased with increasing RF plasmas power.
According to FTIR analysis, owing to the insufficient RF plasmas power, the Si-CH 3
signal is significant observed in 20 W sample. However, the Si-CH3 signal transform to Si-C by increasing the RF plasmas power. Moreover, considering the optical
absorption spectra, the optical absorption oefficient is much broadband and over 105 within visible under 20 W deposition condition. Besides, we also simulate the conversion efficiency of SiC photovoltaic solar cell, which demonstrates 2% conversion efficiency.
We optimize the optical absorption spectrum by detuning the fluence ratio, which enhance the optical absorption coefficient within 300 to 500 nm. Afterward, the
resistivity of p-type and n-type SiC is decreased to 2.8 and 0.31 Ω∙cm. The conversion efficiency of ITO/P-SiC/i-SiC/n-SiC/Al is increased by reducing the thickness of intrinsic SiC, which declining the series resistance simultaneously. Finally, the
conversion efficiency of ITO/P-SiC/ n-SiC/Al is promoted by reducing the thickness of n-type SiC, which decreasing the series resistance to 6 Ω.

並列關鍵字

PECVD ； Si-rich Si1-xCx ； SiC thin film solar cell

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