Study of μc-Si：H films and fabrication of μc-Si：H P-I-N Thin Film Solar Cell Deposited by Electron Cyclotron Resonance Chemical Vapor Deposition (ECRCVD)

使用電子迴旋共振化學氣相沉積系統沉積微晶矽薄膜太陽能電池之研究

蔡昕融(Shin-Rung Tsai)

指導教授 ： 黃惠良

國立清華大學/電機資訊學院/電子工程研究所/碩士(2009年)

摘要

本篇論文在於利用電子迴旋共振化學沉積(ECRCVD)系統來進行沉積非晶和微晶矽薄膜，並且利用不同的氫稀釋比法來成長微晶矽薄膜於矽基板及玻璃基板上，並且利用拉曼(Raman)散射頻譜來用於分析微晶矽薄膜之結晶度與結晶態體積含量，X-ray繞射頻譜則用於分析微晶矽薄膜的擇優取向，而α-step 測厚儀用來量測薄膜厚度，掃描式電子顯微鏡(SEM)作表面晶粒型態的分析，四點探針用來量測摻雜濃度以及展阻量測來測量有效的載子濃度等特性進行分析。
在實驗的過程中，我們固定基版的溫度(2000C)，微波的能量400W~700W，以及製程壓力20mTorr(2×10-2torr)~60mtorr(6×10-2torr)，同時固定上下磁場的電流，分別為60A/100A，改變氫稀釋比例來進行薄膜分析。此外，我們也在矽薄膜中摻雜B2H6及PH3之氣體形成P型以及N型矽薄膜，同時我們也利用四點探針對其電阻率進行量測分析。
實驗結果顯示，我們得到微晶矽薄膜的結晶態體積含量比達70％，當氫稀釋比在98％時，晶粒尺寸大約是359A，非摻雜型多晶矽薄膜的擇優取向為<111>，氫含量也隨著氫稀釋比增加而減少。在摻雜的部分，N-type濃度控制在1×1017~1×1018，P-type濃度在1×1013~1×1014。而在元件特性方面開路電壓為0.41V，短路電流為11.2mA，填充因子為37％。

關鍵字

薄膜太陽能電池 ； 電子迴旋共振化學氣相沉積 ； 非晶矽 ； 微晶矽 ； 多晶矽

並列摘要

This thesis presents the characteristics of microcrystalline silicon (μc-Si) films deposition on silicon wafer and glass substrates and the solar cell fabricated by a-Si/μc-Si films. We deposited both the μc-Si films and a-Si films by electron cyclotron resonance chemical vapor deposition(ECRCVD).
The characterization of μc-Si films and a-Si films were carried out by using Raman scattering, XRD, SEM, SRP, Hall Measurement, α-step, and Four point probe. Raman scattering spectra were used to investigate the films crystallinity and crystalline fraction in the μc-Si/a-Si films. X-ray diffraction pattern(XRD) spectra were used to analyze the μc-Si/a-Si films. Fourier transform infrared(FTIR) absorption spectra were used to study the silicon-hydrogen bonding configurations and the hydrogen content of the μc-Si films. Conductivity measurements were employed to study the electrical properties of μc-Si films and a-Si films. α-step were used to measure the films thickness. Scanning electron microscopy (SEM) were used to analyze grain geometry and top morphology. Spreading Resistance Profiling (SRP) and Four point probe were used to analyze the doping concentration and Sheet resistance.
In our experiments, the growth conditions to prepare the p, I, n, layers of solar cells by using ECRCVD were found. The experimental parameters used in this study are the Top/Bottom magnetic current at 60A and 100A respectively and substrate temperature at 2000C the Microwave power at 400W~700W, the process pressure at 20mtorr~60mtorr. The hydrogen dilution ratio was varied to analyze the characteristics of thin films. In addition, we also doped the films using phosphine(PH¬3) and diborance(B2H6) to form the n-type and p-type silicon thin film.
The experimented results show that, the maximum crystalline fraction obtained was about 70％, and the grain size in these μc-Si films have dimension of about 35.9nm when the dilution ratio was 98%. The preferred orientation of the μc-Si films were found to be<100>, and also it was observed that hydrogen content decreased with the increase of hydrogen ration. The doped concentration of N-type is about 1×1017~1×1018, P-type is about 1×1013~1×1014. In device measurement results, the Voc is about 0.41V, Isc is about 11.2mA, Fill factor is about 37%.

並列關鍵字

Thin film solar cell ； ECRCVD ； amorphous ； microcrystalline ； polycrystalline

參考文獻

[6] 林明獻,太陽能電池技術入門,全華出版社,2007.

[1] International Energy Agency, IEA.

[2] Energy Information Administration, EIA.

[3] Energy Information Administration, EIA.

[9] J. K. Rath and R. E. I. Schropp, “Incorporation of p-type microcrystalline silicon films in amorphous silicon based solar cells in a superstrate structure,” Sol. Energy Materials and Sol. Cells, vol. 53, pp. 189–203, 1998.