臺灣博碩士論文加值系統

本論文主要以超高頻電漿增強式化學氣相沉積系統(VHF- PECVD)研製異質接面太陽能電池。藉由調變氫氣稀釋比[SC %=SiH4/(SiH4+H2)×100 %]、氫氣鈍化、n-type Si摻雜濃度[Yn %= PH3/(SiH4+H2+PH3)×100 %]等實驗設計參數，分析薄膜之沉積速率、穿透率、電阻率、SEM參數等薄膜性質，進而探討薄膜對於異質接面太陽能電池元件特性之影響。實驗結果發現藉由調整薄膜沈積參數，即n-type a-Si之Yn%=0.05 %、厚度15 nm可使異質接面太陽能電池效率達5.28 %，開路電壓(Voc)= 0.51 V，短路電流(Jsc) =21.2 mA/cm2，填充因子(FF)=49.3 %。
利用雷射雕刻及濕蝕刻研製微奈米表面增加吸收照光的p-type Si/intrinsic Si/n-type Si (PIN)接面面積，提升異質接面矽晶太陽能電池光電特性為此論文另一重點，藉由雷射雕刻機直接在矽基片上，使用不同的雕刻參數，包含移動速度、功率、焦距及頻率等並配合濕式糙化製程有效增加PIN接面面積。實驗結果顯示，經由雷射雕刻及濕蝕刻後之表面其反射率在400-1000 nm量測範圍內其反射率皆低於10 %，且雷射加工點數越密集其反射率越低。而異質長接面設計元件之短路電流密度由19.4提升至22.9 mA/cm2，效率由3 %提升至3.6 %。

In this thesis, the improved photovoltaic characteristics of silicon heterojunction were investigated by mean of the very-high-frequency (VHF, 60 MHz) plasma-enhanced chemical vapour deposition (PECVD) under well-controlled discharge conditions. The modulated parameters, including the H2 plasma treatment, the silane concentration [SC %=[SiH4/(SiH4+H2)]×100 %], as well as doping concentration of n-type a-Si [Yn %= PH3/(SiH4+H2+PH3)×100 %] on the characteristics of the heterojunction solar cell were demonstrated. The deposition rates, the optical energy gaps (Eg), incident photon conversion efficiency (IPCE), scanning electron microscope (SEM), UV-VIS-IR spectroscopy and temperature dependent conductivity, respectively, Were studed, the results suggest that by modulating proper conditions, the heterojunction solar cells with a conversion efficiency of around 5.28 %, Jsc of 21.2 mA/cm2, Voc of 510 mV, and Fill factor (FF) of 49.2 % were demonstrated.

Improved photovoltaic characteristics of silicon heterojunction solar cells using micro- and nanostructured surface prepared by laser scribing and wet etching technology were demonstrated in this work. The modulated parameters include the velocity, power density, focus length, and frequency of the laser beam. The results indicate that the reflections of the nanostructured surface fabricated by laser scribing and wet etching technique were lower than 10 % for 400–1000 nm wavelength range. The design of hetero long- junction devices raise the short-circuit current density from 19.4 to 22.9 mA/cm2 and conversion effectivey from 3 % to 3.6%.

摘要....................................................................................................................... i
Abstract ................................................................................................................ ii
致謝.....................................................................................................................iii
目錄..................................................................................................................... iv
表目錄................................................................................................................vii
圖目錄...............................................................................................................viii
第一章 緒論........................................................................................................ 1
1.1 太陽能電池介紹.................................................................................... 1
1.2 太陽能電池發電原理........................................................................... 3
1.3 薄膜的成長機制................................................................................... 4
1.4 電漿原理............................................................................................... 6
1.5 VHF-PECVD 成長矽薄膜之影響性.................................................... 7
1.6 氫化非晶矽薄膜應用於太陽能電池之發展....................................... 8
1.7 異質接面太陽能電池之應用發展..................................................... 11
1.8 雷射雕刻之相關文獻回顧................................................................. 13
1.9 研究動機............................................................................................. 14
第二章 太陽能電池元件製程與量測.............................................................. 15
2.1 非晶矽薄膜製備流程......................................................................... 15
2.2 異質接面元件製備流程..................................................................... 16
2.2.1 玻璃基板清洗步驟............................................................. 17
2.2.2 晶圓準備步驟與清洗......................................................... 17
2.2.3 雷射雕刻系統加工設計..................................................... 18
2.2.3 氫氧化鉀(KOH)溼式蝕刻糙化製程................................. 19
2.2.4 超高頻電漿化學氣相沉積(VHF-PECVD)成長矽薄膜.... 19
2.2.5 使用Sputter 沉積ITO 透明導電薄膜製程....................... 21
2.2.6 熱蒸鍍系統沉積金屬電極................................................. 22
2.2.7 快速退火製程(RTA)........................................................... 23
2.3 光電特性量測..................................................................................... 24
2.3.1 光電轉換效率量測系統..................................................... 24
2.3.2 外部量子(EQE)效率量測系統.......................................... 26
2.3.3 四點探針量測(Four-Point Probe)....................................... 27
2.3.4 光暗電導............................................................................. 28
2.3.5 活化能................................................................................. 29
2.4 材料物性量測..................................................................................... 30
2.4.1 表面輪廓儀(Surface Profile Meter).................................... 30
2.4.2 掃描式電子顯微鏡(Scanning Electron Microscope)......... 31
2.4.3 穿透光譜儀(UV/VIS/IR).................................................... 31
第三章 結果與討論.......................................................................................... 33
3.1 異質接面太陽能電池特性之研究..................................................... 33
3.1.1 調變RTA 退火溫度對於元件串聯電阻特性影響........... 33
3.1.2 加入ITO 透明導電薄膜對元件之影響............................ 36
3.1.3 PIN 與PN 異質接面元件元件差異................................... 39
3.1.4 調變N-type 層摻雜濃度對元件特性影響........................ 42
3.1.5 調變N-type 層不同厚度對元件特性影響........................ 45
3.2 異質長接面元件設計之研究.............................................................. 49
3.2.1 雷射焦距校正與最佳輪廓圖形測試................................. 49
3.2.2 糙化製程之改善................................................................. 54
3.2.3 異質長接面元件設計與元件製作..................................... 57
第四章 結論...................................................................................................... 60
參考文獻............................................................................................................ 63
Extended Abstract
簡歷

[1]W. Hoagland, “Solar energy”, Sci. Amer, Vol. 273, pp. 170-173, 1995.
[2]G. R. Davis, “Energy for plant earth”, Sci Amer, Vol. 263, no. 3, pp.21-27, 1990.
[3]K. N. Amulya and J. Goldemberg, “Energy for the developing world”, Sci Amer, vol. 263, no. 3, pp. 63-71, 1990.
[4]Martin A. Green, “Solar cell efficiency tables”, prog. Photovolt : Res. Appl., vol. 15, pp. 425–430, 2007.
[5]林螢光, “光電子學-原理、元件與應用”, 全華出版社。
[6]B. Streetman, “Solid state electronic devices”, 5nd edition, PRENTICEHALL.
[7]J. Szlufick, “Low-cost industrial technologies of crystalline silicon solar cells”, Proceedings of the IEEE, Vol. 85, No. 5, pp 711-730.
[8]Pallab, Bhattacharya, Semiconductor optoelectronic devices, 2nd edition, prentice hall.
[9]莊達人，VLSI製造技術，高立圖書有限公司，民國89年。
[10]劉博文，半導體元件物理，高立圖書有限公司，民國92年。
[11]S. S. Lyer, M. Arienzo and E. Fresat, “Low-temperature silicon cleaning via hydrogen passivation and conditions for epitaxy”, Appl. Phys. Lett., Vol. 57, p. 893, 1990.
[12]C. C. Tsai, G. B. Anderson and R. Thompson, “Low temperature growth of epitaxial and amorphous silicon in a hydrogen-diluted silane plasma”, Journal of Non-Crystalline Solids, Vol. 137, pp. 673-676, 1991.
[13]P. Chaudhuri, S. Ray and A. K. Barua, “The effect of mixing hydrogen with silane on the electronic and optical properties of hydrogenated amorphous silicon thin films”, Thin Solid Films, Vol. 113, pp. 261-270, 1984.
[14]H. F. Sterling and R. C. G. Swann, “Chemical vapour deposition promoted by r.f. discharge”, Solid-State Electronics, Vol. 8, pp. 653-654, 1965.
[15]R. C. Chittick, J. H. Alexander and H. F. Sterling, “The preparation and properties of amorphous silicon”, J. Electrochem. Soc., Vol. 116, pp. 77-81, 1969.
[16]W. E. Spear and P. G Le Comber, “Investigation of the localised state distribution in amorphous Si films”, Journal of Non-Crystalline Solids, Vol. 8, pp. 727-738, 1972.
[17]W. E. Spear and P. G Le Comber, “Substitutional doping of amorphous silicon”, Solid State Communications, Vol. 17, pp. 1193-1196, 1975.
[18]W. E. Spear and P. Le Comber, “Electronic properties of substitutionally doped amorphous Si and Ge”, Philosophical Magazine, Vol. 33, pp. 935-949, 1976.
[19]A. Triska, D. Dennison and H. Fritzsche, Bull. Am. Phy. Soc., Vol. 20, p. 39, 1975.
[20]D. L. Staebler and C. R. Wronski, “Reversible conductivity changes in discharge-produced amorphous Si”, Appl. Phys. Lett, Vol. 31, p. 292, 1977.
[21]D. L. Staebler, C. R. Wronski, “Optically induced conductivity changes in discharge-produced hydrogenated amorphous silicon”, J. Appl. Phys., Vol. 51, pp. 3262-3268, 1980.
[22]S. Guha, J. Yang, “Effect of microvoids on initial and light-degraded efficiencies of hydrogenated amorphous silicon alloy solar cells”, Appl. Phys. Lett., Vol. 61, pp. 1444-1446, 1992.
[23]P. Delli Veneri, L. V. Mercaldo, C. Minarini, C. Privato, “VHF PECVD microcrystalline silicon: from material to solar cells”, Thin Solid Films, Vol. 451, pp. 269-273, 2004.
[24]R. Fluckiger, J. Meier, M. Goetz, and A. Shah, “Electrical properties and degradation kinetics of compensated hydrogenated microcrystalline silicon deposited by very high-frequency-glow discharge”, J. Appl. Phys., Vol. 77, no. 2, p.712, 1995.
[25]R. Platz and S. Wagner, “Intrinsic microcrystalline silicon by plasma-enhanced chemical vapor deposition from dichlorosilane”, Appl. Phys. Lett., Vol. 73, p. 1236, 1998.
[26]P. Chaudhuri, S. Ray and A. K. Barua, “The effect of mixing hydrogen with silane on the electronic and optical properties of hydrogenated amorphous silicon thin films”, Thin Solid Films, Vol. 113, pp. 261-270, 1984.
[27]P. Torres, J. Meier, R. Flückiger, U. Kroll, J. A. Anna Selvan, H. Keppner, and A. Shah, “Device grade microcrystalline silicon owing to reduced oxygen contamination”, Appl. Phys. Lett., Vol. 69, p. 1373 , 1996.
[28]A. Shah, E. Sauvain, N. Wyrsch, H. Curtins, B. Leutz, D.S. Shen, V. Chu, S. Wagner, H. Schade, H.W.A. Chao , “a-Si:H films deposited at high rates in a ''VHF'' silane plasma: potential for low-cost solar cells”, Electron Lett, Vol. 1, pp. 282-287 ,1988.
[29]L. Guo, M. Kondo, M. Fukawa, K. Saitoh and A. Matsuda, “High rate deposition of microcrystalline silicon using conventional plasma-enhanced chemical vapor deposition”, Jpn. J. Appl. Phys, Vol. 37, pp. 1116-1118 1998.
[30]H. Shirai, T. Arai, “Role of hydrogen in the growth of hydrogenated microcrystalline silicon”, Journal of Non-Crystalline Solids, Vol. 198, pp. 931-934, 1996.
[31]R. Martins, A. Macarico, I. Ferreira, R. Nunes, A. Bicho and E. Fortunato, “Investigation of the amorphous to microcrystalline phase transition of thin Film silicon produced by PECVD”, Thin Solid Films, Vol. 317, pp. 144-148, 1998.
[32]A. Chowdhury, S. Mukhopadhyay, S. Ray, “Fabrication of thin film nanocrystalline silicon solar cell with low light-induced degradation”, Solar Energy Materials & Solar Cells, Vol. 93, pp. 597-603, 2009.
[33]M. Taguchi, Improvement of the conversion efficiency of polycrystalline silicon thin film solar cell, in: Proceedings of the Fifth Photovoltaic and Solar Energy Conference, PVSEC, pp. 689–692, 1990.
[34]E. Maruyama, Sanyo’s challenges to the development of high-efficiency HIT solar cells and the expansion of HIT business, Proceedings of WCPEC-4, Hawaii, pp. 1455–1460, 2006.
[35]S. Taira, “Temperature properties of high-Voc HIT solar cells”, Proceedings of Renewable Energy, pp. 115–118, 2006.
[36]R. Brendel, SUNRAYS: a versatile solar cell ray tracing program for the photovoltaic community, Proceedings of the 12th EC Photovoltaic and Solar Energy Conference, p. 1339, 1994.
[37]F. Edelman, A. Chack, R. Weil, R. Beserman, Y. L. Khait, P. Werner, B. Rech, T. Roschek, R. Carius, H. Wagner, W. Beyer, “Structure of PECVD Si:H films for solar cell applications”, Solar Engery Materials and Solar Cells, Vol 77, pp. 125-143, 2003.
[38]A. Froitzheim, R. Stang, L. Elstner, M. Schmidt, W. Fuhs, Hahn-Meitner-Institut Berlin, “Interface Recombination in Amorphous/Crystalline Sillicon Cells, A Simulation Study”, 29th IEEE Photovoltaic Specialist Conference, pp. 1238-1241, 2002.
[39]U. Das, S. Bowden, M. Burrows, S. Hegedus, R. Birkmire, “Effect of Process Parameter Variation in Deposited Emitter and Buffer Layers on the Peromance of Silicon Heterojuction Solar cells”, 4th IEEE World Conference on Photovoltaic Energy Conversion, Vol. 2, pp. 1283-1286,2006.
[40]S. Y. Lien, “Fabrication and characteristics of n-Si/c-Si/p-Si heterojunction,”solar cells using hot-wire CVD”, Thin Solid Films, Vol. 516, pp. 747– 750, 2008.
[41]Y. Tsunomura, “Twenty-two percent efficiency HIT solar cell”, Sol. Energy Mater. Sol. Cells, Vol. 93, Issues 6-7, pp. 670-673, 2009.