臺灣博碩士論文加值系統

在本篇論文，我們將系統性的調查粗糙化表面的重要性。我們提出高效率HIT太陽能電池使用柱狀架構粗糙化。傳統HIT太陽能電池具有異質接面的結構，其有良好的開路電壓，然而受到反射率、吸收率及遮蔽效應之影響，短路電流密度無法突破限制。多數的學者都知道反射率的重要性，但是都針對單一結構進行研究，並沒有做系統性的整理，如金字塔的大小和角度及柱狀結構的寬度、間距及高度等。在系統性的整理中，我們運用Silvaco TCAD電腦輔助模擬，找出最佳的粗糙化表面結構。首先，針對金字塔的大小及角度找出其最佳化結果，並且探討了不同金字塔表面弧度，利用超橢圓方程式設計，依照 (X / 15)n + (Y / 20)n = 1 此方程式去模擬。其中指數n = 1為金字塔結構，n = 1.8為凹面形狀的結構，而n = 0.2為凸面形狀的結構。從模擬結果得知，凸面形狀的結構有較佳的抗反射效果，其結構與逆金字塔結構相似。改變逆金字塔結構角度，將其結構變成柱狀結構，而柱狀結構有較佳的轉換效率，因為其結構有較佳的反射率表現。經過先前模擬的結果，柱狀結構太陽能電池相較於傳統隨機金字塔結構，更有助於光捕捉及抗反射行為，且為均勻分佈表面，如同粗糙化的功用，使得短路電流密度增加。在理想沉積下1.2 μm柱子間距與1 μm柱寬，蝕刻出柱子高度為6 μm的柱狀結構，比起傳統隨機金字塔粗糙化，轉換效率從24.7 %增進至25.73 %。
實作上，利用金屬輔助蝕刻方法，可以形成高深寬比規律陣列柱狀結構，其濕式蝕刻可達到較少表面缺陷，異質薄膜之介面品質因此提升。表面反射率之量測結果顯示，比起傳統隨機金字塔架構，柱狀架構之反射率可以大大降低，換算加權平均反射率降低了39 %。柱狀結構HIT太陽能電池有最好的元件表現，其開路電壓為0.36 V、短路電流密度為3.75 mA/cm2、填充因子(Full Factor, FF)為66.92 %以及轉換效率為0.91 %。

In this thesis, we would systematically investigate the importance of texturing surface. And we propose high efficiency HIT solar cell with pillar structure. Conventional HIT solar cell is a heterojunction structure which has a good open-circuit voltage. However, the reflectivity and shadowing effect limit the short-circuit current density. Most researchers understood the importance of reflectivity but they didn’t make a systematic investigation, for instance, the impacts from size and angle of pyramid. In order to make a systematic research, we use Silvaco TCAD to find best texturing surface structure. First, we optimized the size and angle of pyramid. The curvature of different pyramid is also discussed. The texturing surface is simulated according to (X / 15)n + (Y / 20)n = 1 which is named super-elliptic equation. The index n = 1 is a pyramid structure, n = 1.8 is a concave shape structure, and n = 0.2 is convex shape structure. From the simulation results, the convex shape of the structure has better anti-reflectivity. Pillar structure solar cells have better light trapping ability and anti-reflectivity than the conventional HIT solar cell. Under the ideal condition, the pillar can be deposited to 1.2 μm of gap, 1 μm of width, and 6 μm of height. Compares to the conventional HIT solar cell, our structure can improve the conversion efficiency from 24.70 % to 25.73 %.
In fabrication, we use the metal-assisted etching to form the high depth and width ratio of pillars. The measurement of surface reflectivity shows that the pillar can decrease the reflectivity by 39 %. Pillar HIT solar cells have the best device of performance, which have the open-circuit voltage is 0.36 V, the short-circuit current density is 3.75 mA/cm2, the fill factor is 66.92 % and the conversion efficiency is 0.91 %.

論文審定書 i
英文審定書 ii
致　謝 iii
摘　要 iv
Abstract v
目錄 vi
圖次 ix
表次 xi
第一章、導論 1
1.1 研究背景 1
1.2 論文回顧 2
1.3 動機 7
第二章、元件製作 8
2.1 模擬元件 8
2.1.1 柱狀結構HIT太陽能電池模擬 8
2.1.2 模擬之物理模型與參數 9
2.2. 元件實作 10
2.2.1 清洗矽晶圓 11
2.2.2 旋轉塗佈 11
2.2.3 黃光製程 12
2.2.4 ICP製程 12
2.2.5 E-Gun製程 12
2.2.6 蝕刻製程 12
2.2.7 RCA清洗製程 13
2.2.8 表面結構蝕刻 14
2.2.9 乾氧熱養法 14
2.2.10 PECVD製程 14
2.2.11 PVD製程 14
第三章、元件設計與模擬 15
3.1 傳統HIT太陽能電池 16
3.1.1 校正傳統HIT太陽能電池 16
3.1.2 模擬金字塔之最佳化 20
3.1.3 探討金字塔結構之角度變化 21
3.1.4 探討金字塔斜邊曲率變化 22
3.2 逆金字塔結構太陽能電池 24
3.3 柱狀結構太陽能電池 26
3.4 各類型太陽能電池最佳化結果之邊際效應比較(Benchmark comparison) 30
3.5 實作量測結果與討論 31
3.5.1 傳統太陽能電池製程討論 31
3.5.2 柱狀結構太陽能電池製程討論 34
3.5.3 太陽能電池結果量測 38
第四章、矽基異質接面三能隙太陽能電池 43
4.1 三能隙p-i-n太陽能電池建置模擬實體圖 43
4.2 加上背表面電場矽基異質接面能隙太陽能電池 45
4.2.1 探討介面之復合速率 48
4.2.2 優化各層薄膜之厚度 49
4.3 增加銦錫氧化物 (Indium Tin Oxide, ITO)作為透明導電薄膜 55
4.4 探討背後電極之是否局部設計 57
4.5 結論 60
第五章、結論與未來展望 61
5.1 結論 61
5.2 未來展望 62
參考文獻 63
附錄A 71
透明導電薄膜 71
抗反射層 72
復合效應 72
輻射復合 (Radiative Recombination) 73
蕭克力萊德霍爾復合 (Shockley-Read-Hall Recombination) 73
歐傑復合 (Auger Recombination) 73
牛頓環 (Newton’s rings) 74
奈米線優點 (Nanowire advantage) 75
論文著述 76

[1]M. Taguchi, A. Yano, S. Tohoda, K. Matsuyama, Y. Nakamura, T. Nishiwaki, K. Fujita, and E. Maruyama, “ 24.7% Record Efficiency HIT Solar Cell on Thin Silicon Wafer,” IEEE Journal of Photovoltaics, vol. 4, pp. 96-99, 2013.
[2]T. Matsuyama, M. Taguchim, M. Tanaka, T. Matsuoka, S. Tsuda, S. Nakano, and Y. Kuwano, “High-Quality p-Type μc-Si Films Prepared by the Solid Phase Crystallization Method,” Japanese Journal of Applied Physics, vol. 29, pp. 2690–2693, 2013.
[3]M. Taguchi, M. Tanaka, T. Matsuyama, T. Matsuoka, S. Tsuda, S. Nakano, Y. Kishi, and Y. Kuwano, “Improvement of the conversion efficiency of polycrystalline silicon thin film solar cell,” in Proc. Int. Photovoltaic Sci. Eng. Conf.-5 Tech. Dig, pp. 689–692, 1990.
[4]H. Fujiwara, M. Kondo, “Effects of a-Si:H layer thicknesses on the performance of a-Si:H/c-Si heterojunction solar cells,” Applied Physics Letters, vol. 101, pp. 054516- 1– 054516- 10, 2007.
[5]D. Adachi, J. L. Hernandez, and K. Yamamoto, “Impact of carrier recombination on fill factor for large area heterojunction crystalline silicon solar cell with 25.1% efficiency,” Applied Physics Letters, vol. 107, pp. 233506-1–233506-4, 2015.
[6]J. B. Heng, J. Fu, B. Kong, Y. Chae, W. Wang, Z. Xie, A. Reddy, K. Lam, C. Beitel, C. Liao, C. Erben, Z. Huang, and Z. Xu, “>23% High-Efficiency Tunnel Oxide Junction Bifacial Solar Cell With Electroplated Cu Gridlines,” IEEE Journal of photovoltaics, vol. 5, pp. 82–86, 2015.
[7]S. Saha, M. M. Hilali, E. U. Onyegam, D. Sarkar, D. Jawarani, R. A. Rao, L. Mathew, R. S. Smith, D. Xu, U. K. Das, B. Sopori, and S. K. Banerjee, “Single heterojunction solar cells on exfoliated flexible 25 μm thick mono-crystalline silicon substrates,” Applied Physics Letters, vol. 102, pp. 163904-1–163904-6, 2013.
[8]S. Y. Herasimenka, W. J. Dauksher, and S. G. Bowden, “>750mV open circuit voltage measured on 50 μm thick silicon heterojunction solar cell,” Applied Physics Letters, vol. 103, pp. 053511-1–053511-5, 2013.
[9]R. Martini, M. Gonzales, F. Dross, A. Masolin, J. Vaes, G. Frederickx, and J. Poortmans, “Epoxy-induced spalling of silicon,” Energy Procedia, vol. 27, pp. 567–572, 2012.
[10]T. Mishima, M. Taguchi, H. Sakata, and E. Maruyama, “Development status of high-efficiency HIT solar cells,” Solar Energy Materials and Solar Cells, vol. 95, pp. 18–21, 2012.
[11]K. Maki, D. Fujishima, H. Inoue, Y. Tsunomura, T. Asaumi, S. Taira, T. Kinoshita, M. Taguchi, H. Sakata, H. Kanno, and E. Maruyama, “High-efficiency HIT Solar Cells with a very Thin Structure Enabling a High Voc,” in Proc 37th IEEE Photovoltaic Specialists Conf. PVSC, pp. 57–61, 2011.
[12]F. J. Henley, “Kerf-free wafering: technology overview and challenges for thin PV manufacturing,” in Proc.35th IEEE Photovoltaic Specialists Conf. PVSC, pp. 1184–1192, 2010.
[13]D. Fujishima, H. Inoue, Y. Tsunomura, T. Asaumi, S. Taira, T. Kinoshita, M. Taguchi, H. Sakata, and E. Maruyama, “High-performance HIT solar cells for thinner silicon wafers,” in Proc 35th IEEE Photovoltaic Specialists Conf. PVSC, pp. 3137–3140, 2010.
[14]L. Serenelli, M. Miliciani, M. Izzi, R. Chierchia, A. Mittiga, M. Tucci, “Advances in screen printing metallization for a-Si:H/c-Si heterojunction solar cells,” in proc. 40th IEEE Photovoltaic Specialists Conf. PVSC, pp. 2528–2532, 2014.
[15]A. Kanevce, W. K. Metzger, “The role of amorphous silicon and tunneling in heterojunction with intrinsic thin layer (HIT) solar cells,” Journal of Applied Physics, vol. 105, pp. 094507-1–094507-8, 2009.
[16]M. Filipic, Z. Holman, F. Smole, S. D. Wolf, C. Ballif, M. Topic, “Amorphous Silicon / Crystalline Silicon Heterojunction Solar Cells – Analysis of Lateral Conduction through the Inversion Layer,” in Proc. 29th IEEE International conference on microelectronics. MIEL, pp. 227–230, 2014.
[17]X. Wen, X. Zeng, W. Liao, Q. Lei, and S. Yin, “An approach for improving the carriers transport properties of a-Si:H/c-Si heterojunction solar cells with efficiency of more than 27 %,” Solar Energy, vol. 96, pp. 168–176, 2013.
[18]Z. C. Holman, A. Descoeudres, L. Barraud, F. Z. Fernandez, J. P. Seif, S. D. Wolf, and C. Ballif, “Current Losses at the Front of Silicon Heterojunction Solar Cells,” IEEE Journal of Photovoltaics, vol. 2, pp. 7–15, 2012.
[19]F. Jay, D. Munoz, T. Desrues, E. Pihan, V. A. D. Oliveira, N. Enjalbert, and A. Jouini, “Advanced process for n-type mono-like silicon a-Si:H/c-Si heterojunction solar cells with 21.5 % efficiency,” Solar Energy Materials and Solar Cells, vol. 130, pp. 690–695. 2014.
[20]S. Kim, J. Lee, V. A. Dao, S. Lee, N. Balaji, S. Ahn, S. Q. Hussain, S. Han, J. Jung, J. Jang, Y. Lee, and J. Yi, “Effects of LiF/Al back electrode on the amorphous/crystalline silicon heterojunction solar cells,” Materials Science and Engineering, vol. 178, pp. 660–664, 2013.
[21]D. Zhang, I. A. Digdaya, R. Santbergen, R.A.C.M.M.V. Swaaij, P. Bronsveld, M. Zeman, J. A. M. V. Roosmalen, and A. W. Weeber, “Design and fabrication of a SiOx/ITO double-layer anti-reflective coating for heterojunction silicon solar cells,” Solar Energy Materials and Solar Cells, vol. 117, pp. 132–138, 2013.
[22]B. Grancic, S. Solntsev, and M. Zeman, “Performance Analysis of Thin-Film Crystalline Silicon-on-Glass Solar Cells,” IEEE Journal of Photovoltaics, vol. 3, pp. 1144–1148, 2013.
[23]S. T. Pantelides, “Defect dynamics and the Staebler–Wronski effect in hydrogenated amorphous silicon,” Physical Review B 36, vol. 36, pp. 3479–3482, 1987.
[24]D. Y. Jeong, K. Kim, H. E. Song, J. Song, S. J. Baik, and J. C. Lee, “Simple and fast fabrication of a-Si:H/c-Si hetero-junction solar cells by dual-chamber hot wire chemical vapor deposition,” Renewable Energy, vol. 68, pp. 397–402, 2014.
[25]Y. Liu, Y. Sun, W. Liu, Z. Zhou, and J. Yao, “Novel High-Efficiency c-Si Compound Heterojunction Solar Cells: HCT (Heterojunction with Compound Thin-layer),” in Proc. 40th IEEE Photovoltaic Specialists Conf. PVSC, pp. 2510–2513, 2014.
[26]X. Hua, Z. P. Li, W. Z. Shen, G. Y. Xiong, X. S. Wang, and L. J. Zhang, “Mechanism of Trapping Effect in Heterojunction With Intrinsic Thin-Layer Solar Cells: Effect of Density of Defect States,” IEEE Transactions on Electron Devices, vol. 59, pp. 1227–1235, 2012.
[27]K. Ma, X. Zeng, Q. Lei, J. Xue, Y. Wang, and C. Zhao, "Texturization and rounded process of silicon wafers for heterojunction with intrinsic thin-layer solar cells," Frontiers of Optoelectronics, vol. 7, pp. 46–52, 2014.
[28]Y. Jiang, X. Zhang, F. Wang, and Y. Zhao, "Optimization of a silicon wafer texturing process by modifying the texturing temperature for heterojunction solar cell applications," RSC Adv., vol. 5, no. 85, pp. 69629–69635, 2015.
[29]Shanghai Industrial μTechnology Research Institute. New Energy. Available: http://www.sitrigroup.com/technologies/new-energy/?lang=zh-hans
[30]J. Zhao, A. Wang, M. A. Green, “24.5% efficiency PERT silicon solar cells on SHE MCZ substrates and cell performance on other SEH CZ and FZ substrates,” Solar Energy Material & Solar Cell, vol. 66, pp. 27–36, 2001.
[31]黃子豪，使用碳化矽窗口層之新穎性交疊式奈米柱HIT太陽能電池架構，國立中山大學電機工程研究所碩士論文，民國一百零四年，頁97。
[32]G. Jia, A. Gawlik, J. Bergmann, B. Eisenhawer, S. Schonherr, G. Andra, and F. Falk, “Silicon Nanowire Solar Cells With Radial p-n Heterojunction on Crystalline Silicon Thin Films: Light Trapping Properties,” IEEE Journal of Photovoltaics, vol. 4, pp. 28–32, 2014.
[33]X. Hua, Y. Zeng, W. Wang, and W. Shen, “Light Absorption Mechanism of c-Si/a-Si Half-Coaxial Nanowire Arrays for Nanostructured Heterojunction Photovoltaics,” IEEE Transaction on Electron Devices, vol. 61, pp. 4007–4013, 2014.
[34]H. M. Li, D. Y. Lee, and W. J. Yoo, IEEE, “Optoelectronic Performance of Radial-Junction Si Nanopillar and Nanohole Solar Cells,” IEEE Transactions on Electron Devices, vol. 59, pp. 2368–2374, 2012.
[35]W. Q. Xie, W. F. Liu, J. I. Oh, and W. Z. Shen, “Optical absorption in c-Si/a-Si:H core/shell nanowire arrays for photovoltaic applications,” Applied Physics Letters, vol. 99, pp. 033107-1–033107-4, 2011.
[36]S. M. Wong, H. Y. Yu, Y. Li, J. Li, X. W. Sun, N. Singh, P. G. Q. Lo, and D. L. Kwong, “Boosting Short-Circuit Current With Rationally Designed Periodic Si Nanopillar Surface Texturing for Solar Cells,” IEEE Transaction on Electron Devices, vol. 58, pp. 3224–3229, 2011.
[37]S. M. Wong, H. Y. Yu, Y. L. Li, J. S. Li, F. Wang, M. F. Yang, N. Singh, P. G. Q. Lo, and D. L. Kwong, “Boosting Short Circuit Current with Rationally Designed Periodic Si Nanopillar Surface Texturing for Thin Film Solar Cell,” in proc International Electron Devices Meeting, IEDM, pp. 31.2.1–31.2.4, 2010.
[38]K. Watanabe, M. Matsumura, T. Hattori, T. Qsabe, and Y. Shimamoto, “Buried PN Junction Nanopillar Solar Cell: A Novel Approach to Reduce Recombination Loss in Surface Nanostructure,” in Proc. 40th IEEE Photovoltaic Specialist Conf. PVSC, pp. 2286–2288, 2014.
[39]B. Dou, R. Jia, H. Li, C. Chen, Z. Jin, X. Liu, and X. Xu, “Enhanced electrode-contact property of silicon nano-textured solar cells via selective etching,” Solar Energy, vol. 99, pp. 95–99, 2014.
[40]H. H. Li, P. Y. Yang, S. M. Chiou, H. W. Liu, and H. C. Cheng, “A Novel Coaxial-Structured Amorphous-Silicon p-i-n Solar Cell With Al-Doped ZnO Nanowires,” IEEE Electron Device Letters, vol. 32, pp. 928–930, 2011.
[41]S. T. Chang, M. Tang, C. X. Huang, and C. W. Chang, “Tandem Thin Film Solar Cell with a Nanoplate Structure,” in Proc. 10th IEEE Nanotechnology Conf. IEEE-NANO, pp. 316–319, 2010.
[42]Z. Pei, S. T. Chang, C. W. Liu, and Y. C. Chen, “Numerical Simulation on the Photovoltaic Behavior of an Amorphous-Silicon Nanowire-Array Solar Cell,” IEEE Electron Device Letters, vol. 30, pp. 1365–1367, 2009.
[43]J. Liu, X. Zhang, G. Dong, Y. Liao, B. Wang, T. Zhang, and F. Yi, “Fabrication of silicon nanopillar arrays by cesium chloride,” Applied Surface Science, vol. 289, pp. 300–305, 2014.
[44]F. Bai, M. Li, T. Gu, D. Song, H.Yu, B. Jiang ,Y. Li, “Porous silicon nanowire arrays with excellent antireflection property,” IEEE Conference Publications. Materials for Renewable Energy and Environment. ICMREE, vol. 2, pp. 490–491, 2013.
[45]F. Es, M. Kulakcı, and R. Turan, “An Alternative Metal-Assisted Etching Route for Texturing Silicon Wafers for Solar Cell Applications,” IEEE Journal of Photovoltaics, vol. 6, pp. 440–446, 2016.
[46]H. Zheng, M. Han, P. Zheng, L. Zheng, H. Qin, and L. Deng, “Porous silicon templates prepared by Cu-assisted chemical etching,” Materials Letters, vol. 118, pp. 146–149, 2014.
[47]H.J. Choi, S. Baek, H. S. Jang, S. B. Kim, B.Y. Oh, and J. H. Kim, “Optimization of metal-assisted chemical etching process in fabrication of p-type silicon wire arrays,” Current Applied Physics, vol. 11, pp. S25–S29, 2011.
[48]F. Toor, H. M. Branz, M. R. Page, K. M. Jones, and H. C. Yuan, “Multi-scale surface texture to improve blue response of nanoporous black silicon solar cells,” Applied Physics Letters, vol. 99, pp.10351-1–10351-4, 2011.
[49]Z. P. Huang, N. Geyer, L. F. Liu, M. Y. Li and P. Zhong, “Metal-assisted electrochemical etching of silicon,” Nanotechnology, vol. 9, pp. 465301, 2010.
[50]L. Yang, Y. Liu, Y. Wang, W. Chen, Q. Chen, J. Wu, A. Kuznetsov, and X. Du, “18.87%-efficient inverted pyramid structured silicon solar cell by one-step Cu-assisted texturization technique,” Solar Energy Materials & solar Cells, vol. 166, pp. 121–126, 2017.
[51]Y. Wang, L. Yang, Y. Liu, Z. Mei, W. Chen, J. Li, H. Liang, A. Kuznetsov and D. Xiaolong, “Maskless inverted pyramid texturization of silicon,” Scientific Reports, pp. 1–6, 2015.
[52]Kyotaro Nakamura, Mari Aoki, Isao Sumita, Hironori Sato, Yuji Kumagai, Yasushi Kawata and Yoshio Ohshita, “Texturization Control for Fabrication of High Efficiency Mono Crystalline Si Solar Cell,” in Proc. 39th IEEE Photovoltaic Spec. Conf, vol.10, pp. 2239–2242, 2013.
[53]S.K. Pang, A.W. Smith, and A. Rohatgi, “Effect of Trap Location and Trap-Assisted Auger Recombination on Silicon Solar Cell Performance,” IEEE Transactions on electron device, vol.42, pp. 662–668, 1995.
[54]J. Allen, N. Kundtz, D. A. Roberts, S. A. Cummer, and D. R. Smith, “Electromagnetic source transformations using superellipse equations,” Applied physics letters, pp.194101-1–194101-3, 2009.
[55]J. L. Hernandez, K. Yoshikawa, A. Feltrin, N. Menou, N. Valckx, E. V. Assche, D. Schroos, K. Vandersmissen, H. Philipsen, J. Poortmans, D. Adachi, M. Yoshimi, T. Uto, H. Uzu, T. Kuchiyama, C. Allebe, N. Nakanishi, T. Terashita, T. Fujimoto, G. Koizumi, and K. Yamamoto, “High Efficiency Silver-Free Heterojunction Silicon Solar Cell,” Japanese Journal of Applied Physics, vol. 51, pp. 1–4, 2012.
[56]H. Sai, K. Saito, and M. Kondo, “Investigation of Textured Back Reflectors With Periodic Honeycomb Patterns in Thin-Film Silicon Solar Cells for Improved Photovoltaic Performance,” IEEE Journal of photovoltaics, vol.3, pp.5–10, 2013.
[57]L. Serenelli, M. Miliciani, M. Izzi, R. Chierchia, A. Mittiga, and M. Tucci, “Advances in screen printing metallization for a-Si:H/c-Si heterojunction solar cells,” in Proc. 40th IEEE Photovoltaic Spec. Conf, pp.2527–2532, 2014.