Please use this identifier to cite or link to this item: http://hdl.handle.net/11455/3007
標題: 探討本質氫化非晶矽對具有金字塔結構異質接面太陽能電池之影響
To Investigate the Influence of i-a-Si:H to Heterojunction Solar Cells with Pyramid Textured Structure
作者: 吳佳蓉
Wu, Chia-Jung
關鍵字: 金字塔結構;heterojunction;異質接面;太陽能電池;solar cells;pyramid textured structure
出版社: 光電工程研究所
引用: [1] 林明獻, 太陽能電池技術入門(修訂版), 全華圖書股份有限公司, 2008 [2] 楊昌中, 能源領域中的奈米科技研究, 工業研究院能源與環境研究所, 中華民國95年12月26日. [3] M. Takahiro, T. Mikio, S. Hitoshi, M. Eiji, “Development status of high-efficiency HIT solar cells,” Solar Energy Materials & Solar Cells, vol.95, pp.18–21, 2011. [4] M. T. M. Tanaka, T. Matsuyama, T. Sawada, S. Tsuda, S. Nakano, H. Hanafusa, Y. Kuwano, &quot;Development of new a-Si / c-Si heterojunction solar cells ACJ-HIT (artificially constructed junction-heterojunction with intrinsic thin layer),&quot; Japanese Journal of Applied Physics , vol. 31, pp. 3518–3522, 1992. [5] http://us.sanyo.com/Solar/SANYO-HIT-Technology [6] Y. Tsunomura, Y. Yoshimine, M. Taguchi, T. Baba, T. Kinoshita, H. Kanno, H. Sakata, E. Maruyama, and M. Tanaka, &quot;Twenty-two percent efficiency HIT solar cell,&quot; Solar Energy Materials and Solar Cells, vol. 93, pp. 670-673, 2009. [7] S. R .Wenham, Applied Photovoltaics, London : Earthscan, 2007. [8] D. A. Neamen, An Introduction to Semiconductor Devices, McGraw-Hill Higher Education, 2006. [9] J. Poortmans, V. Arkhipov, Thin Film Solar Cells Fabrication, Characterization and Applications, John Wiley & Sons Ltd, 2006 [10] H. Seidel, L. Csepregi, A. Heuberger, H. BaumgSrtel, “Anisotropic etching of crystalline silicon in alkaline solutions-I. Orientation dependence and behavior of passivation layers,” Journal of The Electrochemical Society, Vol. 137, pp.3612-3626, November 1990. [11] W. Lang, ” Silicon microstructuring technology,” Materials Science and Engineering, pp.1-55, 1996. [12] 戴寶通, 鄭晃忠, 太陽能電池技術手冊, 台灣電子材料與元件協會, 中華民國九十七年六月. [13] Y. M. Fung, W. Y. Cheung, I. H. Wilson, Dihu Chen, J. B. Xu, and S. P. Wong, “Electron field emission characteristics of textured silicon surface,” Journal of Vacuum Science & Technology B: Microelectronics and Nanometer Structures, vol. 19, pp. 884, 2001. [14] T. Baum, and D. J. Schiffrin, “AFM study of surface finish improvement by ultrasound in the anisotropic etching of Si<100> in KOH for micromachining applications, ” Journal of Micromechanics and Microengineering, Vol.7, pp. 338, 1997. [15] 莊家琛, 太陽工程-太陽電池篇, 全華圖書股份有限公司出版, 中華民國九十六年六月(六版). [16] H. Xiao, Introduction to Semiconductor Manufacturing Technology, Baker & Taylor Books, 2000. [17] 黃惠良, 曾百亨, 太陽電池, 五南圖書出版股份有限公司, 中華民國九十八年十月. [18] S. K. Kim, J. C. Lee, S. J. Park, Y. J. Kim, K. H. Yoon, “Effect of hydrogen dilution on intrinsic a-Si:H layer between emitter and Si wafer in silicon heterojunction solar cell,” Solar Energy Materials & Solar Cells , vol. 92, pp. 298–301, 2008. [19] A.M. Funde, N. A. Bakr, D.K. Kamble, R.R. Hawaldar, D.P. Amalnerkar, S.R. Jadkar, “Influence of hydrogen dilution on structural, electrical and optical properties of hydrogenated nanocrystalline silicon (nc-Si:H) thin films prepared by plasma enhanced chemical vapour deposition (PE-CVD),” Solar Energy Materials & Solar Cells, vol. 92, pp. 1217– 1223, 2008. [20] 程光洵, 拉曼布里淵散射, 北京科學出版社, 2007. [21] K. Pierz, W. Fufs, H. Mell, “Correlation between defect density and Fermi-level position in a-Si:H”, Joural of non-crystalline solids, vol. 114 ,pp 651-653, 1989. [22] T. Sawada, N. Terada, S. Tsuge, T. Baba, T. Takahama, K. Wakisaka, S. Tsuda and S. Nakano, “ High-efficiency a-Si/c-Si heterojunction solar cell,” Hawaii First WCPEC; pp. 5-9, 1994. [23] A. Matsuda, “Thin-film silicon —growth process and solar cell application,” Japanese Journal of Applied Physics, vol. 43, No. 12, pp. 7909–7920, 2004 [24] H. Fujiwara, M. Kondo, ” Interface structure in a-Si:H/c-Si heterojunction solar cells characterized by optical diagnosis technique,” Photovoltaic Energy Conversion, 2006. [25] U. Das, S. Bowden, M. Burrows, S. Hegedus, and R. Birkmire, ”Effect of process parameter variation in deposited emitter snd buffer layer on the performance of silicon heterojunction solar cells,” Photovoltaic Energy Conversion, 2006.
摘要: 
在本篇論文中,主要是研究非晶矽/單晶矽組合而成的異質接面太陽能電池的轉換效率變化;我們改變矽晶圓的表面結構,探討表面結構的變化對於反射率的關係。在n型矽晶圓上,以極高頻電漿輔助化學系統沉積本質氫化非晶矽(i-layer)以及p型氫化非晶矽薄膜(p-layer),並針對本質氫化非晶矽薄膜作調變,製作成異質接面太陽能電池,經由I-V量測結果的電性參數做討論與分析。

在改變矽晶圓表面結構上,使用氫氧化鉀(KOH)對矽晶圓表面進行非等向性蝕刻,由於晶體(100)面和(111)面有不同蝕刻速率的關係,蝕刻後將產生金字塔狀的表面結構。利用氫氧化鉀與異丙醇(IPA)的混合溶液,搭配不同KOH蝕刻液濃度、反應時間進行蝕刻,可將拋光矽晶圓表面蝕刻成粗糙的金字塔狀,達到光封存效果,使反射率下降。

我們採用極高頻(40.68 MHz)電漿輔助化學氣相沉積系統,沉積本質氫化非晶矽薄膜和p型氫化非晶矽薄膜;其優點為沉積薄膜時,可使電漿內產生較高的離子密度以及降低離子轟擊對薄膜造成的損傷,比一般射頻(13.56 MHz)電漿輔助化學氣相沉積系統具有更高的氫原子解離率,可以獲得良好的薄膜品質。在實驗中,我們以不同氫稀釋比、不同製程溫度去分析其薄膜的結構和品質,並利用以上的調變參數,以及不同厚度調變,製作成異質接面太陽能電池。

使用氫氧化鉀濕蝕刻的矽晶圓,製作成異質接面太陽能電池,可發現短路電流密度明顯提升,這是金字塔結構發揮光封存的效果,增加載子的產生,但同時,開路電壓卻有下降的趨勢,這是因為經過濕蝕刻的矽晶圓表面有較多缺陷,經過RCA 清洗步驟後可能無法完全去除這些缺陷,形成較差的氫化非晶矽與單晶矽接面,造成開路電壓下降。將氫氧化鉀濕蝕刻後的矽晶圓進行乾氧化處理,再浸泡於氫氟酸(HF)中,以去除氧化層,來改善矽晶圓表面的缺陷及金屬離子殘留問題,隨即沉積氫化非晶矽薄膜,製成太陽能電池,經計算後的各項電性參數: 轉換效率為8.28 %,開路電壓為0.449 V,短路電流密度為28.84 mA/cm2,填充因子為63.9 %,串聯電阻為3.78 Ω-cm2,分流電阻為2272 Ω-cm2。

In this thesis, the conversion efficiency of amorphous / crystalline Si heterojunction solar cell was studied. First, we changed the surface structures of the Si wafer and investigated the reflectance of these samples. Then, various intrinsic hydrogenated amorphous-Si thin films and p-type hydrogenated amorphous-Si thin films were deposited on the Si wafer by very high frequency plasma enhanced chemical vapor deposition (VHF-PECVD). Finally, the heterojunction solar cells were fabricated and the electrical characteristics were analyzed.

To change surface structures of the Si wafer, we used the potassium hydroxide (KOH) solution to etch the polished ones. And the pyramid structures were shown on the Si wafer due to the different etching rate between the (100) and (111) orientations. In the experiments, the KOH and IPA mixture solutions with different concentrations and various etching times were carried out, and the pyramid structure could be formed on the polished wafer. The average reflectivity of the etched samples decreased, resulting from the effects of light trapping.

VHF-PECVD (40.68 MHz) was used to deposit the intrinsic and p-type hydrogenated amorphous Si thin films because this system could produce the high density and low ion energy plasma which would enhance the deposition rate and reduce ion bombardment. As compared with the radio-frequency plasma enhanced chemical vapor deposition (RF-PECVD, 13.56 MHz), VHF-PECVD could achieve better quality of thin films because of higher generation rate of hydrogen atoms. In the experiments, the H2 dilution ratio, process temperature and film thickness were changed and the structure and quality of thin films were analyzed.

The heterojunction solar cells were fabricated by depositing the hydrogenated amorphous-Si thin films on the textured Si wafer. And the short circuit current density of the solar cells increased obviously, resulting from the pyramid structure of Si wafer to enhance the light trapping. However, the open circuit voltage decreased, due to the high density of defects and the residues of metal ions, coming from the wet etching process. Even after RCA cleaning procedures, they could not be fully removed from the surface of the Si wafer. Therefore, the interface of hydrogenated amorphous-Si / crystalline Si became poor. In order to solve this issue, the textured wafers were oxidized or annealed in the dry and low temperature ambients. And then, the very thin SiO2 layer was removed by diluted HF solution. The electrical parameters of the heterojunction solar cells could achieve the conversion efficiency of 8.28 %, open circuit voltage of 0.449 V, short circuit current density of 28.84 mA/cm2, fill factor of 63.9 %, series resistance of 3.78 Ω-cm2 and shun resistance of 2272 Ω-cm2.
URI: http://hdl.handle.net/11455/3007
其他識別: U0005-1708201317113600
Appears in Collections:光電工程研究所

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