雖然目前仍以共蒸鍍製程製備的CIGS光電轉換效率較佳，但因侷限在小面積和均勻度等問題，其發展有限。然而二階段製程雖為目前量產的技術，但為求成分均勻，需搭配多層膜結構，硒化時，使用的H2Se為有毒氣體，又有組成成分不均勻等問題，製程較為煩瑣，因此，發展一套製程穩定及簡化的CIGS製程有其必要性。
CIGS薄膜的導電性是仰賴本質缺陷，以多晶結構為主的CIGS薄膜光電轉換效率最高，相關研究皆顯示多晶結構的CIGS缺陷，主導效能表現上的差異。而我們以四元靶材濺鍍之薄膜晶粒較小(Cu-poor)，根據Jesse A. Frantz等人研究顯示[1]，晶界會影響載子擴散行為，造成長波長的吸收變差，導致整體光電流較小。而我們的薄膜未經任何熱處理的元件表現有電流阻礙現象，如此大幅降低開路電壓(VOC)和填充因子(FF)，嚴重影響光電轉換效率，故本研究以四元靶材直接濺鍍均勻性高的CIGS薄膜，再經硒化處理，研究薄膜特性的影響，進而改善元件效率。
本實驗分兩部分，第一部分為以低溫鍍製的薄膜再經高溫硒化，研究升溫速率、壓力和溫度對晶粒成長的影響。但高溫下的硒化處理，不僅形成極厚的MoSe2，強烈的體積膨脹使CIGS和Mo的界面附著性變差，且薄膜內部發生嚴重的成分偏離，最終導致效率不佳。為了解決高溫下成分偏差及MoSe2大量生成的問題，4.2節以高溫鍍膜和低溫硒化方式將硒補足。第二部分為高溫鍍膜搭配低溫硒化，藉由更改石墨盒的機構以增加硒的活性，如此高活性之氣體可有效地和薄膜反應，將薄膜中之硒補足至計量比。最後搭配低溫電性量測進行分析，發現低溫硒化消除了N2缺陷，並改善開路電壓和填充因子，使效率大幅提升至8.6%。

Polycrystalline CuIn1-xGaxSe2 (CIGS) solar cell with the highest efficiency was reported using three-stage co-evaporation, which suffers from large-scaled mass manufacture. The alternative approach is to use two-step process. However, the annealing process is usually under H2Se which is toxic to get the high efficiency. Therefore, simplifying the process for fabricating CIGS thin films is very essential.
Polycrystalline CuIn1-xGaxSe2 thin films sputtered from a quaternary target is a promising method. However, the small grain sizes are got by using Cu-poor target. According to Jesse A. Frantz’s research[1], the presence of grain boundaries would affect the diffusion length and transport of carriers through this layer reducing the short circuit current. Moreover, as-deposited films are with current-blocking effect which is very harmful to the fill factor and open circuit voltage. Therefore, we study selenization on the polycrystalline CuIn1-xGaxSe2 thin films sputtered from a quaternary target and try to improve the efficiency.
There are two parts in the study. First, we deposited films under low temperatures and selenization under high temperatures. At high temperatures, MoSe2 is thick and the composition deviation of films was serious. The efficiency is not so good finally. In order to solve these problems, we deposited films under high temperatures and selenization under low temperatures to inhibit current-blocking effect. We increase the activity of selenium vapor by changing the graphite box design and improve the fill factor and open circuit voltage successfully. Finally, the device yielded the efficiency of 8.6%.

[1] R. Y. B. Jesse A. Frantz, Jason D. Myers, Vinh Q. Nguyen, Jasbinder S. Sanghera, Sergey .Maximenko Maria Gonzalez, Joseph G. Tischler, Robert J. Walters, Marina S. Leite, Allan Bruce, Sergey V. Frolov, and Michael Cyrus, "Structural and Electronic Characteristics of Cu(In,Ga)Se-2 Thin Films Sputtered From Quaternary Targets," presented at the PVSC, 2012.
[2] A. Shah, "Photovoltaic Technology: The Case for Thin-Film Solar Cells," Science, vol. 285, pp. 692-698, 1999.
[3] K. D. Decker. (2009) How (not) to resolve the energy crisis. Low-tech Magazine.
[4] S. O. Kasap, Optoelectronics and Photonics: Principles and Practices, 2001.
[5] S.-H. Long, "Effects of Junction Properties on the Performance of the Copper Indium Gallium Diselenide Solar Cells," 2005.
[6] S. S. KULKARNI, "EFFECT OF COMPOSITION, MORPHOLOGY AND SEMICONDUCTING PROPERTIES ON THE EFFICIENCY OF CuIn1-xGaxSe2-ySy THIN-FILM SOLAR CELLS PREPARED BY RAPID THERMAL PROCESSING," University of Pune, 1998.
[7] D. H. P. Jackson, E. Lotter, S. Paetel, R. Wuerz, R. Menner, W. Wischmann, and M. Powalla, "New world record efficiency for Cu(In,Ga)Se2 thin-film solar cells beyond 20%," Progress in Photovoltaics: Research and Application, 2011.
[8] P. G. u. A. H.-J. Lewerenz and H. Jungblut, 1995.
[9] W. B. M. Bar, J. Rohrich, E. Strub, S. Linder, M. C. Lux-Steiner, and Ch.-H. Fischer, T. P. Niesen, F. Karg, "Improvement of minority carrier diffusion length in Si by Al gettering," JOURNAL OF APPLIED PHYSICS, vol. 7, pp. 38-58, 2004.
[10] J. C. C. T. P. Hsieh, C. C. Chuang, and S. Y. Tsai. (2009) Coevaporation Cu(InGa)Se2 Solar Cells-Recent Progress and Future Prospects.
[11] (2013). Sale of CIGS Solar Cell Panels Expected to Reach $1 Billion by 2013.
[12] B. E. M. A. Contreras, K. Ramanathan, J. Hiltner, A. Swartzlander, F. Hasoon, and R. Noufi, "Progress toward 20% efficiency in Cu(In, Ga)Se2 polycrystalline thin-film solar cells," Progress in Photovoltaics: Research and Application, vol. 7, pp. 311-316, 1999.
[13] A. N. C. A. Kaufmann, R. Klenk, and R. Scheer, "Transfer of Cu(In, Ga)Se2 thin film solar cells to flexible substrates using an in situ process control," Thin Solid Films, vol. 480-481, pp. 515-519, 2005.
[14] M. Hall. (2013) EMPA announces 20.4% efficient thin film CIGS-on-polymer cell. PV maganize.
[15] a. H. W. S. U. Rau, "Electronic properties of Cu(In, Ga)Se2 heterojunction solar cells-recent achievements, current understanding, and future challenges," Applied Physics A: Materials Science and Processing vol. 69, pp. 131-147, 1999.
[16] G. K. D. Abou-Ras, D. Bremaud, M. Kalin, F. V. Kurdesu, A. N. Tiwariand, and M. Dobeli, "Formation and characterisation of MoSe2 for Cu(In, Ga)Se2 based solar " Thin Solid Films, vol. 480-481, pp. 433-438, 2005.
[17] B. J. Stanbery, "Copper Indium Selenides and Related Materials for Photovoltaic Devices," Critical Reviews in Solid State and Materials Sciences, vol. 27, p. 45, 2002.
[18] S.-H. W. S. B. Zhang, and Alex Zunger, "Defect physics of the CuInSe2 chalcopyrite semiconductor," PHYSICAL REVIEW B, vol. 57, pp. 9642-9655, 1998.
[19] F. A.-E. Geula Dagan, D. J. Dunlavy, R. J. Matson, and David Cahen, "Defect Level Identification in CuInSez from Photoluminescence Studies " Chemistry of Materials, vol. 2, pp. 286-293, 1989.
[20] H. W. S. U. Rau, "Electronic properties of Cu(In,Ga)Se2 heterojunction solar cells–recent achievements, current understanding, and future challenges," Applied Physics A Materials Science & Processing, vol. 69, pp. 131-147, 1999.
[21] S. R. Kodigala. (2010). Thin films and nanostructures C(In1-XGaX)Se2 based thin film solar cells. 35.
[22] H. W. S. a. U. Rau, "The role of structural properties and defects for the performance of Cu-chalcopyrite-based thin-film solar cells," Physica B, pp. 1081-1085, 2001.
[23] D. C. a. R. Noufi, "Defect chemical explanation for the effect of air anneal on CdS/CuInSe2 solar cell performance," Applied Physics Letter, vol. 54, pp. 558-560, 1998.
[24] J. R. S. a. R. E. HOLLINGSWORTHJ, "PHOTOLUMINESCENCE IN POLYCRYSTALLINE CuInSe2 SOLAR CELLS," Solar Cells, vol. 21, pp. 379-386, 1987.
[25] S. S. L. L.L. Kerr, T.J. Anderson and O.D. Crisalle, "DLTS Characterization of CIGS Cells," presented at the NCPV and Solar Program Review Meeting, 2003.
[26] S. L. a. A. Zunger, "LIMITATION OF THE OPEN-CIRCUIT VOLTAGE DUE TO METASTABLE INTRINSIC DEFECTS IN Cu(In,Ga)Se2 AND STRATEGIES TO AVOID THESE DEFECTS," 33rd IEEE Photovoltaic Specialists Conference, pp. 1-4, 2008.
[27] M. Igalson, A. Urbaniak, and M. Edoff, "Reinterpretation of defect levels derived from capacitance spectroscopy of CIGSe solar cells," Thin Solid Films, vol. 517, pp. 2153-2157, 2009.
[28] M. Igalson, P. Zabierowski, D. Prządo, A. Urbaniak, M. Edoff, and W. N. Shafarman, "Understanding defect-related issues limiting efficiency of CIGS solar cells," Solar Energy Materials and Solar cells, vol. 93, pp. 1290-1295, 2009.
[29] T. Eisenbarth, T. Unold, R. Caballero, C. A. Kaufmann, and H.-W. Schock, "Interpretation of admittance, capacitance-voltage, and current-voltage signatures in Cu(In,Ga)Se[sub 2] thin film solar cells," JOURNAL OF APPLIED PHYSICS, vol. 107, p. 034509, 2010.
[30] D. Rudmann, "Effects of sodium on growth and properties of Cu(In,Ga)Se2 thin films and solar cells," 1973.
[31] U. R. Leeor Kronika, Jean-FrancËois Guillemolesd, Dieter Braungerc, Hans-Werner Schockc, David Cahen, "Interface redox engineering of Cu(In,Ga)Se2 ± based solar cells: oxygen, sodium, and chemical bath effects," Thin Solid Films, pp. 353-359, 2000.
[32] J. H. a. H. Ohldn, "ZnO/CdS/Cu(In,Ga)Se, THIN FILM SOLAR CELLS WITH IMPROVED PERFORMANCE," Conference Record of the Twenty Third IEEE, pp. 364-371, 1993.
[33] D. S. M. Ruckh, M. Kaiser, R. Schaffler, T. Walter, and H. W. Schock, "Influence of substrates on the electrical properties of Cu(In,Ga)se2 thin films," in Proceedings of the 1994 IEEE First World Conference on Photovoltaic Energy Conversion, 1994, pp. 156-159.
[34] V. Probst, "Improved CIS Thin Film Solar Cells Through Novel Impurity Control Techniques," in 13th European Photovoltaic Solar Energy Conference, 1995, pp. 2123-2126.
[35] D. C. Leeor Kronik, and Hans Werner Schock, "Effects of Sodium on Polycrystalline Cu(In,Ga)Se2 and Its Solar Cell Performance," Advanced Materials, pp. 31-35, 1998.
[36] K. R. D. W. Niles, F. Hasoon, R. Noufi, B. J. Tielsch, and J. E. Fulghum, "Na impurity chemistry in photovoltaic CIGS thin films: Investigation with X-ray photoelectron spectroscopy," J. Vac. Sci. Technol. A,, vol. 15, pp. 3044-3049, 1997.
[37] B. E. M. A. Contreras, P. Dippo, J.Webb, J. Granata, K. Ramanathan, S. Asher, A. Swartzlander, and R. Noufi, "On the role of Na and modifications to CIGS absorber materials using thin MF (M=Na, K, Cs) precursor layers," presented at the Conference Record of the Twenty Sixth IEEE Photovoltaic Specialists Conference, 1997.
[38] F. H. B.M. Keyes, P. Dippo, A. Balcioglu, and F. Abulfotuh, "Influence of Na on the Electro-Optical Properties of Cu(In,Ga)Se2," presented at the 26th IEEE Photovoltaic Specialists Conference, 1997.
[39] U. Rau, D. Abou-Ras, and T. Kirchartz, "Advanced characterization techniques for thin film solar cell," 2011.
[40] R. A. M. a. W. S. Chen, "High photocurrent polycrystalline thin-film CdS/CuInSe2 solar cell," Applied Physics Letter, vol. 36, p. 371, 1980.
[41] J. R. T. Andrew M. Gabor, David S. Albin, Miguel A. Contreras, Rommel Noufi, Allen M. Hermann, "High-efficiency CuInxGa1-xSe2 solar cells made from (Inx,Ga1-x)2Se3 precursor films," Applied physics Letter, vol. 65, p. 198, 1994.
[42] M. T. A. Romeo, D. Abou-Ras, D. L. Batzner, F.-J. Haug, M. Kalin, D. Rudmann and A. N. Tiwari, "Development of thin-film Cu(In,Ga)Se2 and CdTe solar cells," Progress in Photovoltaics: Research and Application, vol. 12, pp. 93-111, 2004.
[43] N. Brown. (2013) Solar Frontier Achieves 19.7% CIGS Solar Cell Efficiency, Breaks 10-Year Record. Clean Technica.
[44] a. H. B. I. S. J. Kim, "Preparation and properties of selenized CuInSe2 thin films," Thin Solid Films, vol. 214, pp. 194-199, 1992.
[45] G. M. H. W. K. Kim, W. N. Shafarman, "Ga homogenization by simultaneous H2Se/H2S reaction of Cu-Ga-In precurosr," Solar Energy Materials and Solar cells, vol. 95, p. 235, 2011.
[46] M. C. S. Niki, I. Repins, M. Powalla, K. Kushiya, S. Ishizuka, K. Masubara, "CIGS absorbers and processes," Progress in Photovoltaics: Research and Applications, p. 453, 2011.
[47] V. A. J. Bekker, and M. J. Witcomb, "Influence of selenization techniques on the reaction kinetics of chalcopyrite thin films," Thin Solid Films, vol. 387, pp. 40-43, 2001.
[48] a. J. H. Y. Dong Gwon Moon, a Jihye Gwak,a SeungKyu Ahn,a Ara Cho,a Keeshik Shina, Kyunghoon Yoona and SeJin Ahn, "Cu(In,Ga)Se2 thin films without Ga segregation prepared by the single step selenization of sputter deposited Cu-In-Ga-Se precursor layers," Energy and Environmental Science, vol. 5, pp. 9914-9921, 2012.
[49] A. B. N. Romeo, S. Mazzamuto, D. Menossi and A. Romeo, "CIGS THIN FILMS PREPARED BY SPUTTERING AND SELENIZATION BY USING In2Se3, Ga2Se3 AND Cu AS SPUTTERING TARGETS," presented at the Photovoltaic Specialists Conference (PVSC), 2010 35th IEEE, 2010.
[50] Z. Q. L. J. H. Shi, D. W. Zhang, Q. Q. Liu, Z Sun and S. M. Huang, "Fabrication of Cu(In, Ga)Se2 thin films by sputtering from a single quaternary chalcogenide target," Progress in Photovoltaics: Research and Application, vol. 19, pp. 160-164, 2011.
[51] J. A. Frantz, R. Y. Bekele, V. Q. Nguyen, J. S. Sanghera, A. Bruce, S. V. Frolov, M. Cyrus, and I. D. Aggarwal, "Cu(In,Ga)Se2 thin films and devices sputtered from a single target without additional selenization," Thin Solid Films, vol. 519, pp. 7763-7765, 2011.
[52] D. M. A.J. Zhou, X.G. Kong, X.H. Xu, L.D. Feng, X.Y. Dai, T. Gao, J.Z. Li, "One-step synthesis of Cu(In,Ga)Se2 absorber layers by magnetron sputtering from a single quaternary target," Thin Solid Films, vol. 520, pp. 6068-6074, 2012.
[53] Z. Yu, C. Yan, T. Huang, W. Huang, Y. Yan, Y. Zhang, L. Liu, Y. Zhang, and Y. Zhao, "Influence of sputtering power on composition, structure and electrical properties of RF sputtered CuIn1−xGaxSe2 thin films," Applied Surface Science, vol. 258, pp. 5222-5229, 2012.
[54] X. Zhu, Z. Zhou, Y. Wang, L. Zhang, A. Li, and F. Huang, "Determining factor of MoSe2 formation in Cu(In,Ga)Se2 solar Cells," Solar Energy Materials and Solar cells, vol. 101, pp. 57-61, 2012.
[55] M. A. O. Volobujevaa, J.Raudojaa, E.Mellikova, M. Grossberga, L.Kaupmeesa, and P.Barvinschi, "SEM analysis and selenization of Cu–In alloy films produced by co-sputtering of metals," Solar Energy Materials and Solar cells, vol. 93, pp. 11-14, 2009.
[56] C. M. R. Caballero, and C. Guillen, "Preparation and characterization of CuIn1-xGaxSe2 thin films obtained by sequential evaporations and different selenization processes," Thin Solid Films, vol. 474, pp. 70-76, 2005.
[57] Y. S. Wei Liu, Yu Song, Chang-Jian, Qing He, Feng-Yan Li, and Jian-Guo Tian, "Preparation of High Quality Culn1-xGaxSe2 Thin films by Modified Selenization Procedure of Sequential Sputtering Metallic Precursors," presented at the Photovoltaic Specialists Conference, 2008. PVSC '08. 33rd IEEE, 2008.
[58] X-Ray Material Research Lab.
[59] H. Föll, "Semiconductor - 5.1.2 Recombination and Luminescence."
[60] Y.-F. L. Jia-Min Shieh, Yong-Chang Lin, and Jr-Yau Fang, "Photoluminescence: Principles, Structure, and Applications," Nanocommunication, pp. 28-39.
[61] M. D. Jüri Krustok, Andri Jagomägi, Maarja Grossberg, and Jaan Raudoja, "Device characteristics of CuInSe2-based solar cells," Optical Materials and Applications, vol. 5946, pp. 236-242, 2005.
[62] Y.-S. Su, "Investigation of Sodium Effects on CIGS Thin Film Solar Cells by Electrical and Material Characterization," Department of Material Science and Engineering, National Tsing Hua University, 2013.
[63] J. J. C. David S. Albin, Miguel A. Contreras, Andrew M. Gabor, Rommel Noufi, Andrew L. Tennant, John R. Tuttle, "Recrystallization method to selenization of thin-film Cu(In,Ga)Se.sub.2 for semiconductor device applications," United States Patent, 1995.
[64] T. E. J. J. Scragg, X. Fontane, V. Izquierdo-Roca, A. Perez-Rodriguez, T. Kubart, M. Edoff and C. Platzer-Bjorkman, "Rapid annealing of reactively sputtered precursors for Cu2ZnSnS4 solar cells," Progress in Photovoltaics: Research and Application, vol. 21, pp. 1-8, 2012.
[65] U. A. Haifan Liang, Wei Liu, Jeroen van Duren and Minh Le, "CIGS formation by high temperature selenization of metal precursors in H2Se atmosphere," Solid-State Electronics, vol. 76, pp. 95-100, 2012.
[66] S. N. Y. a. K. S. Andrikopoulos, "Raman scattering study on structural and dynamical features of noncrystalline selenium," Journal of Chemical Physics, vol. 121, pp. 4747-4758, 2004.
[67] P. Z. C. Platzer-Bjo¨ rkman, J. Pettersson, T. To¨ rndahl and M. Edoff, "Improved fill factor and open circuit voltage by crystalline selenium at the Cu(In,Ga)Se2/buffer layer interface in thin film solar cells," Progress in Photovoltaics: Research and Application, pp. 249-256, 2010.
[68] Available: http://digipac.ca/chemical/mtom/contents/glossary/k.htm
[69] T. U. Tobias Eisenbarth, Raquel Caballero, Christian A. Kaufmann, and Hans-Werner Schock, "Interpretation of admittance, capacitance-voltage, and current-voltage signatures in Cu(In,Ga)Se2 thin film solar cells," JOURNAL OF APPLIED PHYSICS, vol. 107, pp. 1-13, 2010.
[70] J. D. C. a. W. N. S. Jennifer T. Heatha, "Bulk and metastable defects in CuIn1-xGaxSe2 thin films using drive-level capacitance profiling," JOURNAL OF APPLIED PHYSICS, vol. 95, pp. 1000-1010, 2003.
[71] D. B. U. Rau, R. Herberholz, H. W. Schock, J.-F. Guillemoles, L. Kronik, and David Cahen, "Oxygenation and air-annealing effects on the electronic properties of Cu(In,Ga)Se2 films and devices," JOURNAL OF APPLIED PHYSICS, vol. 86, pp. 1-9, 1999.
[72] H. Bayhan, "Determination of Defect Distribution in a Ga-rich ZnO/CdS/Cu(In,Ga)Se2 Solar Cell by Admittance Spectroscopy," Turkish Journal of Physics, vol. 29, pp. 17-24, 2005.
[73] D. B. M. Schmidta, R. SchaÈfer, H.W. Schocka and U. Raua, "Infuence of damp heat on the electrical properties of Cu(In,Ga)Se2 solar cells," Thin Solid Films, vol. 361-362, pp. 283-287, 2000.
[74] A. D. Z. Djebbour, A. Migan Dubois, D. Mencaraglia, N. Naghavi , J.-F. Guillemoles and D. Lincot "Admittance spectroscopy of cadmium free CIGS solar cells heterointerfaces," Thin Solid Films, vol. 511-512, pp. 320-324, 2006.
[75] W. N. S. ter T. Erslev, and J. David Cohen, "Metastable properties of Cu(In1-xGax)Se2 with and without sodium," Applies Physics Letters, vol. 98, pp. 1-3, 2011.