無鎘緩衝層/銅銦鎵硒異質接面太陽能電池具備無毒性以及高光伏特性之潛力，已引起眾多關注。然而，異質介面含有很高的缺陷密度，包括空缺、錯位與複合缺陷等，導致嚴重的介面載子複合、介穩行為以及載子傳輸能障，進而降低能量轉換效率。本論文致力於改善無鎘緩衝層/銅銦鎵硒之異質接面特性，以提升其元件表現。我們首先點出異質接面設計之困難，並提出三種方法來解決這些問題：
第一部分，我們提出一種有效、可室溫進行的化學溶液改質方法。研究中使用硫代乙酰胺溶液(硫處理)或硫代乙醯胺-硫化銦混合溶液(硫化銦處理)來改質銅銦鎵硒薄膜表面，進而改善硫化氧鋅/銅銦鎵硒之異質接面。經改質後，元件平均效率可提升超過2 % (絕對值)，且元件介穩性質有明顯改善，光照時間可縮短48 %。此部分研究亦詳細探討化學溶液處理對於介面缺陷鈍化之影響。
第二部分，我們提出一種新穎方式改善濺鍍-硫氧化銦/硒化-銅銦鎵硒之異質接面，包括能帶匹配以及介面性質。研究中控制濺鍍硫氧化銦之背景壓力以摻雜氧至硫化銦薄膜，並藉此調控接面之能帶匹配。而調控硫氧化銦/銅銦鎵硒疊層之後退火溫度，則可優化介面性質。此方式能夠使平均元件效率自2.30 % 提升至10.93 %。此部分研究亦探討元件表現改善之相關機制。
第三部分，我們成功建立一種全濺鍍硫氧化銦/銅銦鎵硒之太陽能電池技術，並探討鈉摻雜與硒摻雜對於缺陷機制與元件表現之影響。當鈉摻雜之銅銦鎵硒吸收層與硫氧化銦緩衝層形成接面時，會引入(硒空缺-銅空缺)之深層受體缺陷，形成載子傳輸的障礙(p+層)，降低填充因子與短路電流表現。藉由硒摻雜可消除(硒空缺-銅空缺)深層缺陷，進而提升其平均效率至11.13 %。我們亦針對鈉摻雜提出一種減少(硒空缺-銅空缺)缺陷的方法，藉由提高銅銦鎵硒薄膜之銅含量，並降低其鈉摻雜含量，其元件平均效率可自4.64 % 提升至 9.04 %。

Cd-free buffer/CIGSe heterojunction solar cells have attracted much attention due to their non-toxicity and potential to enhance the photovoltaic performance. However, the heterointerface may contain a high density of defects, including the vacancies, antisites and defect complexes, leading the severe interface recombination, metastability behavior and the energy barrier blocking carrier transport, lowering the energy conversion efficiency. This dissertation aims to ameliorate the Cd-free buffer/CIGSe heterojunction properties and improves the device performance. We point out the main challenges in designing the heterojunction and propose three approaches to resolving these issues:
In the first part, we demonstrate an effective room-temperature chemical solution treatment, by using thioacetamide (S treatment) or thioacetamide-InCl3 (In-S treatment) solution, on CIGSe surface to engineer the ZnS(O,OH)/CIGSe heterojunction. With treatments, the absolute average efficiency is significantly enhanced over 2 %, and the metastability, in terms of light soaking time, is minimized by 48%. The influences of chemical treatments on defect passivation at the interface are studied carefully.
In the second part, we propose a novel approach to ameliorate the sputtered Inx(O,S)y/selenized CIGSe heterojunction, in terms of band alignment and interface properties. The band alignment was tailored by tuning the base pressure of the sputtering process to incorporate oxygen into deposited In2S3 layers. The interface properties were ameliorated by optimizing the air-annealing temperature on Inx(O,S)y /CIGSe stacked layers. Our approach enables the average efficiency improved from 2.30 % to 10.93 %. The mechanisms responsible for the improvements are investigated.
In the third part, we successfully develop a full sputtered Inx(O,S)y/CIGSe solar cell technology, and investigate the impacts of Na and Se doping on the defect mechanism and device performance. As the Na-doped CIGSe absorbers buffered with Inx(O,S)y layer, the (VSe-VCu) deep acceptor defects were induced, acting as a transport barrier (p+ layer) at interface, decreasing the FF and JSC. By Se-doping, the (VSe-VCu) deep defects could be eliminated, improving the average efficiency to 11.13 %. We also proposed an approach to reducing the (VSe-VCu) defects in Na-doped CIGSe device. By increasing the Cu content and reducing the amount of Na doping, the average efficiency of the corresponding device could be improved from 4.64 % to 9.04 %.

[1] Guidebook on Promotion of Sustainable Energy Consumption: Consumer Organizations and Efficient Energy Use in the Residential Sector. by Economic & Social Commission for Asia & the Pacific, 2002.
[2] N. Ali, a. Hussain, R. Ahmed, M. K. Wang, C. Zhao, B. U. Haq, and Y. Q. Fu, “Advances in nanostructured thin film materials for solar cell applications,” Renewable and Sustainable Energy Reviews, vol. 59, pp. 726–737, Jun. 2016.
[3] N. S. Lewis and D. G. Nocera, “Powering the planet: chemical challenges in solar energy utilization.,” Proceedings of the National Academy of Sciences of the United States of America, vol. 103, no. 43, pp. 15729–35, Oct. 2006.
[4] M. Hosenuzzaman, N. a. Rahim, J. Selvaraj, M. Hasanuzzaman, a. B. M. a. Malek, and a. Nahar, “Global prospects, progress, policies, and environmental impact of solar photovoltaic power generation,” Renewable and Sustainable Energy Reviews, vol. 41, pp. 284–297, Jan. 2015.
[5] J.-B. Lesourd, “Solar photovoltaic systems: the economics of a renewable energy resource,” Environmental Modelling & Software, vol. 16, no. 2, pp. 147–156, Mar. 2001.
[6] “ATHLOC: Advanced Thin Film Hybrid Low Cost PV Towards Cost Reduction of PV Through Material Optimisation and Efficient Solar Cells.” [Online].Available:http://www.qscience.com/doi/abs/10.5339/qfarc.2016.EEPP2576.
[7] K. Kushiya, “CIS-based thin-film PV technology in solar frontier K.K.,” Solar Energy Materials and Solar Cells, vol. 122, pp. 309–313, Mar. 2014.
[8] R. Kamada, T. Yagioka, S. Adachi, A. Handa, K. F. Tai, T. Kato, and H. Sugimoto, “New world record Cu(In, Ga)(Se, S)<inf>2</inf> thin film solar cell efficiency beyond 22%,” in 2016 IEEE 43rd Photovoltaic Specialists Conference (PVSC), 2016, pp. 1287–1291.
[9] D. Hariskos, S. Spiering, and M. Powalla, “Buffer layers in Cu(In,Ga)Se2 solar cells and modules,” Thin Solid Films, vol. 480–481, pp. 99–109, Jun. 2005.
[10] N. Naghavi, D. Abou-Ras, N. Allsop, N. Barreau, S. Bücheler, a. Ennaoui, C.-H. Fischer, C. Guillen, D. Hariskos, J. Herrero, R. Klenk, K. Kushiya, D. Lincot, R. Menner, T. Nakada, C. Platzer-Björkman, S. Spiering, a. N. Tiwari, and T. Törndahl, “Buffer layers and transparent conducting oxides for chalcopyrite Cu(In,Ga)(S,Se)2 based thin film photovoltaics: present status and current developments,” Progress in Photovoltaics: Research and Applications, vol. 18, no. 6, pp. 411–433, Sep. 2010.
[11] A. E. de Wild MJ, Wamback K, “Conference Record,” in 20th European Photovoltaic Solar Energy Conference, Barcelona,, 2005, p. 3143.
[12] T. M. Friedlmeier, P. Jackson, A. Bauer, D. Hariskos, O. Kiowski, R. Wuerz, and M. Powalla, “Improved Photocurrent in Cu(In,Ga)Se2 Solar Cells: From 20.8% to 21.7% Efficiency with CdS Buffer and 21.0% Cd-Free,” IEEE Journal of Photovoltaics, vol. 5, no. 5, pp. 1487–1491, Sep. 2015.
[13] S. Spiering, a. Nowitzki, F. Kessler, M. Igalson, and H. Abdel Maksoud, “Optimization of buffer-window layer system for CIGS thin film devices with indium sulphide buffer by in-line evaporation,” Solar Energy Materials and Solar Cells, vol. 144, pp. 544–550, Jan. 2016.
[14] W. Shockley, “The Theory of p-n Junctions in Semiconductors and p-n Junction Transistors,” Bell System Technical Journal, vol. 28, no. 3, pp. 435–489, Jul. 1949.
[15] “Solar Cell Operation.” [Online]. Available: http://pveducation.org/pvcdrom/iv-curve.
[16] U. Rau, “Tunneling-enhanced recombination in Cu(In, Ga)Se2 heterojunction solar cells,” Applied Physics Letters, vol. 74, no. 1, p. 111, 1999.
[17] U. Rau, a Jasenek, H. . Schock, F. Engelhardt, and T. Meyer, “Electronic loss mechanisms in chalcopyrite based heterojunction solar cells,” Thin Solid Films, vol. 361–362, pp. 298–302, Feb. 2000.
[18] R. Scheer and H.-W. Schock, Chalcogenide Photovoltaics. Weinheim, Germany: Wiley-VCH Verlag GmbH & Co. KGaA, 2011.
[19] U. Rau and H. W. Schock, “Electronic propertiesof Cu(In,Ga)Se2 heterojunction solar cells – recent achievements , current understanding , and future challenges,” vol. 147, pp. 131–147, 1999.
[20] F. Kessler and D. Rudmann, “Technological aspects of flexible CIGS solar cells and modules,” Solar Energy, vol. 77, no. 6, pp. 685–695, Dec. 2004.
[21] C. Hsu, Y. Su, S. Wei, C. Chen, W. Ho, C. Chang, Y. Wu, C. Lin, and C. Lai, “Na-induced efficiency boost for Se-deficient Cu(In,Ga)Se2 solar cells,” Progress in Photovoltaics: Research and Applications, vol. 23, no. 11, pp. 1621–1629, Nov. 2015.
[22] K. Otte, L. Makhova, A. Braun, and I. Konovalov, “Flexible Cu(In,Ga)Se2 thin-film solar cells for space application,” Thin Solid Films, vol. 511–512, pp. 613–622, Jul. 2006.
[23] P. M. P. Salomé, V. Fjallstrom, A. Hultqvist, P. Szaniawski, and U. Zimmermann, “The effect of Mo back contact ageing on Cu(In,Ga)Se2 thin-film solar cells,” no. March 2013, pp. 83–89, 2014.
[24] K.-J. Hsiao, J.-D. Liu, H.-H. Hsieh, and T.-S. Jiang, “Electrical impact of MoSe2 on CIGS thin-film solar cells.,” Physical chemistry chemical physics : PCCP, vol. 15, no. 41, pp. 18174–8, Nov. 2013.
[25] M. Bär, W. Bohne, J. Röhrich, E. Strub, S. Lindner, M. C. Lux-Steiner, C.-H. Fischer, T. P. Niesen, and F. Karg, “Determination of the band gap depth profile of the penternary Cu(In(1−X)Ga)(SYSe(1−Y))2 chalcopyrite from its composition gradient,” Journal of Applied Physics, vol. 96, no. 7, p. 3857, 2004.
[26] M. Jayachandran, M. J. Chockalingam, K. R. Murali, and A. S. Lakshmanan, “CuInSe2 for photovoltaics: a critical assessment,” Materials Chemistry and Physics, vol. 34, no. 1, pp. 1–13, Apr. 1993.
[27] T. Nakada and a. Kunioka, “Direct evidence of Cd diffusion into Cu(In, Ga)Se2 thin films during chemical-bath deposition process of CdS films,” Applied Physics Letters, vol. 74, no. 17, p. 2444, 1999.
[28] T. Wada, S. Hayashi, H. Y., and S. Nishiwaki, “High efficiency Cu(In,Ga)Se2 (CIGS) solar cells with improved CIGS surface,” in 2nd World Conference and Exhibition on Photovoltaic Solar Energy Conversion,, 1998, pp. 403–408.
[29] a. Rockett, D. Liao, J. T. Heath, J. D. Cohen, Y. M. Strzhemechny, L. J. Brillson, K. Ramanathan, and W. N. Shafarman, “Near-surface defect distributions in Cu(In,Ga)Se2,” Thin Solid Films, vol. 431–432, pp. 301–306, May 2003.
[30] T. Nakada and M. Mizutani, “Improved efficiency of Cu(In,Ga)Se2 thin film solar cells with chemically deposited ZnS buffer layers by air-annealing-formation of homojunction by solid phase diffusion,” in Conference Record of the Twenty-Eighth IEEE Photovoltaic Specialists Conference - 2000 (Cat. No.00CH37036), 2000, pp. 529–534.
[31] I. Repins, S. Glynn, J. Duenow, T. J. Coutts, W. Metzger, and M. A. Contreras, “Required Materials Properties for High-Efficiency CIGS Modules Preprint,” NREL report, NREL/CP-520-46235, no. July, 2009.
[32] R. Herberholz, U. Rau, H. W. Schock, T. Haalboom, T. Gödecke, F. Ernst, C. Beilharz, K. W. Benz, and D. Cahen, “Phase segregation, Cu migration and junction formation in Cu(In, Ga)Se2,” The European Physical Journal Applied Physics, vol. 6, no. 2, pp. 131–139, May 1999.
[33] C.-H. Chen, T.-Y. Lin, C.-H. Hsu, S.-Y. Wei, and C.-H. Lai, “Comprehensive characterization of Cu-rich Cu(In,Ga)Se2 absorbers prepared by one-step sputtering process,” Thin Solid Films, vol. 535, pp. 122–126, May 2013.
[34] S. B. Zhang, S. Wei, and A. Zunger, “Defect physics of the CuInSe2 chalcopyrite semiconductor,” vol. 57, no. 16, pp. 9642–9656, 1998.
[35] D. Schmid, M. Ruckh, F. Grunwald, and H. W. Schock, “Chalcopyrite/defect chalcopyrite heterojunctions on the basis of CuInSe2,” Journal of Applied Physics, vol. 73, no. 6, p. 2902, 1993.
[36] J. Pohl and K. Albe, “Intrinsic point defects in CuInSe2 and CuGaSe2 as seen via screened-exchange hybrid density functional theory,” Physical Review B, vol. 87, no. 24, p. 245203, Jun. 2013.
[37] S. Siebentritt, M. Igalson, C. Persson, and S. Lany, “The electronic structure of chalcopyrites-bands, point defects and grain boundaries,” Progress in Photovoltaics: Research and Applications, vol. 18, no. 6, pp. 390–410, Sep. 2010.
[38] C. Persson, Y.-J. Zhao, S. Lany, and A. Zunger, “n-type doping of CuInSe2 and CuGaSe2,” Physical Review B, vol. 72, no. 3, p. 035211, Jul. 2005.
[39] S. Lany and A. Zunger, “Light- and bias-induced metastabilities in Cu(In,Ga)Se2 based solar cells caused by the (VSe-VCu) vacancy complex,” Journal of Applied Physics, vol. 100, no. 11, p. 113725, 2006.
[40] U. Rau, M. Schmitt, F. Engelhardt, O. Seifert, J. Parisi, W. Riedl, J. Rimmasch, and F. Karg, “Impact of Na and S incorporation on the electronic transport mechanisms of Cu(In, Ga)Se2 solar cells,” Solid State Communications, vol. 107, no. 2, pp. 59–63, May 1998.
[41] S.-H. Wei, S. B. Zhang, and A. Zunger, “Effects of Na on the electrical and structural properties of CuInSe2,” Journal of Applied Physics, vol. 85, no. 10, p. 7214, 1999.
[42] H. Ruckh, D. Schmid, 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 1994 IEEE 1st World Conference on Photovoltaic Energy Conversion - WCPEC (A Joint Conference of PVSC, PVSEC and PSEC), vol. 1, pp. 156–159.
[43] L. Kronik, D. Cahen, and H. W. Schock, “Effects of Sodium on Polycrystalline Cu(In,Ga)Se2 and Its Solar Cell Performance,” Advanced Materials, vol. 10, no. 1, pp. 31–36, Jan. 1998.
[44] S.-H. Wei, S. B. Zhang, and A. Zunger, “Effects of Ga addition to CuInSe2 on its electronic, structural, and defect properties,” Applied Physics Letters, vol. 72, no. 24, p. 3199, 1998.
[45] R. Klenk, “Characterisation and modelling of chalcopyrite solar cells,” Thin Solid Films, vol. 387, no. 1–2, pp. 135–140, May 2001.
[46] H. Wilhelm, H.-W. Schock, and R. Scheer, “Interface recombination in heterojunction solar cells: Influence of buffer layer thickness,” Journal of Applied Physics, vol. 109, no. 8, p. 084514, 2011.
[47] M. Buffière, A.-A. El Mel, N. Lenaers, G. Brammertz, A. E. Zaghi, M. Meuris, and J. Poortmans, “Surface Cleaning and Passivation Using (NH4)2S Treatment for Cu(In,Ga)Se2 Solar Cells: A Safe Alternative to KCN,” Advanced Energy Materials, vol. 5, no. 6, p. 1401689, Mar. 2015.
[48] W.-H. Ho, C.-H. Hsu, T.-H. Yeh, Y.-H. Chang, S.-Y. Wei, T.-Y. Lin, and C.-H. Lai, “Room-Temperature Chemical Solution Treatment for Flexible ZnS(O,OH)/Cu(In,Ga)Se2 Solar Cell: Improvements in Interface Properties and Metastability.,” ACS applied materials & interfaces, vol. 8, no. 10, pp. 6709–6717, Mar. 2016.
[49] T. Nakada, K. Matsumoto, and M. Okumura, “Improved efficiency of Cu(In,Ga)Se2 thin film solar cells by surface sulfurization using wet process,” Conference Record of the Twenty-Ninth IEEE Photovoltaic Specialists Conference, 2002., pp. 527–530, 2002.
[50] L. Kronik, U. Rau, J.-F. Guillemoles, D. Braunger, H.-W. Schock, and D. Cahen, “Interface redox engineering of Cu(In,Ga)Se2 – based solar cells: oxygen, sodium, and chemical bath effects,” Thin Solid Films, vol. 361–362, pp. 353–359, Feb. 2000.
[51] R. Scheer, “Activation energy of heterojunction diode currents in the limit of interface recombination,” Journal of Applied Physics, vol. 105, no. 10, p. 104505, 2009.
[52] U. Rau and M. Schmidt, “Electronic properties of ZnO/CdS/Cu(In,Ga)Se2 solar cells — aspects of heterojunction formation,” Thin Solid Films, vol. 387, no. 1–2, pp. 141–146, May 2001.
[53] M. Bär, a. Ennaoui, J. Klaer, T. Kropp, R. Sáez-Araoz, S. Lehmann, a. Grimm, I. Lauermann, C. Loreck, S. Sokoll, H.-W. Schock, C.-H. Fischer, M. C. Lux-Steiner, and C. Jung, “Intermixing at the heterointerface between ZnS∕Zn(S,O) bilayer buffer and CuInS2 thin film solar cell absorber,” Journal of Applied Physics, vol. 100, no. 6, p. 064911, 2006.
[54] T. Nakada, “Nano-structural investigations on Cd-doping into Cu(In,Ga)Se2 thin films by chemical bath deposition process,” Thin Solid Films, vol. 361–362, pp. 346–352, Feb. 2000.
[55] F. Pianezzi, P. Reinhard, A. Chirilă, B. Bissig, S. Nishiwaki, S. Buecheler, and A. N. Tiwari, “Unveiling the effects of post-deposition treatment with different alkaline elements on the electronic properties of CIGS thin film solar cells.,” Physical chemistry chemical physics : PCCP, vol. 16, no. 19, pp. 8843–51, May 2014.
[56] J. Haarstrich, M. Teichmann, H. Metzner, M. Gnauck, C. Ronning, W. Wesch, T. Rissom, C. A. Kaufmann, H. W. Schock, V. Scheumann, and W. Mannstadt, “Buffer-free Cu(In,Ga)Se2-solar cells by near-surface ion implantation,” Solar Energy Materials and Solar Cells, vol. 116, pp. 43–48, Sep. 2013.
[57] M. Sugiyama, A. Kinoshita, A. Miyama, H. Nakanishi, and S. F. Chichibu, “Formation of Zn-doped CuInSe2 films by thermal annealing using dimethylzinc,” Journal of Crystal Growth, vol. 310, no. 4, pp. 794–797, Feb. 2008.
[58] J. Bastek, N. A. Stolwijk, R. Wuerz, A. Eicke, J. Albert, and S. Sadewasser, “Zinc diffusion in polycrystalline Cu(In,Ga)Se2 and single-crystal CuInSe2 layers,” Applied Physics Letters, vol. 101, no. 7, p. 074105, Aug. 2012.
[59] D. Abou-Ras, G. Kostorz, a. Strohm, H.-W. Schock, and a. N. Tiwari, “Interfacial layer formations between Cu(In,Ga)Se2 and InxSy layers,” Journal of Applied Physics, vol. 98, no. 12, p. 123512, 2005.
[60] S. Buecheler, F. Pianezzi, C. Fella, A. Chirila, K. Decock, M. Burgelman, and A. N. Tiwari, “Interface formation between CuIn1−xGaxSe2 absorber and In2S3 buffer layer deposited by ultrasonic spray pyrolysis,” Thin Solid Films, vol. 519, no. 21, pp. 7560–7563, Aug. 2011.
[61] H. Mönig, C.-H. Fischer, R. Caballero, C. A. Kaufmann, N. Allsop, M. Gorgoi, R. Klenk, H.-W. Schock, S. Lehmann, and M. C. Lux-Steiner, “Surface Cu depletion of Cu(In,Ga)Se2 films: An investigation by hard X-ray photoelectron spectroscopy,” Acta Materialia, vol. 57, no. 12, pp. 3645–3651, Jul. 2009.
[62] D. Schmid, M. Ruckh, and H. . Schock, “Photoemission studies on Cu(In, Ga)Se2 thin films and related binary selenides,” Applied Surface Science, vol. 103, no. 4, pp. 409–429, Dec. 1996.
[63] W. Riedl, J. Rimmasch, V. Probst, F. Karg, and R. Guckenberger, “Surface microstructure of CIS thin films produced by rapid thermal processing,” Solar Energy Materials and Solar Cells, vol. 35, pp. 129–139, Sep. 1994.
[64] U. Rau, D. Braunger, R. Herberholz, H. W. Schock, J.-F. Guillemoles, L. Kronik, and D. Cahen, “Oxygenation and air-annealing effects on the electronic properties of Cu(In,Ga)Se2 films and devices,” Journal of Applied Physics, vol. 86, no. 1, p. 497, 1999.
[65] T. Dullweber, G. . Anna, U. Rau, and H. . Schock, “A new approach to high-efficiency solar cells by band gap grading in Cu(In,Ga)Se2 chalcopyrite semiconductors,” Solar Energy Materials and Solar Cells, vol. 67, no. 1–4, pp. 145–150, Mar. 2001.
[66] M. Turcu and U. Rau, “Fermi level pinning at CdS/Cu(In,Ga)(Se,S)2 interfaces: effect of chalcopyrite alloy composition,” Journal of Physics and Chemistry of Solids, vol. 64, no. 9–10, pp. 1591–1595, Sep. 2003.
[67] B. Kramer, Ed., Advances in Solid State Physics, vol. 43. Berlin, Heidelberg: Springer Berlin Heidelberg, 2003.
[68] M. Turcu, O. Pakma, and U. Rau, “Interdependence of absorber composition and recombination mechanism in Cu(In,Ga)(Se,S)2 heterojunction solar cells,” Applied Physics Letters, vol. 80, no. 14, p. 2598, 2002.
[69] S. Siebentritt, “Alternative buffers for chalcopyrite solar cells,” Solar Energy, vol. 77, no. 6, pp. 767–775, Dec. 2004.
[70] A. Niemegeers, M. Burgelman, and A. De Vos, “On the CdS/CuInSe2 conduction band discontinuity,” Applied Physics Letters, vol. 67, no. 6, pp. 843, 1995.
[71] T. Minemoto, T. Matsui, H. Takakura, Y. Hamakawa, T. Negami, Y. Hashimoto, T. Uenoyama, and M. Kitagawa, “Theoretical analysis of the effect of conduction band offset of window/CIS layers on performance of CIS solar cells using device simulation,” Solar Energy Materials and Solar Cells, vol. 67, no. 1–4, pp. 83–88, Mar. 2001.
[72] S.-H. Wei and A. Zunger, “Band offsets and optical bowings of chalcopyrites and Zn-based II-VI alloys,” Journal of Applied Physics, vol. 78, no. 6, p. 3846, 1995.
[73] N. Barreau, J. . Bernède, H. El Maliki, S. Marsillac, X. Castel, and J. Pinel, “Recent studies on In2S3 containing oxygen thin films,” Solid State Communications, vol. 122, no. 7–8, pp. 445–450, Jun. 2002.
[74] N. Barreau, “Indium sulfide and relatives in the world of photovoltaics,” Solar Energy, vol. 83, no. 3, pp. 363–371, Mar. 2009.
[75] Y. S. Lee, J. Heo, S. C. Siah, J. P. Mailoa, R. E. Brandt, S. B. Kim, R. G. Gordon, and T. Buonassisi, “Ultrathin amorphous zinc-tin-oxide buffer layer for enhancing heterojunction interface quality in metal-oxide solar cells,” Energy & Environmental Science, vol. 6, no. 7, p. 2112, 2013.
[76] D. Abou-Ras, T. Kirchartz, and and U. Rau, Advanced Characterization Techniques for Thin Film Solar Cells. Weinheim, Germany: Wiley-VCH Verlag GmbH & Co. KGaA, 2011.
[77] G. D. Gilliland, “Photoluminescence spectroscopy of crystalline semiconductors,” Materials Science and Engineering: R: Reports, vol. 18, no. 3–6, pp. 99–399, Mar. 1997.
[78] R. Scheer, A. Pérez-Rodríguez, and W. K. Metzger, “Advanced diagnostic and control methods of processes and layers in CIGS solar cells and modules,” Progress in Photovoltaics: Research and Applications, vol. 18, no. 6, pp. 467–480, Sep. 2010.
[79] T. Sakurai, K. Taguchi, M. M. Islam, S. Ishizuka, A. Yamada, K. Matsubara, S. Niki, and K. Akimoto, “Time-Resolved Microphotoluminescence Study of Cu(In,Ga)Se2,” Japanese Journal of Applied Physics, vol. 50, no. 5, p. 05FC01, May 2011.
[80] J. Tauc, “Optical properties and electronic structure of amorphous Ge and Si,” Materials Research Bulletin, vol. 3, no. 1, pp. 37–46, Jan. 1968.
[81] H. Ahmed, S. J. McCormack, and J. Doran, “External Quantum Efficiency Improvement with Luminescent Downshifting Layers: Experimental and Modelling,” International Journal of Spectroscopy, vol. 2016, pp. 1–7, 2016.
[82] R. Verma, D. Datta, A. Chirila, D. Güttler, J. Perrenoud, F. Pianezzi, U. Müller, S. Kumar, and A. N. Tiwari, “Optical, structural, and chemical properties of flash evaporated In2S3 buffer layer for Cu(In,Ga)Se2 solar cells,” Journal of Applied Physics, vol. 108, no. 7, p. 074904, 2010.
[83] T. Walter, R. Herberholz, C. Müller, and H. W. Schock, “Determination of defect distributions from admittance measurements and application to Cu(In,Ga)Se2 based heterojunctions,” Journal of Applied Physics, vol. 80, no. 8, p. 4411, 1996.
[84] S. S. Hegedus and W. N. Shafarman, “Thin-film solar cells: device measurements and analysis,” Progress in Photovoltaics: Research and Applications, vol. 12, no. 23, pp. 155–176, Mar. 2004.
[85] P. Jackson, D. Hariskos, R. Wuerz, O. Kiowski, A. Bauer, T. M. Friedlmeier, and M. Powalla, “Properties of Cu(In,Ga)Se2 solar cells with new record efficiencies up to 21.7%,” physica status solidi (RRL) - Rapid Research Letters, vol. 9, no. 1, pp. 28–31, Jan. 2015.
[86] J. D. Bergesen, G. A. Heath, T. Gibon, and S. Suh, “Thin-film photovoltaic power generation offers decreasing greenhouse gas emissions and increasing environmental co-benefits in the long term.,” Environmental science & technology, vol. 48, no. 16, pp. 9834–43, Aug. 2014.
[87] M. Nakamura, N. Yoneyama, K. Horiguchi, Y. Iwata, K. Yamaguchi, H. Sugimoto, and T. Kato, “Recent R&D progress in solar frontier’s small-sized Cu(InGa)(SeS)2 solar cells,” in 2014 IEEE 40th Photovoltaic Specialist Conference (PVSC), 2014, pp. 0107–0110.
[88] T. Yagioka and T. Nakada, “Cd-Free Flexible Cu(In,Ga)Se2 Thin Film Solar Cells with ZnS(O,OH) Buffer Layers on Ti Foils,” Applied Physics Express, vol. 2, p. 072201, Jun. 2009.
[89] D. H. Shin, S. T. Kim, J. H. Kim, H. J. Kang, B. T. Ahn, and H. Kwon, “Study of band structure at the Zn(S,O,OH)/Cu(In,Ga)Se2 interface via rapid thermal annealing and their effect on the photovoltaic properties.,” ACS applied materials & interfaces, vol. 5, no. 24, pp. 12921–7, Dec. 2013.
[90] J.-H. Wi, T. G. Kim, J. W. Kim, W.-J. Lee, D.-H. Cho, W. S. Han, and Y.-D. Chung, “Photovoltaic Performance and Interface Behaviors of Cu(In,Ga)Se2 Solar Cells with a Sputtered-Zn(O,S) Buffer Layer by High-Temperature Annealing.,” ACS applied materials & interfaces, vol. 7, no. 31, pp. 17425–32, Aug. 2015.
[91] C. Platzer-Björkman, T. Törndahl, D. Abou-Ras, J. Malmström, J. Kessler, and L. Stolt, “Zn(O,S) buffer layers by atomic layer deposition in Cu(In,Ga)Se2 based thin film solar cells: Band alignment and sulfur gradient,” Journal of Applied Physics, vol. 100, no. 4, p. 044506, 2006.
[92] D. Cahen and R. Noufi, “Defect chemical explanation for the effect of air anneal on CdS/CuInSe2 solar cell performance,” Applied Physics Letters, vol. 54, no. 6, p. 558, 1989.
[93] T. Nakada, M. Hongo, and E. Hayashi, “Band offset of high efficiency CBD-ZnS/CIGS thin film solar cells,” Thin Solid Films, vol. 431–432, pp. 242–248, May 2003.
[94] L. Larina, D. Shin, J. H. Kim, and B. T. Ahn, “Alignment of energy levels at the ZnS/Cu(In,Ga)Se2 interface,” Energy & Environmental Science, vol. 4, no. 9, p. 3487, 2011.
[95] S.-H. Wei and A. Zunger, “Band offsets at the CdS/CuInSe2 heterojunction,” Applied Physics Letters, vol. 63, no. 18, p. 2549, 1993.
[96] T. Kobayashi, H. Yamaguchi, Z. Jehl Li Kao, H. Sugimoto, T. Kato, H. Hakuma, and T. Nakada, “Impacts of surface sulfurization on Cu(In1−x,Ga x)Se2 thin-film solar cells,” Progress in Photovoltaics: Research and Applications, vol. 23, no. 10, pp. 1367–1374, Oct. 2015.
[97] I. Khatri, I. Matsuyama, H. Yamaguchi, H. Fukai, and T. Nakada, “Surface sulfurization on MBE-grown Cu(In1−x,Gax)Se2 thin films and devices,” Japanese Journal of Applied Physics, vol. 54, no. 8S1, p. 08KC10, Aug. 2015.
[98] D. Ohashi, T. Nakada, and A. Kunioka, “Improved CIGS thin-film solar cells by surface sulfurization using In2S3 and sulfur vapor,” Solar Energy Materials and Solar Cells, vol. 67, no. 1–4, pp. 261–265, Mar. 2001.
[99] R. Knecht, M. S. Hammer, J. Parisi, and I. Riedel, “Impact of varied sulfur incorporation on the device performance of sequentially processed Cu(In,Ga)(Se,S)2 thin film solar cells,” Physica Status Solidi (a), vol. 210, no. 7, pp. 1392–1399, Jul. 2013.
[100] T. Wada, Y. Hashimoto, S. Nishiwaki, T. Satoh, S. Hayashi, T. Negami, and H. Miyake, “High-efficiency CIGS solar cells with modified CIGS surface,” Solar Energy Materials and Solar Cells, vol. 67, no. 1–4, pp. 305–310, Mar. 2001.
[101] T. Kobayashi, H. Yamaguchi, and T. Nakada, “Effects of combined heat and light soaking on device performance of Cu(In,Ga)Se2 solar cells with ZnS(O,OH) buffer layer,” no. February 2013, pp. 115–121, 2014.
[102] T. Kobayashi, T. Kumazawa, Z. Jehl Li Kao, and T. Nakada, “Post-treatment effects on ZnS(O,OH)/Cu(In,Ga)Se2 solar cells deposited using thioacetamide-ammonia based solution,” Solar Energy Materials and Solar Cells, vol. 123, pp. 197–202, Apr. 2014.
[103] M. Buffière, N. Barreau, L. Arzel, P. Zabierowski, and J. Kessler, “Minimizing metastabilities in Cu(In,Ga)Se2/(CBD)Zn(S,O,OH)/i-ZnO-based solar cells,” Progress in Photovoltaics: Research and Applications, vol. 23, no. 4, pp. 462–469, Apr. 2015.
[104] J. Sterner, J. Malmström, and L. Stolt, “Study on ALD In2S3/Cu(In,Ga)Se2 interface formation,” Progress in Photovoltaics: Research and Applications, vol. 13, no. 3, pp. 179–193, May 2005.
[105] A. Singh, C. Coughlan, F. Laffir, and K. M. Ryan, “Assembly of CuIn(1-x)Ga(x)S2 nanorods into highly ordered 2D and 3D superstructures.,” ACS nano, vol. 6, no. 8, pp. 6977–83, Aug. 2012.
[106] K. Otto, a. Katerski, a. Mere, O. Volobujeva, and M. Krunks, “Spray pyrolysis deposition of indium sulphide thin films,” Thin Solid Films, vol. 519, no. 10, pp. 3055–3060, Mar. 2011.
[107] S.-H. Chang, M.-Y. Chiang, C.-C. Chiang, F.-W. Yuan, C.-Y. Chen, B.-C. Chiu, T.-L. Kao, C.-H. Lai, and H.-Y. Tuan, “Facile colloidal synthesis of quinary CuIn1−xGax(SySe1−y)2 (CIGSSe) nanocrystal inks with tunable band gaps for use in low-cost photovoltaics,” Energy & Environmental Science, vol. 4, no. 12, p. 4929, 2011.
[108] Y. S. Lim, H. Kwon, J. Jeong, J. Y. Kim, H. Kim, M. J. Ko, U. Jeong, and D. Lee, “Colloidal solution-processed CuInSe2 solar cells with significantly improved efficiency up to 9% by morphological improvement.,” ACS applied materials & interfaces, vol. 6, no. 1, pp. 259–67, Jan. 2014.
[109] M. Turcu, I. M. Kötschau, and U. Rau, “Composition dependence of defect energies and band alignments in the Cu(In1−xGax)(Se1−ySy)2 alloy system,” Journal of Applied Physics, vol. 91, no. 3, p. 1391, 2002.
[110] J. F. Guillemoles, “Stability of Cu(In,Ga)Se2 solar cells: a thermodynamic approach,” Thin Solid Films, vol. 361–362, pp. 338–345, Feb. 2000.
[111] Z. Q. Li, J. H. Shi, D. W. Zhang, Q. Q. Liu, Z. Sun, Y. W. Chen, Z. Yang, and S. M. Huang, “Cu(In,Ga)Se2 solar cells with double layered buffers grown by chemical bath deposition,” Thin Solid Films, vol. 520, no. 1, pp. 333–337, Oct. 2011.
[112] S. Shimakawa, Y. Hashimoto, S. Hayashi, T. Satoh, and T. Negami, “Annealing effects on Zn1−xMgxO/CIGS interfaces characterized by ultraviolet light excited time-resolved photoluminescence,” Solar Energy Materials and Solar Cells, vol. 92, no. 9, pp. 1086–1090, Sep. 2008.
[113] B. Ohnesorge, R. Weigand, G. Bacher, a. Forchel, W. Riedl, and F. H. Karg, “Minority-carrier lifetime and efficiency of Cu(In,Ga)Se2 solar cells,” Applied Physics Letters, vol. 73, no. 9, p. 1224, 1998.
[114] S. Ishizuka, A. Yamada, M. M. Islam, H. Shibata, P. Fons, T. Sakurai, K. Akimoto, and S. Niki, “Na-induced variations in the structural, optical, and electrical properties of Cu(In,Ga)Se2 thin films,” Journal of Applied Physics, vol. 106, no. 3, p. 034908, 2009.
[115] S. Shirakata, H. Ohta, K. Ishihara, T. Takagi, A. Atarashi, and S. Yudate, “Photoluminescence characterization of surface degradation mechanism in Cu(In,Ga)Se2 thin films grown on Mo/soda lime glass substrate,” Japanese Journal of Applied Physics, vol. 53, no. 5S1, p. 05FW11, May 2014.
[116] G. Dagan, F. Abou-Elfotouh, D. J. Dunlavy, R. J. Matson, and D. Cahen, “Defect level identification in copper indium selenide (CuInSe2) from photoluminescence studies,” Chemistry of Materials, vol. 2, no. 3, pp. 286–293, May 1990.
[117] K. Kushiya and O. Yamase, “Stabilization of PN Heterojunction between Cu(InGa)Se 2 Thin-Film Absorber and ZnO Window with Zn(O,S,OH)x Buffer,” Japanese Journal of Applied Physics, vol. 39, no. Part 1, No. 5A, pp. 2577–2582, May 2000.
[118] J. Serhan, Z. Djebbour, W. Favre, a. Migan-Dubois, a. Darga, D. Mencaraglia, N. Naghavi, G. Renou, J.-F. Guillemoles, and D. Lincot, “Investigation of the metastability behavior of CIGS based solar cells with ZnMgO–Zn(S,O,OH) window-buffer layers,” Thin Solid Films, vol. 519, no. 21, pp. 7606–7610, Aug. 2011.
[119] J. Serhan, Z. Djebbour, a. Darga, D. Mencaraglia, N. Naghavi, G. Renou, D. Lincot, and J.-F. Guillemeoles, “Electrical characterization of CIGSe solar cells metastability with Zn(S,O,OH)–ZnMgO interface buffer layers,” Solar Energy Materials and Solar Cells, vol. 94, no. 11, pp. 1884–1888, Nov. 2010.
[120] N. Naghavi, S. Spiering, M. Powalla, B. Cavana, and D. Lincot, “High-efficiency copper indium gallium diselenide (CIGS) solar cells with indium sulfide buffer layers deposited by atomic layer chemical vapor deposition (ALCVD),” Progress in Photovoltaics: Research and Applications, vol. 11, no. 7, pp. 437–443, Nov. 2003.
[121] D. Abou-Ras, G. Kostorz, D. Hariskos, R. Menner, M. Powalla, S. Schorr, and a. N. Tiwari, “Structural and chemical analyses of sputtered InxSy buffer layers in Cu(In,Ga)Se2 thin-film solar cells,” Thin Solid Films, vol. 517, no. 8, pp. 2792–2798, Feb. 2009.
[122] D. Hariskos, R. Menner, E. Lotter, S. Spiering, and M. Powalla, “Magnetron sputtering of indium sulphide as the buffer layer in Cu(InGa)Se2-based solar cells,” in Proceedings of the 20th European Photovoltaic Solar Energy Conference, 2005, pp. 1713–1716.
[123] D. Abou-Ras, D. Rudmann, G. Kostorz, S. Spiering, M. Powalla, and a. N. Tiwari, “Microstructural and chemical studies of interfaces between Cu(In,Ga)Se2 and In2S3 layers,” Journal of Applied Physics, vol. 97, no. 8, p. 084908, 2005.
[124] M. Bär, N. Barreau, F. Couzinié-Devy, L. Weinhardt, R. G. Wilks, J. Kessler, and C. Heske, “Impact of Annealing-Induced Intermixing on the Electronic Level Alignment at the In2S3/Cu(In,Ga)Se2 Thin-Film Solar Cell Interface.,” ACS applied materials & interfaces, vol. 8, no. 3, pp. 2120–4, Jan. 2016.
[125] J. . Bernède, N. Barreau, S. Marsillac, and L. Assmann, “Band alignment at β-In2S3/TCO interface,” Applied Surface Science, vol. 195, no. 1–4, pp. 222–228, Jul. 2002.
[126] N. Terada, H. Morita, K. Chochi, S. Yoshimoto, M. Mitsunaga, S. Ishizuka, H. Shibata, A. Yamada, K. Matsubara, and S. Niki, “Characterization of electronic structure of oxysulfide buffers and band alignment at buffer/absorber interfaces in Cu(In,Ga)Se2 -based solar cells,” Japanese Journal of Applied Physics, vol. 53, no. 5S1, p. 05FW09, May 2014.
[127] N. Barreau, S. Marsillac, J. C. Bernède, and L. Assmann, “Evolution of the band structure of β-In2S3-3xO3x buffer layer with its oxygen content,” Journal of Applied Physics, vol. 93, no. 9, p. 5456, 2003.
[128] N. Barreau, S. Marsillac, D. Albertini, and J. C. Bernede, “Structural, optical and electrical properties of β-In2S3-3xO3x thin films obtained by PVD,” Thin Solid Films, vol. 403–404, pp. 331–334, Feb. 2002.
[129] C. Bugot, N. Schneider, M. Bouttemy, A. Etcheberry, D. Lincot, and F. Donsanti, “Study of atomic layer deposition of indium oxy-sulfide films for Cu(In,Ga)Se2 solar cells,” Thin Solid Films, vol. 582, pp. 340–344, May 2015.
[130] S. Spiering, a Eicke, D. Hariskos, M. Powalla, N. Naghavi, and D. Lincot, “Large-area Cd-free CIGS solar modules with In2S3 buffer layer deposited by ALCVD,” Thin Solid Films, vol. 451–452, pp. 562–566, Mar. 2004.
[131] S. Gall, N. Barreau, F. Jacob, S. Harel, and J. Kessler, “Influence of sodium compounds at the Cu(In,Ga)Se2/(PVD)In2S3 interface on solar cell properties,” Thin Solid Films, vol. 515, no. 15, pp. 6076–6079, May 2007.
[132] J. V. Li, X. Li, Y. Yan, C.-S. Jiang, W. K. Metzger, I. L. Repins, M. A. Contreras, and D. H. Levi, “Influence of sputtering a ZnMgO window layer on the interface and bulk properties of Cu(In,Ga)Se2 solar cells,” Journal of Vacuum Science & Technology B: Microelectronics and Nanometer Structures, vol. 27, no. 6, p. 2384, 2009.
[133] C.-S. Lee, S. Kim, Y.-M. Shin, B. G. Park, B. T. Ahn, and H. Kwon, “Performance improvement in Cd-free Cu(In,Ga)Se2 solar cells by modifying the electronic structure of the ZnMgO buffer layer,” RSC Advances, vol. 4, no. 69, p. 36784, Aug. 2014.
[134] T. Nakada, K. Furumi, and A. Kunioka, “High-efficiency cadmium-free Cu(In,Ga)Se2 thin-film solar cells with chemically deposited ZnS buffer layers,” IEEE Transactions on Electron Devices, vol. 46, no. 10, pp. 2093–2097, 1999.
[135] H. A. Maksoud, M. Igalson, and S. Spiering, “Influence of post-deposition heat treatment on electrical transport properties of In2S3-buffered Cu(In,Ga)Se2 cells,” Thin Solid Films, vol. 535, pp. 158–161, May 2013.
[136] G. S. Frankel, X.-B. Chen, R. K. Gupta, S. Kandasamy, and N. Birbilis, “Effect of Vacuum System Base Pressure on Corrosion Resistance of Sputtered Al Thin Films,” Journal of the Electrochemical Society, vol. 161, no. 4, pp. C195–C200, Feb. 2014.
[137] a. I. Rogozin, M. V. Vinnichenko, a. Kolitsch, and W. Möller, “Effect of deposition parameters on properties of ITO films prepared by reactive middle frequency pulsed dual magnetron sputtering,” Journal of Vacuum Science & Technology A: Vacuum, Surfaces, and Films, vol. 22, no. 2, p. 349, 2004.
[138] R. Hill, “Energy-gap variations in semiconductor alloys,” Journal of Physics C: Solid State Physics, vol. 7, no. 3, pp. 521–526, Feb. 1974.
[139] M. Maiberg and R. Scheer, “Theoretical study of time-resolved luminescence in semiconductors. I. Decay from the steady state,” Journal of Applied Physics, vol. 116, no. 12, p. 123710, Sep. 2014.
[140] S. Shirakata and T. Nakada, “Time-resolved photoluminescence in Cu(In,Ga)Se2 thin films and solar cells,” Thin Solid Films, vol. 515, no. 15, pp. 6151–6154, May 2007.
[141] M. Morkel, L. Weinhardt, B. Lohmüller, C. Heske, E. Umbach, W. Riedl, S. Zweigart, and F. Karg, “Flat conduction-band alignment at the CdS/CuInSe2 thin-film solar-cell heterojunction,” Applied Physics Letters, vol. 79, no. 27, p. 4482, 2001.
[142] S. Bröker, D. Kück, A. Timmer, I. Lauermann, B. Ümsür, D. Greiner, C. A. Kaufmann, and H. Mönig, “Correlating the Local Defect-Level Density with the Macroscopic Composition and Energetics of Chalcopyrite Thin-Film Surfaces.,” ACS applied materials & interfaces, vol. 7, no. 23, pp. 13062–72, Jun. 2015.
[143] F. Couzinié-Devy, N. Barreau, and J. Kessler, “Influence of absorber copper concentration on the Cu(In,Ga)Se2/(PVD)In2S3 and Cu(In,Ga)Se2/(CBD)CdS based solar cells performance,” Thin Solid Films, vol. 517, no. 7, pp. 2407–2410, Feb. 2009.
[144] Q. Nguyen, K. Orgassa, I. Koetschau, U. Rau, and H. W. Schock, “Influence of heterointerfaces on the performance of Cu(In,Ga)Se2 solar cells with CdS and In(OHx,Sy) buffer layers,” Thin Solid Films, vol. 431–432, pp. 330–334, May 2003.
[145] a. Strohm, L. Eisenmann, R. K. Gebhardt, a. Harding, T. Schlötzer, D. Abou-Ras, and H. W. Schock, “ZnO/InxSy/Cu(In,Ga)Se2 solar cells fabricated by coherent heterojunction formation,” Thin Solid Films, vol. 480–481, pp. 162–167, Jun. 2005.
[146] X. L. Zhu, Y. M. Wang, Z. Zhou, a. M. Li, L. Zhang, and F. Q. Huang, “13.6%-efficient Cu(In,Ga)Se2 solar cell with absorber fabricated by RF sputtering of (In,Ga)2Se3 and CuSe targets,” Solar Energy Materials and Solar Cells, vol. 113, pp. 140–143, Jun. 2013.
[147] N. Romeo, a. Bosio, D. Menossi, C. Catellani, R. Dharmadasa, and a. Romeo, “High efficiency Cu(In,Ga)Se2/CdS thin film solar cells obtained with precursors sputtered from InSe, GaSe and Cu targets,” Thin Solid Films, vol. 535, pp. 88–91, May 2013.
[148] J. H. Shi, Z. Q. Li, 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 Applications, vol. 19, no. 2, pp. 160–164, Mar. 2011.
[149] Y. Su, C. Hsu, C. Chang, and C. Lai, “Investigation of the CIGS thin film solar cells with post-selenized absorbers deposited by sputtering from a single quaternary target using electrical characterization methods,” in 2013 IEEE 39th Photovoltaic Specialists Conference (PVSC), 2013, no. Iv, pp. 2039–2041.
[150] L. Ouyang, M. Zhao, D. Zhuang, J. Han, Z. Gao, L. Guo, X. Li, R. Sun, and M. Cao, “Annealing treatment of Cu(In,Ga)Se2 absorbers prepared by sputtering a quaternary target for 13.5% conversion efficiency device,” Solar Energy, vol. 118, pp. 375–383, Aug. 2015.
[151] C.-H. Chen, W.-C. Shih, C.-Y. Chien, C.-H. Hsu, Y.-H. Wu, and C.-H. Lai, “A promising sputtering route for one-step fabrication of chalcopyrite phase Cu(In,Ga)Se2 absorbers without extra Se supply,” Solar Energy Materials and Solar Cells, vol. 103, pp. 25–29, Aug. 2012.
[152] J. Xiang, X. Huang, G. Lin, J. Tang, C. Ju, and X. Miao, “CIGS Thin Films for Cd-Free Solar Cells by One-Step Sputtering Process,” Journal of Electronic Materials, vol. 43, no. 7, pp. 2658–2666, Apr. 2014.
[153] S. Lindström, “An all-sputtering process and equipment for CIGS solar cells,” Vakuum in Forschung und Praxis, vol. 25, no. 5, pp. 43–45, Oct. 2013.
[154] “Midsummer technology.” [Online]. Available: http://midsummer.se/technology.
[155] M. D. Archer and R. Hill, Eds., Clean Electricity from Photovoltaics. Imperial College Press, London, 2001.
[156] 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)Se2 thin film solar cells,” Journal of Applied Physics, vol. 107, no. 3, p. 034509, 2010.
[157] 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, no. 8, pp. 1290–1295, Aug. 2009.