本研究致力於探討氧硫化鋅/銅銦鎵硒硫[Zn(O,S)/Cu(Inx,Ga1-x)(Sey,S1-y)2, CIGSSe]薄膜太陽能電池元件樣品之成分分布及能帶結構。為了可以利用X光光電子能譜(SRPES)觀測以原子層沉積法(ALD)沉積不同硫氧比的Zn(O,S)透明導電層與吸收層CIGSSe間界面各元素濃度的縱深變化及能帶結構，我們以氬離子濺射(Ar ion sputtering)反覆轟擊樣品直至Zn(O,S)/CIGSSe界面處，並輔以X光吸收光譜術(XAS)來探討S元素摻雜至ZnO內所造成的原子間晶格的改變及結構特性。
隨著S摻雜濃度提高時，價電帶最大值(valence band maximum, VBM)往上提使異質界面的能帶彎曲趨於平緩，使得載子覆合機率降低並提升開路電壓(VOC)而使效率更好；然而，在導電帶上形成spike type阻止光激發光電子的大量通過亦可減少載子覆合的機率。然而，亦利用EXAFS技術來了解價電帶上提的原因可能來自於硫原子取代氧原子的位置使載子覆合機率降低，以得到較好的效率。
另外，未來將研究探討光浴化處理(Light soaking)後的太陽能電池對於提升其效率的機制，並藉由X光光電子能譜量測界面的能帶結構變化。

This study is focused on understanding the depth-dependent profiles and band structure of the Zn(O,S) buffer layer for Cu(In, Ga)(S, Se)2 (CIGSSe) solar cell. Zinc oxysulfide had been grown on the Cu(In, Ga)(S, Se)2 absorber layer as the buffer layer by atomic layer deposition (ALD). In order to measure the variations of elemental distributions and electronic band structure with sulfur doping of ZnO. We used the Ar+ ion sputtering gun to observe near the interface of the Zn(O,S)/CIGSSe and researched by mean of synchrotron radiation photoemission spectroscopy (SRPES). The local distortions of crystal lattices and structural characteristic with sulfur doping of buffer layer was also investigated by using X-ray absorption spectroscopy (XAS).
With the higher concentration sulfur doping of the Zn(O,S) layer exhibits an upward shift of the valence band maximum, which is reducing the band bending and interface recombination to receive a higher VOC. It is also found that the band structure near the interface reveals a spike type, which is beneficial to increase a high VOC without decreasing JSC. We can realize the S 3p occupied state an upward shift of the valence band maximum with increasing sulfur because of the sulfur atoms are substitutionally doped in the oxygen sites, and reducing the interface recombination and band bending at the absorber surface can lead to the improvement in the efficiency of the Cd-free thin film solar cells with Zn(O,S) buffer layer.
In addition, we also investigated the band structure at the interface of the ZnO/CdS/CIGSSe after light soaking treatment by X-ray photoemission spectroscopy.

第一章 序論 9
1-1 前言 9
1-2 研究動機與方向 10
1-3 太陽能電池的基本原理 11
1-4 Zn(O,S)/CIGSSe薄膜太陽能電池的優勢與研究動機 12
1-5 太陽能電池原理 13
1-6 太陽能電池結構 16
1-6-1 基板 17
1-6-2 背電極 17
1-6-3 吸收層 18
1-6-4 透明導電層 21
第二章 儀器設備與實驗原理 23
2-1 同步加速器光源設施與簡介 23
2-2 X光電子能譜 (X-ray Photoelectron Spectroscopy) 26
2-3 X光吸收光譜 (X-ray absorption spectroscopy) 29
第三章、實驗方法 33
3-1 樣品製備與處理 33
3-2 X光光電子能譜量測 34
3-3 X光吸收光譜量測 36
第四章、結果與討論 37
4-1 定量分析 37
4-2 能帶結構 46
4-3 吸收光譜 54
4-4 結論 59
第五章 未來展望 61
第六章 參考文獻 65

[1] 楊德仁， “太陽能電池材料” ， 五南圖書出版股份有限公司 (2008).
[2] J.E Jaffe, A Zunger, “Theory of the band-gap anomaly in ABC2 chalcopyrite semiconductors,” Phys. Rev. B, 29: 1882~1906 (1984).
[3] G. Hanna, A. Jasenek, U. Rau, H.W. Schock, “Influence of the Ga-content on the bulk defect densities of Cu(In,Ga)Se2,” Thin Solid Films, Volume 387, Issues 1-2, 29 May, 71-73 (2001).
[4] Arturo Morales-Acevedo, “Solar Cells - Research and Application Perspectives,” ISBN 978-953-51-1003-3, Published: March 6 (2013).
[5] N.Kohara, S.Nishiwaki, Y.Hashimoto, T.Negami , and T.Wada, “Electrical properties of the Cu(In,Ga)Se2/MoSe2/Mo structure,” Solar Energy Materials and Solar Cells 67 209–215 (2001).
[6] S. Seyrlinga, A. Chirilaa, D. Guttler, P. Blosch, F. Pianezzi, R. Verma, S. Bucheler, S. Nishiwaki , “CuIn1xGaxSe2 growth process modifications: Influences on microstructure, Na distribution, and device properties,” Solar Energy Materials & Solar Cells 95 1477–1481 (2011).
[7] M. C. Joliet1, C. Antoniadis1, R. Andrew1 and L. D. Laude1, “Laser‐induced synthesis of thin CuInSe2 films,” Appl. Phys. Lett. 46, 266 (1985).
[8] Brown B J, “Chemical spray pyrolysis of copper indium diselenide/cadmium sulfide solar cells,” Stanford University, (1989).
[9] W. N. Shafarman and J. Zhu, “Effect of substrate temperature and deposition profile on evaporated Cu(In,Ga)Se2 films and devices,” Thin Solid Films, 361, 473-477 (2000).
[10] M.L. Fearheiley, “The phase relations in the Cu,In,Se system and the growth of CuInSe2 single crystals,” Solar Cells, vol 16, 91-100, (1986).
[11] Rudmann, D., “Effects of Sodium on Growth and Properties of Cu(In,Ga)Se2 Thin Films and Solar Cells,” Department of Physics, 17, (2004).
[12] C. Platzer-Bjo¨ rkman, J. Lu, J. Kessler, L. Stolt, “Interface study of CuInSe2/ZnO and Cu(In, Ga)Se2/ZnO devices using ALD ZnO buffer layers,” Thin Solid Films 431 –432, 321-325 (2003).
[13] Uwe Zimmermann, Marta Ruth, Marika Edoff, “CADMIUM-FREE CIGS MINI-MODULES WITH ALD-GROWN Zn(O,S)-BASED BUFFER LAYERS,” European Photovoltaic Solar Energy Conference 4-8 (2006).
[14] Takashi Minemoto, Akira Okamoto, Hideyuki Takakura, “Sputtered ZnO-based buffer layer for band offset control in Cu(In,Ga)Se2 solar cells,” Thin Solid Films 519, 7568–7571, (2011).
[15] A. Hultqvist, C.Platzer-Bj ¨orkman, E.Coronel, M.Edoff, “Experimental investigation of Cu(In1-x,Gax)Se2/Zn(O1-z,Sz) solar cell performance,” Solar Energy Materials & Solar Cells 95, 497–503, (2011).
[16] Taizo Kobayashi, Tokio Nakada, “Efficient Cu(In,Ga)Se2 thin film solar cells with reduced thickness of ZnS(O,OH) Buffer Layer,” Solar Energy Materials & Solar Cells 117, 526–530, (2013).
[17] C. Platzer-Björkman, T. Törndahl, D. Abou-Ras, J. Malmström, J. Kessler, 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 100, 044506 (2006).
[18] Ji Hyun Choi, Adrian Adalberto Garay, Su Min Hwang, Chee Won Chung, “Influence of oxygen on characteristics of Zn(O,S) thin film deposited by RF magnetron sputtering,” J. Vac. Sci. Technol. 33, No. 4 (2015).
[19] Adam Hultqvist, Jian V. Li, Darius Kuciauskas, Patricia Dippo, Miguel A. Contreras, “Reducing interface recombination for Cu(In, Ga)Se2 by atomic layer depositied buffer ,” APPLIED PHYSICS LETTERS 107, 033906 (2015).
[20] Joonho Bae, Hyunjin Kim, Ee Le Shim, Young Jin Choi, Young Jun Park, and Jong Min Kim, “Fabrication of vertically aligned ZnO nanocone arrays by wet chemical etching on various substrates and enhanced photoluminescence emission from nanocone arrays compared to nanowire arrays”, Phys. Status Solidi A 210, No. 12, 2662 – 2667 (2013).
[21] M. Gaba´ s, N.T.Barrett, J.R.Ramos-Barrado, S.Gotac, T.C.Rojas, “Chemical and electronic interface structure of spray pyrolysis deposited undoped and Al-doped ZnO thin films on a commercial Cz-Si solar cell substrate,” Solar Energy Materials & Solar Cells 93 1356-1365 (2009).
[22] Anneli Önsten , Dunja Stoltz, Pål Palmgren, Shun Yu, Thomas Claesson, Mats Göthelid, and Ulf O. Karlsson, “SO2 interaction with Zn(0001) and ZnO(0001) and the influence of water,” Surface Science 608, 31–43, (2013).
[23] S. Ben Amor, M. Jacquet, P. Fioux and M. Nardin, “XPS characterisation of plasma treated and zinc oxide coated PET,” Applied Surface Science 255, 5052–5061 (2009).
[24] Satoshi Hashimoto, Kichinosuke Hirokawa, Yasuo Fukuda, “Correction of Peak Shift and Classification of Change of X-ray Photoelectron Spectra of Oxides as a Result of Ion Sputtering,” SURFACE AND INTERFACE ANALYSIS 18 (1992).
[25] DENG Hong, B. GONG2, A. J. Petrella2, “Characterization of the ZnO thin film prepared by single source chemical vapor deposition under low vacuum condition,” SCIENCE IN CHINA (Series E) Vol. 46 No. 4, (2003).

[26] M. Gaba´ s, N.T.Barrett, J.R.Ramos-Barrado, S.Gotac, T.C.Rojas, “Chemical and electronic interface structure of spray pyrolysis deposited undoped and Al-doped ZnO thin films on a commercial Cz-Si solar cell substrate,” Solar Energy Materials & Solar Cells 93 1356-1365 (2009).
[27] David W. Niles, Kannan Ramanathan, Falah Hasoon, Rommel Noufi, and Brian J. Tielsch, “Na impurity chemistry in photovoltaic CIGS thin films: Investigation with x-ray photoelectron spectroscopy,” J. Vac. Sci. Technol. A 15, 3044 (1997).
[28] Jon M. Azpiroz and Ivan Infante, “A first-principles study of II–VI (II = Zn; VI =O, S, Se, Te) semiconductor nanostructures,” J. Mater. Chem. 22 (2012).
[29] Joachim Paier, “Cu2ZnSnS4 as a potential photovoltaic material: A hybrid Hartree-Fock density functional theory study,” PHYSICAL REVIEW B 79, 115126 (2009).
[30] Liudmila Larina, Donghyeop Shin and Ji Hye Kim, “Alignment of energy levels at the ZnS/Cu(In,Ga)Se2 interface,” Energy Environ. Sci. 4, 3487-3493 (2011).

[31] Anup L. Dadlani, “Exploring the local electronic structure and geometric arrangement of ALD Zn(O,S) buffer layers using X-ray absorption spectroscopy,” J. Mater. Chem. C 3, 12192-12198 (2015).
[32] C. L. Dong, “Electronic structure of nanostructured ZnO from x-ray absorption and emission spectroscopy and the local density approximation,” PHYSICAL REVIEW B 70, 195325 (2004).
[33] M. Bär, W. Bohne, J. Röhrich and E. Strub, “Determination of the band gap depth profile of the penternary Cu(In(1 X)GaX)(SYSe(1 Y))2 chalcopyrite from its composition gradient,” J. Appl. Phys., Vol. 96, 7 (2004).
[34] Andreas Klein, “Energy band alignment in chalcogenide thin film solar cells from photoelectron spectroscopy,” J. Phys.: Condens. Matter 27, 134201, (2015).
[35] M. T. Nichols, W. Li, D. Pei, G. A. Antonelli, Q. Lin, S. Banna, “Measurement of bandgap energies in low-k organosilicates,” JOURNAL OF APPLIED PHYSICS 115, 094105, (2014).
[36] Jayeeta Lahiri, Matthias Batzill, “Surface Functionalization of ZnO Photocatalysts with Monolayer ZnS,” J. Phys. Chem. C, 112, 4304-4307, (2008).
[37] Taizo Kobayashi, Toyokazu Kumazawa, Zacharie Jehl Li Kao, Tokio Nakada, “Cu(In,Ga)Se2 thin film solar cells with a combined ALD-Zn(O,S) buffer and MOCVD-ZnO:B window layers,” Solar Energy Materials & Solar Cells 119, 129–133, (2013).
[38] Clas Persson, “Strong Valence-Band Offset Bowing of ZnO1-xSx Enhances p-Type Nitrogen Doping of ZnO-like Alloys,” PRL 97, 146403, (2006).
[39] Amin Torabi, Viktor N. Staroverov, “Band Gap Reduction in ZnO and ZnS by Creating Layered ZnO/ZnS Heterostructures,” J. Phys. Chem. Lett. 6, 2075−2080 (2015).
[40] Hao Ming Chen, Chih Kai Chen , Ru-Shi Liu , “A New Approach to Solar Hydrogen Production: a Zno-ZnS Solid Solution Nanowire Array Photoanode,” Adv. Energy Mater., 1 742–747 (2011).
[41] M. Igalson, A. Urbaniak, A. Krysztopa, Y. Aida , “Sub-bandgap photoconductivity and photocapacitance in CIGS thin films and devices,” Thin Solid Films, 519 7489–7492, (2011).
[42] Stephan Lany, Alex 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 100, 113725 (2006).
[43] I.L. Eisgruber, J.E. Granata, J.R. Sites, J. Hou, “Blue-photon modification of nonstandard diode barrier in CuInSe2 solar cells,” Solar Energy Materials and Solar Cells 53, 367-377, (1998).
[44] Takashi Minemoto, Takuya Matsui, Hideyuki Takakura, Yoshihiro Hamakawa, “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 & Solar Cells 67, 83-88, (2001).
[45] Yuanping Sun, Tao He, Hongying Guo, Tao Zhang, Weitian Wang, Zhenhong Dai, “Structural and optical properties of the S-doped ZnO particles synthesized by hydrothermal method,” Applied Surface Science 257, 1125–1128, (2010).
[46] Peter Schroer, Peter Kriiger, Johannes Pollmann, “First-principles calculation of the electronic structure of the wurtzite semiconductors ZnO and ZnS,” PHYSICAL REVIEW B VOLUME 47, NUMBER 12, (1993).
[47] B. K. Meyer, A. Polity, B. Farangis, “Structure properties and bandgap bowing of ZnO1-XSX thin films deposited by reactive sputtering,” Applied Physics Letters Vol. 85 No. 21, (2004).
[48] Seong-Un Park, Rahul Sharma, K. Ashok, San Kang, “A study on composition, structure and optical properties of copper-poor CIGS thin film deposited by sequential sputtering of CuGa/In and In/(CuGa+In) precursors,” Journal of Crystal Growth 359, 1–10 (2012).