臺灣博碩士論文加值系統

本篇論文中，主要探討用化學沐浴沉積法以及射頻濺鍍機製作二硫化錫緩衝層。我們提出奈米球以及奈米牆兩種表面形貌來製作高品質的二硫化錫薄膜並且應用在銅鋅錫硫薄膜太陽能電池上。在薄膜特性分析主要使用拉曼量測、掃描式電子顯微鏡、能量分佈分析儀與吸收光譜儀。
在光學特性、表面形貌以及拉曼光譜分析顯示在SnCl4為0.3M，TAA為0.5M、55℃成長45分鐘的奈米球薄膜，SnCl4為0.1M，TAA為0.15M、60℃成長45分鐘的奈米牆薄膜，以及濺鍍功率30瓦，製成壓力20豪托可以成長出高品質的二硫化錫薄膜。其薄膜擁有很好的覆蓋性及均勻性，並且在光特性方面可以看出在400奈米到1000奈米其穿透率都可以在75%以上且能帶寬度約為3eV。並且，我們發現使用CBD方式來沉積二硫化錫薄膜的品質會比用濺鍍機的方式還來的適合。
最後，使用二硫化錫最佳參數成長在銅鋅錫硫薄膜太陽能電池元件上，而實驗結果可以證明二硫化錫緩衝層可以成功且均勻地沉積在銅鋅錫硫吸收層上。

In this study, the SnS2 buffer layer was investigated by chemical bath deposition and RF sputter. We provided two morphologies, nano-wall and nano-partical to fabricate high quality SnS2 thin films and used this layer to deposit on CZTS thin film solar cell. The characteristic analysis of these films carried out by Raman spectra, scanning electron microscope (SEM), energy dispersive spectrometer (EDS), UV/VIS spectrophotometer.
Optical properties, surface morphology and Raman spectrum are analyzed and we came to the conclusion that the nano-particles deposited with [SnCl4] =0.3M and [TAA] =0.5M for 45min and 55℃, the nano-wall deposited with [SnCl4] =0.1M and [TAA] =0.15M for 45min and 60℃ and the SnS2 thin film deposited with the RF power is 30W and the pressures is 20mTorr have good quality than others. The optical investigations revealed the film was good adhered and uniform and the transmittance was ≧75%, and the optical band gap of these films was found to be about 3eV. And, we found the SnS2 buffer layer with CBD method is better than sputter.
Finally, these good parameters are used for SnS2 layer and incorporated with that of CZTS absorber layer to fabricate the solar cell. We found the SnS2 thin film is successfully and uniformly to deposit on CZTS absorber layer.

誌 謝 1
Abstract II
摘 要 III
Contents IV
List of Figure VII
List of Table X
Chapter 1 Introduction 1
1.1 Solar Energy 1
1.2 Solar Cell History 2
1.3 Thin Film Solar Cells 3
1.4 Objectives of This Thesis 4
Chapter 2 Theory 6
2.1 Solar Spectrum 6
2.2 Principles of solar cell 9
2.2.1 P-N diode 9
2.2.2 I-V Characteristics of P-N Diode 11
2.2.3 Open Circuit Voltage 13
2.2.4 Short Circuit Current 15
2.2.5 Fill Factor 15
2.2.6 Efficiency 16
2.3 CZTS Thin Film Solar Cell Structure 17
2.4 Buffer Layer for Solar Cell 19
2.4.1 Different Deposition of Buffer Layer 21
2.4.2 Structure of Tin Disulfide 22
2.5 Chemical Bath Deposition 23
2.5.1 Mechanism of Thin Film Growth 24
Chapter 3 Experimental 26
3.1 Experimental procedures 26
3.2 Equipment for Experiment 30
3.2.1 Radio Frequency Sputter System (RF sputter) 30
3.3 Measurement Techniques for Experiment 32
3.3.1 Scanning Electron Microscope (SEM) 32
3.3.2 Energy Dispersive X-ray Spectroscopy (EDS) 34
3.3.3 Ultraviolet-visible spectrometer (UV-VIS) 35
3.3.4 Photoluminescence (PL) 36
3.3.5 Raman spectroscopy 37
3.3.6 Solar simulator 38
Chapter 4 Results and Discussion 40
4.1 Mo back contact 40
4.2 CZTS Absorber Layer 41
4.3 I-Zno and ITO Window Layer 44
4.4 SnS2 Buffer Layer 45
4.4.1 Preparing SnS2 Buffer Layer by CBD 46
4.4.2 Nano-particle morphology of SnS2 thin films 46
4.4.2.1 Nano-particle morphology of SnS2 thin films prepared at various temperature by CBD ………………………………………………………………………………47
4.4.2.2 Nano-particle morphology of SnS2 thin films prepared at various tin concentration by CBD 51
4.4.2.3 Nano-particle morphology of SnS2 thin films prepared at various sulfur concentration by CBD 55
4.4.2.4 Nano-particle morphology of SnS2 thin films prepared at various deposition time by CBD 58
4.4.2.5 PL Measurement for Nano-particle morphology of SnS2 thin films by CBD 61
4.4.3 Nano-wall morphology of SnS2 thin films 62
4.4.3.1 Nano-wall morphology of SnS2 thin films prepared at various temperature by CBD…………………………………………………………………………………..62
4.4.3.2 Nano-wall morphology of SnS2 thin films prepared at various tin concentration by CBD 66
4.4.3.3 Nano-wall morphology of SnS2 thin films prepared at various sulfur concentration by CBD 69
4.4.3.4 Nano-particle morphology of SnS2 thin films prepared at various deposition time by CBD 73
4.4.3.5 PL Measurement for Nano-particle morphology of SnS2 thin films by CBD 75
4.4.4 Preparing SnS2 Buffer Layer by Sputter 76
4.4.4.1 The SnS2 thin films prepared at various RF power by sputter 77
4.4.4.2 The SnS2 thin films prepared at various pressure by sputter 80
4.4.5 Comparing CBD and sputter methods for depositing SnS2 thin films 82
4.5 The SnS2 Buffer Layer deposited on CZTS Absorber Layer 83
Chapter 5 Conclusions and Future Work 85
5.1 Conclusions 85
5.2 Future work 87
References 88

[1] http://www.energybandgap.com/power-generation/efficiency-of-solar-panels/
[2] P. Jackson*, D. Hariskos, 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%,” Prog. Photovolt: Res. Appl, vol. 19, pp. 894-897, 2011.
[3] T. K. Todorov, J. Tang, S. Bag, O. Gunawan, T. Gokmen and Y. Zhu, and D. B. Mitzi, “Beyond 11% efficiency: characteristics of State-of-the-Art Cu2ZnSn(S,Se)4 Solar Cells,” Adv. Energy Mater., vol. 3, pp. 34-38, 2013.
[4] P. T. Huang, “Investigation of Zinc-sulfide buffer layer fabricated by RF Sputter for CIAS solar cell application,” Master thesis, National Tsing Hua University, July 2012.
[5] A. Ennaoui, S. Siebentritt, M.Ch. Lux-Steiner, W. Riedl and F. Karg, “High-e efficiency Cd-free CIGSS thin-film solar cells with solution grown zinc compound buffer layers,” Solar Energy Materials & Solar Cells, vol.67, pp.31-40, 2001.
[6] R. Mikami, H. Miyazaki, T. Abe, A. Yamada and M. Konagai, “Chemical bath deposited (CBD)-ZnO buffer layer for CIGS solar cells,” in Pro. 3rd World Conference of Photovoltaic Energy Conversion, Osaka, Japan, 2003, pp. 519.
[7] D. Hariskos, M. Ruckh, U. Rqhle, T. Walter, H.W. Schock, J. Hedstrfm and L. Stolt, “A novel cadmium free buffer layer for Cu(In,Ga)Se2 based solar cells,” Solar Energy Materials and Solar Cells, vol. 41/42, pp. 345-353, 1996.
[8] M. Konagai, Y. Ohtake, and T. Okamoto, “Development of Cu(InGa)Se2 thin film solar cells with Cd-free buffer layers,” Mater. Res. Soc. Symp. Proc., vol. 426, pp.153, 1996.
[9] Y. Tokita, S. Chaisitsak, H. Miyazaki, R. Mikami, A. Yamada, M. Konagai, “Novel In(OH)3:Zn2+ buffer layer for Cu(InGa)Se2 based solar cells,” Jpn. J. Appl. Phys., vol. 41, pp.7407, 2002.
[10] A. Luque, S. Hegedus, Handbook of Photovoltaic Science and Engineering chapter 3, Page 62.
[11] J. Nelson, The Physics of solar cells. London: imperial College Press, 2003.
[12] H. Flammersberger, “Experimental study of Cu2ZnSnS4 thin films for solar cells,” PhD thesis, Uppsala universitet, December 2010.
[13] Photovoltaics CDROM Christiana Honsberg and Stuart Bowden
[14] Sinton RA, Cuevas A. Contactless determination of current-voltage characteristics and minority-carrier lifetimes in semiconductors from quasi-steady-state photo conductance data. 1996, 69: 2510-2512.
[15] 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, 2005.
[16] G. B. Dubrovski, “Crystal structure and electronic spectrum of SnS2,” Physics of The Solid State, vol.40, pp.1557-1562, 1998.
[17] S. M. Pawar, B. S. Pawar, J. H. Kim, Oh-Shim Joo, and C. D. Lokhande, “Recent status of chemical bath deposited metal chalcogenide and metal oxide thin films,” Current Applied Physics, vol.11, pp.117-161, 2011.
[18] P. O’Brien and J. McAleese, “Developing an understanding of the processes controlling the chemical bath deposition of ZnS and CdS,” J. Mater. Chem.,, vol.8, pp.2309-2314, 1998.
[19] K.T.R. Reddy, G. Sreedevi, K. Ramya and R.W. Miles, “Physical properties of nano-crystalline SnS2 layers grown by chemical bath deposition,” Energy Procedia, vol. 15, pp. 340-346, 2012.
[20] S. Liu, X. Yin, Q. Hao, M. Zhang, L. Li, L. Chen, Q. Li, Y. Wang, and T. Wang, “Chemical bath deposition of SnS2 nanowall arrays with improved electrochemical performance for lithium ion battery,” Materials Letters, vol. 64, pp. 2350-2353, 2010.
[21] L. L. Cheng, M. H. Liu, S. C. Wang, M. X. Wang, G. D. Wang, Q. Y. Zhou and Z. Q. Chen, “Nano-flower and nano-wall SnS2 films fabricated with controllable shape and size by the PECVD method,” Semicond. Sci. Technol., vol. 28, pp. 1-8, 2013.
[22] J Li, Y. C. Zhang, and M. Zhang, “Preparation of SnS2 thin films by chemical bath deposition,” Materials Science Forum, vols. 663-665, pp. 104-107, 2011.
[23] JCB Malaquias, “Cu2ZnSnS4 thin films for PV: Comparison of two growth methods,” PhD thesis, Universidade de Aveiro, 2010.
[24] http://en.wikipedia.org/wiki/Sputter_deposition
[25] http://en.wikipedia.org/wiki/Scanning_electron_microscope
[26] James D. Plummer, Michael D. Deal and Peter B. Griffin, Silicon VLSI Technology, Chapter 4, p.174-175, Prentice Hall (2000).
[27] http://en.wikipedia.org/wiki/Energy-dispersive_X-ray_spectroscopy
[28] http://en.wikipedia.org/wiki/Ultraviolet%E2%80%93visible_spectroscopy
[29] T.H. Patel, “Influence of Deposition Time on Structural and Optical Properties of Chemically Deposited SnS Thin Films,” The Open Surface Science Journal, vol. 4, pp. 6-13, 2012.
[30] D. Heiman, “Photoluminescence Spectroscopy,” Physics of Waves and Optics, 2004.
[31] http://en.wikipedia.org/wiki/Raman_spectroscopy
[32] Y. Kamikawa-Shimizu, S. Shimada, M. Watanabe, A. Yamada, K. Sakurai, S. Ishizuka, H. Komaki, K. Matsubara, H. Shibata, H. Tampo, K. Maejima, and S. Niki, “Effects of Mo back contact thickness on the properties of CIGS solar cells,” Phys. Status Solidi A 206, no. 5, pp.1063 –1066, 2009.
[33] K. H. Yoon, S. K. Kim, R. B. V. Chalapathy, J. H. Yun, J. C. Lee and J. Song, “Characterization of a Molybdenum Electrode Deposited by Sputtering and Its Effect on Cu(In,Ga)Se 2 Solar Cel,” Journal of the Korean Physical Society, Vol. 45, No. 4, pp. 1114∼1118, Oct. 2004.
[34] A. Akkari, C. Guasch, N. Kamoun-Turki, “Chemically deposited tin sulphide,” Journal of Alloys and Compounds, vol. 490, pp. 180-183, 2010.
[35] S. K. Panda, A. Antonakos, E. Liarokapis, S. Bhattacharya, and S. Chaudhuri “Optical properties of nanocrystalline SnS2 thin films,” Materials Research Bulletin, vol. 42, pp. 576-583, 2007.
[36] Y. C. Zhang, Z. N. Du, S. Y. Li, and M. Zhang, “Novel synthesis and high visible light photocatalytic activity of SnS2 nanoflakes from SnCl2•2H2O and S powders,” Applied Catalysis B: Environmental, vol. 95, pp. 153-159, 2010.
[37] J. Chao, Z. Xie, X. Duan, Y. Dong, Z. Wang, J. Xu, Bo L., B. Shan, J. Ye, and D. Chen and G. Shen, “Visible-light-driven photocatalytic and photoelectrochemical properties of porous SnSx (x=1,2) architectures,” CrystEngComm, vol. 14, pp. 3163-3168, 2012.