臺灣博碩士論文加值系統

本篇論文將著重在n型矽基板太陽能電池之射極特性的探討以及研究n型矽基板指叉式背電極太陽能電池的光電特性並藉由模擬，設計與優化太陽能電池。我們利用TCAD模擬軟體模擬新結構來探討有哪些因素會影響或增進太陽能電池之效率。
在第二章中主要探討n型指叉式背電極太陽能電池之二維模擬。藉由改變一些電性參數來探討如何影響電池效率，例如表面複合速度、少數載子生命週期以及射極的比例。此外，藉由模擬軟體模擬離子佈值製程的條件，並優化製程上設定的參數，例如離子佈值的劑量以及熱退火溫度。在第三章中，為了得到更高效率太陽能電池，結合了指叉式背電極太陽能電池以及異質接面太陽能電池的優點，稱之為指叉式背電極異質接面太陽能電池。此結構除了幾何結構會影響效率外，非晶矽的材料特性也會影響電池效率。我們利用TCAD 模擬軟體模擬幾何結構的設計以及非晶矽材料的能隙對效率的影響並進行優化。在第四章中則是探討n型太陽能電池之射極特性。藉由以離子佈值的方式做摻雜，製作一個p+/n/p+的對稱性結構並
進行量測，量測方法為準穩態光電導方法，由於離子佈值會在晶圓表面造成損害，若利用合適的熱退火條件以及優化過的濕蝕刻條件來製作射極，對提升太陽能電池的效率是有幫助的。

In this thesis, the characteristics of emitter of n-type Si-based solar cells are investigated and the enhancements of n-type Si-based interdigitated back contact (IBC) solar cells are also studied. The goals of this thesis are to optimize the parameter of solar cells by numerical simulations using technology computer aided design (TCAD) simulator to provide concepts to improve the performances of cells.
Firstly, we vary the surface recombination velocity (SRV), the bulk lifetime and emitter ratio. Then, we simulate the process of the ion implantation by numerical
simulators using TCAD simulator and optimize the parameter in the fabrication, such as the implanted dose and annealing temperature.
Secondly, we combine the advantages of IBC solar cells and heterojunction with intrinsic thin films (HIT) solar cells to get the higher efficiency of solar cells, called interdigitated back contact silicon heterojunction (IBC-SHJ) solar cells. To optimize the efficiency, we simulate the design of the structure and the bandgap of p, i and n-type amorphous Si layers by using TCAD simulator.
Finally, we discuss the characteristics in the emitter of n-type Si-based solar cells. A p+/n/p+ symmetrical structure is fabricated by ion implantation tool. We measure it to analyze the characteristics of the emitter by means of Quasi-Steady-State Photo-conductance (QSSPC) method. It is helpful to improve the efficiency of solar cells by using the appropriate annealing condition and the optimized wet chemically etching condition since the damage is introduced by ion implantation process.

口試委員會審定書 #
誌謝 i
中文摘要 ii
ABSTRACT iii
CONTENTS v
LIST OF FIGURES viii
LIST OF TABLES xiii
Chapter 1 Introduction 1
1.1 Thesis motivation 1
1.2 Thesis outline 2
Chapter 2 Simulation of Interdigitated Back Contact Solar Cells 4
2.1 Introduction 4
2.2 Simulation Tools 5
2.2.1 Device structure and Parameters 5
2.2.2 Simulation Models 6
2.3 Bulk Lifetime and Emitter Ratio 7
2.4 Analysis of the Surface Recombination Velocity 11
2.5 Optimization of Implanted Condition 14
2.5.1 Annealing Temperature Dependence 14
2.5.2 Implanted Dose Dependence 17
2.6 Conclusion 20
Chapter 3 Simulation of Interdigitated Back Contact Silicon Heterojunction Solar Cells 21
3.1 Introduction 21
3.2 Simulation Tools 23
3.2.1 Device Structure and Parameters 23
3.2.2 Simulation Models 25
3.3 Band Gap of Amorphous Silicon 26
3.3.1 Band Gap of P-type Amorphous Silicon 26
3.3.2 Band Gap of N-type Amorphous Silicon 32
3.3.3 Band Gap of Intrinsic Amorphous Silicon 34
3.4 P-type Amorphous Silicon 36
3.5 Front Surface Field 39
3.6 Conclusion 41
Chapter 4 Emitter Recombination in Silicon Solar Cells 43
4.1 Introduction 43
4.1.1 Quasi-Steady-State Photo-conductance Method 44
4.1.2 High Level Injection Regimes 46
4.2 Emitter Saturation Current Density 47
4.3 Symmetrical Emitter Structure 49
4.3.1 Optimization of the Ion Implanted Dose 49
4.3.2 Wet Chemically Etching 52
4.4 Conclusion 58
REFERENCE 59

[1]International Technology Roadmap for Photovoltaic (ITRPV.net) Results 2014.
[2]D. D. Smith, P. Cousins, S. Westerberg, R. De Jesus-Tabajonda, G. Aniero, and Yu-Chen Shen, "Towards the practical limits of silicon solar cells, " IEEE Journal of Photovoltaics 6.4: 1465-1469 (2014).
[3]M. Lu, S. Bowden, U. Das, R. Birkmire. "Interdigitated back contact silicon heterojunction solar cell and the effect of front surface passivation." Appl. Phys. Lett. 91.6: 3507 (2007).
[4]K. Masuko, et al. "Achievement of more than 25% conversion efficiency with crystalline silicon heterojunction solar cell." Photovoltaics, IEEE Journal of 4.6: 1433-1435 (2014).
[5]M. A. Green, Solar cells: Operating principles, Technology and System Applications. 1986, Kensington: UNSW.
[6]D. Ceuster, et al., "Low cost, high volume production of 22% efficiency silicon solar cells." in Proceedings of the 22nd European Photovoltaic Solar Energy Conference, (2007).
[7]P. J. Cousins, et al., "Generation 3: Improved performance at lower cost." Photovoltaic Specialists Conference (PVSC) 35th IEEE, (2010).
[8]J. Renshaw, A. Rohatgi. “Device optimization for screen printed interdigitated back contact solar cells.” Photovoltaic Specialists Conference (PVSC), 37th IEEE (2011).
[9]D. S. Kim , V. Meemongkolkiat, A. Ebong, B. Rounsaville, V. Upadhyaya, A. Das and A. Rohatgi, “2D-Modeling and development of interdigitated back contact solar cells on low-cost substrates”, Photovoltaic Energy Conversion, Conference Record of the 2006 IEEE 4th World Conference on (Volume:2), May (2006).
[10]Sentaurus Device User Guide, Version G-2012.06. Synopsys. Inc., 2012.
[11]P. P. Altermatt, et al. "The surface recombination velocity at boron-doped emitters: Comparison between various passivation techniques. " in Proceedings of the 21st European Photovoltaic Solar Energy Conference, (2006).
[12]http://www.pveducation.org/pvcdrom/solar-cell-operation/shunt-resistance
[13]F. Grank, et al. "High efficiency back-contact back junction silicon solar cells. ", Fraunhofer Institude for Solar Energy Systems (ISE), (2009).
[14]H. Boo, et al. "Effect of high-temperature annealing on ion-implanted silicon solar cells." International Journal of Photoenergy (2012).
[15]M. G. Kang, J. H. Lee, H. Boo, S. J. Tark, H. C. Hwang, W. J. Hwang, H. O. Kang, D. Kim, "Effects of annealing on ion- implanted Si for interdigitated back contact solar cell. " Current Applied Physics 12.6: 1615-1618 (2012).
[16]P. Procel, et al. "Analysis of the impact of doping levels on performance of back contact-back junction solar cells." Energy Procedia 55: 128-132 (2014).
[17]M. Taguchi, A. Yano, S. Tohoda, K. Matsuyama, Y. Nakamura, T. Nishiwaki, K. Fujita, and E. Maruyama, "24.7% Record Efficiency HIT Solar Cell on Thin Silicon Wafer. ", Proc. 39th IEEE PVSC, Tampa, (2013).
[18]R. Stangl, A. Froitzheim, L. Elstner, W. Fuhs, "Amorphous/crystalline silicon heterojunction solar cells, a simulation study. ", in: 17th European PV Conference, Oct., Munich, (2001).
[19]R. Stangl, J. Haschke, M. Bivour, L. Korte, M. Schmidt, K. Lips, B. Rech, "Planar rear emitter back contact silicon heterojunction solar cells.", Solar Energy Materials & Solar Cells 93 (2009).
[20]M. Tucci, L. Serenelli, E. Salza, S. De Iuliis, L.J. Geerligs, D. Caputo, M. Ceccarelli, G. de Cesare, "Back contacted a-Si:H/c-Si heterostructure solar cells. ", The Journal of Non-Crystalline Solids 354 (2008).
[21]S. Herasimenka, K. Ghosh, S. Bowden and C. Honsberg, "2D modeling of silicon heterojunction interdigitated back contact solar cells. ", in: Proc. 35th IEEE Photovoltaic Specialists Conf., Honolulu, HI, (2009).
[22]D. Diouf, J. P. Kleider, T. Desrues, P. J. Ribeyron, "2D simulations of interdigitated back contact heterojunction solar cells based on n-type crystalline silicon.", Physical Status Solidi C Current Topics in Solid State Physics 7 (2010).
[23]D. Diouf, J. P. Kleider, T. Desrues, P. J. Ribeyron, "Effects of the front surface field in n-type interdigitated back contact silicon heterojunctions solar cells. ", Energy Procedia 2 (2010).
[24]L. Meijun, D. Ujjwal, B. Stuart, H. Steven and B. Robert, "Optimization of interdigitated back contact silicon heterojunction solar cells: tailoring hetero interface band structures while maintaining surface passivation. ", Prog. Photovolt: Res. Appl. (2011)
[25]R. Jeyakumar, T. K. Maiti, and Amit Verma. "Influence of emitter bandgap on interdigitated point contact back heterojunction (a-Si:H/c-Si) solar cell performance." Solar Energy Materials and Solar Cells 109 (2013).
[26]S. Herasimenka, K. Ghosh, S. Bowden, "2D Modeling of Silicon Heterojunction Interdigitated Back Contact Solar Cells. ", Proc. 35th IEEE Photovoltaic Specialist Conference 2010 (2010).
[27]M. Tucci, L. Serenelli, S. De Iuliis, M. Izzi1, G. De Cesare, D. Caputo, "Back contact formation for p-type based a-Si:H/c-Si heterojunction solar cells. ", Physica Status Solidi C Current Topics in Solid State Physics 8 (2011).
[28]H. Mimura, Y. Hatanaka, "Energy band discontinuities in a heterojunction of amorphous hydrogenated Si and crystalline Si measured by internal photo-emission. ", Appl. Phys. Lett. 50 (1987).
[29]M. Sebastiani, L. Di Gaspare, G. Capellini, C. Bittencourt, F. Evangelisti, "Low energy yield spectroscopy as a novel technique for determining band offsets: application to the c-Si(1 0 0)/a-Si:H heterostructure. ", Physical Review Letters 75 (1995).
[30]J. Allen, et al. "Interdigitated back contact silicon hetero-junction solar cells: the effect of doped layer defect levels and rear surface i-layer band gap on fill factor using two-dimensional simulations." Photovoltaic Specialists Conference (PVSC), 2011 37th IEEE, (2011).
[31]U. K. Das, S. Bowden, M. Lu, M. A. Burrows, O. Jani, D. Xu, S.S. Hegedus, R. L. Opila, and R.W. Birkmire, "Progress towards high efficiency all back contact heterojunction c-Si solar cells. ", in: Proceedings of the 18th Workshop on Crystalline Silicon Solar Cells and Modules: Materials and Processes, August 3–6, 2008, Vail, CO, (2008).
[32]F. Granek, C. Reichel, & S. W. Glunz, "Stability of front surface passivation of back-contact back-junction silicon solar cells under UV illumination. " In Proc. 24th Eur. Photovoltaic Solar Energy Conf. Exhib (pp. 1047-1050). (2009).
[33]F. Granek, M. Hermle, C. Reichel, A. Grohe, O. Schultz-Wittmann, & S. Glunz, "Positive effects of front surface field in high-efficiency back-contact back-junction n-type silicon solar cells. " In Photovoltaic Specialists Conference, 2008. PVSC''08. 33rd IEEE (pp. 1-5). IEEE, (2008).
[34]M. Hermle, F. Granek, O. Schultz, and S. W. Glunz, “Analyzing the effects of front-surface fields on back-junction silicon solar cells using the charge-collection probability and the reciprocity theorem”, Journal of Applied Physics 103, 054507 (2008)
[35]Y. Nishi and R. Doering, Handbook of Semiconductor Manufacturing Technology, Marcel Dekker, New York, NY, USA, 2000.
[36]J.D. Plummer, M.D. Deal, and P.B. Griffin, Silicon VLSI Technology (Prentice-Hall, Upper Saddle River, NJ, 2000), Chap. 8.
[37]Sinton-Consulting-Inc., http://www.sintonconsulting.com/.
[38]R. A. Sinton, A. Cuevas, and M. Stuckings, "Quasi-steady-state photoconductance, a new method for solar cell material and device characterization.", in Proceedings of the 25th IEEE Photovoltaic Specialists Conference, Washington DC, USA, 457-60 ,(1996).
[39]B. Fischer, "Loss analysis of crystalline silicon solar cells using photoconductance and quantum efficiency measurements.", Dissertation, University Konstanz, (2003).
[40]R. A. Sinton, and R. M. Swanson. "Recombination in highly injected silicon.", Electron Devices, IEEE Transactions on 34.6, (1987).
[41]M. A. Green, "Intrinsic concentration, effective densities of states, and effective mass in silicon.", Journal of Applied Physics, (1990)
[42]P. Pichler, "Intrinsic Point Defects, Impurities, and Their Diffusion in Silicon.", Springer, (2004).
[43]R. Müller, et al. "Defect removal after low temperature annealing of boron implantations by emitter etch‐back for silicon solar cells." physica status solidi (RRL)-Rapid Research Letters 9.1 (2015)
[44]A. W. Stephens, and M. A. Green. "Effectiveness of 0.08 molar iodine in ethanol solution as a means of chemical surface passivation for photo-conductance decay measurements." Solar energy materials and solar cells 45.3 (1997)
[45]T. Maekawa, and S. Yasushi, "Effect of steady bias light on carrier lifetime in silicon wafers with chemically passivated surfaces." Japanese journal of applied physics 35.2A (1996)