黑色矽巨孔洞陣列結構之總討論

第四章 實驗結果與討論

Table 4-2 Reflectance measurement and experiment results of macroporous arrays structure.

Substrate N-type silicon wafer Etching voltage 1 V

Electrolyte 2.5 wt.% HF Additive 1 wt.% MA

Illuminant power Intensity of illuminations: 32000 lux 525 m silicon wafer

Figure 4-22 Comparison of current of PAECE samples on silicon wafers with different thickness.

Figure 4-23 Comparison of etching depth of PAECE samples on various etching times.

Figure 4-24 Comparison of average aspect ratio of PAECE samples on various etching times.

Figure 4-25 Comparison of average reflectance of PAECE samples on various etching times.

Figure 4-26 Comparison of average reflectance of PAECE 0.5 hr on 525 m and 380

m thick substrate.

Figure 4-27 Comparison of average reflectance of PAECE 1 hr on 525 m and 380

m thick substrate.

Figure 4-28 Comparison of average reflectance of PAECE 1.5 hr on 525 m and 380

m thick substrate.

Figure 4-29 Comparison of average reflectance of PAECE 2 hr on 525 m and 380

m thick substrate.

第四章 實驗結果與討論

若就反射率與蝕刻時間討論，其他學者們所進行的研究，其結構反射率雖然 大致上無法得到與本研究相近的反射率結果，但抗反射結構的製備時間短，甚至 是數秒即可完成。而本研究的研究成果，蝕刻時間 30 min 之情況下，孔洞深度約 16 m，深寬比約 3.2 左右。即能夠分別獲得 1.02 %與 1.05 %的反射率，整體而言 亦相當具有潛力。本研究所提出的黑色矽巨孔洞陣列結構，除了具有極佳的抗反 射性之外，亦具有較大的受光表面積。黑色矽巨孔洞陣列結構除了能維持倒金字 塔結構之外，亦有深凹的巨孔洞，此孔洞未來有機會讓光能夠進行多次反應，進 而增加光源吸收機會，預期未來若使用擴散製程來完成後續的 P-N 接面製程，能 夠得到較佳的電池效率。

第四章 實驗結果與討論

Table 4-3 Compared with references in antireflective structure.

Morphology Mechanism R_w Process

time Ref.

第五章 結論與未來展望

第五章 結論與未來展望

3. 多孔矽成長於 380 m 之矽基板，於光輔助電化學蝕刻製程中，當蝕刻時間為 30 min，即可獲得反射率約為 1.05 %之黑色矽巨孔洞結構，此時巨孔洞深度與 深寬比分別約為 16 m 與 3.2。若再將時間延長至 2 hr 時，巨孔洞深度與深寬 比分別約為 58.8 m 與 11.8。同樣可獲得在 525 m 厚度條件下所形成的五種 特殊結構，巨孔洞深度能由 16 m 加深至 58.8 m，進而增加光源吸收面積並 且降低反射率。

4. 多孔矽成長於 525 m 與 380 m 之矽基板，當光輔助電化學蝕刻再搭配反應 性離子粗化蝕刻 25 min，於 1.5 hr 及 2 hr 長時間之電化學蝕刻情況下，皆能降 低反射率。當蝕刻時間為 2 hr，可進一步降低反射率，於 525 m 與 380 m 之 矽基板情況下，可分別得到 0.73 %與 0.7 %的超低反射之矽結構。

5. 由此研究成果驗證，以此技術製備之結構，當在 1.5 hr 與 2 hr 長時間條件下，

其巨孔洞深度約到達 5060 m 能產生良好的光捕捉效應，並且能夠得到極低 之反射率。以黑色矽巨孔洞陣列結構應用於太陽能電池之抗反射結構製備，對 於往後太陽能電池之轉換效率與普及化將有極大的助益。

第五章 結論與未來展望

第五章 結論與未來展望

(a)

(b)

Figure 5-1 Schematic diagram of (a) inverted pyramid and (b) black silicon macroporous arrays structure.

參考文獻

參考文獻

1. T. Markvart,Solar Electricity. Wiley, 2003.

2. 林明獻,太陽電池技術入門,全華圖書股份有限公司,2007 年 10 月.

3. M.A. Green, J. Zhao, A. Wang, and S. R. Wenham, "Very High Efficiency Silicon Solar Cells—Science and Technology", IEEE Transactions on electron device, Vol.

3, 1999.

4. M. A. Green, K. Emery, Y. Hishikawa and W. Warta, "Solar cell efficiency tables (version 33)", Progress in Photovoltaics: Research and Applications, Vol. 17, pp.

8594, 2009.

5. A. W. Blakers and M. A. Green, "20% efficiency silicon solar cells", Applied Physics Letter, Vol. 48, No. 3, pp. 215217, 1986.

6. R. R. King, R. A. Sinton, and R. M. Swanson, "Front and back surface fields for point-contact solar cells ", IEEE, pp. 538544, 1988.

7. A. Metz and R. Hezel "Record efficiencies above 21% for MIS-contacted diffused junction silicon solar cells ", IEEE, pp. 283286, 1997.

8. J. Zhao, A. Wang and M. A. Green, "24.5% Efficiency silicon PERT Cells on MCZ substrates and 24.7% efficiency PERL cells on FZ substrates ", Progress in Photovoltaics: Research and Applications, Vol. 7, pp. 471474, 1999.

9. J. Zhao, A. Wang, P. P. Altermatt, and M. A. Green, "High efficiency PERT cell on N-type silicon substrates", IEEE, pp. 218221, 2002.

10. Rudolf hezel, "High-efficiency OECO Czochralski-silicon solar cells for mass production", Solar Energy Materials Energy & Solar Cells, Vol. 74, pp. 2533, 2002.

11. R. Hezel, "Novel back contact silicon solar cells designed for very high efficiencies and low-cost mass production ", IEEE, pp. 114117, 2002.

12. J.W. Muller, A. Merkle and R. Hezel, "Self-aligning, industrially feasible back contacted silicon solar cells with efficiencies >18 %", FVS PV-UNI-NETZ, Workshop, pp. 141145, 2003.

參考文獻

13. M. Tanaka, S. Okamoto, S. Tsuge and S. Kiyama "Development of HIT solar cells with more than 21% conversion efficiency and commercialization of highest performance HIT modules", 3rd World Conference on Photovoltaic Energy Conversion, pp. 955958, 2003.

14. S. W. Glunz, E. Schneiderlöchner, D. Kray, A. Grohe, M. Hermle, H. Kampwerth, R. Preu, and G. Willeke "Laser-fired contact silicon solar cells on p-and n-substrates", 19th European Photovoltaic Solar Energy Conference, pp. 408411, 2004.

15. O. Schultz, S. W. Glunz and G. P. Willeke "Multicrystalline silicon solar cells exceeding 20% efficiency", Progress in Photovoltaics: Research Application, Vol.

12, pp. 553558, 2004.

16. E.T. Franklin, A. Blakers, K. Weber and V. Everett "20% efficient sliver cells fabricated with a simplified processing sequence", ANZSES, pp. 16, 2006.

17. M. Hofmann, S. Janz, C. Schmidt, S. Kambor, D. Suwito, N. Kohn, J. Rentsch, R.

Preu and S. W. Glunz "Recent developments in rear-surface passivation at Fraunhofer ISE", Solar Energy materials & solar cells, pp.10741078, 2009.

18. F. Granek, M. Hermle, D. M. Huljic, O. S. Wittmann and S. W. Glunz "Enhanced lateral current transport via the front N⁺ diffused layer of N-type high-efficiency back-junction back-contact silicon solar cells", Prog. in Photovolataics: Res. Appl., Vol. 17, pp. 4756, 2009.

19. N. P. Harder, S. Hermann, A. Merkle, T. Neubert, T. Brendemuhl, P. Engelhart, R.

Meyer and R. brendel "Laser-processed high-efficiency silicon RISE-EWT solar cells and characterisation", Physica Status Solidi C, pp.736743, 2009.

20. V. Y. Yerokhova, R. Hezelb, M. Lipinskic, R. Ciachc, H. Nagelb, A. Mylyanycha, and P. Panekc, "Cost-effective methods of texturing for silicon solar cells", Solar Energy Material and Solar Cells, Vol. 72, pp. 291298, 2002.

21. K. Tsujino and M. Matsumura, "Formation of a low reflective surface on crystalline silicon solar cells by chemical treatment using Ag electrodes as the catalyst", Solar Energy Material and Solar Cells, Vol. 90, pp. 15271532, 2006.

22. J. S. Yoo, I. O. Parm, U. Gangopadhyay, Kyunghae Kim, S. K. Dhungel, D.

Mangalaraj, and J. Yi, "Black silicon layer formation for application in solar cells", Solar Energy Material and Solar Cells, Vol. 90, pp. 30853093, 2006.

參考文獻

23. B. C. Chakravarty, J. Tripathi, A. K. Sharma, R. Kumar, K. N. Sood, S. B. Samanta, and S. N. Singh, "The growth kinetics and optical confinement studies of porous Si for application in terrestrial Si solar cells as antireflection coating", Solar Energy Material and Solar Cells, Vol. 91, pp. 701706, 2007.

24. C. H. Sun, W. L. Min, N. C. Lin, P. Jiang and B. Jiang "Templated fabrication of large area subwavelength antireflection gratings on silicon", Applied physics letters, Vol. 91, 231105, 2007.

25. C. T. Wu, F. H. Ko, and C. H. Lin, "Self-organized tantalum oxide nanopyramidal arrays for antireflective structure", Applied Physics Letters, Vol. 90, 171911, 2007.

26. C. H. Sun, P. Jiang and B. Jiang “broadband moth-eye antireflection coatings on silicon", Applied physics letters, Vol. 92, 061112, 2008.

27. K. Nishioka, S. Horita, K. Ohdaira, and H. Matsumura, "Antireflection subwavelength structure of silicon surface formed by wet process using catalysis of single nano-sized gold particle", Solar Energy Material and Solar Cells, Vol. 92, pp.

919922, 2008.

28. M. D. B. Charlton, H. W. Lau, and G. J. Parker, "High aspect ratio photo-assisted electro-chemical etching of silicon and its application for the fabrication of quantum wires and photonic band structures", IEE Colloquium on Microengineering Applications in Optoelectronics, pp. 19, 1996.

29. A. Satoh, "Formation of through-holes on silicon wafer by optical excitation electropolishing method", Japanese Journal of Applied Physics, Vol. 39, pp.

378386, 2000.

30. V. Lehmann and H. Föll, "Formation mechanism and properties of electrochemically etched trenches in n-type silicon", Journal of the Electrochemical Society, Vol. 137, pp. 653658, 1990.

31. V. Lehmann and U. Grüning, "The limits of macropore array fabrication", Thin Solid Films, Vol. 297, pp. 1317, 1997.

32. V. Lehmann, "The physics of macropore formation in low-doped n-type silicon", Journal of the Electrochemical Society, Vol. 140, pp. 28362843, 1993.

33. V. Lehmann, "Porous silicon formation and other photo-electrochemical effects at silicon electrodes anodized in hydrofluoric acid", Applied Surface Science, Vol. 106, pp. 402405, 1996.

參考文獻

34. V. Lehmann, "Porous silicon-a new material for MEMS", Proc. of Micro Electro Mechanical System Workshop, California, USA, pp. 16, 1996.

35. S. O. Kasap, Optoelectronics and photonics, Canada: Prentice Hall, 2001.

36. A. Uhir, "Electrolytic shaping of germanium and silicon", Bell System Technical Journal, Vol. 35, pp. 333347, 1956.

37. S. Rowson, A. Chelnokov, and J. M. Lourtioz, "Two-dimensional photonic crystals in macroporous silicon: From mid-infrared (10 m) to telecommunication wavelengths (1.31.5 m)", Journal of Lightwave Technology, Vol. 17, pp.

19891995, 1999.

38. U. Grüninga, V. Lehmann, S. Ottow, and K. Busch, "Macroporous silicon with a complete two-dimensional photonic band gap centered at 5 µm", Applied Physics Letters, Vol. 68, 747, 1996.

39. F. Müller, A. Birner, U. Gösele, V. Lehmann, S. Ottow, and H. Föll,"Structuring of macroporous silicon for applications as photonic crystals", Journal of Porous Material, 201, 2000.

40. P. Roussel, V. Lysenko, B. Remaki, G. Delhomme, A. Dittmar, and D. Barbier,

"Thick oxidised porous silicon layers for the design of a biomedical thermal conductivity microsensor", Sensor and Actuators A, Vol. 74, pp. 100103, 1999.

41. M. B. Ali, R. Mlika, H. B. Ouada, R. M’ghaïeth, and H. Maâref, "Porous silicon as substrate for ion sensors", Sensor and Actuators A, Vol. 74, pp. 123125, 1999.

42. S. Bastide, A. Albu-Yaron, S. Strehlke, and C. Lévy-Clément, "Formation and characterization of porous silicon layers for application in multicrystalline silicon solar cells", Solar Energy Materials & Solar Cells, Vol. 57, pp.393417, 1999.

43. H. Ohji, S. Izuo, P. J. French, and K. Tsutsumi, "Pillar structures with a sub-micron space fabricated by macroporous-based micromachining", Sensor and Actuators A, Vol. 97-98, pp. 744748, 2002.

44. S. Izuo, H. Ohji, and P. J. French, "A novel electrochemical etching technique for n-type silicon", Sensors and Actuators A, Vol. 97, pp. 720724, 2002.

45. H. Ohji, P.J. French, and K. Tsutsumi, "Fabrication of mechanical in p-type silicon using electrochemical etching", Sensors and Actuators, Vol. 82, pp. 254258, 2000.

46. R. L. Smith and S. D. Collins, "Porous silicon formation mechanisms", Journal of Applied Physics, Vol. 71, pp. 122, 1992.

47. V. Lehmann and S. Ronnebeck, "The physics of macropore formation in low-doped p-type silicon", Journal of the Electrochemical Society, Vol. 146, pp. 29682975, 1999.

參考文獻

48. 吳浩青 等人, "電化學動力學", 科技圖書股份有限公司, pp. 179183, 2001.

49. X. Badel, "Electrochemically etched pore arrays in silicon for X-ray imaging detectors", Ph.D Thesis, The Royal Institute of Technology, pp. 521, 2005.

50. M. I. J. Beale, J. D. Benjamin, M. J. Uren, N. G. Chew, and A. G. Cullis, "An experimental and theoretical study of the formation and microstructure of porous silicon", Journal of Crystal Growth, Vol. 73, pp. 622636, 1985.

51. M. I. J. Beale, N. G. Chew, M. J. Uren, A. G. Cullis, and J. D. Benjamin,

"Microstructure and formation mechanism of porous silicon", Applied Physics Letters, Vol. 46, pp. 8688, 1985.

52. X. G. Zhang, S. D. Collins, and R. L. Smith, "Porous silicon formation and electropolishing of silicon by anodic polarization in HF solution", Journal of the Electrochemical Society, Vol. 136, pp. 15611565, 1989.

53. X. G. Zhang, "Mechanism of pore formation on n-type silicon", Journal of the Electrochemical Society, Vol. 138, pp. 37503756, 1991.

54. R. L. Smith, S. F. Chuang, and S. D. Collins, "A theoretical model of the formation morphologies of porous silicon", Journal of Electronic Materials, Vol. 17, pp.

533541, 1988.

58. R.E. Camacho, et al., “Carbon Nanotube Arrays for Photovoltaic Applications,”

Nanomaterials for Electronic Applications, pp. 3942, 2007.

59. http://www.pvcdrom.pveducation.org/index.html

60. http://www.udel.edu/igert/pvcdrom/APPEND/AM0AM1_5.xls

61. S. Ronnebeck, J. Carstensen, S. Ottow and H. Foll, "Crystal orientation dependence of macropore growth in n-type silicon ", Electrochemical and Solid-State Letters, Vol. 3, pp. 126128, 1999.