Optimization of laser doping process in crystalline silicon solar cells

Year 2013, Volume: 3 Issue: 3, 711 - 716, 01.09.2013

ABHISHEK Sharan Basudev Prasad

Abstract

A large area selective emitter patterning scheme is developed and reported in the present study that features a single additional step compared to the standard process. Initially, trials are conducted to achieve a uniform base sheet resistance of 100±10 Ω/sq in p-type c-Si wafers using POCl3 diffusion on a large area 156 x 156 mm silicon wafers. Thereafter, employing a nanosecond, Q-switched, green laser and phosphosilicate glass layer (PSG) as a dopant source, areas below the front contact fingers are heavily doped while areas between them are kept lowly doped, thus realizing a selective emitter. This study refers to optimization of diffusion parameters to achieve uniform diffusion of base sheet resistance of 100±10 Ω/sq and optimization of laser parameters for achieving localized regions of high doping to attain selective emitter structure.

Keywords

Laser, Doping, Diffusion, Crystalline silicon solar cell, sheet resistance.

References

• Kerr MJ, Cuevas A. General parameterization of Auger recombination in crystalline silicon. Applied Physic Letters 2002; 91: 2473–2480. 10.1063/ 1.1432476.
• Kerr MJ, Schmidt J, Cuevas A, Bultman JH. Surface recombination velocity of phosphorus-diffused silicon solar cell emitters passivated with plasma enhanced chemical vapor deposited silicon nitride and thermal silicon oxide. Journal of Applied Physics 2001; 89: 3821–3826. 10.1063/1.1350633.
• Zhao J, Wang A, Green MA. 24.5% efficiency silicon PERT cells on MCZ substrates and 24.7% effciency PERL Photovoltoltaics: Research and Applications 1999; 7: 471–474. 12)7:6<471::AID.-PIP298>3.0.CO;2-7. Progress in
• 1002/(SICI)1099-159X(199911/
• Engelhart P, Hermann S, Neubert T, Plagwitz H, Grischke R, Meyer R, Klug U, Schoonderbeek A, Stute U, Brendel R. Laser ablation of SiO2 for locally contacted Si solar cells with ultrashort pulses. Progress in Photovoltaics: Research and Applications 2007; 15: 521– 527. 10.1002/ pip.758.
• Szlufcik J, Elgamel HE, Ghannam M, Nijs J, Mertens R. Simple integral screenprinting process for selective emitter polycrystalline silicon solar cells. Applied Physics Letter 1991; 59: 1583–1584. 10.1063/ 1.106291.
• Hopman S, Fell A, Mayer K, Fleischmann C, Drew K, Kray D, Granek F. Study on laser parameters for silicon solar cells with LCP selective emitters. Proceedings if the 24th European photovoltaic solar energy conference, edited by: W. C. Sinke, H. A. Ossenbrink, and P. Helm (WIP, Munich, Germany, 2009), 1072.
• Lauermann T, Dastgheib-Shirazi A, Book F, Raabe B, Hahn G, Haverkamp H, Habermann D, Demberger C, Schmid C. InSECT: an inline selective emitter concept with high efficiencies at competitive process costs improved with inkjet masking technology. Proceedings of the 24th European photovoltaic solar energy conference, edited by: W. C. Sinke, H. A. Ossenbrink, and P. Helm (WIP, Munich, Germany, 2009), 1767.
• Shi Z, Wenham S, Ji J. Mass production of the innovative PLUTO solar cell technology. Proceedings of the 34th IEEE photovoltaic specialists conference, Philadelphia, USA, edited by: (IEEE, New York, USA, 2009), 1922.
• Kooi E. Formation and composition of surface layers and solubility limits of phosphorus during diffusion in silicon. Journal of the Electrochemical Society 1964; 111: 1383– 1387.