Gettering and passivation of high efficiency multicrystalline silicon solar cells
- University Center for Excellence in Photovoltaic Research and Education, Department of Electrical and Computer Engineering, Georgia Institute of Technology, Atlanta, Georgia 30332-0250 (United States)
A detailed study was conducted on aluminum and phosphorus gettering in HEM mc-Si and defect passivation by PECVD SiN in EFG mc-Si to achieve high efficiency solar cells on these promising photovoltaic materials. Solar cells with efficiencies as high as 18.6{percent} (1cm{sup 2} area) were achieved on multicrystalline silicon (mc-Si) grown by the heat exchanger method (HEM) by a process which implements impurity gettering, an effective back surface field, front surface passivation, and forming gas annealing. This represents the highest reported solar cell efficiency on mc-Si to date. PCD analysis revealed that the bulk lifetime in certain HEM samples after phosphorus gettering can be as high as 135 {mu}s. By incorporating a deeper aluminum back surface field (Al-BSF), the back surface recombination velocity (S{sub b}) for 0.65 {Omega}-cm HEM mc-Si solar cells was lowered from 10,000 cm/s to 2,000 cm/s resulting in the 18.6{percent} efficient device. It was also observed that a screen-printed/RTP alloyed Al-BSF process could raise the efficiency of both float zone and relatively defect-free mc-Si solar cells by lowering S{sub b}. However, this process was found to increase the electrical activity of extended defects so that mc-Si devices with a significant defect density showed an overall degradation in performance. In the case of EFG mc-Si, neural network modeling in conjunction with a study of post deposition annealing was used to provide guidelines for effective defect passivation by PECVD SiN films. Appropriate deposition and annealing conditions resulted in a 45{percent} increase in cell efficiency due to AR coating and another 25{endash}30{percent} increase due to defect passivation by atomic hydrogen. {copyright} {ital 1997 American Institute of Physics.}
- OSTI ID:
- 564852
- Report Number(s):
- CONF-961178-; ISSN 0094-243X; TRN: 9722M0020
- Journal Information:
- AIP Conference Proceedings, Vol. 394, Issue 1; Conference: National Renewable Energy Laboratory (NREL)/Sandia National Laboratories (SNL) photovoltaics program review meeting, Lakewood, CO (United States), 18-22 Nov 1996; Other Information: PBD: Feb 1997
- Country of Publication:
- United States
- Language:
- English
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