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High efficiency screen‐printed EFG Si solar cells through rapid thermal processing‐induced bulk lifetime enhancement
Author(s) -
Nakayashiki K.,
Meemongkolkiat V.,
Rohatgi A.
Publication year - 2005
Publication title -
progress in photovoltaics: research and applications
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.286
H-Index - 131
eISSN - 1099-159X
pISSN - 1062-7995
DOI - 10.1002/pip.569
Subject(s) - materials science , wafer , optoelectronics , passivation , silicon , carrier lifetime , quantum efficiency , scanning electron microscope , doping , enhanced data rates for gsm evolution , thermal , nanotechnology , composite material , telecommunications , physics , computer science , meteorology , layer (electronics)
This paper shows that one second (1 s) firing of Si solar cells with screen‐printed Al on the back and SiN x anti‐reflection coating on the front can produce a high quality Al‐doped back‐surface‐field (Al‐BSF) and significantly enhance SiN x ‐induced defect hydrogenation in the bulk Si. Open‐circuit voltage, internal quantum efficiency measurements, and cross‐sectional scanning electron microscopy pictures on float‐zone silicon cells revealed that 1 s firing in rapid thermal processing at 750°C produces just as good a BSF as 60 s firing, indicating that the quality of Al‐BSF region is not a strong function of RTP firing time at 750°C. Analysis of edge‐defined film‐fed grown (EFG) Si cells showed that short‐term firing is much more effective in improving the hydrogen passivation of bulk defects in EFG Si. Average minority‐carrier lifetime in EFG wafers improved from ∼3 to ∼33 μs by 60 s firing but reached as high as 95μs with 1 s firing, resulting in 15·6% efficient screen‐printed cells on EFG Si. Copyright © 2004 John Wiley & Sons, Ltd.