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a-Si:H/c-Si Heterojunction Solar Cells on 50 µm Thick Wafers With Rear Point Contacts
S. Amtablian, M. Labrune, P. Carroy, J. Dupuis, E. Fourmond, A. Kaminski-Cachopo, A. Fave, P. Roca i Cabarrocas, P.-J. Ribeyron, M. Lemiti
Thin Film Paste, Layer Transfer Process, a-Si:H/c-Si Heterojunction, Rear Point Contacts
Thin Films
Subtopic: Thin Film Crystalline Silicon
Event: 23rd European Photovoltaic Solar Energy Conference and Exhibition, 1-5 September 2008, Valencia, Spain
Session: 3AV.1.17
2242 - 2245
ISBN: 3-936338-24-8
Paper DOI: 10.4229/23rdEUPVSEC2008-3AV.1.17
0,00 EUR
Document(s): paper


Crystalline silicon thin film processes for thicknesses in the 20 - 80 @m range are more and more interesting given the issue of silicon shortage. Layer Transfer Processes (LTP) were widely investigated to obtain thin films because of the unavailability of suitable wire sawing. LTP avoids hazardous handling with fragile layers and silicon waste during sawing. In addition, a-Si:H/c-Si heterojunction solar cells are well suited to reduce the photovoltaic power cost. High efficiency on bulk substrate has been demonstrated by Sanyo Corporation and the low temperature process, less than 250 °C, ensures economical gain. In this paper, we present the fabrication of 26 cm2 solar cells on 50 -70 @m thick CZ wafers. The emitter is obtained either by a-Si:H (n+) deposition or by phosphorus diffusion. A 10 % efficiency solar cell on 52 @m thick silicon substrate has been achieved with a-Si:H/c-Si heterojunction. Further improvement is expected with an optimized ITO deposition and a progress in fill factor. Moreover, we also evaluate the effects of rear point contacts obtained by lithography through a dielectric layer. LBIC measurement has been used and a relative 10 % enhancement of photogenerated current has been observed at wavelength 980 nm on no contacted area compared to point contacts area. Moreover defects at the silicon metallization interface can be revealed. Such characterization has been made on 45 @m thick transferred layer.