APIVT-Grown Silicon Thin Layers and PV Devices: Preprint
Large-grained (5-20 ..mu..m) polycrystalline silicon layers have been grown at intermediate temperatures of 750-950C directly on foreign substrates without a seeding layer by iodine vapor transport at atmospheric pressure with rates as high as 3 mm/min. A model is constructed to explain the atypical temperature dependence of growth rate. We have also used this technique to grow high-quality epitaxial layers on heavily doped CZ-Si and on upgraded MG-Si substrates. Possible solar cell structures of thin-layer polycrystalline silicon on foreign substrates with light trapping have been examined, compared, and optimized by two-dimensional device simulations. The effects of grain boundary re-combination on device performance are presented for two grain sizes of 2 and 20 mm. We found that 104 cm/s recombination velocity is adequate for 20-m m grain-sized thin silicon, whereas a very low recombination velocity of 103 cm/s must be accomplished in order to achieve reasonable performance for a 2- mm grain-sized polycrystalline silicon device.
- Research Organization:
- National Renewable Energy Lab., Golden, CO (US)
- Sponsoring Organization:
- US Department of Energy (US)
- DOE Contract Number:
- AC36-99GO10337
- OSTI ID:
- 15006971
- Report Number(s):
- NREL/CP-520-31441
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
36 MATERIALS SCIENCE
ATMOSPHERIC PRESSURE
ATMOSPHERIC PRESSURE IODINE VAPOR TRANSPORT (APIVT)
EPITAXIAL LAYERS
GRAIN BOUNDARY
GRAIN SIZE
IODINE
MICROCRYSTALLINE SILICON
PERFORMANCE
PV
RECOMBINATION
RECOMBINATION VELOCITY
SILICON
SINGLE JUNCTION
SOLAR CELLS
SOLAR ENERGY - PHOTOVOLTAICS
SUBSTRATES
TEMPERATURE DEPENDENCE
TRANSPORT
TRAPPING
TWO-DIMENSIONAL DEVICE
VELOCITY