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High levels of carrier injection in polycrystalline Si may arise, for example, in solar cells under concentrated sunlight. Mechanisms for non-radiative carrier recombination include trap-mediated SRH and higher-order processes, e.g., Auger recombination [1]. In this paper we present our experimental results for intensity-dependent carrier lifetimes and conduction currents in polycrystalline Si wafers illuminated with pulses of up to 50 Sun intensity. We also use a computational model for carrier transport that includes both SRH and Auger recombination mechanisms, in order to explain our experiments. The model allows quantifying recombination rate dependence on carrier concentration. Our goal is to relate the recombination rates to Si microstructure and defect densities [2] that are revealed by IR PL images. We acknowledge the NSF support through grant 1505377. [1] A. Richter, S.W. Glunz, F. Werner, J. Schmidt, and A. Cuevas, Improved quantitative description of Auger recombination in crystalline silicon, Phys. Rev. B 86, 165202 (2012). [2] H. C. Sio, T. Trupke, D. Macdonald, Quantifying carrier recombination at grain boundaries in multicrystalline silicon wafers through photoluminescence imaging. J. Appl. Phys. 116, 244905 (2014).
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Carrier transport in polycrystalline silicon at high optical injection: transient photoconductance vs. numerical modeling
This paper discusses our experimental results obtained for several p-type polycrystalline Si wafers using transient photoconductance decay method in combination with a numerical model that accounts for the carrier density dependence of recombination lifetime. Using peak illumination intensities of up to 65 Suns, we are able to estimate the recombination rates for the various carrier recombination mechanisms separately. The model with such realistic recombination parameters produces a realistic diffusion length of minority carriers in Si at high optical injection. Our approach can be applied to the characterization of semiconductor materials for concentrator photovoltaics as well as to design of optoelectronic devices.
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- Award ID(s):
- 1505377
- PAR ID:
- 10025816
- Date Published:
- Journal Name:
- 44th IEEE-PVSC
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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