Abstract
This work adapts a model to simulate the carrier injection dependent minority carrier lifetime of crystalline silicon passivated with hydrogenated amorphous silicon at elevated temperatures. Two existing models that respectively calculate the bulk lifetime and surface recombination velocity are used and the full temperature dependency of these models are explored. After a thorough description of these temperature dependencies, experimental results using this model show that the minority carrier lifetime changes upon annealing of silicon heterojunction structures are not universal. Furthermore, comparisons of the temperature dependent model to using the room temperature model at elevated temperatures is given and significant differences are observed when using temperatures above 100 °C. This shows the necessity of taking temperature effects into account during in-situ annealing experiments.
Highlights
Silicon Heterojunction (SHJ) solar cells are the world record holding silicon-based solar cell technology. Kaneka holds this record with 26.33 % conversion efficiency using the SHJ concept in an interdigitated back contact (IBC) solar cell.[1]
In order to improve the performance of solar cells based on this technology a deep understanding of the surface passivation of crystalline silicon (c-Si) wafers using hydrogenated amorphous silicon (a-Si:H) is vital
Given the metastable nature of defects in a-Si:H as observed through the StaeblerWronski Effect,[3] research groups have been investigating the effect of light soaking and annealing on the passivation quality of a-Si:H in SHJ structures.[4,5]
Summary
Silicon Heterojunction (SHJ) solar cells are the world record holding silicon-based solar cell technology. The passivation quality at the surface is a large factor in achieving the high open circuit voltage (V OC) necessary to reach such high conversion efficiencies.[2] Given the metastable nature of defects in a-Si:H as observed through the StaeblerWronski Effect,[3] research groups have been investigating the effect of light soaking and annealing on the passivation quality of a-Si:H in SHJ structures.[4,5] One way to investigate this effect is to use photoconductance decay (PCD) measurements to study the carrier injection dependent lifetime of wafers passivated with a-Si:H.6. This is followed by annealing experiments to show a potential application of this temperature dependent model
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