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Assessment of Bulk and Interface Quality for Liquid Phase Crystallized Silicon on Glass
摘要： This paper reports on the electrical quality of liquid phase crystallized silicon (LPC-Si) on glass for thin-film solar cell applications. Spatially resolved methods such as light beam induced current (LBIC), microwave photoconductance decay (MWPCD) mapping, and electron backscatter diffraction were used to access the overall material quality, intra-grain quality, surface passivation, and grain boundary (GB) properties. LBIC line scans across GBs were fitted with a model to characterize the recombination behavior of GBs. According to MWPCD measurement, intra-grain bulk carrier lifetimes were estimated to be larger than 4.5 μs for n-type LPC-Si with a doping concentration in the order of 1016 cm?3. Low-angle GBs were found to be strongly recombination active and identified as highly defect-rich regions which spatially extend over a range of 40–60 μm and show a diffusion length of 0.4 μm. Based on absorber quality characterization, the influence of intra-grain quality, heterojunction interface, and GBs/dislocations on the cell performance were separately clarified based on two-dimensional (2-D)-device simulation and a diode model. High back surface recombination velocities of several 105 cm/s are needed to get the best match between simulated and measured open circuit voltage (Voc), indicating back surface passivation problem. The results showed that Voc losses are not only because of poor back surface passivation but also because of crystal defects such as GBs and dislocation.
关键词： Bulk lifetime,heterojunction,grain boundaries (GBs),two-dimensional (2-D)-device simulation,liquid phase crystallized silicon (LPC-Si),light beam induced current (LBIC)
更新于2025-11-14 15:25:21
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[IEEE 2018 4th IEEE International Conference on Emerging Electronics (ICEE) - Bengaluru, India (2018.12.17-2018.12.19)] 2018 4th IEEE International Conference on Emerging Electronics (ICEE) - Mapping of Bulk Diffusion Length and Effective Back Surface Recombination Velocity in Silicon Solar Cells
摘要： Mapping of diffusion length (L) in the bulk region and effective back surface recombination velocity (SRV) in Al-BSF and PERC Si solar cells has been carried out by utilizing the spectral response (SR) at desired wavelengths. Light beam induced current (LBIC) technique was used to generate the maps of SR and re?ectivity (R) on cell area (6”x6”). MATLAB tool was used to convert the spatial maps of SR and R into L and SRV. We found that (i) the distribution of L in multi-crystalline cells varied from grain to grain in wide range (150-600 μm) while in mono-crystalline cells, it varied in rather narrow range (450-600 μm) ; (ii) the values of SRV for PERC cells (120-250 cm/sec for mono-crystalline and 100-250 cm/sec for multi-crystalline) and Al-BSF cells (320-400 cm/sec for mono-crystalline and 250-350 cm/sec for multi-crystalline) differ by considerable magnitude due to passivation quality at back side. Three multi-crystalline Al-BSF Si solar cells of cell ef?ciencies 17.6%, 17.9% and 18.1% were investigated with the proposed methodology and demonstrated that the ef?ciency de?cit is primarily due to defects present in bulk material and poor back surface passivation.
关键词： Light beam induced current,Surface recombination velocity,Diffusion length,Si solar cells
更新于2025-09-23 15:19:57