Fabrication And Characterization Of High-Energy Radiation Resistant Bsf Solar Cell
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Date
2015-06
Authors
ALI, KHURAM
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Abstract
The present research work deals with the fabrication and characterization of crystalline silicon (c-Si) solar cells with and without back surface field (BSF)/front surface passivation (FSP) as well as the as-grown Si solar cell. The study also combines the low cost optimization of the BSF-FSP solar cell devices to form radiation resistance Si solar cell. In the first part, Si solar cells with and without BSF (n+-p-p+) were fabricated. BSF cells with antireflection coating (ARC) were optimized with and without FSP while non-BSF cells without FSP were fabricated with and without ARC. The solar cells were characterized through electrical (AM 1.5 G, 100 mW/cm2), optical, and morphological measurements. The optimized BSF sample shows the highest current density (J = 24.79 mA/cm2), higher open circuit voltage (Voc = 473.44 mV), and low series resistance (Rs = 4.03 Ω) compared to the solar cells without BSF and FSP. In the second stage, the fabricated solar cells were characterized for their radiation tolerance using the experimental techniques such as dark current-voltage (I-V), capacitance-voltage (C-V), and frequency dependent conductance (Gp) measurements. Capacitance-Voltage measurements of the optimized BSF-FSP solar cell represent that there is a decrease in the impurity concentration (ND) from 2.0 x 1015 cm-3 to 1.20 x 1015 cm-3, while increase in depletion layer width (WD) from 0.41 μm to 0.58 μm at zero volt bias and 1.21 μm to 1.59 μm at -2 volt bias due to electron irradiation. The increase in density of interface states (Nss) from 1.82 x 1012 eV-1 cm-2 to 2.48 x 1012 eV-1 cm-2 and trap time constant (τ) from 1.25 × 10-5 s to 1.65 × 10-5 s was observed from the conductance-
frequency measurements of the BSF-FSP solar cell. The results showed that the BSF Si solar cell with FSP shows the highest efficiency recovery ratio of 92% and the minimum series resistance (Rs) recovery difference of 0.99% as compared to other non-BSF, non FSP solar cells. Achieving of uniformity of doping over the large area (2 × 2 cm2) is also the problem that has been circumvented in our design and careful fabrication of solar cells.
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Fabrication And Characterization Of High-Energy , Radiation Resistant Bsf Solar Cell