Mitigation of Light Induced Degradation and, Light and Elevated Temperature Induced Degradation Mechanisms in Boron Doped Czochralski Grown Silicon Wafers

Date

2024-1-8

Author

Özyahni, Vahdet

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The degradation of solar cells is critical for their long-term performance. If the recombination concentration is high, the rate of electricity generation from the solar cell will be lowered significantly. Within this thesis, two commonly known degradation mechanisms of light-induced degradation (LID) and, light and elevated temperature-induced degradation (LeTID) on boron doped silicon wafers were investigated. To understand the effect of base resistivity on B-O LID defect mechanism, three different base resistivity groups of samples with 0.2, 1.5 and 650 Ω.cm were used as substrates. Also, a fast regeneration method that is an alternative to illuminated annealing with halogen lamp and hot plate method, was proposed by a 915 nm diode laser. Moreover, two different silicon nitride (SiNx) passivation layers were deposited to identical samples to investigate the effect of different passivation layers on both LID and LeTID mechanisms. According to the results, 0.2 and 1.5 Ω.cm base resistivity samples showed a significant degradation due to B-O defects, while 650 Ω.cm base resistivity samples did not at all. Moreover, the concentration of hydrogen that diffused from both SiNx passivation layers to bulk was calculated. Diffused hydrogen concentrations from both passivation layers were enough for the passivation of B-O defects in each base resistivity sample. Although there was a significant difference in the concentration of diffused hydrogen atoms inside the bulk, the extent of LeTID was identical for differently passivated SiNx samples. However, it was seen that increased hydrogen concentration inside the bulk caused a faster formation of LeTID.

Subject Keywords

LID, LeTID

URI

https://hdl.handle.net/11511/108186

Collections

Graduate School of Natural and Applied Sciences, Thesis