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Multicrystalline Silicon’s Surface Improvement by Using Acid Etching for Obtaining Best Results and High Efficiency Solar Cells
Ayman A. Elamin, Ghayah Alsulaim and Y. H. Elbashar
In this paper, we propose a new method on improving the reflectivity of multicristalline silicon for obtaining a high conversion efficiency solar cell by using chemical etching process. Two kinds of NaOH:KOH solution were used, the first one was the NaOH:KOH = 1:1 solution with NaOH concentrations of 5%, 10%, 15%, 20%, 25%, and 30%. Basing in the best result for the first one (30% NaOH concentration).The second one uses the solution NaOH:KOH:HF ratio of 1:1:1, 1:2:1, 1:3:1, 1:4:1, 1:5:1, and 1:6:1.
For the first kind of solution we evaluated the morphology of the textured surfaces and the reflectance spectra from the surfaces. SEM micrographics showed that a few number of grain boundaries were founded in the sample with 30% NaOH concentration. This result was also confirmed by the measurement of reflectance that equal 39%. In the second kind of solution SEM micrographics and reflectance measurement for all specimen shows that high reflection equal to 44% was obtained with the ratio of solution 1:4:1. Using the specimen that have reflection 39% and 44% founded in the first and second kind solution, I-V characteristic were applied. We found that the output (Isc & Voc) is higher for the first specimen that has a reflectance of 39% than the second specimen with a reflectance 44%.
Keywords: Multicrystalline silicon, chemical etching process, acid solution, electrical performance