A comparative study based on optical and electrical performance of micro- and nano-textured surfaces for silicon solar cells

• Nano-textured surface fabricated using soft UV-NIL possess excellent anti-reflection property.
• Pattern transfer by plasma etching causes reduction in minority carrier lifetime.
• Appropriate DRE process allows lifetime recovery by two orders of magnitude.
• Despite area enlargement nano-textured surface possesses better electrical properties than micro-textured surface.

In this contribution, we report on the optical and electrical properties of textured silicon surfaces usually incorporated in solar cell fabrication. In order to study the influence of different texturisation processes, nano-texturing was accomplished by soft UV-NIL process while the micro-textured surfaces were prepared using TMAH solution. The nano-textured surfaces were found to be superior in terms of optical performance but the passivation of these structures was solely limited by the fabrication process itself. Any defect or damage caused during the pattern transfer (plasma etch) process acts as a recombination centre which significantly reduces carrier lifetime. By systematically removing the plasma induced damage from the surface, it was possible to improve the effective lifetime from 24.4 μs to 1092 μs. We report that, despite of the enlarged surface area compared to micro-textured surface, our nano-texture surface possess excellent optical properties and higher lifetime.

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