Surface texturing via copper-assisted chemical etching, and passivation using intrinsic amorphous silicon bilayers for silicon heterojunction solar cells

Date

2025-8

Author

Altınsoy, Büşra

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This thesis investigates advanced surface engineering techniques for crystalline silicon (c-Si) solar cells, focusing on light trapping and passivation. In the first part, copper-assisted chemical etching (CACE) was applied to fabricate randomly distributed inverted pyramids on c-Si surfaces. The anisotropy, size, and uniformity of the resulting microstructure were influenced by the etchant composition, etching duration, and the initial surface morphology, whether in the as-cut form or after pre- treatments such as KOH etching or black silicon formation. Chain-like distributions of inverted pyramids formed on DWS wafers reduced the surface reflectance to as low as 5%. In the second part, intrinsic hydrogenated amorphous silicon (i-a-Si:H) bilayers were developed for surface passivation in silicon heterojunction (SHJ) solar cells. By controlling the process power and hydrogen dilution during plasma-enhanced chemical vapor deposition (PECVD), the porosity and hydrogen bonding configurations of the i-a-Si:H layers were tuned. An optimized bilayer (i1/i2) consisting of a porous i1 layer and a dense i2 layer, followed by hydrogen plasma treatment (HPT), significantly enhanced effective carrier lifetime and improved open-circuit voltage (Voc). Modifications to the porous layer’s microstructure had a critical role in passivation performance, as this layer acted both as a diffusion barrier and as a regulator of hydrogen interaction at the c-Si interface. Different bilayer configurations were further integrated onto the front and rear sides of SHJ solar cells to assess their impact on device performance. These findings offer practical guidance for optimizing both light management and passivation strategies in crystalline silicon photovoltaics.

Subject Keywords

Silicon heterojunction solar cells, Copper-assisted chemical etching, Intrinsic amorphous silicon bilayers, Surface passivation, Light management

URI

https://hdl.handle.net/11511/116118

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Graduate School of Natural and Applied Sciences, Thesis