Title:	Novel Approach for Self-Aligned Local Polysilicon Layer Formation
Author(s):	Y. Cai, R. Chen, B.J. Hallam, F.E. Rougieux
Keywords:	Etching, Laser Processing, a-Si/µ-Si
Topic:	Silicon Materials and Cells
Subtopic:	High Temperature Route for Si Cells
Event:	38th European Photovoltaic Solar Energy Conference and Exhibition
Session:	2DV.3.12
Pages:	321 - 325
ISBN:	3-936338-78-7
Paper DOI:	10.4229/EUPVSEC20212021-2DV.3.12
Price:	0,00 EUR
Document(s):	paper, poster

Abstract/Summary:

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In this work, we investigate the use of localised laser recrystallisation on full-area amorphous silicon layers to enable an approach for local polysilicon contact formation. We show that laser recrystallisation paired with selective etching of amorphous silicon enables localised polysilicon layers with high aspect ratios. We demonstrate that a 32 wt% potassium hydroxide solution is suitable to achieve selective etching on hydrogenated amorphous silicon with a comparatively higher etch rate of about 100 nm per minute while avoiding significant etching of the polysilicon regions, with a vertical etch rate of up to 50 nm per minute on a <100> c-Si surface. We confirm that a 2 nm interfacial oxide can survive laser processing via its FTIR peak at 1079 cm-1 . We propose a cell process using this method to fabricate selective tunnel-oxide polysilicon contacts.