Nanoindentation and Stability Response of Sub-100 nm PECVD-Grown Silicon Nitride Single- and Double-Layer Antireflection Coatings

초록

This study presents a comprehensive mechanical and environmental stability assessment of sub-100 nm PECVD-grown silicon nitride (SiNx) antireflection coatings in single-layer (SLAR) and double-layer (DLAR) configurations for photovoltaic applications. Nanoindentation was performed on SiNx SLAR 75 nm with refractive index as 2.05 and SiNx DLAR as 55 nm/30 nm, R.I = 1.90/2.10 for top and bottom layer films following deposition temperature ranging from 300 to 400 degrees C. SiNx SLAR thin film exhibited excellent thermal resilience with hardness decreasing only slightly (15.845-15.666 GPa) and reduced modulus remaining stable (similar to 165 GPa), while SiNx DLAR coatings showed softening with an similar to 2.3 GPa drop in hardness and similar to 10 GPa in modulus, attributed to hydrogen effusion and matrix relaxation. Mean contact depths remained within 30% of the film thickness, validating the Oliver-Pharr modeling. AFM scans confirmed dense, defect-free surfaces with R-q 0.704 nm for SiNx SLAR and 0.355 nm for DLAR, establishing a high-quality baseline for durability tests. Under damp heat aging (85 degrees C/85% RH), minority carrier lifetime declined by 4.41% in SiNx SLAR and 2.65% DLAR, with subsequent H-2-forming gas annealing enabling a partial recovery of 4.13% for SLAR and 2.59% for DLAR. These findings highlight the need to balance mechanical durability and thermal stability in designing reliable antireflection coatings for high-efficiency silicon solar cells.

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