Broadband Reflection Minimization Using Silver Ultra Thin Film Sandwiched Between Silicon Nitride Layers for c-Si Solar Cell Application

Abstract

Wafer thickness reduction is the main trend for cost reduction of crystalline silicon (c-Si) solar cells. For better light trapping in lower thickness wafers where traditional texturization method may not be promising, alternative techniques are being explored. Here, reflection minimization using silver ultra thin film sandwiched between silicon nitride (SiNx) antireflection coating (ARC) layers on c-Si substrate is reported. SiNx ARC layers were deposited by plasma-enhanced chemical vapor deposition (PECVD) and silver ultra thin film by e-beam evaporation; 41 % reflection reduction for silver ultra thin film sandwiched in SiNx ARC layers as compared to standard 80 nm thin SiNx ARC on c-Si substrate is shown. The sandwiched structure gives 8.1 % weighted total reflectance for wavelength range of 300–1,200 nm as compared to standard 80-nm SiNx-based ARC which gives 13.8 %. Also, comparison of this Ag ultra thin film-based sandwiched geometry is done with randomly distributed nanoparticle (NP)-based ARC geometry. It is shown that optically, the sandwiched Ag ultra thin film-based device geometry is more promising than Ag NP-based device geometry and standard 80-nm SiNx-based geometry for broad wavelength range of 300–1,200 nm.