Effects of silver nanoparticles layer thickness towards properties of black silicon fabricated by metal-assisted chemical etching for photovoltaics

Abstract

This paper investigates effects of silver nanoparticles (Ag NPs) layer thickness towards properties of black silicon (b-Si) fabricated by two-step metal-assisted chemical etching for potential application in photovoltaic (PV) devices. Ag NPs with different layer thicknesses (1.3–5.1 µm) are deposited on monocrystalline silicon (mono c-Si) wafers by electroless chemical deposition in AgNO3/HF aqueous solution for 10–40 s. This is followed by etching in HF:H2O2:DI H2O aqueous solution for 20 s. Surface morphological investigation confirms presence of b-Si nanowires with height of 250–577 nm and diameter of 100–200 nm. The b-Si nanowires suppress broadband reflectance from the wafers over 300–1100 nm wavelength region, due to refractive index grading effect. Sample with Ag NPs layer thickness of 5.1 µm exhibits b-Si nanowires with average height of 577 nm and average diameter of 200 nm after etching. This sample demonstrates the lowest weighted average reflectance of 5.5% compared to other samples. This sample exhibits absorption of 96.5% at wavelength of 600 nm. The enhanced broadband light absorption leads to maximum potential short-circuit current density (Jsc(max)) of 39.7 mA/cm2, or 51% relative enhancement compared to planar reference sample.