Wafer-scale nanowire array black silicon with excellent near-infrared absorption (>90.2 %)

Abstract

Black silicon (BS) with micro-nanotexturing exhibits outstanding optical properties, leading to broad applications in the optoelectronic field. However, due to limitations in silicon’s band gap and other material parameters, BS generally shows poor light absorption capabilities in the infrared range (>1100 nm). Here, we propose and fabricate a wafer-scale nanowire array BS with excellent near-infrared absorption. This structure is prepared by metal-assisted chemical etching (MACE) and randomly decorated with gold nanoparticles (Au-NPs) through a de-wetting process. Simulation results show that the maximum exciton generation rate (G_max) of the fabricated structure reaches 3.3 × 10²⁷ s⁻¹, demonstrating its high application potential in optoelectronic fields. Furthermore, the synergy effect between the Au-NPs induced localized surface plasmon resonance (LSPR) and the nanostructures achieved ultralow broadband (300–2000 nm) total reflectivity and transmittivity (below 3.8 % and 6 %, respectively), showcasing its exceptional absorption capability (1100–2000 nm, the theoretical value exceeds 90.2 %). Our proposed approach is not affected by the morphology of the silicon surface, enables the efficient and low-cost fabrication of tunable nanostructures on 4, 6 or 8-inch wafer-scales, making it highly valuable in fields such as optoelectronics, microelectronics, and photovoltaic conversion.