Preparing wafer-scale omnidirectional broadband light-harvesting nanostructures in a few seconds

Abstract

In this study, we combined intruded nanocluster (INC)-based catalysts with ultrasound-assisted etching to obtain, within only a few seconds, wafer-scale nanostructures exhibiting excellent antireflective properties. We chose the INC catalysts because their high density of atomic-scale gold nanoclusters could be used to prepare highly dense silicon nanostalactite (SNS) structures, which can exhibit excellent antireflective properties even at relatively shallow etching depths. By applying ultrasonic oscillation during the etching process, gas bubbles were detached instantly and the exchange rate of the etching solution was improved significantly. Using this approach, we could prepare antireflective SNS structures with an average reflectance of approximately 2% over the range of 350 to 1000 nm within an etching time of 10 s. We also constructed INC-based SNS structures on the surfaces of micrometer-scale silicon pyramids to decrease the angular dependence of their surface reflection. These micro/nano hybrid structures effectively suppressed the average reflectance to 1.6% at normal incidence and to approximately 3.5% at an incident angle of 60°—excellent omnidirectional and broadband antireflective properties. Notably, such micro/nano hybrid structures could also be prepared within very short etching times.