Fabrication of high anti-reflection nanowires on silicon using two-stage metal-assisted etching

Abstract

In this paper, a novel two-stage metal-assisted etching (MAE) method is proposed for the fabrication of a high anti-reflection silicon nanowire array. In the first stage of etching, a high-concentration etchant is implemented in a short etching time to enable the uniform and complete deposition of coniferous-like silver on the wafer surface. Following the first stage, a low-concentration etchant for producing a vertical and uniform silicon nanowire array is processed in a relatively long etching time. Experimental results demonstrate that the proposed two-stage MAE method can produce high anti-reflection silicon nanowire array on a 6" silicon wafer requiring only a relatively simple and low-cost process. The P-type high-resistance silicon wafer that is etched under the two-stage MAE with the first-stage and second-stage processing time of 30 s and 15 min, respectively, can achieve an average reflectivity of 1.89% for the light spectrum from 200 nm to 1000 nm. In the UV and visible-light regions, the average reflectivity is 1.49% and 1.89%, respectively. The low reflectivity in the UV region enables the absorption of high-energy photons, while the low reflectivity at the IR region allows the absorption of a significant number of photons from sunlight.