Improved antireflection properties and optimized structure for passivation of well-separated, vertical silicon nanowire arrays for solar cell applications

•The fabrication method is simple, controllable, and low-cost.•Well-separated and vertically aligned SiNW arrays were fabricated.•The reflectance of array is less than 1% over a wide wavelength range.•Conformal coating of a-Si on SiNWs was realized by PECVD for effective passivation.

Large-area, well-separated, and vertically aligned silicon nanowire (SiNW) arrays with excellent antireflection properties were fabricated through a combination of anodic aluminum oxide template and metal-assisted chemical etching, followed by supercritical drying. Less than 1% reflectance was achieved over the wavelength range of 200–600 nm, and 23% reduction in average reflectance was observed over the 200–1000 nm range, compared with the conical-frustum structure array by natural drying. Furthermore, the well-separated SiNW arrays considerably facilitated the conformal coating of the plasma-enhanced chemical vapor deposited amorphous silicon layer on the SiNW surface, which could result in effective passivation of surface states. Therefore, such well-separated and vertically aligned SiNW arrays are highly promising for solar cell application.