Fabrication of Orientation-Tunable Si Nanowires on Silicon Pyramids with Omnidirectional Light Absorption.

In this work, the different orientation of SiNWs on Si pyramids by a two step MACE method have been fabricated. By tuning the structure of Ag catalyst film and controlling the concentration of HO or the etching temperature, the tunability of the orientation of SiNWs from <111> to <100> on Si pyramids was realized. Si structures composed of Si pyramids and SiNWs exhibit better omnidirectional light-trapping ability by multiple reflections. Si structures with structural tunability and enhanced light harvesting performance will find a wide variety of significant applications in solar cells, photodetectors, and optoelectronic devices.