High efficiency n-ZnO/p-Si core–shell nanowire photodiode based on well-ordered Si nanowire array with smooth surface

A highly efficient n-ZnO/p-Si core–shell nanowire (NW) photodiode was fabricated using ZnO grown by atomic layer deposition (ALD) on a well-ordered Si NW array. Si NW arrays were prepared by metal-assisted chemical etching, for which a metal mesh with a well-organized nanohole array was made using anodic aluminum oxide. This resulted in a good arrangement, smooth surface, and small diameter distribution of the Si NW array. Consequently, ZnO layers with various thicknesses from 15 to 30 nm were deposited by the ALD method. Because of the smooth surface of the well-ordered Si NWs yielding low surface roughness scattering, the resulting photodiode showed significantly improved device characteristics.