Decisive role of dopants in the optical properties of vertically aligned silicon nanowires prepared by metal-assist chemical etching

Abstract

Silicon nanowires (SiNWs) were prepared by metal-assist chemical etching (MACE) from different doping types and resistivity of Si wafers, <100> orientation. The coexistence of Si nanocrystals (SiNCs) and SiNWs was revealed in both types of the semiconductor. From the p-type samples, heavily doped with boron (B), intense red-light emission was observed. High-resolution transmission electron microscopy (HR-TEM) images of this sample type shown numerous SiNCs in the porous surface of the SiNWs walls. These SiNCs were proposed to be responsible for the characterized optical properties of the material. The microscopic links between the photoluminescence behavior, the dopants, and the formation of SiNCs were presented and discussed.