Abstract
In this work, the first‐principles study based on density functional theory was applied to investigate the geometries, electronic structures, and optical properties in four directions of the Si‐NWs surface, which are modified by oxygen atoms. The results show that the geometries, band structures, and optical properties of the Si‐NWs are affected by the modification of oxygen atoms. The Si─Si bonds adjacent to the region modified by oxygen atoms elongate, the cell volumes decrease, while the energy gaps of Si‐NWs narrow. Evident impurity bands appear on the energy bands of the modified Si‐NWs, forming S═O double bonds. A blue shift of the perpendicular component spectra of the dielectric constant relative to parallel spectra can be observed for Si [100]‐NW, Si [111]‐NW, and Si [112]‐NW. At the same time, the real and imaginary parts of the dielectric function spectra of all Si‐NWs are red‐shifted after the modification by oxygen atoms, and the spectra of Si [111]‐NWs forming Si═O double bonds are the most significant red‐shifted. These results can provide a theoretical reference for preparing nano‐silicon optoelectronic materials and devices.