Effect of silicon doping on the electronic and optical properties of phosphorous nanotubes

Abstract

Using many-body ab initio calculations, the direction-dependent electronic and the optical properties of silicon doped phosphorene nanotubes are investigated in the DFT framework. Both pure armchair (APNT) and zigzag phosphorene nanotubes (ZPNT) are estimated to be semi-conductor with a direct bandgap in which their valance band maximum and conduction band minimum are placed at the Г-Z zone, while all doped by silicon nanotubes represent metallic behavior. In addition, due to the weaker sp3 hybridization of phosphorus atoms through zigzag phosphorene nanotubes, they have narrower bandgaps than the APNTs. For all simulated APNTs except those with 2% silicon, the atomic configuration is symmetrical respect to the z axis. Moreover, by parallel to the tube axis polarization, for all APNTs, the first intra-band optical band gap is less than 1 eV. The silicon dopant decreases the gap between the highest valence and the lowest conduction bands which leads to smaller inter-band optical transition as well.