Electronic band gap engineering of silicene allotropes: configuration-edge hydrogenation synergistic effect

Abstract

Due to their superior physical and chemical properties, Silicene nanomaterials have gained prominence in optoelectronics and electronic devices. This paper studies the effects of period width and edge hydrogenation on the system stability and electronic properties of three different configurations of single-layer intrinsic tetra-octacyclic silicene nanoribbons (TO-SiNR) based on the density functional theory tight-binding method (SCC-DFTB). Our calculations reveal that the intrinsic TO-SiNRs still maintain a long-range ordered low-energy stable structure after relaxation. Under the synergistic effect of geometric configuration and edge hydrogenation, TO-SiNRs with different period widths exhibit semiconductor or metal properties. Among them, the configuration of regular-TO-SiNRs is the most stable and shows a direct narrow band gap of 0.553 eV at one-period width. Increasing the period width can effectively adjust the electronic band gap of TO-SiNRs so that the band gap gradually decreases and the electronic properties semiconductor to metal transition. In addition, the period width is also one of the key factors affecting the charge transfer of nanoribbons. The more narrow the period width, the more obvious the charge transfer. Edge hydrogenation can lead to the atomic reconstruction of TO-SiNRs, affecting its stability and charge transfer and band gap characteristics. These findings are expected to provide theoretical support for the design, synthesis, and performance regulation of new silicene semiconductor materials.