First Principles Study on the Electronic Structure and Interface Stability of Hybrid Silicene/Fluorosilicene Nanoribbons

Structures, Mobilities, and Electronic Properties of Functionalized Silicene: Superhalogen BO2 Adsorption

The narrow band gap of silicene severely hinders its application in nanoelectronic devices. Therefore, it is significant to open the band gap of silicene and maintain its high carrier mobility. And for that, the adsorption of different coverage superhalogens BO₂ on the silicene surface have been investigated based on density functional theory and the CALYPSO method. The results show that BO₂ unit prefers to adsorb on silicene with adjacent mode irrespective of the size of substrate. The electronic structure analysis indicates that the density of states near the Fermi level are mainly contributed by Si-p and BO₂-p orbitals. (BO₂)_n-silicene exhibits metallic character with the exception of (BO₂)₂ adsorbed on 4 × 4 supercell. As for (BO₂)₂-silicene, silicene transforms from a gapless direct semiconductor to an indirect semiconductor. Furthermore, the effective electron mass of two BO₂ superhalogens on 4 × 4 silicene is estimated and found to be smaller than that of graphene. It is expected to result in higher electron mobility.

Structural stability and the electronic properties of a (SiH)2O-formed siloxene sheet: a computational study

Very recently, a (SiH)₂O-formed siloxene sheet has been synthesized in an experiment [S. Li, et al. J. Mater. Chem. A 2016, 4, 15841]. Utilizing first-principles calculations, we have systematically investigated the structural stability and the physical properties of this (SiH)₂O sheet. We have found a dynamically stable structure because it is a puckered one with bent Si-O-Si connections, which leads to an anisotropic elastic behaviour with negative Poisson ratios. The (SiH)₂O sheet has a strain-tunable direct band gap whose valence and conduction band edges straddle the redox potentials of water even in the presence of stress (either tensile or compressive). The calculated carrier mobilities are prominently anisotropic: in its zigzag direction the electron mobility reaches a high value of 5.39 × 10³ cm² V^-1 s^-1, while the hole mobility remains small. These different carrier mobilities permit fast charge separation and transfer, which is crucial for efficient solar-to-electric energy conversion for photovoltaic and water splitting applications. Similar to phosphorene, a typical linear dichroism phenomenon is also present in the (SiH)₂O sheet. Due to its outstanding electronic properties, the (SiH)₂O sheet is a promising material in the fields of nano-electronics, sustainable energy and fuel generation.

Defections induced hydrogenation of silicene: a density functional theory calculation study

Vacancy defects significantly depress the energy barrier for dissociative adsorption of H₂ on silicene, which can open the band gap of silicene.