H-Si bonding-induced unusual electronic properties of silicene: a method to identify hydrogen concentration

TL;DR

This study uses first principles calculations to explore how hydrogen bonding affects silicene's electronic properties, revealing potential methods to determine hydrogen concentration via spectroscopic peaks.

Contribution

The paper introduces a novel approach to identify hydrogen concentration in silicene by analyzing characteristic peaks in density of states and energy bands.

Findings

H-Si bonds significantly alter electronic properties depending on configuration and concentration.

Distinct spectral features correlate with hydrogen concentration, enabling spectroscopic identification.

Different hydrogen configurations lead to semiconducting or nearly metallic behaviors.

Abstract

Hydrogenated silicenes possess peculiar properties owing to the strong H-Si bonds, as revealed by an investigation using first principles calculations. The various charge distributions, bond lengths, energy bands, and densities of states strongly depend on different hydrogen configurations and concentrations. The competition of strong H-Si bondings and weak sp3 hybridization dominate the electronic properties. Chair configurations belong to semiconductors, while the top configurations show a nearly dispersionless energy band at the Fermi level. Both two systems display H-related partially flat bands at middle energy, and recovery of low-lying \pi bands during the reduction of concentration. Their densities of states exhibit prominent peaks at middle energy, and the top systems have a delta-funtion-like peak at E=0. The intensity of these peaks are gradually weakened as the concentration decreases, providing an effective method to identify the H-concentration in scanning tunneling spectroscopy experiments.