First-Principles Prediction of Graphene-Like XBi (X=Si, Ge, Sn) Nanosheets

TL;DR

This study predicts stable single-layer XBi nanosheets (X=Si, Ge, Sn) with unique electronic and thermoelectric properties using first-principles calculations, highlighting their potential as 2D materials.

Contribution

The paper introduces the first computational prediction of stable single-layer XBi nanosheets with detailed stability, electronic, and thermoelectric property analyses.

Findings

XBi monolayers are dynamically and thermally stable.

SiBi is an indirect band gap semiconductor; GeBi and SnBi are metallic with SOC.

SiBi shows promising thermoelectric performance at higher temperatures.

Abstract

Research progress on single-layer group III monochalcogenides have been increasing rapidly owing to their interesting physics. Herein, we predict the dynamically stable single-layer forms of XBi (X=Ge, Si, or Sn) by using density functional theory calculations. Phonon band dispersion calculations and ab-initio molecular dynamics simulations reveal the dynamical and thermal stability of predicted nanosheets. Raman spectra calculations indicate the existence of 5 Raman active phonon modes 3 of which are prominent and can be observed in a possible Raman measurement. Electronic band structures of the XBi single-layers investigated with and without spin-orbit coupling effects (SOC). Our results show that XBi single-layers show semiconducting property with the narrow band gap values without SOC. However only the single-layer SiBi is an indirect band gap semiconductor while GeBi and SnBi exhibit metallic behaviors by adding spin-orbit coupling effects. In addition, the calculated linear-elastic parameters indicate the soft nature of predicted monolayers. Moreover, our predictions for the thermoelectric properties of single-layer XBi reveal that SiBi is a good thermoelectric material with increasing temperature. Overall, it is proposed that single-layer XBi structures can be alternative, stable 2D single-layers with their varying electronic and thermoelectric properties.