Variability of structural and electronic properties of bulk and monolayer Si2Te3

TL;DR

This study provides a theoretical analysis of bulk and monolayer Si2Te3, revealing how dimer orientations influence its structural and electronic properties, with potential for tunable applications in nanodevices.

Contribution

It is the first comprehensive theoretical investigation of Si2Te3's properties in both bulk and monolayer forms, highlighting the effects of dimer reorientation.

Findings

Lattice constant varies up to 5% with dimer orientation

Band gap varies up to 40% depending on dimer reorientation

Monolayer band gap is 0.4 eV larger than bulk for lowest-energy configuration

Abstract

Since the emergence of monolayer graphene as a promising two-dimensional material, many other monolayer and few-layer materials have been investigated extensively. An experimental study of few-layer Si2Te3 was recently reported, showing that the material has diverse properties for potential applications in Si-based devices ranging from fully integrated thermoelectrics to optoelectronics to chemical sensors. This material has a unique layered structure: it has a hexagonal closed-packed Te sublattice, with Si dimers occupying octahedral intercalation sites. Here we report a theoretical study of this material in both bulk and monolayer form, unveiling a fascinating array of diverse properties arising from reorientations of the silicon dimers between planes of Te atoms. The lattice constant varies up to 5% and the band gap varies up to 40% depending on dimer orientations. The monolayer band gap is 0.4 eV larger than the bulk-phase value for the lowest-energy configuration of Si dimers. These properties are, in principle, controllable by temperature and strain, making Si2T3 a promising candidate material for nanoscale mechanical, optical, and memristive devices.