Band-gap tuning and optical response of two-dimensional Si$_x$C$_{1-x}$: A first-principles real space study of disordered 2D materials

TL;DR

This paper develops a real-space computational method to analyze how chemical disorder affects the electronic structure and optical properties of 2D Si$_x$C$_{1-x}$ alloys, aiding band gap engineering for optoelectronic devices.

Contribution

It introduces a novel real-space approach combining ASR and TB-LMTO to study disordered 2D materials beyond the Dirac-cone approximation.

Findings

Disorder significantly alters electronic structure and optical response.

Quantitative predictions match experimental and theoretical data.

Method enables targeted band gap engineering in 2D materials.

Abstract

We present a real-space formulation for calculating the electronic structure and optical conductivity of such random alloys based on the Kubo-Greenwood formalism interfaced with the augmented space recursion (ASR) [A. Mookerjee, J. Phys. C: Solid State Phys. {\bf 6}, 1340 (1973)] formulated with the Tight-binding Linear Muffin-tin Orbitals (TB-LMTO) basis with van Leeuwen-Baerends corrected exchange (vLB) [Singh et al, Phys. Rev B {\bf 93}, 085204, (2016)]. This approach has been used to quantitatively analyze the effect of chemical disorder on the configuration averaged electronic properties and optical response of 2D honeycomb siliphene Si$_{x}$C$_{1-x}$ beyond the usual Dirac-cone approximation. We predicted the quantitative effect of disorder on both the electronic-structure and optical response over a wide energy range, and the results discussed in the light of the available experimental and other theoretical data. Our proposed formalism may open up a facile way for planned band gap engineering in opto-electronic applications.