Halogenation of SiC for band-gap engineering and excitonic functionalization

TL;DR

This study uses advanced computational methods to analyze how fluorine and chlorine functionalization of SiC affects its electronic and optical properties, revealing stable, wide-bandgap materials with bright excitons suitable for optoelectronic applications.

Contribution

It provides the first systematic theoretical investigation of halogenated SiC's optical and excitonic properties using density functional and many-body perturbation theory.

Findings

Wide band-gaps of around 4 eV in halogenated SiC.

Presence of bright excitons with binding energies up to 1.75 eV.

Potential for applications in solar cells, coatings, and excitonic Bose-Einstein condensation.

Abstract

The optical excitation spectra and excitonic resonances are investigated in systematically functionalized SiC with Fluorine and/or Chlorine utilizing density functional theory in combination with many-body perturbation theory. The latter is required for a realistic description of the energy band-gaps as well as for the theoretical realization of excitons. Structural, electronic and optical properties are scrutinized and show the high stability of the predicted two-dimensional materials. Their realization in laboratory is thus possible. Huge band-gaps of the order of 4 eV are found in the so-called GW approximation, with the occurrence of bright excitons, optically active in the four investigated materials. Their binding energies vary from 0.9 eV to 1.75 eV depending on the decoration choice and in one case, a dark exciton is foreseen to exist in the fully chlorinated SiC. The wide variety of opto-electronic properties suggest halogenated SiC as interesting materials with potential not only for solar cell applications, anti-reflection coatings or high-reflective systems but also for a possible realization of excitonic Bose-Einstein condensation.