First-Principles Calculations of Group-IV Carbide Quantum Dots and Single-Layer Heterojunctions with Optical Activity and Short-Wave Infrared Emission for Efficient Gas Sensing

The recently successful large-area bottom-up synthesis of a two-dimensional honeycomb layer of silicon carbide (SiC) ( Phys. Rev. Lett. 2023, 130, 076203) has unquestionably outstretched the conventional routes to tackle the intriguing underlying physics of graphene-like monolayers with diverse functional sectors. In this work, we have tailored group-IV carbide monolayers such as SiC, germanium carbide (GeC), and their single-layer heterojunction ( J. Appl. Phys. 2022, 132, 184301) to have six stable quantum dots (QDs) and critically explored their electronic nature, magnetic edges, and electronic transitions with subsequent characterization of circular dichroism (CD) and high sensitivity toward environmentally hazardous gases through first principles. Quantum dots (QDs) with zigzag edges reveal their spin-split electronic nature with traces of fluorescence around the short-wave infrared (SWIR) region. Interestingly, polar QDs of SiC–GeC, however, display chiral nature with an asymmetric point group, which have been explored using vibrational and electronic circular dichroism. The presence of the junctions between two different carbides promptly enhances the gas sensitivity to 70%, which is significantly higher than its constituents, providing an alternate route map in extending the boundaries of the environment-friendly application sector.