Computational exploration of SF6 adsorption and decomposition on SiGe and calcium-decorated SiGe surfaces

Abstract

This study investigates the sensitivity and selectivity of gas adsorption (SF₆, SO₂F₂, SOF₂, SO₂, and HF) on SiGe surfaces and Ca atom-decorated SiGe surfaces using Density Functional Theory (DFT). The optimized structures, bond lengths, and angles of the gas molecules are analyzed, providing valuable insights into their geometric features and bonding configurations. For every gas on both surfaces, important variables such as adsorption energy, and charge transfer are examined. In particular, there is a significant increase in charge transfer and adsorption energy when SF₆ interacts with Ca$2D-SiGe as opposed to the SiGe surface. To emphasize changes in band gap and electronic structure, the study explores electronic properties such as density of states (DOS) and projected density of states (PDOS) spectra before and after gas adsorption. Electron density differences (EDD) analysis is used to clarify the type of interactions, including accumulation and depletion of charge. The results reveal that all gases except HF/ Ca$2D-SiGe showed chemical adsorption. The study also takes into account recovery time, an important metric for sensor materials, which is calculated for the breakdown gases of SF₆ on both surfaces at different temperatures and shows potential uses for gas detection. Future research should focus on a broader range of gas molecules and their interactions with SiGe and Ca-decorated SiGe surfaces. Ultimately, the integration of SiGe-based sensor devices in real-world applications such as environmental monitoring, industrial safety, and medical diagnostics can be explored to understand the broader potential of these materials in the field of gas detection.