Detection of SF6 decomposition components by pristine and Cr-doped GaN based on the first-principles theory

Abstract

In this work, the first-principles theory is used to simulate the adsorption behavior of four SF6 characteristic decomposed gases on the pristine and Cr-doped GaN (Cr-GaN). The feasibility of the GaN for application as a gas sensor was evaluated in terms of adsorption energy, adsorption distance, transfer charge, density of state, and band structure. The results show that the adsorption energy of pristine GaN upon H2S, SOF2, and SO2F2 are all more than −0.60 eV, and both the gas molecules and pristine GaN have little geometric deformation, which is physical adsorption. The pristine GaN is more sensitive to SO2, in which the adsorption energy is less than −0.80 eV, and the deformation of GaN is obvious, which is chemical adsorption. The adsorption energies of Cr-GaN upon four gases are significantly improved over three times, which indicates the chemisorption nature. Besides, the band gap of the Cr-GaN is largely reduced, making it behave semi-metallic and magnetic properties. All the simulation studies in this paper provide a theoretical basis for the material selection of SF6 decomposition gas detection and scavenge.