High switching ratio and inorganic gas sensing performance in BeN₄based nanodevice: a first-principles study

Recently, Dirac material BeN₄has been synthesized by using laser-heated diamond anvil-groove technology (Bykovet al2021Phys. Rev. Lett.126175501). BeN₄layer, i.e. beryllonitrene, represents a qualitatively class of two-dimensional (2D) materials that can be built of a metal atom and polymeric nitrogen chains, and hosts anisotropic Dirac fermions. Enlighten by this discovered material, we study the electronic structure, anisotropic transport properties and gas sensitivity of 2D BeN₄using the density functional theory combined with non-equilibrium Green's function method. The results manifest that the 2D BeN₄shows a typical semi-metallic property. The electronic transport properties of the intrinsic BeN₄devices show a strong anisotropic behavior since electrons transmitting along the armchair direction is much easier than that along the zigzag direction. It directly results in an obvious switching characteristic with the switching ratio up to 10⁵. Then the adsorption characteristics indicate that H₂S, CO, CO₂and H₂molecules are physisorption, while the NH₃, NO, NO₂, SO₂molecules are chemisorption. Among these chemisorption cases, the 2D gas sensor devices show an extremely high response for SO₂recognition, and the high anisotropy of the original 2D BeN₄device still maintains after adsorbing gas molecules. Finally, high switching ratio and inorganic gas sensing performance of BeN₄monolayer could be clearly understood with local density of states, bias-dependent spectra, scattered state distribution. In general, the results indicate that the designed BeN₄devices have potential practical application in high-ratio switching devices and high gas-sensing molecular devices.