Theoretical Study of Anisotropic Carrier Mobility for Two-Dimensional Nb ₂Se ₉ Material

Abstract

Finding new materials with satisfying all the desired criteria for nanodevices is an extremely difficult work. Here, we introduce a novel Nb ₂Se ₉ material as a promising candidate, capable of overcoming some physical limitations, such as a suitable band gap, high carrier mobility, and chemical stability. Unlike graphene, it has a noticeable band gap and no dangling bonds at surfaces that deteriorate transport properties, owing to its molecular chain structure. Using density functional theory (DFT) calculations with deformation potential (DP) theory, we find that the electron mobility of 2D Nb ₂Se ₉ across the axis direction reaches up to 2.56 × 10 ³ cm ² V ^–1 s ^–1 and is approximately 2.5–6 times higher than the mobility of other 2D materials, such as MoS ₂, black phosphorous, and InSe, at room temperature. Moreover, the mobility of 2D Nb ₂Se ₉ is highly anisotropic (μ _a /μ _c ≈ 6.5). We demonstrate the potential of 2D Nb ₂Se ₉ for applications in nanoscale electronic devices and, possibly, mid-infrared photodetectors.