Synthesis and electrical properties of 2D cubic vanadium nitride.

Due to the exceptional physical and chemical properties, vanadium nitride (VN) films exhibit significant potential for a wide range of applications. However, their non-layered structure has hindered their integration into two-dimensional nano-electronic devices, primarily due to the challenges associated with synthesizing well-defined 2D films. This study proposed an efficient method for the synthesis of 2D vanadium nitride films through a two-step growth process that combines chemical vapor deposition with atomic substitution. For the first time, VN films with thicknesses close to the atomic level were fabricated, and the relationship between the thickness and electrical properties was studied. Transmission electron microscopy (TEM) characterization demonstrated a well-defined crystalline structure and verified the cubic VN phase formation. X-ray photoelectron spectroscopy (XPS) coupled with chemical state analyses confirmed the exclusive composition of VN. Atomic force microscopy (AFM) quantification established ultrathin VN film thickness down to 3.2 nm, exhibiting exceptional surface uniformity. A four-electrode configuration was fabricated on VN films for sheet resistance evaluation, revealing thickness-dependent electrical characteristics, achieving an optimal sheet resistance of 16 Ω sq at 68.1 nm. Transfer characteristic analysis conclusively confirmed metallic conduction behavior in the synthesized films. The temperature-dependent test showed the sheet resistance is insensitive to temperature change. This methodology establishes the efficacy of the atomic substitution method for fabricating non-layered 2D transition metal nitrides (TMNs) with enhanced functionality, offering crucial insights for developing next-generation nanoelectronics based on non-layered TMN architectures.