Conversion of 1D\nNb<sub>2</sub>Se<sub>9</sub> Nanowires\nto 2D Conductive NbSe<sub>2</sub> via Hydrogen Annealing: Structural\nand Electrical Characterization

Van\nder Waals (vdW) materials, consisting of multiple layers held\ntogether by weak vdW forces, have garnered significant interest due\nto their tunable electronic, optical, and mechanical properties. In\nthis study, a one-dimensional (1D) Nb<sub>2</sub>Se<sub>9</sub> nanowire\ntemplate, known for its p-type semiconductor characteristics, was\nsynthesized and converted into a conductive NbSe<sub>2</sub> nanowire\nthrough hydrogen annealing. The conversion process, performed at 300\nand 500 °C, maintained the wire morphology and passed through\nan intermediate NbSe<sub>3</sub> phase. Structural analysis confirmed\nthe conversion, showing preferred orientation growth in the vdWs direction\n[002]. Raman and X-ray diffraction results indicated that residual\nSe in the material increased interlayer distances and caused stress\nin the out-of-plane direction. Electrical measurements demonstrated\nthat the converted NbSe<sub>2</sub> exhibited metallic properties\nwith linear <i>I</i>–<i>V</i> curves and\nohmic contact. The NbSe<sub>2</sub> nanowires converted at 300 °C\nexhibited superior performance, with a breakdown current density of\n2.01 MA cm<sup>–2</sup>, surpassing conventional nano metallic\nwire materials like Si, Cu, and SnO<sub>2</sub>. This study highlights\nthe potential of NbSe<sub>2</sub> nanowires for applications in nano\ndevices, leveraging their high electrical conductivity and structural\nintegrity maintained at low process temperatures suitable for back-end-of-line\n(BEOL) processes.