Influence of hydrogen incorporation on conductivity and work function of VO 2 nanowires

We report improved conductance by reducing the work function via incorporation of hydrogen into VO ₂ nanowires. The VO ₂ nanowires were prepared using the chemical vapor deposition method with V ₂ O ₅ powder on silicon substrates at 850 °C. Hydrogenation was carried out using the high-pressure hydrogenation method. Raman spectroscopy confirmed that the incorporated hydrogen atoms resulted in a change in the lattice constant of the VO ₂ nanowires (NWs). To quantitatively measure the work function of the nanowires, Kelvin probe force microscopy (KPFM) was employed at ambient conditions. We found that the work function decreased with increasing H ₂ pressure, which also resulted in increased conductance. This is associated with hydrogen diffused into the VO ₂ that acts as a donor to elevate the Fermi level, which was also confirmed by KPFM. From these results, tuning of the reversible electrical properties of VO ₂ NWs, including the conductance and work function, can be achieved by incorporating hydrogen at relatively moderate temperatures.