Electrical and optical properties of polycrystalline NbO2 thin films grown by solid phase crystallization

We studied electrical and optical properties of polycrystalline NbO
₂
thin films grown by solid phase crystallization. Amorphous precursor films were deposited on glass substrates by pulsed laser deposition. Systematic evolution of optical and electrical properties of the amorphous films demonstrates fine tuning of oxygen content in the films. An optimized polycrystalline NbO
₂
film exhibited an indirect band-gap of 0.7 eV comparable with bulk value. However, resistivity of 2 × 10
²
Ωcm for the film was still much lower than bulk value of 1 × 10
⁴
Ωcm. Both oxygen-rich and poor deposition condition resulted in further reduction in resistivity. These results indicate that nonstoichiometry plays a crucial role in performance of electronic devices using NbO
₂
.