Vanadium oxide films deposited on sapphire substrate with in situ AlN stress layer: structural, electric, and optical properties

Vanadium oxide (VO _x ) thin films were grown on single crystal sapphire substrates by pulsed laser deposition under various O₂ partial pressures. In situ AlN layer was inserted between the substrate and VO _x films as induced stress layer. The significant influences of AlN layer on the structural, electric, and optical properties of the as-grown films were investigated systemically. The results indicated that pure monoclinic phase VO₂ film with (020) preferred orientation was successfully achieved under the optimized O₂ partial pressure. Moreover, a lowered semiconductor-to-metal transition temperature and a higher optical transmittance in visible and near-infrared regions were achieved due to the introduction of AlN-induced stress layer. Our achievements suggested that it might be a promising method to modulate VO₂ transition characteristics by inducing AlN-induced stress layer.