Effects of Ti-W codoping on the optical and electrical switching of vanadium dioxide thin films grown by a reactive pulsed laser deposition

Thin films of thermochromic VO2, V1-xWxO2 and V1-x-yWxTiyO2 (x=0.014, and y=0.12) were synthesized onto quartz substrates using a reactive pulsed laser deposition technique. The films were then characterized by x-ray diffraction and x-ray photoelectron spectroscopy. The W and Ti dopant effects on the semiconductor-to-metal phase transition of VO2 were investigated by measuring the temperature dependence of their electrical resistivity and their infrared transmittance. Remarkably strong effects of Ti-W codoping were observed on both the optical and electrical properties of V1-x-yWxTiyO2 films. The IR transmittance was improved, while the transition temperature could be varied from 36degreesC for W-doped VO2 film to 60degreesC for Ti-W codoped VO2 film. In addition, at room temperature, a higher temperature coefficient of resistance of 5.12%/degreesC is achieved. Finally, both optical and electrical hysteresis are completely suppressed by Ti-W codoping the VO2 films. (C) 2004 American Institute of Physics.