Phase changeable vanadium dioxide (VO2) thin films grown from vanadium pentoxide (V2O5) using femtosecond pulsed laser deposition

There are significant challenges accompanied by fabricating a pure crystalline VO2(M1) thin film with an abrupt metal to insulator phase change properties. Most fabrication methods yield an amorphous VO(2)thin film that requires a post-annealing process to be converted into crystalline VO2(M1). Hence, the thickness of VO2(M1) films produced is very limited. In this work, we report the growth of pure VO2(M1) crystalline thin films onto a sapphire substrate in an oxygen atmosphere by the femtosecond pulsed laser deposition technique and using vanadium pentoxide (V2O5) as an ablation target. The thin films were deposited at substrate temperatures of 25 degrees C, 400 degrees C, and 600 degrees C, which reveal the crystallized structures of VO2(M1) without post-annealing. The thin film deposited at a substrate temperature of 600 degrees C exhibits a sharp and an abrupt metal-to-insulator transition (MIT) at a temperature of 66.0 +/- 2.5 degrees C with nearly four orders of magnitude of the resistivity change (3.5 decades) and a narrow MIT hysteresis width of 3.9 degrees C. Furthermore, the influence of the substrate temperature, nanoparticle or grain size, and film thickness on the MIT parameters such as sharpness of the transition temperature, hysteresis width, and amplitude are discussed for potential applications of tunable antennas, terahertz planar antennas, and RF-microwave switches.