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

Abstract

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 VO2 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 °C, 400 °C, and 600 °C, which reveal the crystallized structures of VO2 (M1) without post-annealing. The thin film deposited at a substrate temperature of 600 °C exhibits a sharp and an abrupt metal-to-insulator transition (MIT) at a temperature of 66.0 ± 2.5 °C with nearly four orders of magnitude of the resistivity change (3.5 decades) and a narrow MIT hysteresis width of 3.9 °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.

Influence of lattice strain on Er3+ ions activated magnesium zirconium phosphate phosphors: Morphological, structural, and photoluminescence properties

“…Furthermore, the peak shifting, broadening and increasing intensity of the nanophosphors diffraction peaks occurred at 2θ = 20.07 • and 44.62 • [Fig. 2 (b) and (c)] can be ascribed to combine effect of crystal structure variation owing to presence of Er 3+ and other factors including crystallite size, and lattice strain [23,24]. Additionally, these changes in the XRD patterns could be attributed to crystalline transformation from longrange order to short-ranger order.…”

“…Conversely, instrumental broadening effect was eliminated from these measurements by initially performing XRD of standard silicon powder under the same experimental condition where we observed the peak width centred at ~ 36 • [ not shown here]. Initially, the average crystallite size (D c ) of each nanophosphor as-prepared was estimated by using Debye-Scherrer's equation based on peak broadening, which is given below [23,24,25];…”

“…where λ is the wavelength of incident X-ray beam in nanometres (λ = 0.15406 nm), β is the full width half maximum of the peak in radians, 2θ is the scattering Bragg angle in radians, and k is a constant whose value depends on particle shape (0.95). In addition to the Debye-Scherrer equation, Williamson-Hall (W-H) method was also employed to elevate crystallite size for comparison and lattice strain [23,24,25,26,27].…”

Infrared optical properties modulation of VO2 thin film fabricated by ultrafast pulsed laser deposition for thermochromic smart window applications

“…Increasingly vanadium dioxide (VO 2 ) (M1) is a technologically important metal oxide, owing to its remarkable change in first-order insulator-to-metal transition (IMT) at a critical temperature of around 68 °C 1 , 2 . The phase transition temperature of VO 2 (M1) thin films can be triggered using external stimuli such as thermal, electrical, and ultrafast optical excitations.…”

Vanadium Dioxide–Iridium Composite Development: Specific Near Infrared Surface Plasmon Resonance

“…Indeed, the VO 2 MIT is characterized by rapid (10 −9 -10 −12 ns) [9], huge and sharp changes in physical properties such as optical absorption, dielectric function and electrical and thermal conductivity [10]. However, obtaining a pure VO 2 phase is very challenging due to its narrow range of thermodynamic stability among some seventeen vanadium oxides, explaining the diverse chemical or physical techniques studied to grow VO 2 thin film [11][12][13][14]. Pulsed laser deposition is one of the most interesting processes to deposit pure VO 2 thin films, by controlling several deposition parameters such as temperature, pressure and fluence [15,16].…”