Date/Time: 04-23-2019 - Tuesday - 05:00 PM - 07:00 PM
Arun Umarji1 Devanshi Bhardwaj1 Inyalot Tadeo1

1, Indian Institute of Science, Bengaluru, , India

VO2 being a transition metal oxide is the most fascinating material of research as it shows a semiconductor to metal transition (SMT) near to room temperature (TSMT ~ 68 οC). It undergoes a structural change from M1, monoclinic phase (Space group: P21/c) to R, tetragonal phase (Space group: P42/mnm).1 Due to this phase transition, it is used for various applications like smart windows, metamaterial, bolometers, etc.2 Herein, we report the synthesis of device quality VO2 thin films. Various methods like home-built Ultrasonic Nebulised Spray Pyrolysis of Aqueous Combustion Mixture (UNSPACM)3, Chemical Vapor Deposition (CVD)4, Pulsed Laser Deposition (PLD) and DC Reactive sputtering have been employed for the synthesis of phase pure VO2 thin films. The structural characterization has been carried out by XRD and Raman measurements which confirms the M1 phase of VO2 at room temperature followed by high-temperature measurements to study the phase change. Temperature-dependent resistance measurements confirm the SMT transition at TSMT ~68 οC with a three-four order of magnitude change in resistance. Temperature-dependent IR measurements show ~80% change in reflectance across the phase transition where the thin film acts as an IR reflector (T>TSMT). Effect of dopant (W, Mo, Sc, Ce etc.) has been studied where the TSMT was reduced to 25 οC with 2 at % W doping. Our preliminary attempts to make metamaterials will also be presented.

1. Goodenough, J. B., The two components of the crystallographic transition in VO2. Journal of Solid State Chemistry 1971, 3 (4), 490-500.
2. Yang, Z.; Ko, C.; Ramanathan, S., Oxide Electronics Utilizing Ultrafast Metal-Insulator Transitions. Annual Review of Materials Research 2011, 41 (1), 337-367.
3. R. Bharathi, N. R., A. M. Umarji, Metal-insulator transition characteristics of vanadium dioxide thin films synthesized by ultrasonic nebulized spray pyrolysis of an aqueous combustion mixture. Journal of Physics D: Applied Physics 2015, 48 (30), 305103.
4. R. Bharathi; Pradhan, J. K.; Ramakrishna, S. A.; Umarji, A. M., Thermochromic VO2 thin films on ITO-coated glass substrates for broadband high absorption at infra-red frequencies. Journal of Applied Physics 2017, 122 (16), 163107.

Meeting Program

Symposium Sessions

5:00 PM–7:00 PM Apr 23, 2019 (US - Arizona)

PCC North, 300 Level, Exhibit Hall C-E