Low-cost VO2(M1) thin films synthesized by ultrasonic nebulized spray pyrolysis of an aqueous combustion mixture for IR photodetection. Issue 18 (29th March 2019)

• Record Type: Journal Article
• Authors: Tadeo, Inyalot Jude; Mukhokosi, Emma P.; Krupanidhi, Saluru B.; Umarji, Arun M.
• Is Part Of: RSC advances. Volume 9:Issue 18(2019)
• Page Start: 9983
• Page End: 9992
• Publication Date: 2019-03-29
• Subjects: Chemistry -- Periodicals; 540.5
• DOI: 10.1039/c9ra00189a
• Languages: English
• ISSNs: 2046-2069

Abstract

Abstract : We report detailed structural, electrical transport and IR photoresponse properties of large area VO2 (M1) thin films deposited by a simple cost-effective two-step technique. Abstract : We report detailed structural, electrical transport and IR photoresponse properties of large area VO2 (M1) thin films deposited by a simple cost-effective two-step technique. Phase purity was confirmed by XRD and Raman spectroscopy studies. The high quality of the films was further established by a phase change from low temperature monoclinic phase to high temperature tetragonal rutile phase at 68 °C from temperature dependent Raman studies. An optical band gap of 0.75 eV was estimated from UV-visible spectroscopy. FTIR studies showed 60% reflectance change at λ = 7.7 μm from low reflectivity at low temperature to high reflectivity at high temperature in a transition temperature of 68 °C. Electrical characterization showed a first order transition of the films with a resistance change of four orders of magnitude and TCR of −3.3% K −1 at 30 °C. Hall-effect measurements revealed the n-type nature of VO2 thin films with room temperature Hall mobility, μ e of 0.097 cm 2 V −1 s −1, conductivity, σ of 0.102 Ω −1 cm −1 and carrier concentration, n e = 5.36 × 10 17 cm −3 . In addition, we fabricated a high photoresponsive IR photodetector based on VO2 (M1) thin films with excellent stability and reproducibility in ambient conditions using a low-cost method. The VO2 (M1) photodetector exhibited high sensitivity, responsivity, quantum efficiency, detectivity and photoconductive gain of 5.18%, 1.54 mA W −1, 0.18%, 3.53 × 10 10 jones and 9.99 × 10 3 respectively upon illumination with a 1064 nm laser at a power density of 200 mW cm −2 and 10 V bias voltage at room temperature.