IR photoresponsive VO2 thin films and electrically assisted transition prepared by single-step chemical vapor deposition

• Published in: Journal of materials chemistry. C, Materials for optical and electronic devices Vol. 8; no. 36; pp. 12543 - 12550
• Main Authors: Rajeswaran, Bharathi, Inyalot, Jude Tadeo, Umarji, Arun M
• Format: Journal Article
• Language: English
• Published: Cambridge Royal Society of Chemistry 01.01.2020
• Subjects: Absorptivity; Atomic force microscopy; Chemical synthesis; Chemical vapor deposition; Microscopy; Morphology; Phase transitions; Quantum efficiency; Room temperature; Surface roughness; Thin films; Vanadium oxides
• ISSN: 2050-7526; 2050-7534
• DOI: 10.1039/d0tc02785e

Photodetection based on active materials such as VO2 is less complex and less expensive. Usually such a detector's performance depends on the properties of active materials like the absorption coefficient, structural morphology and band gap width. Herein, we report the photoresponse of high quality VO2 thin films synthesized by a single-step chemical vapor deposition. The phase was identified by X-ray diffraction and confirmed by Raman spectroscopic studies. Morphological studies by atomic force microscopy and scanning electron microscopy revealed uniform well packed grains in the thin films with a surface roughness of 54 ± 0.9 nm. Temperature variable I–V analysis of the thin films exhibited a first order transition with changes in resistance of 3 orders of magnitude and a temperature coefficient of resistance of −1.25% K−1 at 30 °C. The infrared photodetector fabricated with synthesized VO2 thin films showed good photoresponse properties with excellent stability and reproducibility at room temperature giving responsivity, sensitivity, quantum efficiency and detectivity of 7.13 × 10−2 mA W−1, 1272.7%, 5.71 × 10−3% and 1.06 × 1011 Jones respectively after exposing the films to a 1550 nm laser at a power density of 250 mW cm−2 and 10 V bias. We also demonstrated a field assisted thermally induced phase transition by out of plane electrical and piezoforce microscopy measurements on the films.