Scandium: An efficient dopant to modulate the optical spectrum of vanadium dioxide (VO2)

• Published in: SN applied sciences Vol. 2; no. 9; p. 1553
• Main Authors: Bhardwaj, Devanshi, Umarji, A. M.
• Format: Journal Article
• Language: English
• Published: Cham Springer International Publishing 01.09.2020; Springer Nature B.V
• Subjects: 4. Materials (general); Applied and Technical Physics; Chemistry/Food Science; Combustion; Crystal structure; Dopants; Doping; Earth Sciences; Energy gap; Engineering; Environment; Hydrocarbons; Materials Science; Morphology; Nitrates; Phase transitions; Photoelectron spectroscopy; Photoelectrons; Pyrolysis; Raman spectra; Raman spectroscopy; Research Article; Scandium; Smart materials; Spray pyrolysis; Tensile strain; Thin films; Vanadium; Vanadium dioxide; Vanadium oxides; Wavelengths; Windows (apertures); Vanadium dioxide; Smart windows; Optical spectrum; Doping; Scandium
• ISSN: 2523-3963; 2523-3971
• DOI: 10.1007/s42452-020-03332-7

Transparency of VO 2 thin films in the visible region is an important aspect of study for its use in smart window applications. In this regard, we experimentally validate the theoretical prediction regarding the influence of scandium (Sc) doping on modulating the optical spectrum of VO 2 . Sc-doped nano-crystalline VO 2 , bulk and thin films were synthesised using a two-step process involving a rapid non-equilibrium solution combustion process and ultrasonic nebulised spray pyrolysis of aqueous combustion mixture respectively; followed by a reduction step. The presence of Sc was determined by X-ray photoelectron spectroscopy where a peak observed at 530.06 eV is attributed to Sc–O interaction. Raman spectra showed a shift in 611 cm −1 peak position to a lower wavenumber due to tensile strain arising from Sc doping. Sc-doped VO 2 thin films showed semiconductor to metal transition of four orders of magnitude change in resistance. Sc-doping increased the band gap from 1.76 eV for undoped to 2.02 eV with 2.0 at. % of doping thereby making the films more transparent in the visible region of the optical spectrum. This shift in the band gap of VO 2 was consistent with the theoretical reports. Thus, Sc is a potential dopant for modulating the optical spectrum of VO 2 for its application in smart windows.