Fig. 1. (a) XRD of vanadium pentoxide thin film; (b) Raman atlas of vanadium pentoxide thin film; (c) (d) XPS spectra of V2p and O1s in vanadium pentoxide thin film

Fig. 2. (a) Transmission spectrum of vanadium pentoxide film, insert map is the absorbance of vanadium pentoxide film; (b) Tauc diagram obtained by transmission spectrum; (c) the (n, k) spectra of the vanadium pentoxide thin film; (d) Tauc diagram obtained by ellipsometry spectrum; (e) the dielectric constant spectra; (f) example figure of the thin film model

Fig. 3. (a) Change-temperature transmission diagram of vanadium pentoxide thin film; (b) local magnification of the dashed portion of Fig. 3 (a)

Fig. 4. (a) Tauc diagram of vanadium pentoxide film at 300 K; (b) diagram of the two band gaps varying with temperature; (c) (d) variation of the first and second bandgaps with temperature and linear fitting