183954.fig.004a
(a)
183954.fig.004b
(b)
183954.fig.004c
(c)
183954.fig.004d
(d)
Figure 4: (a) and (b) versus which is determined from extinction coefficient and the extrapolating dashed lines are drawn to obtain the value of the band gap and , respectively. (b) is the enlarged low photon energy portion of versus . (c) Schematic diagram of electronic band structures in the VO2 film. (d) Variation of optical band gap of VO2 thin films deposited at different O2-Ar ratios.