Fig. 6
The optical transmittance of the SSNO films fabricated at (a) different oxygen pressures and (b) different substrate temperatures in the wavelength range of 200-1800 nm. The plots of (αhν)1/2 versus hν and (αhν)2 versus hν for the films with various oxygen pressures are shown in Fig. 6c and d, respectively. The inset in Fig. 6d shows the direct and indirect band-gap energy variations by varying oxygen pressure from 1 × 10−3 to 20 Pa