Fig. 5From: Optical Constants and Band Gap Evolution with Phase Transition in Sub-20-nm-Thick TiO2 Films Prepared by ALD a Refractive index n spectra and b extinction coefficient k spectra for TiO2 ultrathin films with different thicknesses after annealing at 400 °C. The insert of a shows plot of peak position versus ALD cycles. The insert of b shows plots of (αE)1/2 vs. E for TiO2 ultrathin films with different thicknesses after annealing at 400 °CBack to article page