Crystallization Kinetics of Amorphous Sputtered Nb-Doped TiO2Thin Films

The crystallization kinetics of amorphous sputtered Nb-doped TiO2(TNO) thin films during isothermal annealing was examined using in situX-ray diffraction (XRD) measurements. A Johnson-Mehl-Avrami analysis yielded Avrami exponents in the range of 2.0 to 2.7 for TNO films with various oxygen contents, indicating that the crystallization of amorphous TNO films is essentially two-dimensional. The two-dimensional crystal growth is also confirmed by ex situpolarized-light optical microscopic observations of grains, which have much larger lateral sizes than the film thickness.