SEDL / STP / STP954-EB / STP23126S

Crystallization of Titania Films by Thermal Heating

Rujkorakarn, R
Colorado State University, Fort Collins, CO

Hsu, LS
Colorado State University, Fort Collins, CO

She, CY
Colorado State University, Fort Collins, CO

Pages: 9    Published: Jan 1986

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Abstract

Two types of low-loss, low-scatter submicron thick titania films, deposited by ion-sputtering at room temperature, were thermally annealed in air. Upon heating to about 350°C, these amorphous films show evidence of crystallization. Using a sensitive Raman spectroscopic technique, the crystalline structures are identified as anatase in one case (Type A) and rutile in the other (Type B). This amorphous-crystalline transformation coincides with a decrease in optical transmission and small changes in refractive index and energy gap of the film, along with a dramatic increase (∼100-fold) in elastic light scattering. Further heating of Type A films beyond 900°C shows a second phase transformation to anatase-rutile mixtures.