TiO2 Thin Film Transistor by Atomic Layer Deposition

In this study, TiO2 films were deposited using thermal Atomic Layer Deposition (ALD) system. It is observed that as-deposited ALD TiO2 films are amorphous and not suitable as TFT channel material. In order to use the film as channel material, a post-annealing process is needed. Annealed films transform into a polycrystalline form containing mixed anatase and rutile phases. For this purpose, devices are annealed at 475 degrees C and observed that their threshold voltage value is 6.5(V), subthreshold slope is 0.35 V/dec, Ion/Ioff ratios 2.5x10(6) and mobility value is 0.672 cm(2)/V.s. Optical response measurements showed that devices exhibits decent performance at ultraviolet region where TiO2 has band to band absorption mechanism.