TiO₂thin film transistor by atomic layer deposition

Abstract

In this study, TiO₂ films were deposited using thermal Atomic Layer Deposition (ALD) system. It is observed that asdeposited 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°C and observed that their threshold voltage value is 6.5^V, subthreshold slope is 0.35 V/dec, I_on/I_off ratios 2.5×106 and mobility value is 0.672 cm²/V.s. Optical response measurements showed that devices exhibits decent performance at ultraviolet region where TiO₂ has band to band absorption mechanism.