Browsing by Author "Aygün, Levent E."
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Item Open Access TiO2 thin film transistor by atomic layer deposition(SPIE, 2013) Okyay, Ali Kemal; Oruç, Feyza B.; Çimen, Furkan; Aygün, Levent E.In this study, TiO2 films were deposited using thermal Atomic Layer Deposition (ALD) system. It is observed that asdeposited ALD TiO 2 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 6.5V, subthreshold slope is 0.35 V/dec, Ion/Ioff 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 TiO 2 has band to band absorption mechanism. © 2013 SPIE.Item Open Access Tunable visible response of ZnO thin-film phototransistors with atomic layer deposition technique(IEEE, 2012) Aygün, Levent E.; Bozkurt-Oruç, Feyza; Okyay, Ali KemalWe fabricated TFPT with 14-nm-thick n-ZnO channel at 80°C by ALD technique. The drain to source photocurrent due to UV photons can be tuned by changing gate voltage. We also observed that the absorption of sub-bandgap photons could be prevented by operating at positive gate bias. This property could be used for light modulators for visible regime. Moreover, this could be applied to the smart glass technology for electrical voltage controlled transparency. Furthermore, solar-blind UV detectors could also be designed with this technology. © 2012 IEEE.