Browsing by Subject "Absorption mechanisms"
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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 ZnO based optical modulator in the visible wavelengths(SPIE, 2013) Okyay, Ali Kemal; Aygun, Levent E.; Oruç, Feyza B.In order to demonstrate tunable absorption characteristics of ZnO, photodetection properties of ZnO based thin-film transistors are investigated. By controlling the occupancy of the trap states, the optical absorption coefficient of ZnO in the visible light spectrum is actively tuned with gate bias. An order of magnitude change of absorption coefficient is achieved. An optical modulator is proposed exploiting such tunable absorption mechanism. © 2013 SPIE.