Indium Aluminum Zinc Oxide Phototransistor with HfO₂ Dielectric Layer through Atomic Layer Deposition

Bottom-gate indium aluminum zinc oxide thin-film transistors (TFTs) are fabricated with a HfO₂ dielectric layer using plasma enhanced atomic layer deposition (PEALD). The electrical properties and photoresponse are both affected by the method of post annealing. A device that is annealed at a temperature of less than 200°C has a better Ion/Ioff of 71\times 10^{{8}}$ and a lower subthreshold swing (S.S.) of only 0.21 V/dec. This demonstrates that proper annealing treatment increases the performance of the device. The photoresponse is also calculated. A TFT that is not annealed has a poor photoresponse and a lower rejection ratio. Annealing at a temperature of less than 200 °C gives a good photoresponse of 0.2 A/W and a high rejection ratio of .86\times 10^{{5}}$. An IAZO TFT with a HfO₂ dielectric layer that is deposited using PEALD is applicable in UV sensing technology.