Indium Aluminum Zinc Oxide Thin Film Transistor With Al₂O₃ Dielectric for UV Sensing

Two bottom-gate indium aluminum zinc oxide thinfilm transistors (TFTs) were fabricated with different dielectric layers. The TFT with Al2O3deposited through atomic layer deposition (ALD) had higher field mobility of 0.48 cm2/V·s, Ion/Ioff of 9.7 x 107, and lower subthreshold swing of 0.3 V/dec. The hysteresis of the two devices showed that the device with Al2O3dielectric layer had a lower threshold voltage shift (-0.065 V) compared with that of the device with the SiO2dielectric layer (-0.352 V). These results revealed that the device with Al2O3dielectric layer had fewer interface traps between the active layer and dielectric layer than the device with the SiO2dielectric layer deposited through plasma-enhanced chemical vapor deposition. Because of the improvement of interface traps, the device with Al2O3dielectric layer had high responsivity (6.18 A/W) and rejection ratio (1.74 x 103); this device has high potential for use in ultraviolet sensing applications.