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 Al
₂
O
₃
deposited through atomic layer deposition (ALD) had higher field mobility of 0.48 cm
²
/V·s, Ion/Ioff of 9.7 x 10
⁷
, and lower subthreshold swing of 0.3 V/dec. The hysteresis of the two devices showed that the device with Al
₂
O
₃
dielectric layer had a lower threshold voltage shift (-0.065 V) compared with that of the device with the SiO
₂
dielectric layer (-0.352 V). These results revealed that the device with Al
₂
O
₃
dielectric layer had fewer interface traps between the active layer and dielectric layer than the device with the SiO
₂
dielectric layer deposited through plasma-enhanced chemical vapor deposition. Because of the improvement of interface traps, the device with Al
₂
O
₃
dielectric layer had high responsivity (6.18 A/W) and rejection ratio (1.74 x 10
³
); this device has high potential for use in ultraviolet sensing applications.