Gate bias stress stability under light irradiation for indium zinc oxide thin-film transistors based on anodic aluminium oxide gate dielectrics

Thin-film transistors (TFTs) using indium zinc oxide as the active layer and anodic aluminium oxide (Al(2)O(3)) as the gate dielectric layer were fabricated. The device showed an electron mobility of as high as 10.1 cm(2) V(-1) s(-1), an on/off current ratio of as high as similar to 10(8), and a turn-on voltage (V(on)) of only -0.5V. Furthermore, this kind of TFTs was very stable under positive bias illumination stress. However, when the device experienced negative bias illumination stress, the threshold voltage shifted to the positive direction. It was found that the instability under negative bias illumination stress (NBIS) was due to the electrons from the Al gate trapping into the Al(2)O(3) dielectric when exposed to the illuminated light. Using a stacked structure of Al(2)O(3)/SiO(2) dielectrics, the device became more stable under NBIS.