Fabrication optimization to improve performance of gallium-doped zinc oxide thin film transistors

We reported the bottom gate type fully transparent Ga-doped ZnO TFTs fabricated on glass substrate at room temperature. The effect of O
₂
/Ar ratio during channel layer deposition on the electrical properties of the device was investigated. The results showed that the TFTs fabricated at O
₂
/Ar ratio of 25/75 exhibited the best characteristic with the saturation mobility of 14.15cm
²
/V·s, the subthreshold swing (SS) of 422mV/dec, the threshold voltage (V
_t
) of 4.9V and the on/off current ratio of 2×10
⁷
. Futhermore, the effect of post-annealing temperature was studied, too. It turned out the properties of TFTs were improved after post-annealing, and which reached the best after 250°C post-annealing, with the saturation mobility of 262.49 cm
²
/V·s, the subthreshold swing of 138mV/dec, the threshold voltage of 3V and the on/off current ratio of 2×10
⁹
.