Effect of active layer thickness on device performance of a-LZTO thin-film transistors

The dependence of the electrical properties of amorphous lanthanum–zinc–tin–oxides (a-LZTOs)-based top-gate thin-film transistors (TFTs) on active layer thicknesses (dT) is investigated. It is found that the on-to-off current ratio (Ion/off) of TFT improved with the thickness of LZTO active layer decreased from 84 nm to 32 nm, whereas the saturation mobility and the subthreshold swing of device degraded. The improvement in Ion/off is attributed to the decrease in off-current of TFT due to an increase in resistance of the very thin LZTO film. Moreover, the deterioration in properties of device with the thin active layer is associated with the trap states incorporated in TFT and interface scattering effect.

► The device properties of a-LZTO TFTs with various LZTO thicknesses were examined.
► As LZTO thickness decreased, Ion/off improved, whereas μsat and SS degraded.
► Mechanism about the dependence of TFTs’ property on LZTO thickness was studied.