Abstract:

In order to optimize the processing parameters of ZnO thin- film transistors (ZnO- TFTs),ZnO- TFTs were fabricated by means of RF (Radio Frequency) magnetron sputtering,with the ZnO thin- films of different thickness as the active layer,and the effects of the active layer thickness on the electrical properties of ZnO- TFTs were inves-tigated.Experimental results indicate that (1) the ZnO- TFT device shows the best performance at the active layer thickness of about 65nm; (2) when the active layer is too thin,the ZnO film is of a poor crystallinity and is of a large number of holes and defects,thus resulting in a lower carrier mobility and a smaller on/off current ratio; and (3) when the active layer is too thick (more than 65nm),the carrier mobility and on/off current ratio of the ZnO-TFT decrease with the increase of the active layer thickness,because the conductive path of high resistance region near the source and the drain electrodes increases with the increase of the active layer thickness.

Key words: thin- film transistors, zinc oxide, active layer thickness, electrical properties