Electrical Features of an Amorphous Indium-Gallium-Zinc-Oxide Film Transistor Using a Double Active Matrix with Different Oxygen Contents

The electrical characteristics of amorphous indium-gallium-zinc-oxide (a-IGZO) thin film transistors (TFTs) are systematically studied using a double a-IGZO active layer that is composed of a-IGZO(x) (oxygen-ion-poor region) and a-IGZO(y) (oxygen-ion-rich-region). An active layer is designed to have a serially-stacked bi-layer matrix with different oxygen contents, providing the formation of different electron conduction channels. Two different oxygen contents in the active layer are obtained by varying the O-2 partial pressure during sputtering. The a-IGZO TFT based on a double active layer exhibits a high mobility of 9.1 cm(2)/Vsec, a threshold voltage (V-T) of 16.5 V, and Delta V-T shifts of less than 1.5 V under gate voltage stress. A possible electrical sketch for the double active layer channel is also discussed.