Thin film transistor, active matrix substrate, and image pickup device
A thin film transistor including: source and drain electrodes, an active layer that contacts the source and drain electrodes and contains an oxide semiconductor, a gate electrode that controls current flowing between the source and drain electrodes via the active layer, a first insulating film that separates the gate electrode from the source and drain electrodes and the active layer, a bias electrode that is arranged at the opposite side of the active layer from the gate electrode, and has an electric potential fixed independently from the gate electrode, and a second insulating film that separates the bias electrode from the source and drain electrodes and the active layer.
1. An active matrix substrate comprising:
a plurality of thin film transistors, each thin film transistor comprising:
source and drain electrodes,
an active layer that contacts the source and drain electrodes and contains an oxide semiconductor, a gate electrode that controls current flowing between the source and drain electrodes via the active layer,
a first insulating film that separates the gate electrode from the source and drain electrodes and the active layer,
a bias electrode that is arranged at the opposite side of the active layer from the gate electrode, and has an electric potential fixed independently from the gate electrode, and
a second insulating film that separates the bias electrode from the source and drain electrodes and the active layer, wherein
the plurality of thin film transistors are arranged on a support, and
all the bias electrodes are interconnected such that they are all electrically common with one another.
2. The active matrix substrate of claim 1 , wherein the second insulating film is a gallium oxide film.
3. The active matrix substrate of claim 1 , wherein the carrier concentration in the active layer is 3×10 17 cm −3 or more.
4. The active matrix substrate of claim 1 , wherein the electric potential of the bias electrode is fixed within the range of −2 to +0.5 V.
5. The active matrix substrate of claim 1 , wherein the bias electrode has light shielding properties.