Thin film transistor and thin film transistor array panel including the same

1. A thin film transistor comprising:

a gate electrode on a substrate;

a source electrode on the gate electrode;

a drain electrode at a same layer as the source electrode, and spaced apart from and facing the source electrode;

an oxide semiconductor layer between the gate electrode and the source electrode or between the gate electrode and the drain electrode; and

a gate insulating layer between the gate electrode and the source electrode or between the gate electrode and the drain electrode,

wherein the oxide semiconductor layer comprises a continuous layer of amorphous titanium oxide doped with niobium.

2. The thin film transistor of claim 1 , wherein

an amount of niobium doped to the titanium oxide is in a range from equal to or more than about 1 atomic percent to equal to or less than about 17 atomic percent.

3. The thin film transistor of claim 1 , wherein

the gate electrode is between the substrate and the oxide semiconductor layer, and

the oxide semiconductor layer is between the source electrode and the gate electrode, and between the drain electrode and the gate electrode.

4. The thin film transistor of claim 3 , further comprising

an etch stopper overlapping a channel portion of the oxide semiconductor layer, and overlapping edges of side surfaces of the source electrode and the drain electrode, the side surfaces facing each other,

the facing source and drain electrodes exposing the etch stopper.

5. The thin film transistor of claim 4 , further comprising

an insulating layer on the source electrode and the drain electrode, and overlapping the exposed etch stopper between the source electrode and the drain electrode.

6. The thin film transistor of claim 5 , wherein

the etch stopper comprises an oxide or nitride comprising silicon.

7. The thin film transistor of claim 6 , wherein

the insulating layer comprises at least one of silicon oxide, silicon nitride or silicon oxynitride.

8. The thin film transistor of claim 1 , wherein

the oxide semiconductor layer is between the gate electrode and the substrate, and

the source electrode and the drain electrode are between the oxide semiconductor layer and the substrate.

9. A thin film transistor array panel comprising:

a substrate;

a gate line on the substrate and comprising a gate electrode;

a gate insulating layer on the gate line;

an oxide semiconductor layer on the gate insulating layer;

a data line on the oxide semiconductor layer and connected to a source electrode;

a drain electrode on the oxide semiconductor layer and facing the source electrode; and

a passivation layer on the data line, the source electrode and the drain electrode,

wherein the oxide semiconductor layer comprises a continuous layer of amorphous titanium oxide doped with niobium, and

wherein the oxide semiconductor comprising the titanium oxide contacts the passivation layer.

10. The thin film transistor array panel of claim 9 , wherein

an amount of niobium doped to the titanium oxide is in a range from equal to or more than about 1 atomic percent to equal to or less than about 17 atomic percent.

11. The thin film transistor array panel of claim 9 , wherein

the oxide semiconductor layer except for a channel portion, has a same plane shape as the source electrode, the drain electrode and the data line.

12. The thin film transistor array panel of claim 11 , further comprising

a pixel electrode on the passivation layer,

wherein

the passivation layer comprises a contact hole, and

the pixel electrode and the drain electrode are connected through the contact hole.