THIN FILM TRANSISTORS, METHOD OF FABRICATING THE SAME, AND ORGANIC LIGHT-EMITTING DIODE DEVICE USING THE SAME

1 . A thin film transistor comprising:

a substrate;

a semiconductor layer disposed on the substrate and comprising a source/drain region and a channel region;

a gate electrode disposed at a position corresponding to the channel region of the semiconductor layer;

an insulating layer disposed between the semiconductor layer and the gate electrode to insulate the semiconductor layer and the gate electrode from each another; and

source/drain electrodes electrically connected to the source/drain region of the semiconductor layer;

wherein the semiconductor layer is made of poly-Si comprising grains having a grain size deviation within a range of substantially ±10%.

2 . The thin film transistor of claim 1 , wherein a growing direction of the grains is parallel to a direction of a current flow in the semiconductor layer.

3 . The thin film transistor of claim 1 , wherein the grain size is a distance between adjacent grain boundaries that are perpendicular to a growing direction of the grains.

4 . The thin film transistor of claim 1 , wherein the semiconductor layer is crystallized by illuminating the semiconductor layer with a laser through an opening in a mask.

5 . The thin film transistor of claim 1 , wherein the semiconductor layer is crystallized by illuminating the semiconductor layer with a laser at least two times.

6 . The thin film transistor of claim 1 , wherein the semiconductor layer is crystallized by:

illuminating a first region of the semiconductor layer with laser light in a first laser illumination; and

illuminating a second region of the semiconductor layer with laser light in a second laser illumination so that the second region overlaps the first region and is moved relative to the first region by more than 50% of a width of the first region.

7 . An organic light-emitting diode (OLED) comprising:

a substrate;

a semiconductor layer disposed on the substrate and comprising a source/drain region and a channel region;

a gate electrode disposed at a position corresponding to the channel region of the semiconductor layer;

a gate insulating layer disposed between the semiconductor layer and the gate electrode to insulate the semiconductor layer and the gate electrode from each other;

source/drain electrodes electrically connected to the source/drain region of the semiconductor layer;

a pixel electrode electrically connected to one of the source/drain electrodes;

an organic layer, comprising an organic light-emitting layer, disposed on the pixel electrode; and

an opposing electrode disposed on the organic layer;

wherein the semiconductor layer is made of poly-Si comprising grains having a grain size deviation within a range of substantially ±10%.

8 . A method of fabricating a thin film transistor comprising:

providing a substrate;

forming a semiconductor layer comprising a source/drain region and a channel region on the substrate;

forming a gate electrode disposed at a position corresponding to the channel region of the semiconductor layer;

forming a gate insulating layer between the semiconductor layer and the gate electrode to insulate the semiconductor layer and the gate electrode from one another; and

forming source/drain electrodes electrically connected to the source/drain region of the semiconductor layer;

wherein the semiconductor layer is made of poly-Si comprising grains having a grain size deviation within a range of substantially ±10%.

9 . The method of claim 8 , wherein the semiconductor layer is crystallized by a sequential lateral solidification (SLS) crystallization method.

10 . The method of claim 8 , wherein a growing direction of the grains is parallel to a direction of a current flow in the semiconductor layer.

11 . The method claim 8 , wherein the grain size is a distance between adjacent grain boundaries that are perpendicular to a growing direction of the grains.

12 . The method of claim 8 , wherein the semiconductor layer is crystallized by illuminating the semiconductor layer with a laser through an opening in a mask.

13 . The method of claim 8 , wherein the semiconductor layer is crystallized by illuminating the semiconductor layer with a laser at least two times.

14 . The method of claim 8 , wherein the semiconductor layer is crystallized by:

illuminating a first region of the semiconductor laser light in a first laser illumination; and

illuminating a second region of the semiconductor layer with laser light in a second laser illumination so that the second region overlaps the first region and is moved relative to the first region by more than 50% of a width of the first region.

15 . A thin film transistor comprising:

a substrate;

a gate electrode;

a semiconductor layer disposed between the substrate and the gate electrode, the semiconductor layer comprising:

a source region;

a drain region; and

a channel region disposed between the source region and the drain region, the channel region being substantially aligned with the gate electrode;

an insulating layer disposed between the semiconductor layer and the gate electrode;

a source electrode electrically connected to the source region; and

a drain electrode electrically connected to the drain region;

wherein the semiconductor layer is made of poly-Si comprising grains having a grain size deviation within a range of substantially ±10%.

16 . The thin film transistor of claim 15 , wherein the poly-Si comprises:

primary grain boundaries that are substantially perpendicular to a direction of a current flow in the semiconductor layer; and

secondary grain boundaries that are substantially parallel to the direction of the current flow in the semiconductor layer;

wherein:

a distance between adjacent ones of the primary grain boundaries is a grain size.

17 . The thin film transistor of claim 16 , wherein each of the primary grain boundaries is formed by a different illumination of the semiconductor layer with laser light.

18 . The thin film transistor of claims 17 , wherein each different illumination of the semiconductor layer except a first illumination illuminates a region of the semiconductor layer that overlaps a region of the semiconductor layer that was illuminated in an immediately preceding illumination by less than 50% of a width of the region of the semiconductor layer that was illuminated in the immediately preceding illumination.

19 . A method of fabricating a thin film transistor comprising:

forming an amorphous silicon (a-Si) layer supported by a substrate;

illuminating the a-Si layer with laser light to crystallize the a-Si layer to form a polysilicon (poly-Si) layer;

forming an insulating layer so that the poly-Si layer is between the substrate and the insulating layer;

forming a gate electrode so that the insulating layer is between the poly-Si layer and the gate electrode;

implanting impurities into the poly-Si layer using the gate electrode as a mask to form a source region and a drain region in the poly-Si layer on opposite sides of a channel region in the poly-Si layer, the channel region being substantially aligned with the gate electrode;

forming a source electrode electrically connected to the source region; and

forming a drain electrode electrically connected to the drain region;

wherein the poly-Si layer comprises grains having a grain size deviation within a range of substantially ±10%.

20 . The method of claim 19 , wherein the illuminating of the a-Si layer comprises illuminating the a-Si layer with a laser through an opening in a mask a plurality of times, the mask being moved relative to the substrate by more than 50% and less than 100% of a width of the opening of the mask between each of the illuminations of the a-Si layer.