Thin film transistor array substrate for an X-ray detector and method of fabricating the same

1. A thin film transistor (TFT) array substrate for an X-ray detector comprising:

a substrate;

a gate line formed on the substrate;

a data line crossing the gate line;

a thin film transistor including a gate electrode, a source electrode, and a drain electrode;

a first electrode connected to the drain electrode;

a passivation layer formed over the gate line, the data line, the thin film transistor and the first electrode;

a photoconductor formed over the passivation layer and connected to the first electrode; and

a second electrode formed on the photoconductor,

wherein the photoconductor comprises a first silicon layer with n-type impurities, an undoped second silicon layer, and a third silicon layer with p-type impurities,

wherein the first, second and third silicon layers are sequentially disposed, and

wherein a bottom surface of the undoped second silicon layer contacts the passivation layer.

2. The TFT array substrate of claim 1 , further comprising a planarization layer formed over the passivation layer and the second electrode.

3. The TFT array substrate of claim 2 , further comprising a bias line formed over the planarization layer and connected to the second electrode.

4. The TFT array substrate of claim 1 , wherein the photoconductor comprises a first silicon layer with n-type impurities, an undoped second silicon layer, and a third silicon layer with p-type impurities, the first, second and third silicon layers sequentially formed.

5. The TFT array substrate of claim 4 , wherein a boundary of the first silicon layer is located within a boundary of the second silicon layer.

6. The TFT array substrate of claim 1 , wherein the photoconductor is formed to extend over the thin film transistor.

7. The TFT array substrate of claim 5 , wherein the photoconductor is formed to extend over the thin film transistor.

8. The TFT array substrate of claim 1 , wherein a first boundary of the photoconductor is located between a first end of the gate line and a first end of an adjacent gate line, the first boundary of the photoconductor located outside a boundary of the first electrode.

9. The TFT array substrate of claim 8 , wherein the distance between the first end of the gate line and the first boundary of the photoconductor is shorter than that between the boundary of the first electrode and the first boundary of the photoconductor.

10. The TFT array substrate of claim 8 , wherein the photoconductor includes a first silicon layer with n-type impurities, an undoped second silicon layer, and a third silicon layer with p-type impurities, the first, second and third silicon layers sequentially formed, and a boundary of the first silicon layer located within a boundary of the second silicon layer.

11. The TFT array substrate of claim 8 , wherein the photoconductor is formed to extend over the thin film transistor.

12. The TFT array substrate of claim 1 , wherein a first boundary of the photoconductor is located between a first end of the data line and a first end of an adjacent data line, the first boundary of the photoconductor located outside a boundary of the first electrode.

13. The TFT array substrate of claim 12 , wherein a distance between the first end of the data line and the first boundary of the photoconductor is shorter than that between the boundary of the first electrode and the first boundary of the photoconductor.

14. The TFT array substrate of claim 12 , wherein the photoconductor includes a first silicon layer with n-type impurities, an undoped second silicon layer, and a third silicon layer with p-type impurities, the first, second and third silicon layers sequentially formed, and a boundary of the first silicon layer is located within a boundary of the second silicon layer.

15. The TFT array substrate of claim 1 , wherein the photoconductor overlaps at least a portion of the passivation layer and overlaps the first electrode, the portion of the passivation layer being disposed between the photoconductor and the first electrode.

16. A method of fabricating a thin film transistor (TFT) array substrate for an X-ray detector, the method comprising:

providing a substrate;

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

forming a data line crossing the gate line, a source electrode, and a drain electrode on the substrate;

forming a first electrode on the substrate to be connected to the drain electrode;

forming a passivation layer over the gate line, the data line, the source electrode, the drain electrode, and the first electrode;

forming a first contact hole on the passivation layer;

forming a photoconductor over the passivation layer and the first electrode exposed by the first contact hole; and

forming a second electrode on the photoconductor,

wherein the photoconductor comprises a first silicon layer with n-type impurities, an undoped second silicon layer, and a third silicon layer with p-type impurities,

wherein the first, second and third silicon layers are sequentially disposed, and

wherein a bottom surface of the undoped second silicon layer contacts the passivation layer.

17. The method of claim 16 , wherein the first electrode is formed at the same time as the drain electrode.

18. The method of claim 16 , further comprising forming a planarization layer over the passivation layer and the second electrode.

19. The method of claim 18 , further comprising:

forming a second contact hole over the planarization layer, and

forming a bias line over the planarization layer that is connected to the second electrode through the second contact hole.

20. The method of claim 16 , wherein the forming of the photoconductor comprises sequentially stacking a first silicon layer with n-type impurities, an undoped second silicon layer, and a third silicon layer with p-type impurities, and

wherein a boundary of the first silicon layer is located within a boundary of the second silicon layer.