X-ray detector

An X-ray detector, comprising:

• a thin film transistor substrate, which comprises a substrate, a plurality of data lines and a plurality of gate lines intersected to define a plurality of pixel regions, wherein each of the pixel regions comprises at least one thin film transistor, and the thin film transistor comprises:
• a gate electrode, disposed on the substrate;
• a gate insulating layer, disposed on the gate electrode;
• a semiconductor layer, disposed on the gate insulating layer, wherein a width of a projection area of the semiconductor layer vertically projected on the gate electrode has been smaller than a width of a projection area of the gate electrode vertically projected on the substrate;
• an etching stop layer, disposed on the semiconductor layer;
• a source electrode and a drain electrode, respectively disposed on the etching stop layer;
• a passivation layer, covering the source electrode and the drain electrode;
• and
• a photo-diode array layer, having a plurality of photo-diodes electrically connected to the corresponding thin film transistor;
• wherein the source electrode is electrically connected to the semiconductor layer through a first conductive via hole having a first base portion at the semiconductor layer, the drain electrode is electrically connected to the semiconductor layer through a second conductive via hole having a second base portion at the semiconductor layer, and at least one of projection areas of the first and second base portions vertically projected on the substrate has a non-overlapping region beyond a projection area of the semiconductor layer vertically projected on the substrate.