Array substrate for display device

An array substrate for a display device, comprising:

• gate and data lines on a substrate including a pixel region and crossing each other to define the pixel region;
• a thin film transistor (TFT) on the substrate and connected to the gate and data lines, the TFT including a first gate electrode, a gate insulating layer on the first gate electrode, an active layer of intrinsic polycrystalline silicon on the gate insulating layer, an interlayer insulating layer on the active layer and including first and second active contact holes, which respectively expose both sides of the active layer, first and second ohmic contact layers contacting the active layer, a source electrode on the first ohmic contact layer, a drain electrode on the second ohmic contact layer, and a second gate electrode over the active layer;
• and
• a pixel electrode connected to the drain electrode and disposed in the pixel region,
• wherein the first and second ohmic contact layers contact the active layer through the first and second active contact holes, respectively.

An array substrate for a display device, comprising:

• a substrate having a pixel region, the pixel region including a switching region, a driving region and a storage region;
• a gate line, a data line and a power line on the substrate, the gate and data lines crossing each other to define the pixel region;
• a switching thin film transistor (TFT) on the substrate and arranged in the switching region, the switching TFT connected to the gate and data lines and including a first switching gate electrode, a switching gate insulating layer on the first switching gate electrode, a switching active layer of an intrinsic polycrystalline silicon on the switching gate insulating layer, first and second switching ohmic contact layers contacting the switching active layer, a switching source electrode on the first switching ohmic contact layer, and a switching drain electrode on the second switching ohmic contact layer;
• a driving TFT on the substrate and arranged in the driving region, the driving TFT connected to the switching TFT and the power line and including a first driving gate electrode, a driving gate insulating layer on the first driving gate electrode, a driving active layer of intrinsic polycrystalline silicon on the driving gate insulating layer, first and second driving ohmic contact layers contacting the driving active layer, a driving source electrode on the first driving ohmic contact layer, and a driving drain electrode on the second driving ohmic contact layer;
• and
• a pixel electrode connected to the driving drain electrode and disposed in the pixel region,
• wherein the switching TFT further includes a second switching gate electrode over the switching active layer, and the second switching gate electrode is disposed at the same layer as and extends from the gate line.

An array substrate for a display device, comprising:

• gate and data lines on a substrate including a pixel region and crossing each other to define the pixel region;
• a thin film transistor (TFT) on the substrate and connected to the gate and data lines, the TFT including a first gate electrode, a gate insulating layer on the first gate electrode, an active layer of intrinsic polycrystalline silicon on the gate insulating layer, first and second ohmic contact layers contacting the active layer, a source electrode on the first ohmic contact layer, a drain electrode on the second ohmic contact layer, and a second gate electrode over the active layer;
• and
• a pixel electrode connected to the drain electrode and disposed in the pixel region,
• wherein the second gate electrode is disposed at the same layer as and extends from the gate line.