Thin film transistor and display substrate having the same

A display substrate, comprising:

• a base substrate;
• a first thin film transistor disposed on the base substrate and comprising a first gate electrode and a first semiconductor active layer;
• a second thin film transistor electrically connected to the first thin film transistor, the second thin film transistor comprising a second gate electrode and a second semiconductor active layer;
• and
• an organic light emitting device electrically connected to the second thin film transistor,
• wherein:
• the first semiconductor active layer comprises a first material and the second semiconductor active layer comprises a second material different from the first material;
• the first thin film transistor comprises a first source electrode connected to one side of the first semiconductor active layer and a first drain electrode connected to an other side of the first semiconductor active layer, and the second film transistor comprises a second source electrode connected to one side of the second semiconductor active layer and a second drain electrode connected to an other side of the second semiconductor active layer;
• each of the first source electrode, the second source electrode, the first drain electrode, and the second drain electrode comprises:
• a first conductive layer comprising one of copper, a copper alloy, aluminum, and an aluminum alloy;
• a second conductive layer disposed on the first conductive layer;
• and
• a third conductive layer disposed under the first conductive layer;
• each of the second conductive layer and the third conductive layer comprises a molybdenum-nickel-titanium alloy;
• and
• the molybdenum-nickel-titanium alloy contains nickel of about 15 at % to about 30 at % with respect to an aggregate of the molybdenum-nickel-titanium alloy, and titanium of about 10 at % to about 20 at % with respect to the aggregate of the molybdenum-nickel-titanium alloy.