Display substrate having quantum well for improved electron mobility and display device including the same

A display substrate including a thin film transistor comprising:

• a gate electrode;
• a first semiconductor pattern formed on the gate electrode and comprising amorphous silicon;
• a second semiconductor pattern formed on the first semiconductor pattern and comprising an oxide;
• a source electrode formed on the second semiconductor pattern;
• and
• a drain electrode formed on the second semiconductor pattern and separated from the source electrode.

A display device comprising:

• a first display substrate;
• a second display substrate facing the first display substrate;
• and
• a liquid crystal layer interposed between the first display substrate and the second display substrate,
• wherein the first display substrate comprises:
• gate wiring;
• a first semiconductor pattern formed on the gate wiring and having a first energy bandgap;
• a second semiconductor pattern formed on the first semiconductor pattern,
• wherein the second semiconductor pattern comprises an oxide and has a second energy bandgap which is greater than the first energy bandgap;
• data wiring formed on the first semiconductor pattern;
• and
• a pixel electrode electrically connected to the data wiring.