Thin film transistor

A thin film transistor comprising:

• a gate electrode, an insulating medium layer and at least one Schottky diode unit, wherein the insulating medium layer is located on the gate electrode, the at least one Schottky diode unit is located on a surface of the insulating medium layer and insulated from the gate electrode via the insulating medium layer, each of the at least one Schottky diode unit comprises:
• a first electrode located on the surface of the insulating medium layer, wherein the first electrode comprises a first metal layer and a second metal layer, the first metal layer covers the second metal layer, the second metal layer is between the insulating medium layer and the first metal layer, and one end of the second metal layer is extended from the first metal layer to form a step structure in the first electrode;
• a second electrode located on the surface of the insulating medium layer and apart from the first electrode, wherein the second electrode comprises a third metal layer and a fourth metal layer, the third metal layer covers the fourth metal layer, the fourth metal layer is between the insulating medium layer and the third metal layer, and one end of the third metal layer protrudes from the fourth metal layer to form an inverted step structure;
• and
• a semiconductor structure comprising a first end and a second end, wherein the first end of the semiconductor structure is sandwiched by the first metal layer and the second metal layer, the second end of the semiconductor structure is sandwiched by the third metal layer and the fourth metal layer, a portion of the semiconductor structure between the first end and the second end is defined as a middle portion, the step structure of the first electrode and the inverted step structure of the second electrode are both located between the first end and the second end of the semiconductor structure, and near the middle portion of the semiconductor structure, the semiconductor structure is a carbon nanotube structure.