Organic thin film transistor

An organic thin film transistor, comprising:

• a substrate;
• a source/drain layer located on the substrate, and having a source region and a drain region;
• a first buffer layer located between the source region and the drain region, and covering at least one portion of the source region and at least one portion of the drain region, wherein a top surface of the first buffer layer is not lower than a top surface of the source region and a top surface of the drain region;
• a semiconductor layer located on the source/drain layer and the first buffer layer, wherein the first buffer layer is located among the semiconductor layer, the source region, the drain region, and the substrate;
• a barrier layer located on the substrate, wherein the first buffer layer is located among the semiconductor layer, the source region, the drain region, and the barrier layer;
• a second buffer layer located on the barrier layer, wherein the first buffer layer is located among the semiconductor layer, the source region, the drain region, and the second buffer layer;
• a gate insulating layer covering the source/drain layer and the semiconductor layer;
• and
• a gate electrode located on the gate insulating layer, wherein a portion of the gate insulating layer is located between the gate electrode and the semiconductor layer.