According to one embodiment of the present invention, a semiconductor device is disclosed and includes a substrate, a semiconductor channel layer, a semiconductor barrier layer, a gate electrode, a first electrode, and a dielectric layer. The semiconductor channel layer is disposed on the substrate, and the semiconductor barrier layer is disposed on the semiconductor channel layer. The gate electrode is disposed on the semiconductor barrier layer. The first electrode is disposed at one side of the gate electrode. The first electrode includes a body portion and a vertical extension portion. The body portion is electrically connected to the semiconductor barrier layer, and the bottom surface of the vertical extension portion is lower than the top surface of the semiconductor channel layer. The dielectric layer is disposed between the vertical extension portion and the semiconductor channel layer.

According to one embodiment of the present disclosure, a method of fabricating a semiconductor device is disclosed and includes the following steps: providing a substrate; forming a semiconductor channel layer on the substrate; forming a semiconductor barrier layer on the semiconductor channel layer; performing an etching process to expose a portion of the semiconductor channel layer; forming a dielectric layer covering the semiconductor barrier layer and the exposed semiconductor channel layer; and forming a first electrode after forming the dielectric layer, where the first electrode comprises a body portion and a vertical extension portion, the body portion is electrically connected to the semiconductor barrier layer, and a bottom surface of the vertical extension portion is lower than a top surface of the semiconductor channel layer.