Abstract
The invention relates to a semiconductor device with improved gate leakage current. The semiconductor device comprises a substrate; a first nitride semiconductor layer over the substrate; a second nitride semiconductor layer over the first nitride semiconductor layer and having an energy gap greater than that of the first nitride semiconductor layer; a source contact and a drain contact over the second nitride semiconductor layer; a doped third nitride semiconductor layer over the second nitride semiconductor layer and between the drain contact and the source contact; and a gate electrode overthe doped third nitride semiconductor layer. The doped third nitride semiconductor layer has at least one protrusion extending in a direction substantially parallel to an interface of the first nitride semiconductor layer and the second nitride semiconductor layer, thereby achieving an effect of improving a gate leakage current phenomenon.