Abstract
Some embodiments of the present invention provide a semiconductor device. The semiconductor device comprises a semiconductor substrate. A donor-supply layer is over the semiconductor substrate. The donor-supply layer includes a top surface. A gate structure, a drain, and a source are over the donor-supply layer. A passivation layer conformally covers over the gate structure and the donor-supply layer. A gate electrode is over the gate structure. An electric field plate is disposed on the passivation layer between the gate electrode and the drain. The electric field plate includes a bottom edge. The gate electrode has a first edge in proximity to the electric field plate, and the electric field plate includes a second edge facing the first edge, wherein a horizontal distance between the first edge and the second edge is within a range of from about 0.05 to about 0.5 micrometers.