Abstract
A semiconductor device includes a first and a second nitride-based semiconductor layers, a doped nitride-based semiconductor layer, a plurality of negatively-charged ions, a source electrode, and a drain electrode. The negatively-charged ions are selected from a highly electronegative group and distributed within a plurality of depletion regions which extend downward from the doped nitride-based semiconductor layer and are located beneath the gate electrode. Any pair of the adjacent depletion regions are separated from each other. The source electrode is disposed above the second nitride-based semiconductor layer and spaced apart from the depletion regions. The drain electrode is disposed above the second nitride-based semiconductor layer and spaced apart from the depletion regions.