Abstract
A nitride-based semiconductor device includes a first and second nitride-based semiconductor layers, a doped III-V semiconductor layer, a gate electrode, a first and second source/drain (S/D) electrodes. The doped III-V semiconductor layer is disposed over the second nitride-based semiconductor layer and has first and second current-leakage barrier portions which extends downward from atop surface of the doped III-V semiconductor layer. The gate electrode is disposed above the doped III-V semiconductor layer, in which the gate electrode has a pair of opposite edges between the first and second current-leakage barrier portions. One of the edges of the gate electrode coincides with the first current-leakage barrier portion. The first current-leakage barrier portion is located between the first S/D electrode and the gate electrode. The second current-leakage barrier portion is located between the second S/D electrode and the gate electrode.