Abstract
A nitride-based semiconductor device includes a first nitride-based semiconductor layer, a second nitride-based semiconductor layer, a source electrode and a drain electrode, an etch resistant layer, and a gate electrode. The second nitride-based semiconductor layer is disposed on the first nitride-based semiconductor layer and has a bandgap greater than a bandgap of the first nitride-based semiconductor layer. The source electrode and the drain electrode are disposed on the second nitride-based semiconductor layer. The etch resistant layer is disposed on the second nitride-based semiconductor layer. The etch resistant layer makes contact with the second nitride-based semiconductor layer and extends from the second nitride-based semiconductor layer to a position higher than the source electrode and the drain electrode. The gate electrode is disposed over the second nitride-based semiconductor layer and has a bottom potion and a middle portion over the bottom portion and wider than the bottom portion.