Abstract
The nitride-based semiconductor device includes a source electrode, a drain electrode, a first gate electrode, and a second gate electrode. The first gate electrode is disposed between the source electrode and the drain electrode. The first gate electrode includes a first gate bottom portion and a first gate top portion. The first gate top portion is over and wider than the first gate bottom portion. The second gate electrode is disposed over the first gate electrode and between the source electrode and the drain electrode. The second gate electrode includes a second gate bottom portion and a second gate top portion. The second gate bottom portion is in contact with the first gate bottom portion. The second gate top portion is over and wider than the second gate bottom portion.