Abstract
A semiconductor device includes a first nitride-based semiconductor layer and a second nitride-based semiconductor layer, a first p-type doped nitride-based semiconductor layer, a first electrode, and a second electrode. The first p-type doped nitride-based semiconductor layer is disposed over the second nitride-based semiconductor layer and has a bottom surface in contact with the second nitride-based semiconductor layer. The first p-type doped nitride-based semiconductor layer has a hydrogen concentration decreasing progressively in a direction from the bottom surface toward a top surface of the first p-type doped nitride-based semiconductor layer. The first electrode is disposed on the first p-type doped nitride-based semiconductor layer, and is in contact with the top surface of the first p-type doped nitride-based semiconductor layer. The second electrode is disposed over the second nitride-based semiconductor layer to define a drift region.