Nitride-based semiconductor device and method for manufacturing the same

A method for manufacturing a semiconductor device, comprising:

• forming a first nitride-based semiconductor layer;
• forming a second nitride-based semiconductor layer on the first nitride-based semiconductor layer;
• forming a doped nitride-based semiconductor layer over the second nitride-based semiconductor layer;
• forming a third nitride-based semiconductor layer on the doped nitride-based semiconductor layer;
• and
• forming a fourth nitride-based semiconductor layer on the third nitride-based semiconductor layer, wherein the third and fourth nitride-based semiconductor layers have the same composition and different physical characteristics.

A nitride-based semiconductor device, comprising:

• a first nitride-based semiconductor layer;
• a second nitride-based semiconductor layer disposed on the first nitride-based semiconductor layer, wherein the second nitride-based semiconductor layer has a bandgap higher than a bandgap of the first nitride-based semiconductor layer;
• a doped nitride-based semiconductor layer disposed over the second nitride-based semiconductor;
• a third nitride-based semiconductor layer disposed on the doped nitride-based semiconductor layer and narrower than the doped nitride-based semiconductor layer;
• and
• a fourth nitride-based semiconductor layer disposed on the third nitride-based semiconductor layer and narrower than the doped nitride-based semiconductor layer, wherein the third and fourth nitride-based semiconductor layers have the same composition and different physical characteristics, and the third nitride-based semiconductor layer is thinner than the fourth nitride-based semiconductor layer.