Nitride semiconductor device

A nitride semiconductor device, comprising:

• a substrate having a first surface and a second surface opposite to each other;
• a nucleation layer disposed on the first surface of the substrate;
• a doped nitride semiconductor layer disposed on the nucleation layer;
• a doped first buffer layer disposed on the doped nitride semiconductor layer, wherein the doped first buffer layer is doped by a dopant comprising carbon (C), iron (Fe), or a combination thereof, and a doping concentration of the doped first buffer layer is 1×1019/cm3 or more;
• a channel layer disposed on the doped first buffer layer, wherein the doped first buffer layer is disposed between the doped nitride semiconductor layer and the channel layer;
• a barrier layer disposed on the channel layer;
• a first electrode disposed on the barrier layer;
• and
• a second electrode electrically connected to the doped nitride semiconductor layer.

A nitride semiconductor device, comprising:

• a substrate;
• a nucleation layer disposed on the substrate;
• a P-type gallium nitride layer disposed on the nucleation layer;
• a doped first buffer layer disposed on the P-type gallium nitride layer, wherein the doped first buffer layer is doped by a dopant comprising carbon (C), iron (Fe), or a combination thereof;
• a channel layer disposed on the doped first buffer layer, wherein the doped first buffer layer is disposed between the P-type gallium nitride layer and the channel layer;
• a barrier layer disposed on the channel layer;
• a first electrode disposed on the barrier layer;
• a second electrode disposed on the barrier layer and electrically connected to P-type gallium nitride layer;
• a gate electrode disposed on the barrier layer and located between the first electrode and the second electrode;
• and
• a doped region disposed at least in a portion of the P-type gallium nitride layer, wherein the doped region is extended from below the first electrode to be partially overlapped with the second electrode, wherein the doped region is doped by neutral atoms.