A nitride semiconductor and method of making the same are provided. In embodiments, a method for manufacturing a nitride semiconductor includes: providing a nitride semiconductor material including at least one main dopant defining a p-type portion; doping the nitride semiconductor material with at least one co-dopant co-located with the main dopant, wherein the co-dopant reduces gas-enhanced diffusion of the main dopant by a component in an ambient gas during annealing; and annealing the nitride semiconductor material under pressure, thereby producing an annealed nitride semiconductor material with an activated main dopant. In implementations, a nitride semiconductor is produced including an annealed nitride semiconductor material doped with magnesium (Mg) and oxygen (O) in an activated p-type portion, wherein the Mg and O are present at a ratio of 2:1.

According to some embodiments of the present disclosure, methods of forming a semiconductor device on a semiconductor layer having opposing first and second surfaces are disclosed. An n-type doped region including an n-type dopant may be formed at the first surface of the semiconductor layer. A p-type dopant source layer including a p-type dopant may be formed on the n-type doped region. The p-type dopant may be diffused from the p-type dopant source layer through the n-type doped region into the semiconductor layer to form a p-type doped region of the semiconductor layer, and the p-type doped region of the semiconductor layer may be between the n-type doped region and the second surface of the semiconductor layer. After diffusing the p-type dopant, the p-type dopant source layer may be removed.