Transition metal doped II-V nitride material films exhibit ferromagnetic properties at or above room temperature. A III-V nitride material film may be doped with a transition metal film in-situ during metal-organic chemical vapor deposition and/or by solid-state diffusion processes. Doping of the III-V nitride material films may proceed in the absence of hydrogen and/or in the presence of nitrogen. In some embodiments, transition metal-doped III-V nitride material films comprise carbon concentrations of at least 10¹⁷ atoms per cubic centimeter.