Semiconductor Schottky barrier devices include a wide bandgap semiconductor layer, a Schottky barrier metal layer on the wide bandgap semiconductor layer and forming a Schottky junction, a current spreading layer on the Schottky barrier metal layer remote from the wide bandgap semiconductor layer and two or more diffusion barrier layers between the current spreading layer and the Schottky barrier metal layer. The first diffusion barrier layer reduces mixing of the current spreading layer and the second diffusion barrier layer at temperatures of the Schottky junction above about 300° C. and the second diffusion barrier layer reduces mixing of the first diffusion barrier layer and the Schottky barrier metal layer at the temperatures of the Schottky junction above about 300° C.