Method and system for forming doped regions by diffusion gallium nitride materials

A method of forming doped regions in gallium nitride materials, the method comprising:

• providing a gallium nitride substrate structure, the gallium nitride substrate structure including:
• a buffer layer formed on a substrate;
• a first epitaxial gallium nitride layer formed on the buffer layer;
• a second epitaxial gallium nitride layer formed on the first epitaxial gallium nitride layer;
• and
• an epitaxial aluminum gallium nitride layer formed on the second epitaxial gallium nitride layer;
• forming a mask on the epitaxial aluminum gallium nitride layer, the mask exposing one or more portions of a top surface of the epitaxial aluminum gallium nitride layer;
• depositing a magnesium-containing gallium nitride layer on the one or more portions of the top surface of the epitaxial aluminum gallium nitride layer;
• concurrently with depositing the magnesium-containing gallium nitride layer, forming one or more magnesium-doped regions in the epitaxial aluminum gallium nitride layer by diffusing magnesium into the epitaxial aluminum gallium nitride layer through the one or more portions, wherein the magnesium-containing gallium nitride layer provides a source of magnesium dopants;
• removing the magnesium-containing gallium nitride layer;
• and
• removing the mask.