Method and system for carbon doping control in gallium nitride based devices

A method of manufacturing a vertical JFET, the method comprising:

• providing an n-type GaN-based substrate having a surface and a first electrical contact opposing the surface;
• forming an epitaxial n-type drift layer coupled to at least a portion of the n-type GaN-based substrate and operable to conduct current in a direction substantially orthogonal to the surface;
• forming a masking material coupled to a portion of the epitaxial n-type drift layer;
• forming an n-type channel structure coupled to the epitaxial n-type drift layer, wherein gases including a group V element and a group III element used in forming the n-type channel structure are adjusted such that a molar ratio of the group V element to the group III element is at least 5,000;
• forming an n-type contact layer coupled to the n-type channel structure and substantially parallel to the surface;
• forming a second electrical contact electrically coupled to the n-type contact layer;
• forming a p-type gate region electrically coupled to the n-type channel structure;
• and
• forming a third electrical contact electrically coupled to the p-type gate region.

A method of growing an n-type GaN-based epitaxial layer, the method comprising:

• placing a GaN-based substrate in an MOCVD reactor;
• forming an oxide coupled to a portion of a surface of the GaN-based substrate;
• flowing a gas containing gallium and carbon into the MOCVD reactor;
• and
• flowing a gas containing nitrogen into the MOCVD reactor, wherein a molar ratio of nitrogen to gallium is at least 5,000;
• and
• growing the n-type GaN-based epitaxial layer.