Method and system for doping control in gallium nitride based devices

A vertical JFET formed by a method comprising:

• providing a GaN-based substrate having a surface and a first electrical contact opposing the surface, the GaN-based substrate characterized by a doping density of an n-type dopant greater than about 1×1018 cm−3;
• forming a GaN-based drift layer coupled to the GaN-based substrate and operable to conduct current in a direction substantially orthogonal to the surface, wherein forming the GaN-based drift layer comprises:
• doping the substrate with an n-type dopant to cause the doping density of the n-type dopant to be between about 1×1014 cm−3 and about 1×1018 cm−3, and
• doping the drift layer with indium to cause the indium concentration of the drift layer to be less than about 1×1016 cm−3 and to cause the carbon concentration of the drift layer to be less than about 1×1016 cm−3;
• forming an n-type channel layer coupled to the GaN-based drift layer;
• forming an n-contact layer coupled to the GaN-based drift layer and substantially parallel to the surface;
• forming a second electrical contact electrically coupled to the n-contact layer;
• forming a p-type gate region electrically coupled to the n-type channel layer;
• and
• forming a third electrical contact electrically coupled to the p-type gate region.