Highly uniform group III nitride epitaxial layers on 100 millimeter diameter silicon carbide substrates

1. In a method of epitaxial growth of Group III nitride layers on substrates using source gases consistent with metal organic chemical vapor deposition, the improvement comprising:

growing a heterostructure formed from two Group III nitride epitaxial layers that differ sufficiently in composition from one another to generate a two-dimensional electron gas at their interface in an atmosphere containing no more than about 5 percent hydrogen and on a substrate that is at least 100 mm in diameter.

2. A method according to claim 1 comprising growing the heterostructure on a semi-insulating substrate.

3. A method according to claim 1 , wherein the heterostructure comprises:

an epitaxial layer of gallium nitride on the substrate, and

an epitaxial layer of Al x Ga 1−x N where 0<x≦1 on the gallium nitride layer.

4. A method according to claim 3 further comprising the step of growing a nucleation layer on the substrate prior to the step of growing the gallium nitride epitaxial layer.

5. A method according to claim 1 comprising growing the heterostructure using trimethyl gallium, trimethyl aluminum, and ammonia as source gases.

6. A method according to claim 5 comprising using silane as a silicon source gas for doping an aluminum gallium nitride epitaxial layer in the heterostructure.

7. A method according to claim 1 comprising growing the heterostructure on a semi-insulating silicon carbide substrate.