Gallium nitride integrated circuits

A device having a monolithic microwave integrated circuit comprises:

• a substrate having:
• a barrier layer disposed on the substrate, the barrier layer including an aluminum gallium nitride (AlGaN) material and including a drain region, a source region, and a gate region;
• and
• a channel layer disposed between a surface of the substrate and the barrier layer, the channel layer including a gallium nitride (GaN) material;
• a gate electrical contact disposed on the gate region of the barrier layer, the gate electrical contact including one or more non-gold-based metallic materials;
• a source electrical contact disposed on the source region of the barrier layer, the source electrical contact including a non-gold-based metallic material of the one or more non-gold-based metallic materials;
• a drain electrical contact disposed on the drain region of the barrier layer, the drain electrical contact including the non-gold-based metallic material of the one or more non-gold-based metallic materials;
• and
• a capacitor including a first plate, a second plate, and a dielectric material disposed between the first plate and the second plate, wherein at least a portion of the first plate is disposed on at least one of the channel layer or the barrier layer;
• the second plate is disposed on the dielectric material;
• and the first plate and the second plate include the non-gold-based metallic material of the one or more non-gold-based metallic materials.