Film bulk acoustic resonator (fbar) devices with 2deg bottom electrode

An integrated circuit device comprising:

• a first layer comprising a first single crystal III-N compound;
• a second layer comprising a second single crystal III-N compound on the first layer;
• an air cavity underneath at least a portion of the first layer;
• an insulation material positioned between the air cavity and the first layer;
• a top electrode on the second layer;
• and
• a bottom electrode comprising metal and laterally adjacent to and in contact with sidewalls of the first layer, such that a top portion of the first layer is between portions of the bottom electrode;
• wherein a two-dimensional electron gas (2DEG) region is inducible in the first layer.

A method of producing a resonator device, the method comprising:

• depositing insulation material on a monocrystalline substrate;
• etching a trench in the insulation material to expose the underlying substrate;
• epitaxially depositing a first layer into the trench and so that the first layer laterally overflows onto an upper surface of the insulation mateial;
• epitaxially depositing at least part of a second layer on the first layer to provide a two-dimensional electron gas (2DEG) region in the first layer adjacent to the second layer;
• forming a bottom electrode laterally adjacent to and in contact with sidewalls of the first layer, such that a top portion of the first layer is between portions of the bottom electrode, the bottom electrode being on the insulation material and comprising metal;
• and
• forming an air cavity underneath at least a portion of the first layer.