Gallium nitride (GaN) three-dimensional integrated circuit technology is described. In an example, an integrated circuit structure includes a layer including gallium and nitrogen, a plurality of gate structures over the layer including gallium and nitrogen, a source region on a first side of the plurality of gate structures, a drain region on a second side of the plurality of gate structures, the second side opposite the first side, and a drain field plate above the drain region wherein the drain field plate is coupled to the source region. In another example, a semiconductor package includes a package substrate. A first integrated circuit (IC) die is coupled to the package substrate. The first IC die includes a GaN device layer and a Si-based CMOS layer.