A method of making a mounted gallium nitride (GaN) device includes obtaining a device structure comprising a silicon layer, a silicon carbide (SiC) layer over the silicon layer, and a GaN layer over the SiC layer. The GaN layer is processed to form an active layer of active devices and interconnect over the GaN layer. After the step of processing the GaN layer, a gold layer is formed on the silicon layer. The device structure is attached to a heat sink structure using the gold layer. The mounted GaN device includes the SiC layer over the polysilicon layer and the GaN layer over the SiC layer. The active layer is over the GaN layer.