Semiconductor device and method

A semiconductor device includes a composite layer having a first and second opposing surfaces. The composite layer includes a mesa and a first insulating layer. The mesa has top and bottom surfaces and side faces. The side faces are embedded in the first insulating layer. The mesa includes a Group III nitride-based multilayer structure providing a Group III nitride based device having first and second electrodes arranged on the mesa top surface. First and second outer contacts are positioned on the second surface of the composite layer. A first conductive via extends through the first insulating layer and is electrically coupled to the first electrode on the mesa top surface and to the first outer contact. A second conductive via extends through the first insulating layer and is electrically coupled to the second electrode on the mesa top surface and to the second outer contact.