Lateral Epitaxial Overgrowth of GaN for Electronic Devices

WiTech proposes the development of ultra low dislocation density GaN wafers for very high performance electronic device applications using Lateral Epitaxial Overgrowth (LEO) on lattice mismatched sapphire substrates. Dislocations in GaN are ubiquitous, a direct result of the lack of a lattice matched substrate for GaN thin films. Lateral Epitaxn'al Overgrowth is a process by which crystal growth is accomplished in directions parallel to the plane of the substrate. This innovative growth technique relieves strain between GaN films and the substrate and provides a means to terminate dislocation propagation in epitaxial films. Achieving device quality LEO material (very low dislocation density, very high electron mobility, high electronic quality insulating buffers) will be undertaken as the primary goal of the process development. During phase I we will initiate the development of LEO GaN wafers and evaluate the electrical and structural quality of the LEO material. At the end of phase II, WiTech will have prototype 2 sapphire substrates. Utilizing innovative device design, very high performance X-band GaN power HEMT devices with wide gate peripheries will be fabricated to demonstrate the significance of the improved LEO GaN material quality.