Low-Defect GaN Surrogate Substrates by Epitaxial Lateral Overgrowth

We propose exploratory development of new epitaxial growth technologies for low-defect GiN epitaxial structures and surrogate substrates. A significant feature of our approach is epitaxial latval overgrowth for "defect filtering." We present arguments that such epitaxial lateral overgrowth will lead to GaN material of unprecedented quality with respect to defects, stress, and purity. In the Phase I program, three methods will be experimentally assessed for GaN lateral overgrowth: 1. vapor-phase epitaxy, 2. "nitride conversion", and 3. vapor-liquid-solid growth. Epitaxial lateral overgrowth will also be developed for new device structures that incorporate "buried" mirrors to form optical cavities, "buried" metal electrodes, and new methods for dielectric isolation. In a subsequent Phase II program, large-area (> 150 mm) GaN surrogate substrates and specific device applications (such as LEDs, UV detectors, and VCSELs) would be demonstrated. The proposed technology will provide low-cost, high-quality, large-area substrates, for GaN semiconductor device applications. New optoelectronic device structures, including high-efficiency blue LEDs, VCSELs, high-temperature electronic devices, and ultraviolet photodiodes will be developed.