Gallium-Nitride Substrates for Improved, Solid-State Lighting

73109S03-I Gallium-nitride-based LEDs have the potential to replace incandescent lighting in many applications, due to their high-efficiency operation. ¿ This high-payoff for gallium-nitride (GaN) LEDs centers around UV-stimulated phosphors for solid-state white lighting. However, due to the lack of materials and processing technology for GaN, this potential has not yet been realized. This project will develop a process for producing LED structures with low-defect densities on GaN substrates. The single-crystal GaN substrate will have structural and thermal properties that will allow the production of low-defect-density thin films, which will increase lifetime, brightness, and yields in optoelectronic devices. A nitride MOVPE growth process will be employed to grow GaN epitaxial layers on the substrate material. Phase I will optimize GaN epitaxial growth as well as fabricate quantum well LEDs on single crystal GaN substrates. Epitaxial layers and device characteristics will be correlated to GaN substrate quality. The initial focus will be to develop quantum well LED devices operating in a wavelength range less than 450 nm, the range of greatest interest for commercial applications. Commercial Applications and Other Benefits as described by awardee: The homoepitaxial growth of GaN on single crystal GaN substrates should result in increased lifetime and brightness in optoelectronics and increased power and frequency in microelectronic devices. Low-defect-density GaN films should lead to the commercialization of blue lasers in data storage and solid-state white LED lighting.