Developing Epi-Ready Gallium Nitride Wafer Surfaces

While acceptable optoelectronics and high power electronic devices have been commercialized on non-native substrates, a change to native III-nitride substrates promises significant improvements in device performance and reliability. Realization of these gains requires well- oriented, well-prepared native substrates with minimal subsurface damage in order to grow low- dislocation density epitaxial films. We propose the development of commercially viable wafer finishing processes and characterization techniques to produce GaN substrate surfaces optimized for epitaxial film growth. The production of epi-ready surfaces will be achieved with in-house wafer orientation control systems and the minimization of subsurface damage through the development of lapping and chemical mechanical polishing CMP) processes at our state of the art facilities. Equally important is the development of non-destructive x-ray based characterization techniques to probe the surface and sub-surface regions to rapidly evaluate chemical composition and crystalline quality throughout the process development. The research team brings a world class combination of processing knowledge and analytical expertise that will enable us to achieve a commercially viable process for the preparation of an epi-ready GaN surfaces. On these polished surfaces, we expect to be able to grow epitaxial films with dislocation densities less than 105 cm-2, to improve device performance and efficiency, contributing to DOEs goal of a reduction in energy consumption. Gallium nitride enables semiconductor device operation at much higher voltages, frequencies, and temperature than conventional silicon based devices, as well as being an important material system for light emitting diodes. When grown on native substrates, further improvements in materials properties, and device performance and lifetime can be realized. Surface preparation of gallium nitride wafers remains an undeveloped aspect of the manufacturing process, and improvements in this area will enable further gains in GaN device performance.