Ultrahigh Quality GaN Films

The feasibility of chemical beam epitaxy to grow ultrahigh quality GaN thin films will be developed. This process will allow the growth of GaN on high thermal conductivity substrates and enable the fabrication of precision superlattice structures. GaN will be grown using Ga effusion cells and ammonia-in an ultrahigh vacuum environment. This growth rate will be in the 1 micron per hour range at temperatures between 700 and 950 C. During growth, the process will be controlled using reflection high-energy electron diffraction, Resorption mass spectroscopy, and cathodoluminescence. With these monitors, the growth conditions will be set precisely, allowing excellent reproducibility. The films will be examined after growth by atomic force microscopy, x-ray diffraction, scanning cathodoluminescence, and characterized by Hall and capacitance- voltage measurements. This process will enable us to supply ultra- high quality GaN films to an emerging, national technology.