Work done in collaboration with Sandia National Laboratories, Albuquerque, NM and University of New Mexico, Albuquerque, NM
We have developed a process for depositing device-quality epitaxial GaN films directly on unaligned polycrystalline or amorphous substrates. The process includes an ion-beam assisted deposition (IBAD) texturing process for biaxially aligned
films as a template for epitaxy. The IBAD process enables low-cost, large-area flexible metal foils to be used as potential alternatives to single-crystal sapphire and silicon wafers for GaN electronic and optoelectronic devices. Epitaxial GaN films
are then grown by MOCVD on these engineered flexible substrates. We have achieved high-quality GaN films of several microns on polycrystalline metal foils that have in-plane and out-of-plane crystallinity of less than 1° FWHM and typical
threading dislocation densities of 4-8 x 108/cm2.
We use the GaN films on IBAD/polycrystalline metal foil as a template to deposit epitaxial multi-quantum well light emitting diode (LED) InGaN structures. From these layered structures we have successfully fabricated the first LED devices
made entirely on metal foil. We observe photoluminescence intensities from the LED structures up to 70% of devices fabricated on sapphire. We will present data on performance of such devices, discuss how these LED devices could be
manufactured using roll-to-roll processes, as well as how new applications of LEDs are enabled.
This work was funded by the US Department of Energy ARPA-E Agency.