We have developed an ion beam assisted deposition (IBAD) texturing process for biaxially aligned films as substrates for GaN epitaxy. The IBAD process enables low-cost, large-area flexible metal foil substrates to be used as potential alternatives to single-crystal sapphire and silicon for GaN electronic devices. Epitaxial GaN films are grown by the MOCVD process on these engineered flexible substrates. We have achieved epi GaN films of several microns on polycrystalline metal foils that have in-plane and out-of-plane alignment of less than 1° FWHM and typical threading dislocation densities of 4-8 x 10^8/cm^2.
We use the epitaxial 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 LED devices. These are the first LED devices fabricated directly on metal foil. We observe photoluminescence intensities from the LED structures up to 70% of those fabricated on sapphire. We will present data on performance of such devices and how these LED devices could be printed using a roll-to-roll process.
This work was supported by the Department of Energy ARPA-E agency.
Vladimir Matias, Christopher J. Sheehan, Daniel D. Koleske, Brendan P. Gunning, Ashwin K. Rishinaramangalam, and Daniel Feezell, "Fabrication of InGaN LEDs on flexible metal foils (Conference Presentation)," Proc. SPIE 10554, Light-Emitting Diodes: Materials, Devices, and Applications for Solid State Lighting XXII, 1055406 (Presented at SPIE OPTO: January 29, 2018; Published: 14 March 2018); https://doi.org/10.1117/12.2294597.5751477500001.
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Study of self-shadowing effect as a simple means to realize nanostructured thin films and layers with special attentions to birefringent obliquely deposited thin films and photo-luminescent porous silicon