Enhanced uniformity of III-nitride nanowire arrays on bulk metallic glass and nanocrystalline substrates

Abstract

Nanowires possess unique strain relieving properties making them compatible with a wide variety of substrates ranging from single crystalline semiconductors, amorphous ceramics, and polycrystalline metals. Flexible metallic foils are particularly interesting substrates for nanowires for both flexible optoelectronics and high throughput manufacturing techniques. However, nanowires grown on polycrystalline metals exhibit grain-dependent morphologies. As an alternative route, the authors demonstrate the growth of highly uniform III-Nitride nanowires on bulk metallic glass (amorphous metal) and nanocrystalline Pt metal films using molecular beam epitaxy. Nanowire arrays on metallic glass substrates show uniformity over length scales >100 μm. The quality of these nanowires is explored by photoluminescence spectroscopy. The electrical characteristics of individual nanowires are measured via conductive atomic force microscopy, and mesoscale light-emitting diodes (LEDs) are fabricated. Nanowires grown on nanocrystalline Pt films showed an increase in output power by a factor of up to 32, and an increase in the overall LED efficiency by up to 13× compared with simultaneously grown nanowire LEDs on bare Si.