GaN‐Based Deep‐Nano Structures: Break the Efficiency Bottleneck of Conventional Nanoscale Optoelectronics

Abstract

Conventional semiconducting nanowire optoelectronic devices generally exhibit low efficiency, due to dominant nonradiative surface recombination. Here, it is shown that such a critical challenge can be potentially addressed by exploiting semiconducting structures in the deep‐nanoregime. The epitaxy and structural and optical characteristics of GaN‐based micro‐network nanostructures grown on Si wafer are studied. These complex nanostructures have lateral dimensions as small as a few nanometers. Detailed scanning transmission electron microscopy studies suggest that the self‐assembled micro‐network nanostructures are monocrystalline, despite the porous nature. Significantly, such micro‐network nanostructures exhibit ultrabright emission in the visible spectrum. Compared to conventional InGaN nanowire structures with similar surface area, the surface recombination velocity of such deep‐nanostructures is reduced by nearly two orders of magnitude, which is evidenced by the extremely bright luminescence emission as well as the long carrier lifetime measured under low excitation conditions. This study offers a new path for the design and development of next generation high efficiency nanoscale optoelectronic devices.A detailed study of the epitaxy and characterization of GaN/InGaN micro‐network structures in the deep‐nanoregime is performed. These strain‐relaxed micro‐network nanostructures show negligible nonradiative surface recombination and remarkable enhancement in exciton oscillator strength. As such, they exhibit significantly reduced surface recombination velocity compared to nanowires evidenced by drastically enhanced photoluminescence intensity and long carrier lifetime at room temperature.