Integration of Indium Gallium Nitride with Nanostructures on Silicon Substrates for Potential Photovoltaic Applications

Abstract

InGaN nanostructures are proposed to be grown on Si substrates for photovoltaic applications by utilizing nanostructured growth templates. Through combinatory approaches based on nanoimprint lithography, uniform, highly-ordered, tunable aspect-ratio SiNy nanoporous and Si nanopillared templates were first fabricated on AlN/Si and Si substrates respectively. Preliminary MOCVD conditions for InGaN heteroepitaxy on bare AlN/Si were also established. Nano-selective-area-growth was subsequently performed on the nanoporous templates to achieve ordered InGaN nanopyramid arrays. Compared with control films, structural quality of nanopyramids is improved through dislocation filtering, confinement, and bending. The impact of growth temperature, pressure, duration and V/III ratio on In content x, morphological, structural and PL qualities were studied. Compared to control films, nanopyramids yielded higher x, lower average reflectance (< 9%) and a multi-fold increase in photoluminescence intensity with tunable emission from 3.05 eV to 1.93 eV. Lastly, functional InGaN/GaN MQW core-shell nanopyramid arrays were successfully grown crack-free unlike the control.