Rectangular Cavity-Induced Photoluminescence Enhancement in InGaN/GaN Nanowire Mesh: A Combination of Frequency Selectivity, Carrier Confinement, and Higher Active Volume

Quantum-confined structures for light-emitting devices provide improved carrier and photon dynamics. However, increased confinement through nanostructures reduces the active device area, leading to a reduced resultant luminescence. While the luminescence efficiency is high, the effective luminescence is diminished. This work addresses this issue by having interconnected nanowire structures in the form of a mesh, which increases the active area without losing the benefits of extreme quantum confinement and forming a lateral optical cavity. The cavity brings in additional frequency selectivity tuned to the emission of the nanowires. We have considered an InGaN/GaN multiple-quantum-well (MQW) heterostructure transformed into a rectangular nanowire mesh to enhance luminescence efficiency. The MQW region is restructured into a rectangular nanowire mesh using electron beam lithography and dry/wet etching techniques. Photoluminescence (PL) measurements reveal significantly improved emission intensity, up to an order of magnitude higher for the nanowire mesh structure than the planar MQW, attributed to enhanced carrier confinement, photon extraction, and optical cavity. Femtosecond differential absorption spectroscopy demonstrates faster carrier capture into the mesh region and provides an improved supply of carriers into the active region. Time-resolved PL via time-correlated single-photon counting (TCSPC) confirms higher radiative recombination rates in the mesh. Arrhenius analysis shows higher thermal activation energy for the mesh, indicating suppression of nonradiative channels. Finite-Difference Time-Domain (FDTD) simulations confirm optical cavity resonance within the nanowire mesh, aligning well with the experimental PL peak. The emission wavelength tunability through cavity pitch engineering suggests a viable route for wavelength-selective devices. Our results collectively demonstrate that the nanowire mesh structure simultaneously enhances carrier injection, radiative efficiency, and light extraction, offering a promising platform for high-efficiency optoelectronic devices such as light-emitting diodes and lasers.