A porous InGaN/GaN blue light-emitting diode isdemonstrated using selective area sublimation. Transmissionelectron microscopy reveals that the structure is porous down tothe Si substrate; however, the porosity is higher in the GaN buffer,while smaller pores are observed in the active region. This changeof porosity between the active region and the buffer is explained bythe modification of the dislocation pattern in the heterostructure,which is evidenced by weak beam transmission electronmicroscopy on a nonporosified reference sample. Cathodolumi-nescence mapping and electron beam-induced current microscopy(EBIC) analyses are used to probe the impact of porosification onthe optical and electrical properties of the structure at nanoscaledimensions. It is observed that neither the quantum well emissionnor the p−n junction EBIC spatial profile was degraded after porosification with respect to the nonannealed reference sample. A light-emitting diode with a fully porous active region is fabricated using a parylene pore filling for electrical insulation, and its electroluminescence is analyzed.

Light-assisted micronanoscale temperature control in a complex nanoparticle network has attracted a lot of research interest. Many efforts have been put into the optical properties of nanoparticle networks, and only a few investigations have reported its light-induced thermal behavior. We consider a two-dimensional (2D) square-lattice nanoparticle ensemble made of typical metal Ag with a radius of 5 nm. The effect of complex multiple scattering and thermal accumulation on light-induced thermal behavior in plasmonic resonance frequency (around 383 nm) is analyzed through the Green's function approach. The regime borders of both multiple scattering and thermal accumulation effects on the photothermal behavior of the 2D square-lattice nanoparticle ensemble are figured out clearly and quantitatively. The dimensionless parameter φ is defined as the ratio of a full temperature increase to that without considering the multiple scattering or thermal accumulation to quantify the multiple scattering and thermal accumulation effects on photothermal behavior. The more compact the nanoparticle ensemble is, the stronger the multiple scattering effect on thermal behavior is. When the lattice spacing increases to dozens times of the radius, the multiple scattering becomes insignificant. When φ≈1 (lattice spacing increases to hundreds times of the radius), the thermal accumulation effects are weak and can be neglected safely. The polarization-dependent distribution of the temperature increase of nanoparticles is observed only in the compact nanoparticle ensemble, while for a dilute ensemble, such a polarization-dependent temperature increase distribution can no longer be observed. This work may help with the understanding of the light-induced thermal transport in the 2D particle ensemble.

We propose and numerically implement a local probe of the static self-induced heterogeneity characterizing glass-forming liquids. The method relies on the equilibrium statistics of the overlap between pairs of configurations measured in mesoscopic cavities with unconstrained boundaries. By systematically changing the location of the probed cavity, we directly detect spatial variations of the overlap fluctuations. We provide a detailed analysis of the statistics of a local estimate of the configurational entropy and we infer an estimate of the surface tension between amorphous states, ingredients that are both at the basis of the random first-order transition theory of glass formation. Our results represent the first direct attempt to visualize and quantify the self-induced heterogeneity underpinning the thermodynamics of glass formation. They pave the way for the development of coarse-grained effective theories and for a direct assessment of the role of thermodynamics in the activated dynamics of deeply supercooled liquids.