Microscopic mapping of infrared modulated photoluminescence spectra with a spatial resolution of ∼2 μm.

Infrared photoluminescence (PL) spectroscopy with micron-scale spatial resolution is essential for the optoelectronic characterization of narrow-gap microstructures and single defects, yet it poses significant challenges due to the exceedingly weak PL signal and strong background thermal emission. This work introduces an infrared micro-PL (μPL) mapping system that achieves a spatial resolution of ∼2 μm, leveraging the inherent advantages of the step-scan Fourier transform infrared spectrometer-based modulated PL technique in the mid- and far-infrared regions. The configuration of the experimental system is described, and a theoretical upper limit of spatial resolution is derived to be about 1.

Mid-infrared photoluminescence revealing internal quantum efficiency enhancement of type-I and type-II InAs core/shell nanowires: publisher's note.

This publisher's note contains corrections to Opt. Lett.47, 5208 (2022)10.

A Sequential Electrospinning of a Coaxial and Blending Process for Creating Double-Layer Hybrid Films to Sense Glucose.

This study presents a glucose biosensor based on electrospun core-sheath nanofibers. Two types of film were fabricated using different electrospinning procedures. Film F1 was composed solely of core-sheath nanofibers fabricated using a modified coaxial electrospinning process.

Mid-infrared photoluminescence revealing internal quantum efficiency enhancement of type-I and type-II InAs core/shell nanowires.

Internal quantum efficiency (IQE) is an important figure of merit for photoelectric applications. While the InAs core/shell (c/s) nanowire (NW) is a promising solution for efficient quantum emission, the relationship between the IQE and shell coating remains unclear. This Letter reports mid-infrared PL measurements on InAs/InGaAs, InAs/AlSb, and InAs/GaSb c/s NWs, together with bare InAs NWs as a reference.

Hybrid Films Prepared from a Combination of Electrospinning and Casting for Offering a Dual-Phase Drug Release.

One of the most important trends in developments in electrospinning is to combine itself with traditional materials production and transformation methods to take advantage of the unique properties of nanofibers. In this research, the single-fluid blending electrospinning process was combined with the casting film method to fabricate a medicated double-layer hybrid to provide a dual-phase drug controlled release profile, with ibuprofen (IBU) as a common model of a poorly water-soluble drug and ethyl cellulose (EC) and polyvinylpyrrolidone (PVP) K60 as the polymeric excipients. Electrospun medicated IBU-PVP nanofibers (F7), casting IBU-EC films (F8) and the double-layer hybrid films (DHFs, F9) with one layer of electrospun nanofibers containing IBU and PVP and the other layer of casting films containing IBU, EC and PVP, were prepared successfully.

Hole array enhanced dual-band infrared photodetection.

Photonic structures have been attracting more attention due to their ability to capture, concentrate and propagate optical energy. In this work, we propose a photon-trapping hole-array structure integrated in a nip InAsSb-GaSb heterostructure for the enhancement of the photoresponse in both near- and mid-infrared regions. The proposed symmetrical hole array can increase the photon lifetime inside the absorption layer and reduce reflection without polarization dependence.

Spatially resolved and two-dimensional mapping modulated infrared photoluminescence spectroscopy with functional wavelength up to 20 μm.

The pixel-scale nonuniformity of the photoelectric response may be due either to the in-plane electronic inhomogeneity of the narrow-gap semiconductor or to the craft fluctuation during the fabrication process, which limits the imaging performance of the infrared focal plane array (FPA) photodetector. Accordingly, a nondestructive technique is most desirable for examining the spatial uniformity of the optoelectronic properties of the narrow-gap semiconductor to identify the origin of the FPA response nonuniformity. This article introduces a spatially resolved and two-dimensional mapping infrared photoluminescence (PL) technique, especially suitable for characterizing FPA narrow-gap semiconductors, based on the modulated PL method with a step-scan Fourier transform infrared spectrometer.

Self-Seeded MOCVD Growth and Dramatically Enhanced Photoluminescence of InGaAs/InP Core-Shell Nanowires.

We report on the growth and characterization of InGaAs/InP core-shell nanowires on Si-(111) substrates by metal-organic chemical vapor deposition (MOCVD). The strain at the core-shell interface induced by the large lattice mismatch between the InGaAs core and InP shell materials has strong influence on the growth behavior of the InP shell, leading to the asymmetric growth of InP shell around the InGaAs core and even to the bending of the nanowires. Transmission electron microscopy (TEM) measurements reveal that the InP shell is coherent with the InGaAs core without any misfit dislocations.

Nanoscale distribution of Bi atoms in InPBi.

The nanoscale distribution of Bi in InPBi is determined by atom probe tomography and transmission electron microscopy. The distribution of Bi atoms is not uniform both along the growth direction and within the film plane. A statistically high Bi-content region is observed at the bottom of the InPBi layer close to the InPBi/InP interface.

Midinfrared Photoluminescence up to 290 K Reveals Radiative Mechanisms and Substrate Doping-Type Effects of InAs Nanowires.

Photoluminescence (PL) as a conventional yet powerful optical spectroscopy may provide crucial insight into the mechanism of carrier recombination and bandedge structure in semiconductors. In this study, mid-infrared PL measurements on vertically aligned InAs nanowires (NWs) are realized for the first time in a wide temperature range of up to 290 K, by which the radiative recombinations are clarified in the NWs grown on n- and p-type Si substrates, respectively. A dominant PL feature is identified to be from the type-II optical transition across the interfaces between the zinc-blend (ZB) and the wurtzite (WZ) InAs, a lower-energy feature at low temperatures is ascribed to impurity-related transition, and a higher-energy feature at high temperatures originates in the interband transition of the WZ InAs being activated by thermal-induced electron transfer.

Anomalous photoluminescence in InP1-xBix.

Low temperature photoluminescence (PL) from InP1-xBix thin films with Bi concentrations in the 0-2.49% range reveals anomalous spectral features with strong and very broad (linewidth of 700 nm) PL signals compared to other bismide alloys. Multiple transitions are observed and their energy levels are found much smaller than the band-gap measured from absorption measurements.

Infrared photoreflectance investigation of resonant levels and band edge structure in InSb.

Temperature-dependent infrared photoreflectance (PR) is employed on InSb for clarifying resonant levels (RLs) and band edge structure. Abundant PR features are well resolved around the bandgap and are verified to be of electronic inter-level transitions rather than the Franz-Keldysh oscillations. The evolution of the critical energies with temperature reveals the nature of the PR processes, from which one acceptor RL, two donor RLs, and a shallow acceptor level are quantitatively identified, and a detailed band edge structure is derived.