High-Performance Multiwavelength GaNAs Single Nanowire Lasers.

In this study, we report a significant enhancement in the performance of GaNAs-based single nanowire lasers through optimization of growth conditions, leading to a lower lasing threshold and higher operation temperatures. Our analysis reveals that these improvements in the laser performance can be attributed to a decrease in the density of localized states within the material. Furthermore, we demonstrate that owing to their excellent nonlinear optical properties, these nanowires support self-frequency conversion of the stimulated emission through second harmonic generation (SHG) and sum-frequency generation (SFG), providing coherent light emission in the cyan-green range.

Wafer-scale integration of GaAs/AlGaAs core-shell nanowires on silicon by the single process of self-catalyzed molecular beam epitaxy.

GaAs/AlGaAs core-shell nanowires, typically having 250 nm diameter and 6 μm length, were grown on 2-inch Si wafers by the single process of molecular beam epitaxy using constituent Ga-induced self-catalysed vapor-liquid-solid growth. The growth was carried out without specific pre-treatment such as film deposition, patterning, and etching. The outermost Al-rich AlGaAs shells form a native oxide surface protection layer, which provides efficient passivation with elongated carrier lifetime.

Designing Semiconductor Nanowires for Efficient Photon Upconversion via Heterostructure Engineering.

Energy upconversion via optical processes in semiconductor nanowires (NWs) is attractive for a variety of applications in nano-optoelectronics and nanophotonics. One of the main challenges is to achieve a high upconversion efficiency and, thus, a wide dynamic range of device performance, allowing efficient upconversion even under low excitation power. Here, we demonstrate that the efficiency of energy upconversion via two-photon absorption (TPA) can be drastically enhanced in core/shell NW heterostructures designed to provide a real intermediate TPA step via the band states of the narrow-bandgap region with a long carrier lifetime, fulfilling all the necessary requirements for high-efficiency two-step TPA.

Self-assembled nanodisks in coaxial GaAs/GaAsBi/GaAs core-multishell nanowires.

III-V semiconductor nanowires (NWs), such as those based on GaAs, are attractive for advanced optoelectronic and nanophotonic applications. The addition of Bi into GaAs offers a new avenue to enhance the near-infrared device performance and to add new functionalities, by utilizing the remarkable valence band structure and the giant bowing in the bandgap energy. Here, we report that alloying with Bi also induces the formation of optically-active self-assembled nanodisks caused by Bi segregation.

Effects of thermal annealing on localization and strain in core/multishell GaAs/GaNAs/GaAs nanowires.

Core/shell nanowire (NW) heterostructures based on III-V semiconductors and related alloys are attractive for optoelectronic and photonic applications owing to the ability to modify their electronic structure via bandgap and strain engineering. Post-growth thermal annealing of such NWs is often involved during device fabrication and can also be used to improve their optical and transport properties. However, effects of such annealing on alloy disorder and strain in core/shell NWs are not fully understood.

Controlling Bi-Provoked Nanostructure Formation in GaAs/GaAsBi Core-Shell Nanowires.

We control the formation of Bi-induced nanostructures on the growth of GaAs/GaAsBi core-shell nanowires (NWs). Bi serves as not only a constituent but also a surfactant and nanowire growth catalyst. Thus, we paved a way to achieve unexplored III-V nanostructures employing the characteristic supersaturation of catalyst droplets, structural modifications induced by strain, and incorporation into the host GaAs matrix correlated with crystalline defects and orientations.

Near-Infrared Lasing at 1 μm from a Dilute-Nitride-Based Multishell Nanowire.

A coherent photon source emitting at near-infrared (NIR) wavelengths is at the heart of a wide variety of applications ranging from telecommunications and optical gas sensing to biological imaging and metrology. NIR-emitting semiconductor nanowires (NWs), acting both as a miniaturized optical resonator and as a photonic gain medium, are among the best-suited nanomaterials to achieve such goals. In this study, we demonstrate the NIR lasing at 1 μm from GaAs/GaNAs/GaAs core/shell/cap dilute nitride nanowires with only 2.

Annealing induced atomic rearrangements on (Ga,In) (N,As) probed by hard X-ray photoelectron spectroscopy and X-ray absorption fine structure.

We study the effects of annealing on (Ga,In) (N,As) using hard X-ray photoelectron spectroscopy and X-ray absorption fine structure measurements. We observed surface oxidation and termination of the N-As bond defects caused by the annealing process. Specifically, we observed a characteristic chemical shift towards lower binding energies in the photoelectron spectra related to In.

Dilute Nitride Nanowire Lasers Based on a GaAs/GaNAs Core/Shell Structure.

Nanowire (NW) lasers operating in the near-infrared spectral range are of significant technological importance for applications in telecommunications, sensing, and medical diagnostics. So far, lasing within this spectral range has been achieved using GaAs/AlGaAs, GaAs/GaAsP, and InGaAs/GaAs core/shell NWs. Another promising III-V material, not yet explored in its lasing capacity, is the dilute nitride GaNAs.

GaAsBi/GaAs multi-quantum well LED grown by molecular beam epitaxy using a two-substrate-temperature technique.

We report a GaAsBi/GaAs multiple quantum well (MQW) light emitting diode (LED) grown by molecular beam epitaxy using a two-substrate-temperature (TST) technique. In particular, the QWs and the barriers in the intrinsic region were grown at the different temperatures of [Formula: see text] = 350 °C and [Formula: see text] respectively. Investigations of the microstructure using transmission electron microscopy (TEM) reveal homogeneous MQWs free of extended defects.

Metamorphic GaAs/GaAsBi Heterostructured Nanowires.

GaAs/GaAsBi coaxial multishell nanowires were grown by molecular beam epitaxy. Introducing Bi results in a characteristic nanowire surface morphology with strong roughening. Elemental mappings clearly show the formation of the GaAsBi shell with inhomogeneous Bi distributions within the layer surrounded by the outermost GaAs, having a strong structural disorder at the wire surface.

Suppression of non-radiative surface recombination by N incorporation in GaAs/GaNAs core/shell nanowires.

III-V semiconductor nanowires (NWs) such as GaAs NWs form an interesting artificial materials system promising for applications in advanced optoelectronic and photonic devices, thanks to the advantages offered by the 1D architecture and the possibility to combine it with the main-stream silicon technology. Alloying of GaAs with nitrogen can further enhance performance and extend device functionality via band-structure and lattice engineering. However, due to a large surface-to-volume ratio, III-V NWs suffer from severe non-radiative carrier recombination at/near NWs surfaces that significantly degrades optical quality.

Selective synthesis of compound semiconductor/oxide composite nanowires.

Semiconductor/oxide composite nanowires (NWs) were synthesized by molecular beam epitaxial growth and subsequent wet oxidation. Nonselective and selective oxidation conditions applied to the GaAs/AlGaAs core-shell NWs grown on silicon substrates produced GaOx/AlGaOx and GaAs/AlGaOx NWs, respectively. The oxidized amorphous AlGaOx shell produced cathodoluminescence over a wide spectral range encompassing ultraviolet and visible wavelengths, possibly sourced from molecular species related to oxygen.

Growth of dilute nitride GaAsN/GaAs heterostructure nanowires on Si substrates.

The concept of band engineering dilute nitride semiconductors into nanowires is introduced. Using plasma-assisted molecular beam epitaxy, dilute nitride GaAsN/GaAs heterostructure nanowires are grown on silicon (111) substrates. Growth of the nanowires under high As overpressure results in a regular wire diameter of 350 nm with a length exceeding 3 μm.

Epitaxial lift-off for sample preparation of x-ray absorption fine structure.

We propose a simple sample preparation technique of x-ray absorption fine structure (XAFS) for its application to the individual layer of practical compound semiconductor devices. An epitaxial lift-off process enables the investigation of pure uppermost thin epitaxial layer without containing information of the bottom-side layers as well as substrate. The plain procedure offers smooth thin film with desired thickness preserving its crystallographic structure, suitable for the measurement.