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Near-Infrared Lasing at 1 μm from a Dilute-Nitride-Based Multishell Nanowire
摘要： A coherent photon source emitting at near-infrared (NIR) wavelengths is at the heart of a wide variety of applications ranging from telecommunications, 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 2.5 % of nitrogen. The achieved lasing is characterized by an 'S'-shape pump-power dependence and narrowing of the emission line-width. Through examining the lasing performance from a set of different single NWs, a threshold gain, g_th, of 4100 – 4800 cm^{-1}, was derived, with a spontaneous emission coupling factor, β, up to 0.8, which demonstrate the great potential of such nanophotonic material. The lasing mode was found to arise from the fundamental HE11a mode of the Fabry-Perot cavity from a single NW, exhibiting optical polarization along the NW axis. Based on temperature dependence of the lasing emission, a high characteristic temperature, T_0, of 160(±10) K is estimated. Our results, therefore, demonstrate a promising alternative route to achieve room-temperature NIR NW lasers thanks to the excellent alloy tunability and superior optical performance of such dilute nitride materials.
关键词： dilute nitride,GaAs/GaNAs/GaAs,core/shell/cap structure,Nanowire lasers
更新于2025-09-23 15:23:52
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Nitrogen mapping from ADF imaging analysis in quaternary dilute nitride superlattices
摘要： A method for the determination of N distribution in dilute nitride GaAsSbN superlattices (SLs) by using different STEM imaging settings is proposed. The method combines the simultaneous acquisition under Low Angle (LA-) and High Angle (HA-) Annular Dark Field (ADF) conditions by exploiting two different dedicated angle intervals. On one hand, HAADF technique gives information that principally depends on the atomic number (Sb sensitive) and on the other hand, N atoms produce high static atomic displacements affecting the image intensity especially under LAADF conditions. However, the simultaneous presence of Sb and N supposes an important handicap to differentiate both elements. N distribution maps could be obtained from suitable normalization and the separation of the intensity ratios in regions with/without Sb. Semi-quantitative maps are also available by combination of the results from high-resolution X-ray diffraction and energy dispersive X-Ray spectroscopy techniques. Type-I (GaAsSbN/GaAs) and type-II (GaAsSb/GaAsN) SL structures are evaluated using the proposed methodology. Differences in the N distribution between both samples such as inhomogeneities and cluster formation are discussed. Specifically, we have found a greater number of N-rich regions in type-I structure as compared to their type-II counterparts, which could have an influence on the optical response of each design.
关键词： STEM,Dilute nitride,Compositional distribution,Superlattice structures
更新于2025-09-23 15:22:29
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[IEEE 2019 European Space Power Conference (ESPC) - Juan-les-Pins, France (2019.9.30-2019.10.4)] 2019 European Space Power Conference (ESPC) - Narrow Bandgap Dilute Nitride Materials for 6-junction Space Solar Cells
摘要： Narrow bandgap p-i-n dilute nitride GaInNAsSb junctions, for use as bottom cell in 6-junction solar cells, are reported. In particular, we demonstrate a high optical quality for GaInNAsSb junction with a bandgap ~0.78 eV, corresponding to a N content of 6.2%. Under AM0 illumination, such cell exhibits a photocurrent of 36.6 mA/cm2. By extracting the parameters of the experimental cell, we estimate the the AM0 efficiency of a 6-junction multijunction solar cell employing the GaInNAsSb junction, to attain a value of 33%. Further improvements are discussed towards achieving the full potential of the 6-junction design.
关键词： GaInNAsSb,dilute nitride,molecular beam epitaxy,multijunction solar cell
更新于2025-09-23 15:21:01
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Nitrogen pair-induced temperature insensitivity of the band gap of GaNSb alloys
摘要： The temperature dependence of the band gap of GaNxSb1-x films with x ≤ 1.3% has been studied in the 1.1–3.3 μm (0.35–1.1 eV) range using infrared absorption spectroscopy between 4.2 and 300 K. As with other dilute nitride semiconductors, the temperature dependence of the band gap is reduced by alloying with nitrogen when compared to the host binary compound. However, for GaNSb, the smallest variation of the band gap with temperature is observed for samples with the lowest N content for which the band gap is almost totally insensitive to temperature changes. This contrasts with the more widely studied GaNxAs1-x alloys in which the band gap variation with temperature decreases with increasing N content. The temperature-dependent absorption spectra are simulated within the so-called band anticrossing model of the interaction between the extended conduction band states of the GaSb and the localized states associated with the N atoms. The N next-nearest neighbor pair states are found to be responsible for the temperature insensitivity of the band gap of the GaNSb alloys as a result of their proximity to the conduction band edge giving them a more pronounced role than in GaNAs alloys.
关键词： band anticrossing,GaSb,dilute nitride,GaNSb,band gap
更新于2025-09-19 17:15:36
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Electronic structures and optical gain of dilute nitride GaAs nanowires
摘要： The electronic structures and optical gain of GaAs1%xNx nanowires are calculated via the band anticrossing model together with the eight-band k & p theory. We ?nd that the optical gain spectra show an obvious red shift, and the gain increases slightly with increasing nitrogen content. The transverse magnetic (TM) gain is approximately 8.5 times larger than the transverse electric (TE) gain when the radius R is 3 nm, which indicates that GaAs1%xNx nanowires can be used as TM linearly polarized lasers in the near-infrared range. However, when R is 6 nm, the TM gain approaches the corresponding TE gain. In this case, GaAs1%xNx nanowires are not suitable for linearly polarized lasers.
关键词： optical gain,electronic structures,GaAs nanowires,dilute nitride,band anticrossing model,k & p theory
更新于2025-09-10 09:29:36
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Surfactant-induced chemical ordering of GaAsN:Bi
摘要： We have examined the in?uence of an incorporating surfactant on chemical ordering in GaAsN:Bi alloys. Epitaxy with a (2 (cid:2) 1) reconstruction leads to the formation of GaAsN alloys, while the introduction of a Bi ?ux induces long-range chemical ordering of the {111} planes of GaAsN:Bi. We propose a mechanism in which Bi enhances the alignment of dimer rows along the [110] direction, facilitating N incorporation beneath surface dimers and Bi incorporation between dimer rows to form alternating N-rich and Bi-rich {111} planes. These ?ndings suggest a route to tailoring the local atomic environment of N and Bi atoms in a wide range of emerging dilute nitride-bismide alloys.
关键词： surfactant,molecular-beam epitaxy,chemical ordering,dilute nitride-bismide alloys,GaAsN:Bi
更新于2025-09-10 09:29:36