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Solid-state nanopore devices with plasmonic nanoantennas are powerful tools that allow for working with individual particles and molecules in solution as well as providing light-induced control of ionic current flow through them. However, the ionic current flow manipulation by light still requires high power densities and, thus, results in the optical heating of the nanopore. Here, we solve this problem by using a 5 nm nanopore in the gap of a plasmonic bow-tie nanoantenna on a SiNx membrane irradiated by a broadband spectrum of incident light. In this regime, photons are not only strongly localized around the nanopore but also efficiently excite and trap charge carriers on defect states in the band gap of the material of the nanopore walls. As a result, ionic current flow modulation is achieved with several orders of magnitude lower power densities (around 0.035 W/cm²) from a white-light lamp than in previous works employing spectrally narrow laser sources (100-105 W/cm²). The lamp irradiation causes a 21% increase in conductivity for a nanopore without a nanoantenna and a 35% increase in conductivity for a nanoantenna-decorated nanopore at the same power of irradiation. The revealed low-intensity approach for ionic current control is preferable for the study of biological objects. [ABSTRACT FROM AUTHOR]

Epitaxial InAs-based nanowire (NW) arrays have recently gained attention as promising materials for infrared optoelectronics. To shift the spectral sensitivity of NW-based photodetectors, we for the first time investigated dilute nitride InAsN nanowires on Si(111). The growth of InAsN nanowires with a wurtzite phase was achieved through a self-induced mechanism using plasma-assisted molecular beam epitaxy. Two growth strategies were employed to synthesize InAsN and InAs/InAsN core–shell nanowires, allowing for independent control over the morphology and optical properties. According to the photoluminescence measurement and performed ab initio calculations for the wurtzite InAsN structure, we estimate the atomic concentration of the incorporated nitrogen in the studied structure as 0.5–0.7%. Transmission electron microscopy and X-ray diffraction reveal a wurtzite crystal lattice volume shrinkage with an increase in nitrogen content. Our results demonstrate the potential of dilute nitride InAsN for strain and band gap engineering in NW photodetectors on Si. [ABSTRACT FROM AUTHOR]

Crystal phase and strain engineering in epitaxial nanowire (NW) heterostructures provide a widely tunable functionality for future nanoscale light emitters and photodetectors. Thus, InAs band gaps can be finely tuned in the mid-infrared range by introducing a mechanical strain through lattice mismatch in core–shell NWs. Here, we demonstrate that the inhomogeneity of the InP shell thickness leads to a non-uniform stress field and a local variation in the degree of surface passivation along the InAs NW length which both have a strong effect on the recombination mechanisms. Catalyst-free InAs NWs with a coherent nanometer thick InP shell were grown on Si(111) by means of molecular beam epitaxy. Temperature-dependent photoluminescence (PL) studies (5–150 K) allow us to distinguish the surface passivation and strain-induced effects. Non-trivial temperature dependence in contrast to the expected monotonic band gap shrinkage with temperature was found. At high temperatures (100–150 K), radiative recombination predominantly occurs in the NW regions, which have a thicker InP shell and, as a result, are free from surface states. In turn, the coherently grown InP shell induces a tensile strain in the InAs NW core and leads to a blue shift in an emission energy by a 45–50 meV at 100 K. In contrast, at low temperatures (<100 K), the PL band undergoes a red shift with decreasing temperature since photogenerated carriers are able to radiatively recombine at band gap energy minima at the unstrained NW regions. According to the performed ab initio calculations, observed emission is attributed to the interband optical transitions of the hexagonal InAs polytype with an intermediate band gap energy (435 meV at 5 K) lying between the zinc-blende and wurtzite values. Current observations are in a great demand for stress-induced band gap tuning in the functional nanoheterostructures. [ABSTRACT FROM AUTHOR]

We suggest an approach to mass sensing via tracing the shift of the node position as an alternative to current sensing approaches based on the detection of the frequency shift. We demonstrate the compatibility of our approach with fast and versatile in situ resonator fabrication and mass measurements by means of a scanning electron microscope. The proposed sensing mechanism is minimally affected by parasitic deposition during the measurement. Within this approach, we demonstrate the measurement of several femtogram masses for single-segmented amorphous carbon nanowire cantilevers. We use the experimental results to extract material parameters of the cantilever fabricated inside a microscope chamber. We use these material parameters to model the mass-sensing performance of the double-segmented cantilever geometry. Double-segmented cantilevers show Fano resonances originated from the coupling between top and bottom segment resonances. This coupling leads to two- to three-fold responsivity enhancement in comparison to a single-segment cantilever. Our approaches to mass sensing and sensitivity estimation are general and can be extended to other cantilever materials applied for mass and force measurements. [ABSTRACT FROM AUTHOR]

Nanoscale electrically driven light-emitting sources with tunable wavelength represent a milestone for implementation of integrated optoelectronic chips. Plasmonic nanoantennas exhibiting an enhanced local density of optical states (LDOS) and strong Purcell effect hold promise for fabrication of bright nanoscale light emitters. Here, we justify gold parabola-shaped nanobumps and their ordered arrays produced by direct ablation-free femtosecond laser printing as broadband plasmonic light sources electrically excited by a probe of scanning tunneling microscope (STM). I-V curves of the probe-nanoantenna tunnel junction reveal characteristic bias voltages correlating with visible-range localized (0.55 and 0.85 μm) and near-IR (1.65 and 1.87 μm) collective plasmonic modes of these nanoantennas. These multiband resonances confirmed by optical spectroscopy and full-wave simulations provide enhanced LDOS for efficient electrically driven and bias-tuned light emission. Additionally, our studies confirm remarkable applicability of STM for accurate study of optical modes supported by the plasmonic nanoantennas at nanoscale spatial resolution.

The architecture of transparent contacts is of utmost importance for creation of efficient flexible light-emitting devices (LEDs) and other deformable electronic devices. We successfully combined the newly synthesized transparent and durable silicone rubbers and the semiconductor materials with original fabrication methods to design LEDs and demonstrate their significant flexibility. We developed electrodes based on a composite GaP nanowire-phenylethyl-functionalized silicone rubber membrane, improved with single-walled carbon nanotube films for a hybrid poly(ethylene oxide)-metal-halide perovskite (CsPbBr 3 ) flexible green LED. The proposed approach provides a novel platform for fabrication of flexible hybrid optoelectronic devices.

Electrically driven plasmonic nanoantennas can be integrated as a local source of the optical signal of advanced photonic schemes for on-chip data processing. The inelastic electron tunneling provides the photon generation or launch of surface plasmon waves. This process can be enhanced by the local density of optical states of nanoantennas. In this paper, we used scanning tunnel microscopy-induced light emission to probe the local optoelectronic properties of single gold nanodiscs. The electromagnetic field distribution in the vicinity of plasmonic structures was investigated with high spatial resolution. The obtained photon maps reveal the nonuniform distribution of electromagnetic near-fields, which is consistent with nanoantenna optical modes. Also, the analysis of derived I ( V ) curves showed a direct correlation between the nanoantenna optical states and the appearance of features on current-voltage characteristics.

We propose a novel approach for efficient tuning of optical properties of a high refractive index subwavelength nanoparticle with a magnetic Mie-type resonance by means of femtosecond laser irradiation. This concept is based on ultrafast photoinjection of dense (>10(20) cm(-3)) electron-hole plasma within such nanoparticle, drastically changing its transient dielectric permittivity. This allows manipulation by both electric and magnetic nanoparticle responses, resulting in dramatic changes of its scattering diagram and scattering cross section. We experimentally demonstrate 20% tuning of reflectance of a single silicon nanoparticle by femtosecond laser pulses with wavelength in the vicinity of the magnetic dipole resonance. Such a single-particle nanodevice enables designing of fast and ultracompact optical switchers and modulators.