Optical transmission matrix as a probe of the photonic strength

We demonstrate that optical transmission matrices (TM) of disordered complex media provide a powerful tool to extract the photonic interaction strength, independent of surface effects. We measure TM of strongly scattering GaP nanowires and plot the singular value density of the measured matrices and a random matrix model. By varying the free parameters of the model, the transport mean free path and effective refractive index, we retrieve the photonic interaction strength. From numerical simulations we conclude that TM statistics is hardly sensitive to surface effects, in contrast to enhanced backscattering or total transmission based methods.We acknowledge support from ERC grant 27948, NWOVici, STW, the Royal Society, and EPSRC through fellowship EP/J016918/1

Probing Nucleation Mechanism of Self-Catalyzed InN Nanostructures

The nucleation and evolution of InN nanowires in a self-catalyzed growth process have been investigated to probe the microscopic growth mechanism of the self-catalysis and a model is proposed for high pressure growth window at ~760 Torr. In the initial stage of the growth, amorphous InNx microparticles of cone shape in liquid phase form with assistance of an InNx wetting layer on the substrate. InN crystallites form inside the cone and serve as the seeds for one-dimensional growth along the favorable [0001] orientation, resulting in single-crystalline InN nanowire bundles protruding out from the cones. An amorphous InNx sheath around the faucet tip serves as the interface between growing InN nanowires and the incoming vapors of indium and nitrogen and supports continuous growth of InN nanowires in a similar way to the oxide sheath in the oxide-assisted growth of other semiconductor nanowires. Other InN 1D nanostructures, such as belts and tubes, can be obtained by varying the InN crystallites nucleation and initiation process

A facile chemical conversion synthesis of Sb2S3 nanotubes and the visible light-driven photocatalytic activities

We report a simple chemical conversion and cation exchange technique to realize the synthesis of Sb2S3 nanotubes at a low temperature of 90°C. The successful chemical conversion from ZnS nanotubes to Sb2S3 ones benefits from the large difference in solubility between ZnS and Sb2S3. The as-grown Sb2S3 nanotubes have been transformed from a weak crystallization to a polycrystalline structure via successive annealing. In addition to the detailed structural, morphological, and optical investigation of the yielded Sb2S3 nanotubes before and after annealing, we have shown high photocatalytic activities of Sb2S3 nanotubes for methyl orange degradation under visible light irradiation. This approach offers an effective control of the composition and structure of Sb2S3 nanomaterials, facilitates the production at a relatively low reaction temperature without the need of organics, templates, or crystal seeds, and can be extended to the synthesis of hollow structures with various compositions and shapes for unique properties

Nanowire and electronic device

The nanowire ( 10 ) comprises a first region ( 1 ), a second region ( 2 ), and a third region ( 3 ), wherein the diameter (c) of the second region ( 2 ) is greater than the diameters (a) of the first and the third region ( 1, 3 ), therewith interrupting at least partially the quantization of the nanowire ( 10 ) and giving the second region a smaller bandgap. The second region ( 2 ) has a length (b) in axial direction of less than 100 nm, preferably less than 20 nm. The nanowire ( 10 ) can be used in an (opto-)electronic device having electrodes as a quantum dot, a single-electron transistor, or the like

Tunable radiation emitting semiconductor device

A tunable radiation emitting semiconductor device includes at least one elongated structure at least partially fabricated from one or more semiconductor materials exhibiting a bandgap characteristic including one or more energy transitions whose energies correspond to photon energies of light radiation. The structure is operable to emit light radiation in response to a current flow therethrough. Moreover, the elongated structure is fabricated to be sufficiently narrow for quantum confinement of charge carriers associated with the current flow to occur therein. Furthermore, the structure further includes an electrode arrangement for applying an electric field to the elongated structure for causing bending of its bandgap characteristic for modulating a wavelength of the light radiation emitted in operation from the structure in response to the current flow therethrough

Semiconductor sensor device, diagnostic instrument comprising such a device and method of manufacturing such a device

The invention relates to a semiconductor sensor device (10) for sensing a substance comprising at least one mesa- shaped semiconductor region (11) which is formed on a surface of a semiconductor body (12) and which is connected at a first end to a first electrically conducting connection region (13) and at a second end to a second electrically conducting connection region (14) while a fluid (20) comprising a substance (30) to be sensed can flow along the mesa- shaped semiconductor region (11) and the substance (30) to be sensed can influence the electrical properties of the mesa-shaped semiconductor region (11), wherein the mesa-shaped semiconductor region (11) comprises viewed in a longitudinal direction subsequently a first semiconductor subregion (1) comprising a first semiconductor material and a second semiconductor subregion (2); comprising a second semiconductor material different from the first semiconductor material. According to the invention the first semiconductor material comprises a IV element material and the second semiconductor material comprises a III-V compound. Due to difference in surface chemistry between subregions 1,2 a substance (30) like an antibody to which a protein signaling a disease can be bonded can be more selectively attached to the desired first region (1)

Optical information recording medium

The invention relates to an optical information recording medium and methods and devices to record and read information thereto and thereof. The optical information recording medium comprises luminescent nano-elements. The nano-element species differ in at least one luminescence wavelength. Therefore, a specific luminescence signal is obtained in accordance with the nano-element species irradited by a reading light beam. Methods and devices to record and read information by using such optical information recording media are also described

Resonant electron tunneling through semiconducting nanocrystals in a symmetrical and an asymmetrical junction

We studied resonant electron tunneling through individual CdSe and CdS nanocrystals in two types of configuration. With nanocrystals electrodeposited on bare gold, the spectra show resonant tunneling via discrete unoccupied (CB region) and occupied levels (VB region) at positive and negative bias, respectively. In this asymmetrical configuration, the bias is only distributed across the tip/dot barrier; this allows one, in principle, to derive the electronic structure of nanocrystals from tunneling spectra. With colloidal nanocrystals covalently anchored to a gold substrate via hexane dithiol, tip-to-gold and gold-to-tip tunneling occurs via the same set of unoccupied levels

Semiconductor device comprising a heterojunction

A semiconductor device with a heterojunction. The device comprises a substrate and at least one nanostructure. The substrate and nanostructure is of different materials. The substrate may e.g. be of a group IV semiconductor material, whereas the nanostructure may be of a group III-V semiconductor material. The nanostructure is supported by and in epitaxial relationship with the substrate. A nanostructure may be the functional component of an electronic device such as a gate-around-transistor device. In an embodiment of a gate-around-transistor, a nanowire ( 51 ) is supported by a substrate ( 50 ), the substrate being the drain, the nanowire the current channel and a top metal contact ( 59 ) the source. A thin gate dielectric ( 54 ) is separating the nanowire and the gate electrode ( 55 A, 55 B)

Semiconductor device with tunable energy band gap

The present invention relates to a semiconductor device in which energy band gap can be reversibly varied. An idea of the present invention is to provide a device, which is based on a semiconducting material (306) in mechanical contact with a material that exhibits a reversible volume change when properly addressed, e.g. a phase change material (307). The device can, for example, be implemented in light emitting, switching and memory in applications. The semiconducting material can be reversibly strained by applying a local volume expansion to the phase change material. The resulting band gap variation of the semiconducting material can be utilized to tune the color of the light emitted from e.g. an LED or a laser. In other fields of application, contact resistance in semiconductor junctions can be controlled, and this feature is highly advantageous in memories and switches