Multispectral and Circular Polarization-Sensitive Carbon Dot-Polydiacetylene Capacitive Photodetector.

Multispectral photodetectors (MSPs) and circularly polarized light (CPL) sensors are important in opto-electronics, photonics, and imaging. A capacitive photodetector consisting of an interdigitated electrode coated with carbon dot/anthraquinone-polydiacetylene is constructed. Photoexcitation of the carbon dots induces transient electron transfer to the anthraquinone moieties, and concomitant change in the film dielectric constant and recorded capacitance.

Size-Selective Detection of Nanoparticles in Solution and Air by Imprinting.

Monitoring of nanoparticles (NPs) in air and aquatic environments is an unmet challenge accentuated by the rising exposure to anthropogenic or engineered NPs. The inherent heterogeneity in size, shape, and the stabilizing shell of NPs makes their selective recognition a daunting task. Thus far, only a few technologies have shown promise in detecting NPs; however, they are cumbersome, costly, and insensitive to the NPs morphology or composition.

Red Microalgal Sulfated Polysaccharide-CuO Complexes: Characterization and Bioactivity.

The anion-exchange capacity of the cell-wall sulfated polysaccharide of the red microalga sp. can be exploited for the complexation of metal ions (e.g.

Why do nanowires grow with their c-axis vertically-aligned in the absence of epitaxy?

Images of uniform and upright nanowires are fascinating, but often, they are quite puzzling, when the substrate is clearly not an epitaxial template. Here, we reveal the physics underlying one such hidden growth guidance mechanism through a specific example - the case of ZnO nanowires grown on silicon oxide. We show how electric fields exerted by the insulating substrate may be manipulated through the surface charge to define the orientation and polarity of the nanowires.

Method for electrical characterization of nanowires.

The ability to control conductivity in semiconductor nanostructures is often challenged by surface states trapping the majority of the charge carriers. Addressing this challenge requires a reliable method for assessing electrical properties such as carrier concentration and mobility. Unfortunately, here we are facing another challenge, as the Hall effect is geometrically inapplicable to nanowires while the field effect model is also challenged by the geometry of the common nanowire field effect transistor, and can only yield channel mobility which is very different from Hall mobility.

Photoinduced oxygen release and persistent photoconductivity in ZnO nanowires.

Photoconductivity is studied in individual ZnO nanowires. Under ultraviolet (UV) illumination, the induced photocurrents are observed to persist both in air and in vacuum. Their dependence on UV intensity in air is explained by means of photoinduced surface depletion depth decrease caused by oxygen desorption induced by photogenerated holes.

A two-colour heterojunction unipolar nanowire light-emitting diode by tunnel injection.

We present a systematic study of the current-voltage characteristics and electroluminescence of gallium nitride (GaN) nanowire on silicon (Si) substrate heterostructures where both semiconductors are n-type. A novel feature of this device is that by reversing the polarity of the applied voltage the luminescence can be selectively obtained from either the nanowire or the substrate. For one polarity of the applied voltage, ultraviolet (and visible) light is generated in the GaN nanowire, while for the opposite polarity infrared light is emitted from the Si substrate.

Catalytic hydride vapour phase epitaxy growth of GaN nanowires.

Catalytic growth of GaN nanowires by hydride vapour phase epitaxy is demonstrated. Nickel-gold was used as a catalyst. Nanowire growth was limited to areas patterned with catalyst.