Electrical transport through a single nanoscale semiconductor branch point

ABSTRACT. Semiconductor tetrapods are three dimensional branched nanostructures, representing a new class of materials for electrical conduction. We employ the single electron transistor approach to investigate how charge carriers migrate through single nanoscale branch points of tetrapods. We find that carriers can delocalize across the branches or localize and hop between arms depending on their coupling strength. In addition, we demonstrate a new single-electron transistor operation scheme enabled by the multiple branched arms of a tetrapod: one arm can be used as a sensitive arm-gate to control the electrical transport through the whole system. Electrical transport through nanocrystals, 1 molecules, 2,3 nanowires 4,5 and nanotubes 6,7 display novel quantum phenomena. These can be studied using the single electron transistor approach to successively change the charge state by one, to reveal charging energies, electronic level spacings, an

Imaging a 1-electron InAs quantum dot in an InAs/InP nanowire

Nanowire heterostructures define high-quality few-electron quantum dots for nanoelectronics, spintronics and quantum information processing. We use a cooled scanning probe microscope (SPM) to image and control an InAs quantum dot in an InAs/InP nanowire, using the tip as a movable gate. Images of dot conductance vs. tip position at T = 4.2 K show concentric rings as electrons are added, starting with the first electron. The SPM can locate a dot along a nanowire and individually tune its charge, abilities that will be very useful for the control of coupled nanowire dots

Low oxygen affects photophysiology and the level of expression of two-carbon metabolism genes in the seagrass <i>Zostera muelleri</i>

© 2017, Springer Science+Business Media B.V. Seagrasses are a diverse group of angiosperms that evolved to live in shallow coastal waters, an environment regularly subjected to changes in oxygen, carbon dioxide and irradiance. Zostera muelleri is the dominant species in south-eastern Australia, and is critical for healthy coastal ecosystems. Despite its ecological importance, little is known about the pathways of carbon fixation in Z. muelleri and their regulation in response to environmental changes. In this study, the response of Z. muelleri exposed to control and very low oxygen conditions was investigated by using (i) oxygen microsensors combined with a custom-made flow chamber to measure changes in photosynthesis and respiration, and (ii) reverse transcription quantitative real-time PCR to measure changes in expression levels of key genes involved in C4 metabolism. We found that very low levels of oxygen (i) altered the photophysiology of Z. muelleri, a characteristic of C3 mechanism of carbon assimilation, and (ii) decreased the expression levels of phosphoenolpyruvate carboxylase and carbonic anhydrase. These molecular-physiological results suggest that regulation of the photophysiology of Z. muelleri might involve a close integration between the C3 and C4, or other CO2 concentrating mechanisms metabolic pathways. Overall, this study highlights that the photophysiological response of Z. muelleri to changing oxygen in water is capable of rapid acclimation and the dynamic modulation of pathways should be considered when assessing seagrass primary production

Multiple Polymorphisms Affect Expression and Function of the Neuropeptide S Receptor (NPSR1)

Peer reviewe

Heterostructures incorporated in one-dimensional semiconductor materials and devices

As an alternative to traditional top-down techniques for fabrication of one-dimensional devices we here report an approach wherein a bottom-up technique is used to create one-dimensional device structures. We use the vapor-liquid-solid growth method, in which a catalytically active gold nanoparticle forms a eutectic alloy with the nanowire constituents. Our method of growth allows atomically abrupt interfaces between different III-V semiconductors, also for highly mismatched combinations for which conventional growth techniques can not be used. Special emphasis is put on the processing of ohmic contacts to nanowires. We describe the transport properties of nanowires containing heterostructures from which band off-sets between two different binary materials are determined. Finally, we report the creation of double-barrier resonant tunneling diodes in which a single InAs quantum dot surrounded by InP tunnel barriers acts as the active element in the device, resulting in energetically sharp resonant tunneling peaks reflecting tunneling into zero-dimensional states of the quantum dot

Heterointerfaces in III-V semiconductor nanowhiskers

We have investigated heterostructures formed within Vapor-Liquid-Solid grown III-V nanowhiskers. The growth conditions that are typical for chemical beam epitaxy facilitate the creation of atomically abrupt interfaces. In this paper we investigate the properties of heterostructure interfaces including switching of either the column-V material (As, P) or the column-III material (In, Ga)