Search results for "TUNNEL"
showing 10 items of 576 documents
Integrated SINIS refrigerators for efficient cooling of cryogenic detectors
2002
In this paper we report recent results obtained with large area superconductor-insulator-normal metal-insulator-superconductor tunnel junction coolers. With the devices we have successfully demonstrated electronic cooling from 260 mK to 80 mK with a cooling power of 20 pW at 80 mK. At present, we are focusing on obtaining similar performance in cooling cryogenic detectors. Additionally, we present recent results of successful operation of a metalsemiconductor structure with a Schottky barrier acting as the tunnel barrier and the possibility to use this kind of structures for on-chip cooling.
Direct observation of localized surface plasmon coupling
1999
We report on the direct observation of localized surface plasmon coupling using a photon scanning tunneling microscope. The surface plasmons are excited in gold nanostructures tailored by electron beam lithography. Electromagnetic energy transfer from a resonantly excited nanoparticle to a nanowire, which is not directly excited by the incident light is observed. Our experimental results appear to be in good agreement with theoretical computations based on Green's dyadic technique.
Mapping surface plasmon propagation by collection-mode near-field microscopy
2011
Surface plasmon propagation along striped Gold structures has been investigated by collection-mode near-field microscopy, leading to map the field intensity at the structure surface and to assess the system behavior at the nanoscale.
Surface plasmon polariton propagation across a gentle silver step
2001
Abstract Surface plasmon polaritons (SPPs) are excited with light of wavelength λ1=632.8 nm on or near a gentle Ag/Ag step structure using focused beam, prism coupling and detected using a bare, sharpened fibre tip. The tip–sample separation is controlled by means of an evanescent optical field at wavelength λ2=543.5 nm in a photon scanning tunnelling microscope (PSTM). The SPP propagation properties are first characterised on both the thin and thick sections of the Ag film structure either side of the step, both macroscopically, using attenuated total reflection, and microscopically from the PSTM images; the two techniques yield very good agreement. It is found that the SPP propagation len…
Noise and Microwave Properties of Set-Transistors
2002
Electron tunneling through a small tunnel junction with capacitance C 0 is suppressed by the so-called Coulomb blockade if the charging energy E c = e 2/2C∑ is larger than the thermal energy k B T 1. This effect is observed in a single electron tunneling transistor (SETT), which is a nano-meter size three-terminal device in which two leads connect to a small metallic island through two tunnel junctions. The excess charge on the island is regulated by the potential of the capacitively coupled gate electrode. The SETT is a very sensitive electrometer, noise levels of 10−5e/√Hz have been reached.2,3 A similar device, the electron pump, is made by connecting two or more islands in series throug…
Heteroepitaxial growth of Co on W(110) investigated by scanning tunneling microscopy
2003
We investigated the growth of Co submonolayers on bcc W(110) by scanning tunneling microscopy. Due to the strong Co-W bonding, monolayers of Co grow in equilibrium pseudomorphically on W(110) until the monolayer is almost completed. When excess atoms are deposited atop the pseudomorphic monolayer, it transforms to a close-packed (cp) monolayer with misfit dislocation lines parallel to $[11\ifmmode\bar\else\textasciimacron\fi{}0]$ (Nishiyama-Wassermann orientation). The structure of the cp monolayer, as concluded from atomically resolved STM images, deviates from the rigid hard-sphere model of a cp (111) layer. Details of the structure are compared to a structure model previously proposed by…
Low Temperature Afterglow from SrAl <sub>2</sub>O <sub>4</sub>: EU, Dy, B Containing Glass
2020
SrAl2O4: Eu, Dy, B particles were added in a phosphate glass (90NaPO3-10NaF (in mol%)) using the direct doping method. For the first time, the composition of the particles prior to and after embedding them in the glass was analysed using EPMA analysis. Boron was found to be incorporated in already distorted surroundings creating new trapping centers in the particles which are thought to be favourable for the tunnelling process and so for the afterglow at 10K. Despite the partial decomposition of the particles, the glass exhibit afterglow at low temperature confirming to be promising materials for low temperature applications.
Surface properties of AlInGaN/GaN heterostructure
2016
Abstract Surface structural, electronic and electrical properties of the quaternary alloy AlInGaN/GaN heterostructures are investigated. Surface termination, atomic arrangement, electronic and electrical properties of the (0001) surface and (10–11) V-defect facets have been experimentally analyzed using various surface sensitive techniques including spectroscopy and microscopy. Moreover, the effect of sub-band gap (of the barrier layer) illumination on contact potential difference (VCPD) and the role of oxygen chemisorption have been studied.
ZnS Ultrathin interfacial layers for optimizing carrier management in Sb2S3-based photovoltaics
2021
Antimony chalcogenides represent a family of materials of low toxicity and relative abundance, with a high potential for future sustainable solar energy conversion technology. However, solar cells based on antimony chalcogenides present open-circuit voltage losses that limit their efficiencies. These losses are attributed to several recombination mechanisms, with interfacial recombination being considered as one of the dominant processes. In this work, we exploit atomic layer deposition (ALD) to grow a series of ultrathin ZnS interfacial layers at the TiO2/Sb2S3 interface to mitigate interfacial recombination and to increase the carrier lifetime. ALD allows for very accurate control over th…
Electron refrigeration in hybrid structures with spin-split superconductors
2017
Electron tunneling between superconductors and normal metals has been used for an efficient refrigeration of electrons in the latter. Such cooling is a nonlinear effect and usually requires a large voltage. Here we study the electron cooling in heterostructures based on superconductors with a spin-splitting field coupled to normal metals via spin-filtering barriers. The cooling power shows a linear term in the applied voltage. This improves the coefficient of performance of electron refrigeration in the normal metal by shifting its optimum cooling to lower voltage, and also allows for cooling the spin-split superconductor by reverting the sign of the voltage. We also show how tunnel couplin…