Search results for "JUNCTION"
showing 10 items of 862 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.
Revisiting the electronic properties of Molecular Semiconductor – Doped Insulator (MSDI) heterojunctions through impedance and chemosensing studies
2015
Abstract The core activity of this work was to give a new interpretation of the electronic behavior of Molecular Semiconductor – Doped Insulator heterojunctions (MSDI), a new organic device combining two molecular materials with very different electronic properties. We focused on understanding the phenomenon occurring at the interface of fluorinated and non-fluorinated phthalocyanines that appears to be a determining factor for the electronic charge transport in the two-component thin film and ultimately deciding the nature of gas sensing, as illustrated with ozone and ammonia chosen as examples of accepting and donating gases. The impedance measurements showed that the Schottky contact bet…
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…
Molecular Semiconductors — Doped Insulator (MSDI) heterojunctions as new conductometric devices for chemosensing in wet atmosphere.
2015
Most of the gas sensors are based on resistors with inorganic materials and more rarely on other conductometric devices (diodes or transistors). Conductometric sensors have also been designed with molecular materials. Thus, in 2009, Molecular Semiconductor — Doped-insulator (MSDI) heterojunctions were built around a heterojunction between a molecular semiconductor (MS) and a doped-insulator (DI). The MS must be more conductive than the sublayer to take advantage of the heterojunction. The MS is generally of p-type and DI can be of p-type (p-MSDI) or n-type (n-MSDI) material. The energy barrier at the interface depends on the difference in the charge carrier density in the two layers, leadin…
Photonic crystals based on two-layer opaline heterostructures
2002
AbstractOptical properties of several heterostructures representing two-layer opaline photonic crystals have been examined. Two separate stop-bands have been observed both in transmission and emission spectra. The effect of the interface disorder on the optical spectra was not observed, probably, due to the insufficient degree of order of the opaline layers.
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.
Conducting Polymers for Ammonia Sensing: Electrodeposition, Hybrid Materials and Heterojunctions
2017
International audience; Polyaniline (PANI) with electrodonating and electrowithdrawing substituents were electrodeposited and studied as sensing materials in resistors and heterojunctions. Whereas the dimethoxyaniline leads to a highly conductive material, the tetrafluoroaniline leads to a poor conducting polymer. However, this latter was used in heterojunctions, associated with a highly conductive material, the lutetium bisphthalocyanine LuPc2. Elsewhere, hybrid materials combining polypyrrole (PPy) with ionic macrocycles as counterions were also electrosynthesized and used as sensing material in resistors, for the detection of ammonia. They exhibit a higher sensitivity compared to PPy pre…
Inkjet Printable ZnO/PEDOT:PSS Heterojunction for Thin Flexible Semi-Transparent Optoelectronic Sensors
2020
International audience; Flexible sensors play an increasing role in printed electronics and are of interest for optoelectronic applications in flexible robotics and industrial automation. Thus, we have investigated the hybrid inorganic-organic junction between ZnO and PEDOT:PSS (poly(3,4-ethylenedioxythiophene) polystyrene sulfonate). A thin ITO (indium tin oxide) layer on PET (polyethylene terephthalate) foils was used as substrate electrode. ZnO was deposited from a nanoparticle (NP) suspension by electrophoretic deposition. For comparison, we have used three different methods for the deposition of PEDOT:PSS, namely (i) drop casting, (ii) dip-coating, (iii) inkjet printing. For the result…
Energy level determination in bulk heterojunction systems using photoemission yield spectroscopy: case of P3HT:PCBM
2018
Financial support provided by Scientific Research Project for Students and Young Researchers Nr. SJZ2015/20 realized at the Institute of Solid State Physics, University of Latvia, is greatly acknowledged. This work has been supported by the Latvian State Research Program on Multifunctional Materials IMIS2. Jennifer Mann from Physical Electronics is greatly acknowledged for providing UPS data.
Ultrastructure of the Perineurium
2014
The perineurium is composed of multiple concentric single-cell layers enclosing individual nerve fascicles. Each layer has a thickness equivalent to the width of a perineurial cell. Groups of these cells join by means of tight junctions and desmosomes to form layers that function as a barrier against diffusion of particles across them. Perineurial internal layers have more of these specialized unions among perineurial cells, which are proximal to nerve fascicles.