Electrical Conduction Mechanism in Ultrathin, Evaporated Metal Films
TL;DR: In this paper, the authors investigated the electrical conduction mechanism in the film plane of ultrathin, evaporated metal films and showed that the conductivity depends exponentially on reciprocal temperature, and it should be independent of field at low fields.
Abstract: The electrical conduction mechanism in the film plane of ultrathin, evaporated metal films was investigated. These films consist of a planar array of many small discrete islands. The conduction process consists of, first, charge carrier creation which is thermally activated and involves charge transfer between initially neutral particles, and, second, the drift velocity of these charges in an applied field. Charge transfer between particles occurs by tunneling. The following features were predicted and can be verified experimentally: the conductivity depends exponentially on reciprocal temperature, and it should be independent of field at low fields. Deviations from the exponential temperature dependence can be understood in terms of a spectrum of activation energies, while deviations from Ohm's law at high fields can be explained readily in terms of a field dependent activation energy.
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01 Apr 1999
TL;DR: In this paper, the basic physics of single-electron devices, as well as their current and prospective applications are reviewed, and some byproduct ideas which may revolutionize random access memory and digital-data-storage technologies are presented.
Abstract: The goal of this paper is to review in brief the basic physics of single-election devices, as well as their-current and prospective applications. These devices based on the controllable transfer of single electrons between small conducting "islands", have already enabled several important scientific experiments. Several other applications of analog single-election devices in unique scientific instrumentation and metrology seem quite feasible. On the other hand, the prospect of silicon transistors being replaced by single-electron devices in integrated digital circuits faces tough challenges and remains uncertain. Nevertheless, even if this replacement does not happen, single electronics will continue to play an important role by shedding light on the fundamental size limitations of new electronic devices. Moreover, recent research in this field has generated some by-product ideas which may revolutionize random-access-memory and digital-data-storage technologies.
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Cites background from "Electrical Conduction Mechanism in ..."
...The manipulation of single electrons was demonstrated in the seminal experiments by Millikan at the very beginning of the century, but in solid state circuits it was not implemented until the late 1980s, despite some important earlier background work [1-5]....
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TL;DR: In this article, the transition from the metallic regime to the dielectric regime (10−50 A size isolated metal particles in an insulator continuum) is associated with the breaking up of a metal, where the volume fraction of metal, x, was varied from x = 1 to x = 0.05.
Abstract: Granular metal films (50–200,000 A thick) were prepared by co-sputtering metals (Ni, Pt, Au) and insulators (SiO2, Al2O3), where the volume fraction of metal, x, was varied from x = 1 to x = 0.05. The materials were characterized by electron micrography, electron and X-ray diffraction, and measurements of composition, density and electrical resistivity at electric fields e up to 106 V/cm and temperatures T in the range of 1.3 to 291 K. In the metallic regime (isolated insulator particles in a metal continuum) and in the transition regime (metal and insulator particles in a metal continuum) and in the transition regime (metal and insulator labyrinth structure) the conduction is due to percolation with a percolation threshold at x⋍0.5. Tunnelling measurements on superconductor-insulator-granular metal junctions reveals that the transition from the metallic regime to the dielectric regime (10–50 A size isolated metal particles in an insulator continuum) is associated with the breaking up of a metal ...
1,088 citations
TL;DR: In this paper, a review of the thermal properties of mesoscopic structures is presented based on the concept of electron energy distribution, and, in particular, on controlling and probing it, and an immediate application of solidstate refrigeration and thermometry is in ultrasensitive radiation detection, which is discussed in depth.
Abstract: This review presents an overview of the thermal properties of mesoscopic structures. The discussion is based on the concept of electron energy distribution, and, in particular, on controlling and probing it. The temperature of an electron gas is determined by this distribution: refrigeration is equivalent to narrowing it, and thermometry is probing its convolution with a function characterizing the measuring device. Temperature exists, strictly speaking, only in quasiequilibrium in which the distribution follows the Fermi-Dirac form. Interesting nonequilibrium deviations can occur due to slow relaxation rates of the electrons, e.g., among themselves or with lattice phonons. Observation and applications of nonequilibrium phenomena are also discussed. The focus in this paper is at low temperatures, primarily below $4\phantom{\rule{0.3em}{0ex}}\mathrm{K}$, where physical phenomena on mesoscopic scales and hybrid combinations of various types of materials, e.g., superconductors, normal metals, insulators, and doped semiconductors, open up a rich variety of device concepts. This review starts with an introduction to theoretical concepts and experimental results on thermal properties of mesoscopic structures. Then thermometry and refrigeration are examined with an emphasis on experiments. An immediate application of solid-state refrigeration and thermometry is in ultrasensitive radiation detection, which is discussed in depth. This review concludes with a summary of pertinent fabrication methods of presented devices.
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TL;DR: In this article, the authors discuss the role of disordered structures in the evolution of the electron in disordered structure and propose a method to find disordered electron structures in a graph.
Abstract: (1967). Electrons in disordered structures. Advances in Physics: Vol. 16, No. 61, pp. 49-144.
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555 citations
TL;DR: In this article, the structure of eight different metals in thicknesses from 30 to 500A has been observed in the electron microscope and correlated with their optical properties, slow rates in general giving more aggregated structure and increased light absorption.
Abstract: The structure of evaporated films of eight different metals in thicknesses from 30 to 500A has been observed in the electron microscope and correlated with their optical properties. The stable form of films thinner than a characteristic thickness was found to be aggregated. For each film the absorptions for wave-lengths in the visible were determined from the measured transmissions and reflections. The rate of formation is shown to affect the structure and the optical properties, slow rates in general giving more aggregated structure and increased light absorption.The Garnett theory has been used to explain the peculiar variation with thickness of the optical properties of thin metallic films in terms of the observed structure of the films and the bulk properties of the metal. The presence or absence of absorption maxima and their change with wave-length can be predicted qualitatively on the basis of this theory for all the films studied.
374 citations
TL;DR: In this article, the structure of thin metallic films was studied by means of electron diffraction and electron microscopy, and the effects of varying experimental conditions on the film structure of selected metals were reported.
Abstract: The structure of thin metallic films was studied by means of electron diffraction and electron microscopy. Microcrystal size can be correlated with the melting point of the metals, those with high melting points producing continuous films of small unoriented microcrystals while those with low melting points produce large microcrystals oriented preferentially with respect to the substrate. The effects of varying experimental conditions on the film structure of selected metals are reported. The electron beam of the electron microscope affects metals with low melting points most directly, producing melting, sublimation or crystallization. Variations in the velocity of the impinging atom, obtained by passing thermal atoms through a mechanical velocity selector, produce no effect for metals whose vapor is monatomic. Antimony whose vapor is found to consist of polyatomic molecules as well as atoms produces films whose grain size seems to vary with the size of the molecules forming the antimony film. The rate of...
103 citations
TL;DR: In this article, a plotzliche-irreversibel Widerstandsabnahme with zunehmender temperatures is proposed, in which the authors show that the Widersstands of Sb, Te-Schichten, As, Te, Fe, and Ag Schichten kondensiert and allmahlich auf Zimmertemperatur erwarmt.
Abstract: Im Hochvakuum werden bei 800 abs. Spiegel oder durchsichtige dunne Schichten aus Sb, As, Te, Fe und Ag aus der Dampfphase kondensiert und dann allmahlich auf Zimmertemperatur und daruber erwarmt. Bei Sb- und Te-Schichten von 35 bis 325 mμ Dicke nimmt der Widerstand bei zunehmender Erwarmung plotzlichirreversibel um mehrere Zehnerpotenzen ab, das spektral fur\(\mathfrak{E}\) ⊥ und\(\mathfrak{E}\) ∥ gemessene Lichtreflexionsvermogen betrachtlich zu. Vor der sprunghaften Widerstandsabnahme hat diereversible Widerstandskurve einen negativen Temperaturkoeffizienten, besitzt also die Eigenschaft einesHalbleiters. Die plotzliche Widerstandsabnahme erfolgt bei 2700 abs. (Sb) und 2980 abs. (Te). Fur Arsen liegt die entsprechende Temperatur bei etwa 6500 abs. Es ist wahrscheinlich, das sich Sb-, Te- und As-Schichten wahrend ihres unmetallischen Zustands in einer Art Vorstufe der dichtesten Kugelpackung befinden. Da diese von der Kristallstruktur dieser Halbmetalle stark abweicht, kann die starke und plotzliche Widerstandsabnahme durch die Strukturverschiedenheit und die frei werdende Umwandlungswarme erklart werden. — Bei dennormalen Metallen ist der Strukturunterschied zwischen der Vorstufe der dichtesten Kugelpackung und ihrem Kristallsystem wesentlich geringer als bei den Halbmetallen. Sie konnen daher im reinen Zustand nur dann alshalbleitende Schichten kondensieren, wenn die Wirkung der Krafte zwischen den Metallatomen durch die von der Unterlage ausgeubtenAdsorptionskrafte herabgesetzt wird. In der Tat zeigen sehrdunne Fe-Schichten (3 mμ) eine bei etwa 150° abs. beginnende plotzlicheirreversible Widerstandsabnahme um mehrere Zehnerpotenzen und unterhalb dieser Temperatur, nachdem sie wieder eingekuhlt wurden, einereversible Widerstandsabnahme mit zunehmender Temperatur, also das Verhalten einesHalbleiters. Wie Halbleiter verhalten sich auch sehr dunne AgSchichten, de en Widerstand jedoch bei hoherer Temperatur irreversibel bis zu unmesbar hohen Werten anwachst, da die Schicht vermutlich koaguliert. —Auf die ievesiblen Leitfahigkeits-Temperaturkurven aller untersuchten Halbmetalle und Metalle im unmetallischen (halbleitenden) Zustand kann man die Beziehung χ=χ0·e−ΔE/2kT anwenden, die gut erfullt ist, und die Konstanten χ0 und ΔE zu berechnen getattet. (χ0 Mas fur die Zahl der Leitungselektronen liefernden Zentren;Δ E Energiedifferenz zwischen dem besetzten und dem nachsthoheren beim absoluten Nullpunkt unbesetzten Energieband.) Es besteht ein eindeutiger Zusammenhang zwischen den ΔE- Werten und den Ionisierungs. potentialen der freien Atome.
30 citations