Repeated deposition studies of the occurrence of large scale coalescence and effect of electric field on the ageing of island silver films
TL;DR: In this article, the authors investigated the influence of a dc electric field on the growth and post-deposition resistance changes in island Ag-films deposited on glass substrates at room temperature.
About: This article is published in Vacuum.The article was published on 1988-01-01. It has received 6 citations till now. The article focuses on the topics: Coalescence (physics) & Thin film.
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TL;DR: In this paper, the effect of magnetic field on the occurrence of large scale coalescence (LSC) is studied through repeated deposition technique, and the results show that the effect is more pronounced on smaller islands than on larger ones.
Abstract: The results of studies carried out on the effect of magnetic field on the ageing of island silver films, deposited on glass substrates held at room temperature in a vacuum of Torr are presented in this article. The effect of magnetic field on the occurrence of large scale coalescence (LSC) is studied through the repeated deposition technique. A magnetic field of the order of 100 Oe reduces the ageing rate due to the flattening of islands but variation of the field in the same range does not affect ageing significantly. The effect of magnetic field is more pronounced on smaller islands than on larger ones. The application of magnetic field causes LSC to occur at an earlier stage.
16 citations
TL;DR: In this article, the effect of overlayers of Al2O3, SiO2 and MoO3 on the instability of discontinuous copper films at room temperature and at 125 K, are reported.
Abstract: The results of investigations carried out on the effect of overlayers of Al2O3, SiO2 and MoO3 on the instability of discontinuous copper films at room temperature and at 125 K, are reported. For one film, long-term stability was studied for more than 1500 h. The overlayers are inadequate in preventing movement of the islands both at room temperature and at 125 K and in providing protection against attack by atmospheric gases. The films, when exposed to the atmosphere, show a large increase in resistance in a well-defined pressure range of ≃5 × 10−2 torr, corroborating our earlier findings. TheI-V characteristics at 125 K were nonlinear, the non-linearity being attributed to field-induced structural changes.
7 citations
TL;DR: In this paper, the post deposition resistance changes in discontinuous silver films deposited in a vacuum of 2 × 10−6 torr on glass substrates maintained at near liquid nitrogen temperatures have been studied.
Abstract: The post deposition resistance changes in discontinuous silver films deposited in a vacuum of 2 × 10−6 torr on glass substrates maintained at near liquid nitrogen temperatures have been studied. Reduced agglomeration rates in comparison with films studied at room temperature were obtained, supporting the thermally assisted mobility coalescence model explaining the post deposition resistance increase. The non-linearI-V characteristics of one of the films followed by observations of resistance changes before and after field effect measurements on the other films have been explained as arising due to field-induced structural changes. The investigations of the variation of film resistance with temperature revealed a transition temperature. A fall in resistance with increasing temperature below the transition temperature has been explained by an increase in the number of thermally charged islands. The increase in resistance with temperature above the transition temperature is due to an increase in the thermally assisted mobility coalescence.
5 citations
TL;DR: In this paper, experiments carried out on the stability of discontinuous silver films with overtayers of A12Os and SiO2 studied at room temperature and at 125 K were carried out.
Abstract: Results are given of experiments carried out on the stability of discontinuous silver films with overtayers of A12Os and SiO2 studied at room temperature and at 125 K. Long term stability (upto 3500 h) of two films is achieved after ageing for 700 h. The overlayers of A12O3 and SiO2 are unableto prevent oxidation and attack by water vapour of the metal islands resulting in the initial changes in resistance on exposure to atmosphere. Overlayers of A12O3 and SiO2 also do not prevent resistance increase of the films in vacuum (2 × 10−4 Pa) studied at both, room temperature and at 125 K. Resistance measurements as a function of the chamber pressure during exposure to atmosphere reveal that the films oxidise in a well defined pressure range of 6.6 Pa. Non-linear current-voltage (I-U) characteristics are observed for all the films which is explained as due to a field induced structural change as indicated by an irreversible resistance change.
Es werden die Ergebnisse von Untersuchungen der Stabilitat von diskontinuierlichen Silberschichten mit A12O3- und SiO2-uberzugen bei Raumtemperatur und 125 K mitgeteilt. Langzeitstabilitat (bis zu 3500 h) von zwei Schichten wird nach Alterung uber 700 h erhalten. A12O3- und SiO2-uberzuge sind nicht in der Lage, Oxydation und Wasserdampfeinflusse auf die metallischen Inseln zu verhindern, was zu Anderungen des Anfangswiderstands in Abhangigkeit von der Einwirkung der Atmosphare resultiert. A12O3- und SiO2-uberzuge verhindern auch nicht den Widerstandsanstieg der Schichten im Vakuum (2 × 10−4 Pa) der sowohl bei Zimmertemperatur als auch bei 125 K untersucht wird. Widerstandsmessungen in Abhangigkeit vom Kammerdruck wahrend der Einwirkung der Atmosphare zeigen, das die Schichten in einem wohldefinierten Druckbereich von 6,6 Pa oxydieren. Nichtlineare Strom-Spannungs (I-U)-Charakteristiken werden fur alle Schichten beobachtet, was durch das Auftreten einer feldinduzierten strukturellen Anderung, die durch eine irreversible Widerstandsanderung angezeigt wird, erklart wird.
4 citations
TL;DR: In this paper, the results of aging experiments carried out on copper island films deposited on fused quartz substrates held at 380 K in a vacuum of 1×10−5 Torr were presented.
Abstract: Presented in this communication are the results of aging experiments carried out on copper island films deposited on fused quartz substrates held at 380 K in a vacuum of 1×10−5 Torr. Ion‐bombardment cleaning of the substrates prior to deposition of the films was found to significantly alter the aging rates in the films. The mobility coalescence model was operative during the aging process, and it is inferred from the data that adsorbed gases on the substrate surface affect the nucleation and reduce the mobility of copper islands, which reduces the aging rate. The mean island sizes were determined for some of the films from activation energy measurements.
2 citations
References
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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.
699 citations
TL;DR: In this article, an electric field applied in the plane of a metal film during deposition induces coalescence of the three-dimensional island-like structure at an earlier stage of the film growth than is obtained without the field.
Abstract: It has been found that an electric field applied in the plane of a metal film during deposition induces coalescence of the three‐dimensional island‐like structure at an earlier stage of the film growth than is obtained without the field. The surface area of the three dimensional islands is increased under applied electric field. The critical thickness, at which the electrically continuous film is obtained, decreases with the increase of electric field. The decrease is more rapid at higher substrate temperatures. Enhanced orientation effects and fewer structural defects have been observed in films deposited under applied field and are attributed to the recrystallization during induced coalescence.The observed short range order in the coalescence pattern indicates that the applied field transfers and redistributes the electrostatic charges on the islands. It is shown that the presence of a small number of electrostatic charges increases the surface energy and thus the surface area considerably. The electros...
135 citations
TL;DR: In this paper, the authors observed that discontinuous gold films exhibit temperature-dependent morphological changes following deposition and observed that the initial deposited nuclei are nearly circular and have a doubled peaked size distribution.
Abstract: Vacuum‐deposited discontinuous gold films are observed to exhibit temperature‐dependent morphological changes following deposition This effect is observed on both carbon and silicon monoxide substrates For substrate temperatures between approximately 450° to 750°K the initial deposited nuclei are nearly circular and have a doubled‐peaked size distribution Because of resolution limitations only the part of the distribution with the large sizes is quantitatively examined and discussed Analysis of the distributions at different time intervals following deposition shows a shift in both the mean radius and the dispersion and a decrease in the number of nuclei per unit area These changes are discussed in terms of possible mass transfer along the surface
96 citations
TL;DR: In this paper, experimental results on the behavior of discontinuous metal films on amorphous substrates of carbon and silicon monoxide are extended and reviewed in terms of possible mechanisms to account for the experimental behavior.
Abstract: Experimental results on the behavior of discontinuous metal films on amorphous substrates of carbon and silicon monoxide are extended and reviewed. These results are discussed in terms of possible mechanisms to account for the experimental behavior. The mechanism of island motion with subsequent coalescence is selected, for it agrees best with the observed results. This mechanism is used as a basis for a calculation in which the behavior of the islands is treated by statistical methods. Solutions predict the time and temperature dependence for the mean radius and dispersion of the island distribution. Comparison to experiment is favorable and yields a quantity which corresponds to the binding energy of gold islands to carbon or to silicon monoxide substrates. For the gold‐carbon case, the binding energy is 1.29±0.04 eV, while the gold‐silicon monoxide case yields 1.52±0.23 eV.
72 citations
TL;DR: In this article, the kinetics of mobility coalescence in a thin discontinuous film are investigated provided that the deposition is completed and the process proceeds in a pure form, and the analysis is made on the basis of the mathematical formalism developed by Smoluchowski for description of the colloid rapid coagulation.
67 citations