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Journal ArticleDOI

Ageing and field effect studies on discontinuous silver films at near liquid nitrogen temperatures

01 Nov 1987-Journal of Materials Science (Kluwer Academic Publishers)-Vol. 22, Iss: 11, pp 4173-4176
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.
Citations
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Journal ArticleDOI
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

Journal ArticleDOI
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

Journal ArticleDOI
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

Journal ArticleDOI
TL;DR: In this article, the effect of magnetic field on the aging rates of island silver films was investigated and it was observed that the application of a magnetic field of strength 80 G during and after growth of the island film reduced the aging rate.
Abstract: The authors present the results of investigations carried out on the effect of magnetic field on the aging rates of island silver films deposited on glass substrates held at room temperature in a vacuum of 1*10-5 Torr. It is observed that the application of a magnetic field of strength 80 G during and after growth of the island film reduces the aging rate and the effect is more significant for thinner (higher resistance) films. On the basis of the mobility coalescence model it is suggested that the applied field tends to flatten the islands.

2 citations

Journal ArticleDOI
S. El-Gamal1
TL;DR: In this paper, the effect of strain on the I-V characteristics of discontinuous silver films and determination of their gauge factor was studied and it was found that a deviation from linearity is observed at higher voltages (>60 V) and at particular voltage.
Abstract: Three films (A, B and C) of discontinuous silver films whose mass thicknesses (d m ) are 6, 12 and 18 A, respectively were deposited onto Corning 7059 glass substrates at ambient temperature using a thermal evaporation technique. The increase in dc resistance (R dc ), in air, with time (time-ageing) was monitored till short-term stability was achieved. The effect of strain on the I–V characteristics of discontinuous silver films and determination of their gauge factor (v) was studied and it was found that; (1) a deviation from linearity is observed at higher voltages (>60 V) and at particular voltage, the electric current increases as d m increases (2) R dc increases as the tensional strain (ɛ) increases and the dependence of fractional change of resistance on e is linear with no hysteresis (3) v decreases as d m increases and the high values of ν for these films candidates them to be miniature strain sensors. The data of this work are discussed on the ground that the thermally activated tunneling is the mechanism responsible for the electrical conduction in discontinuous silver films.

2 citations

References
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Journal ArticleDOI
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

Book
01 Jan 1974

116 citations

Journal ArticleDOI
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

Journal ArticleDOI
TL;DR: In this article, the effect of adsorbate gases on the nucleation and growth characteristics of gold thin films on glass surfaces was studied using resistance measurements and electron microscopy techniques, and it was found that the adsorption of hydrogen, nitrogen and oxygen on the glass substrates after glow discharge cleaning was found to influence the island structure and coalescence of discontinuous gold films.

45 citations

Journal ArticleDOI
TL;DR: In this paper, the electrical resistance of vacuum-deposited island films of gold after deposition has been investigated and it was found that the morphological change of the island particles due to surface self-diffusion, provided that the electron transport between the island particle obeys the relationship derived by Neugebauer and Webb.

44 citations