Presented in this paper are the results of an investigation into 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. Based on the functional dependence of the film resistance on time, an agglomeration rate is defined with the theory of mobility coalescence invoked to explain the resistance changes in these films. It was found that the magnitude of the electric field (9 V/cm) did not influence the post-deposition coalescence but did affect the initial resistance of the film. Films studied under relative humidity conditions of greater than 85% showed an interesting crossover of the functioanl dependence of the film resistance on time consistent with earlier findings in this laboratory. Repeated deposition studies revealed that the agglomeration rate fell drastically beyond a particular deposition cycle indicating that the percolation threshold had been reached with the occurrence of large scale coalescence (LSC). © 1988.

V. Damodara das

V. Sivaramakrishnan

Aging of materials

electric conductivity

Electric field effects

Films - Growing

ISLAND SILVER FILMS

LARGE SCALE COALESCENCE

SILVER AND ALLOYS

IIT Madras is a public technical and research university located in Chennai, Tamil Nadu. Founded in 1959, it is recognised as an Institute of National Importance.

IIT Madras has been ranked as the top engineering institute in India for four years in a row by the National Institutional Ranking Framework of the MHRD

It currently offers undergraduate, postgraduate and research degrees across 16 disciplines in Engineering, Sciences, Humanities and Management. About 596 faculty belonging to science and engineering departments and centres of the Institute are engaged in teaching, research and industrial consultancy.

IIT Madras

Repeated deposition studies of the occurrence of large scale coalescence and effect of electric field on the ageing of island silver films

Vacuum

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. © 1990 IOP Publishing Ltd.

Journal of Physics D: Applied Physics

Influence of a magnetic field on the aging rates of island silver films

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. The I-V characteristics at 125 K were nonlinear, the non-linearity being attributed to field-induced structural changes. © 1988 Chapman and Hall Ltd.

Journal of Materials Science

Effect of overlayers on the instability of copper island films

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. Copyright © 1988 WILEY‐VCH Verlag GmbH &amp; Co. KGaA

physica status solidi (a)

Studies on the stability of discontinuous silver films with overlayers of Al2O3 and SiO2

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-linear I-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. © 1987 Chapman and Hall Ltd.

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

The post-deposition dc electrical-resistance increase of island copper films deposited on glass substrates at room temperature and at a pressure of 2×10-5 torr is studied. Films in the resistance range 10-95 M/ were studied under different conditions to ascertain the role of residual gases and substrate-surface contaminants on the agglomeration rate. Mobility coalescence of small islands of Cu giving rise to an agglomerated film structure is assumed to explain the post-deposition resistance increase. It was found that the logarithm of the normalized resistance [ln(R/R0); R0 is the initial resistance of the film at a time t=0] varies linearly as the logarithm of the time elapsed after the cessation of deposition. The constant of proportionality in the above relationship, termed the agglomeration rate m, shows an interesting oscillatory dependence on the initial resistance of the film and the condition of study. Nearly all the maxima and minima of m for two of the conditions studied in detail as a function of the initial resistance occur at about the same initial resistance values with the films having almost the same structure at these points. An argument is put forward based on the oscillatory nature of the effective tunneling barrier as a function of the island size to explain this unusual behavior. It is found that the presence of a thin film of water vapor on the substrate surface impedes the agglomeration rate to a great extent while the presence of adsorbed O2 and N2 decreases the energy for surface migration of islands of copper thereby increasing the agglomeration rate. © 1986 The American Physical Society.

Physical Review B

Oscillatory behavior of the agglomeration rate in island copper films

Journal of Physics C: Solid State Physics

Resistive inhomogeneity in discontinuous metal films

Journal of Applied Physics

Morphology and size distributions of islands in discontinuous films

Thin Solid Films

Room temperature oxidation rate constants of ultra- thin (discontinuous) molybdenum films

The electrical properties of ultrathin gold films during and after their growth on glass

Journal	Vacuum
ISSN	0042207X
Open Access	No