Bismuth antimonide (composition 80:20) alloy thin films have been prepared by vacuum deposition at different substrate temperatures and, after annealing, their resistances have been recorded as a function of temperature, between 77 K and 500 K. The observed resistance against temperature behaviour of the films, and the effect of thickness and substrate temperature during deposition of the films, has been explained by considering that these films behave as semiconductors; the overlap between valence and conduction bands being removed due to the presence of antimony, the influence of a quantum size effect and the fact that the grain size of the films formed is a function of thickness and substrate temperature. © 1981 Chapman and Hall Ltd.

V. Damodara das

N. Meena

Electric properties

Semiconductor materials

Thermal effects

BISMUTH ANTIMONY COMPOUNDS

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IIT Madras

Electrical properties of Bi80Sb20 alloy thin films, vacuum-deposited at different substrate temperatures

Journal of Materials Science

Bismuth thin films of thickness 720 Å have been vacuum deposited at various substrate temperatures on glass substrates and their resistances are recorded as a function of temperature after annealing the films at 200°C. The resistance (R) versus temperature (t) curves show anomalous behaviour, in that the resistance first decreases as the temperature increases and then increases as the temperature increases, thus showing a minimum in resistance, Rmin at a temperature tmin. The position of Rmin (i.e. tmin) and the magnitude of Rmin vary with substrate temperature. However, no such anomalous behaviour is observed for the film deposited at room temperature and its resistance monotonically decreases with increase in temperature. These observations have been explained by considering that the bismuth films behave as narrow band gap semiconductors because of the quantum size effect and by the facts that in polycrystalline films the electronic mean free path will be limited by the grain size and also that the average grain size of the film increases as the substrate temperature during deposition increases. © 1981.

Vacuum

Anomalous variation of resistance in bismuth thin films and the effect of substrate temperature

Tin antimonide alloy films, vacuum-deposited at room temperature onto glass substrates, were heated to a maximum temperature of about 300 °C and the changes in their electrical resistance with temperature were recorded. The initial lattice distortion energy spectra of the films have been determined from the resistance-temperature data. It is found that the F0(E)max and Emax values vary from 200×10-4 to 700×10-4 ohms;cm/eV and from 1.55 to 1.74 eV respectively and that they depend upon the thickness of the film. The resistivities of the films due to thermal vibrations alone have been calculated and it is found that the calculated resistivity values for films of different thicknesses are in good agreement with the size effect theory. © 1974.

Journal	Journal of Materials Science
Publisher	Kluwer Academic Publishers
ISSN	00222461
Open Access	No