Showing papers by "V. Damodara Das published in 1982"
TL;DR: In this paper, the initial lattice distortion energy spectra of as-grown bismuth thin films have been evaluated and it is found that the defects have preferential activation energy values around 1.06 eV, 1.14 eV and 1.32 ev.
Abstract: Bismuth thin films of various thicknesses between 15 nm and 350 nm were vacuum deposited at room temperature on to glass substrates, immediately after which they were twice heat treated at a uniform rate. During the heat treatment, the resistance changes were monitored and, using these data, the initial lattice distortion energy spectra of as-grown bismuth thin films have been evaluated. It is found that the defects have preferential activation energy values around 1.06 eV, 1.14 eV and 1.32 ev. It is also found that ∫F0 (E) dE oscillates with thickness, which is attributed to the quantum size effect.
6 citations
TL;DR: In this paper, Wismuth thin films of different thicknesses between about 20 and 225 nm are vacuum deposited at room temperature in a vacuum of 3 × 10−3 Pa. The films are heat-treated "in situ" and the resistances monitored.
Abstract: Bismuth thin films of different thicknesses between about 20 and 225 nm are vacuum deposited at room temperature in a vacuum of 3 × 10−3 Pa. The films are heat-treated “in situ” and the resistances monitored. It is found that the resistivity-temperature plots of the films after heat-treatment are non-linear and exhibit a minimum whose position is a function of thickness. It is also found that the films behave as semiconductors, the band gap decreasing with increasing thickness. The observations are interpreted on the basis of quantum size effect and the limitation of the electronic mean free path by the grain size of the films.
Dunne Wismuth-Schichten verschiedener Dicken zwischen 20 und 225 nm werden bei Zimmer-temperatur im Vakuum von 3 × 10−3 Pa hergestellt. Die Schichten werden “in situ” getempert und der Widerstand verfolgt. Es wird gefunden, das die Widerstands-Temperatur-Verlaufe der Schichten nach der Warmebehandlung nichtlinear sind und ein Minimum aufweisen, dessen Lage von der Schichtdicke abhangt. Es wird ebenfalls gefunden, das sich die Schichten wie Halbleiter verhalten, wobei die Bandlucke mit zunehmender Schichtdicke abnimmt. Die Beobachtungen werden auf der Grundlage des Quantensize-Effekts und der Begrenzung der mittleren freien Weglange der Elektronen durch die Korngrose der Schichten erklart.
3 citations
TL;DR: In this paper, the grain size and density in NaCl thin films of equal thickness were vacuum deposited on NaCl substrates at different deposition rates both in high vacuum (2×10−5 Torr) and poor vacuum (1×10 −3 Torr).
Abstract: Tin thin films of equal thickness were vacuum deposited on NaCl substrates at different deposition rates both in high vacuum (2×10−5 Torr) and poor vacuum (1×10−3 Torr). These films were examined by electron microscopy and the grain size and density in the films were determined. It was found that both in poor and high vacuum, as the deposition rate was increased the grain size decreased and grain density increased. However, the deposition rate must be increased by an order of magnitude in order to observe large changes in the grain size and density. It was also observed that the films prepared in poor vacuum, especially at low deposition rates, consist of islands with jagged edges. These observations have been interpreted on the basis of nucleation theory and the effect of adsorbed/chemisorbed gases on island growth in these films.
2 citations
TL;DR: In this article, the initial lattice distortion energy spectra of tin antimonide alloy have been determined using Vand's theory and it has been found that for angles of deposition below 50°, defect density increases with increasing angle of deposition.
Abstract: Thin films of tin antimonide alloy have been vacuum deposited on glass substrates at room temperature at different angles of deposition. These films have been heat-treated in situ and their electrical resistance has been continuously monitored during the heating-cooling cycle. From the resistance against temperature data during heat-treatment, “initial lattice distortion energy spectra” of these films have been determined using Vand's theory. It has been found that for angles of deposition below 50°, the defect density increases with increasing angle of deposition. At higher angles of deposition, the resistance against temperature behaviour during heat-treatment is different. This is attributed to the columnar structure of the film. It is also found that preferential decay energies of the defects exist and these are 1.45 and 1.80 eV.
1 citations