Author
Charles Feldman
Bio: Charles Feldman is an academic researcher. The author has contributed to research in topics: Dielectric & Thin film. The author has an hindex of 5, co-authored 8 publications receiving 150 citations.
Topics: Dielectric, Thin film, Volta potential, Photography, Electrical contacts
Papers
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TL;DR: In this article, the sharpness of the Curie transition depends to a large extent on the size of the BaTiO3 crystallites and the structure of the film seems to influence the dielectric constant and the saturation and remanent polarization.
Abstract: Ferroelectric films of BaTiO3 approximately 1 to 2 microns thick have been formed on platinum substrates by evaporation in a vacuum and a subsequent heat treatment in air. The structure of the crystallites which make up the films is mainly perovskite with the hexagonal phase as a minor constituent. Dielectric measurements show that the Curie temperature is about 120°C. The sharpness of the Curie transition depends to a large extent on the size of the BaTiO3 crystallites. The structure of the film seems to influence the dielectric constant and the saturation and remanent polarization of the film.
67 citations
TL;DR: In this article, the authors studied the temperature dependency of resistance of vacuum deposited gold and platinum films between room temperature and 400° and 600° C, respectively, and showed that the observed behavior can be attributed to a linear combination of the resistance of the individual grains or aggregates and the resistance due to gaps or potential barriers between the grains.
Abstract: The temperature dependency of resistance of vacuum deposited gold and platinum films between room temperature and 400° and 600° C, respectively, has been studied. Particular emphasis has been placed on the transition between thick, continuous films with positive temperature coefficients and thin, granular, or lacunary films with negative temperature coefficients. In addition to the low positive coefficients usually observed in this transition region, a minimum in the resistance vs temperature curve is observed. It is shown that the observed behavior can be attributed to a linear combination of the resistance of the individual grains or aggregates and the resistance due to gaps or potential barriers between the grains. The behavior in the transition region depends critically on the size of both the barriers and grains in the film.
23 citations
19 citations
TL;DR: In this paper, the authors measured the dielectric constant of vacuum-deposited ZnS films as a function of thickness in the range of 350 A to 4 μ.
Abstract: The dielectric constant of vacuum‐deposited ZnS films was measured as a function of thickness in the range of 350 A to 4 μ. For room temperature deposition, a sharp anomaly was found in the dielectric constant vs thickness curve. The highest measured constant was 34.7 at a thickness of 900 A. As the thickness increased, the dielectric constant dropped sharply and a shallow minimum less than bulk value (8.3) was observed. This minimum was 5.3 at about 1 μ. At thickness greater than 2 μ the dielectric constant was about 10. For increasing substrate deposition temperatures, 150° and 250°C, the dielectric constant approached bulk values, the anomalous peak broadened, and the maximum occurred at greater film thicknesses. The dielectric loss curves showed minima at film thicknesses corresponding to the region on the thicker side of the anomalous peaks where the dielectric constant first became or approached bulk value. It is postulated that the departure of dielectric constant from bulk values is related to the...
19 citations
TL;DR: Negative resistance and switching in amorphous B thin films observed in Ti electrodes have been observed in this article, noting volt-ampere characteristics of these thin films, and
Abstract: Negative resistance and switching in amorphous B thin films observed in Ti electrodes, noting volt-ampere characteristics
16 citations
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TL;DR: The work function of gold films prepared by evaporation of spectrographically pure gold under ultra-high vacuum was determined in this paper, using photoelectric emission and retarding potential technique.
214 citations
TL;DR: In this paper, surface-plasmon (SP) coupling was used to increase the photoluminescence (PL) intensities and decay rates of CdSe quantum dots.
Abstract: We obtained very bright light emission from CdSe quantum dots (QDs) by using the surface-plasmon (SP) coupling technique. 23-fold enhanced photoluminescence (PL) intensities and two-fold increased PL decay rates are observed when the QDs are located on evaporated gold films. This enhancement is not effective for CdSe cores with ZnS shells (ZnS/CdSe). The reason for this difference can be explained by using the SP dispersion diagram and by considering the SP coupling mechanism. We discuss the inherent merits and demerits of this technique to increase the emission efficiency. This technique will enable high-speed and efficient light emission for optically as well as electrically pumped light emitters.
162 citations
TL;DR: The most popular theory to date is that of tunnelling between islands with an electrostatic activation energy associated with single island charging as discussed by the authors, which has not yet been fully and satisfactorily explained.
157 citations
TL;DR: BaTiO3 thin films having a perovskite structure were deposited onto stainless steel and fused quartz substrates by sol-gel processing as discussed by the authors, and the dielectric constant and optical transmission were also measured.
Abstract: BaTiO3 thin films having a perovskite structure were deposited onto stainless steel and fused quartz substrates by sol‐gel processing. Crystalline, transparent, and crack‐free films of 5000 A thickness were fabricated by spinning and post‐deposition annealing at a temperature of 600 °C. Ferroelectric properties were confirmed by P‐E hysteresis loops. The dielectric constant and optical transmission were also measured.
144 citations