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Subject: search.filters.subject.530Institute: search.filters.UBSInstitut.1. Physikalisches InstitutInstitute: search.filters.UBSInstitut.Sonstige EinrichtungStart date: 1980End date: 1989Publication Type: search.filters.UBSTyp.Zeitschriftenartikel

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    A study of the ground state of acceptors in silicon from thermal transport experiments
    (1981) Goer, Anne M. de; Locatelli, Marcel; Lassmann, Kurt
    Thermal conductivity measurements of silicon crystals doped with Bor In have shown the presence of several phonon scattering processes. The resonant effect observed below 1 K is ascribed to the existence of a distribution of splittings N(δ) of the Γ8 ground state of the acceptor, which could be related to the presence of oxygen and carbon impurities. In two cases, the maximum of N(δ) occurs for δ max near 6 GHz, in agreement with previous ultrasonic studies.
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    Down-conversion of high-frequency acoustic phonons
    (1987) Galkina, Tatjana I.; Blinov, A. Y.; Bonch-Osmolovskii, M. M.; Koblinger, Otto; Lassmann, Kurt; Eisenmenger, Wolfgang
    Measurements of phonon transport in amorphous media can give valuable information on the structural properties of these materials and may be of practical interest for its own concerning the question of thermalization in electronic devices. The existence of two-level systems in a-Si:H as one of these technically important materials has been concluded from measurements of dispersion and attenuation of acoustic surface waves.
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    Polarization profiles of polyvinylidene fluoride films polarized by a focused electron beam
    (1989) Schilling, Doris; Dransfeld, Klaus; Bihler, Eckardt; Holdik, Karl; Eisenmenger, Wolfgang
    The depth profiles of the polarization in films of polyvinylidene fluoride (PVDF) as well as in vinylidene‐fluoride–trifluoroethylene (VDF‐TrFE) copolymer films polarized by a focused electron beam were investigated using the piezoelectrically generated pressure step method. The dominant polarization exhibits a broad maximum inside the film. The position of this maximum depends not only on the energy of the incident electrons but also on the material parameters of the sample. Close to the surface exposed to the electron beam we have in addition observed a small secondary maximum of opposite polarization (amounting to about 1 mC/m2). A qualitative model is presented for the poling of films of PVDF and its copolymers with TrFE by focused electron beam accounting for most of the observed features. The application of electron beams for the poling of ferroelectric films allows the production of piezoelectric bimorphs. By using a well‐focused electron beam also ferroelectric domains of very small lateral dimensions can be created which could become important for ferroelectric data storage.