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Publication Type: search.filters.UBSTyp.KonferenzbeitragSubject: search.filters.subject.530Author: search.filters.author.Lassmann, KurtStart date: 1980End date: 1989

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Now showing 1 - 7 of 7
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    Influence of defects on the splitting of the acceptor ground state in silicon
    (1984) Ambrosy, Anton; Lassmann, Kurt; Goer, Anne M. de; Salce, Bernard; Zeile, Heinrich
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    Linear stark coupling to the ground state of effective mass acceptors
    (1989) Köpf, Andreas; Ambrosy, Anton; Lassmann, Kurt
    It is shown by dielectric resonance absorption at 24 GHz and by ultrasonic resonance spectroscopy between 5 and 10 GHz that linear coupling of the electric field to the ground state of effective mass acceptors in Si exists and has a distinct chemical shift from B to In.
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    Ultrasonic spectroscopy of the acceptor ground state in cubic semiconductors
    (1980) Lassmann, Kurt; Zeile, Heinrich
    In the following we will discuss ultrasonic measurements on p-type semiconductors reflecting spontaneous and defect sensitive modifications of the acceptor ground state.
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    Shallow traps correlated with deep impurities in silicon as obtained by phonon induced conductance
    (1986) Burger, Wilfried; Lassmann, Kurt; Holm, Claus; Wagner, Peter
    At low temperatures shallow neutral donors and acceptors in silicon can bind an extra carrier to form the so-called D- and A+ centers. With the method of phonon-induced electrical conductivity (PIC) we find the same threshold energies for the detachment of these carriers associated with the shallow impurities P and B, as have been obtained previously by FIR measurements. This shows that the detachment is by a one-phonon process. We find that there is no central cell correction for the binding to the deeper acceptors Al and Ga, whereas for In+ the binding energy is as large as 5,8 meV. We interprete this dependence on acceptor species as another example of the shallow-deep instability of the binding energy with the variation of the central cell potential.
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    One-phonon ionization of neutral donors in germanium
    (1989) Gienger, Martin; Groß, Peter; Lassmann, Kurt
    Here we show by phonon spectroscopy with superconducting tunnelling junctions that one-phonon excitations from the ground state to the conduction band (CB) are measurable as phonon induced conductivity (PIC) changes in the special case of donors in Ge. For the conductivity thresholds we find somewhat smaller binding energies than evaluated from optical measurements whereas for the 1s-singlet to 1s-triplet ground state splitting as seen by elastic phonon scattering we obtain the optical values.
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    Phonon-induced electrical conductance in semiconductors
    (1986) Lassmann, Kurt; Burger, Wilfried
    The bath of thermal phonons is a well-known source of impedance to electronic conduction in solids. Turning the tables, a change in electronic conductance may be used for phonon detection, as will be discussed in the following.
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    Phonon scattering at acceptors with gamma8 ground states in semiconductors
    (1980) Sigmund, Ernst; Lassmann, Kurt
    The ground state of acceptors in cubic semiconductors is fourfold degenerate and the interaction with the lattice vibrations leads to the possibility of a Jahn-Teller effect, causing a dynamical splitting of the electronic levels. However, due to the extended nature of the wave function of the defect, random internal fields may have dominant influence to destroy the J.T. effect. Such an influence should be smaller for deeper acceptors, where the wavefunctions are more concentrated.