Electron energy relaxation times from ballistic-electron-emission spectroscopy

Using a Green’s-function approach that incorporates band-structure effects, and a complementary k-space Monte-Carlo analysis, we show how to get a theoretically consistent determination of the inelastic mean free path λee(E) due to electron-electron interaction from ballistic electron emission spectroscopy. Exploiting experimental data taken at T=77K on a thin-Au film (ee(E) predicted by the standard Fermi-liquid theory provides excellent agreement between theoretical and experimental I(V) spectra. In agreement with theories for real metals, an enhancement of λee(E) by a factor of two with respect to its electron-gas value is found

Hot electron transport in Ballistic Electron Emission Spectroscopy: band structure effects and k-space currents

Using a Green's function approach, we investigate band structure effects in the BEEM current distribution in reciprocal space. In the elastic limit, this formalism provides a 'parameter free' solution to the BEEM problem. At low temperatures, and for thin metallic layers, the elastic approximation is enough to explain the experimental I(V) curves at low voltages. At higher voltages inelastic effects are approximately taken into account by introducing an effective RPA-electron lifetime, much in similarity with LEED theory. For thick films, however, additional damping mechanisms are required to obtain agreement with experiment.Comment: 4 pages, 3 postscript figures, revte

Energy relaxation of an excited electron gas in quantum wires: many-body electron LO-phonon coupling

We theoretically study energy relaxation via LO-phonon emission in an excited one-dimensional electron gas confined in a GaAs quantum wire structure. We find that the inclusion of phonon renormalization effects in the theory extends the LO-phonon dominated loss regime down to substantially lower temperatures. We show that a simple plasmon-pole approximation works well for this problem, and discuss implications of our results for low temperature electron heating experiments in quantum wires.Comment: 10 pages, RevTex, 4 figures included. Also available at http://www-cmg.physics.umd.edu/~lzheng

THEORY OF ONE- AND TWO-PHONON DEFORMATION POTENTIALS IN SEMICONDUCTORS

A theory of deformation potentials for charge carriers in tetrahedral semiconductors is presented. The model is based on an LCAO-formulation and is able to predict optical one-phonon deformation potentials for 36 materials and intravalley two-phonon deformation potentials in Ge,Si and III-V compounds. The comparison with the known experimental deformation potentials shows very good agreement between theory and experiment

Structure and polarity of 8CB films evaporated onto solid substrates

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Hot electron transport in Ballistic Electron Emission Spectroscopy: Band structure effects and k_∥-space currents

Using a Green's function approach, we investigate band structure effects in the BEEM current distribution in k∥-space. In the elastic limit, this formalism provides a "para meter free" solution of the BEEM problem. At low temperatures, and for thin metallic layers, the elastic approximation is enough to explain the experimental I(V) curves at low voltages. At higher voltages inelastic effects are approximately taken into account by introducing an effective RPA-electron lifetime, much in similarity with LEED theory. For thick films, however, additional damping mechanisms are required to obtain agreement with experiment

A Theoretical Analysis of Ballistic Electron Emission Microscopy: Band Structure Effects and Attenuation Lengths

Using a quantum mechanical approach, we compute the ballistic electron emission microscopy current distribution in reciprocal space to compare experimental and theoretical spectroscopic I(V) curves. In the elastic limit, this formalism is a "parameter-free" representation of the problem. At low voltages, low temperatures, and for thin metallic layers, the elastic approximation is enough to explain the experiments (ballistic conditions). At low temperatures, inelastic effects can be taken into account approximately by introducing an effective electron-electron lifetime as an imaginary part in the energy. Ensemble Monte Carlo calculations were also performed to obtain ballistic electron emission microscopy currents in good agreement with the previous approach

A Theoretical Analysis of Ballistic Electron Emission Microscopy: Band Structure Effects and Attenuation Lengths

Using a quantum mechanical approach, we compute the ballistic electron emission microscopy current distribution in reciprocal space to compare experimental and theoretical spectroscopic I(V) curves. In the elastic limit, this formalism is a "parameter-free" representation of the problem. At low voltages, low temperatures, and for thin metallic layers, the elastic approximation is enough to explain the experiments (ballistic conditions). At low temperatures, inelastic effects can be taken into account approximately by introducing an effective electron-electron lifetime as an imaginary part in the energy. Ensemble Monte Carlo calculations were also performed to obtain ballistic electron emission microscopy currents in good agreement with the previous approach