Regensburg 2004 – scientific programme
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TT: Tiefe Temperaturen
TT 20: Metall-Isolator-Überg
änge
TT 20.8: Talk
Wednesday, March 10, 2004, 16:15–16:30, H18
Crossover from Coulomb to Fermi Glass in Si:P studied by high frequency conductivity measurements — •Marco Hering1,2, Marc Scheffler1, M. Dressel1 und Hilbert v. Löhneysen2 — 11. Physikalisches Institut, Universität Stuttgart, 70550 Stuttgart, Germany — 2Physikalisches Institut, Universität Karlsruhe, 76128 Karlsruhe, Germany
In highly doped but still insulating Si:P various transport mechanisms are possible. At very low energies hopping processes between disordered, localized electronic states dominate the transport and hence Si:P can be considered as a model system for so called insulating electron glasses.
We studied the electrodynamics of these systems in a frequency range between 50 GHz and 1200 GHz using a coherent source cw THz spectrometer. At liquid helium temperatures the influence of electron-electron interactions play an important role and a transition from the so called Coulomb Glass at lower frequencies to the Fermi Glass at higher frequencies could be observed. We also studied the influence of different doping concentrations and temperature on the frequency dependant conductivity and the dielectric constant. We compare the results of these measurements with the well established theory of A. L. Efros and B. I. Shklovskii.
16:30 Pause