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Zawartość zarchiwizowana w dniu 2022-12-23

Investigation of the metal-non-metal transition

Cel



The aim of this project is the detailed investigation of quantum transport at low temperatures on doped semiconductors with hopping transport, i.e.on the dielectric side of the metal-insulator transition (MIT) and very close to the critical impurity concentration of the MIT.

The project will put emphasis on the following: growth by the Czochralskii technique of enriched 74Ge monocrystals with different isotope relation between 74Ge and 70Ge; mass-spectrometry of the isotopic abundance in the monocrystals and neutron-transmutation doping (NTD) of the germanium monocrystals with changed isotopic abundance with well controlled neutron doses of SYMBOL 70 \f "Symbol" = 2.2 . 1018 - 9.0 . 1019 cm-3.

The following will be investigated: relevant impurities and compensating centres due to the neutron transmutation doping in Ge by SIMS; Hall-factor, Hall-mobility and impurity concentration; compensation degree by the temperature dependence of conductivity and Hall-effect from room temperature down to mK temperatures and comparison with the impurity concentration and compensation from the mass-spectroscopic analysis; temperature dependence of conductivity and magnetoconductivity of selected samples down to T = 30 mK with emphasis on the effect of negative magnetoresistance; ESR at mK-temperature on selected samples very close to the MIT and tuning through the MIT by uniaxial stress; growth of CdTe monocrystals with different impurity concentration and compensation by chemical doping.

The investigation of the quantum interference phenomena in the magneto conductance at hopping and study of the crossover from Mott's variable range hopping to Efros-Shklovskii variable range hopping will also be undertaken.



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System finansowania

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Koordynator

Freie Universität Berlin
Wkład UE
Brak danych
Adres
Arnimallee 14
14195 Berlin
Niemcy

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Koszt całkowity
Brak danych

Uczestnicy (3)