Regensburg 2004 – wissenschaftliches Programm
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DS: Dünne Schichten
DS 12: Schichteigenschaften II
DS 12.3: Vortrag
Mittwoch, 10. März 2004, 15:45–16:00, HS 31
Temperature stability and charge transport in thin (d < 4 nm) metal oxide films: A comparative investigation of aluminium oxide and tantalum oxide — •Yanka Jeliazova1, Michael Kayser1, Beate Mildner1, Eckart Hasselbrink1, and Detlef Diesing2 — 1Institut für Physikalische Chemie, Universität Duisburg-Essen, Campus Essen — 2Institut für Schichten und Grenzflächen 3, Forschungszentrum Jülich
Thin layers of insulating metal oxides with high dielectric constant are currently considered as a possible replacement for the conventional silicon oxide gate dielectric. To suppress leakage currents the energy barrier at the metal/oxide interface must be sufficiently high. Additionally high temperature stability is desirable for the application in integrated circuits. In order to characterize the energy dependence (application of a bias voltage) of charge transport across the oxide film tunnel systems of metal/metal oxide/silver were grown. These systems consist of thin films of aluminium or tantalum and their oxides, and silver film as a second electrode. The thickness of the oxides was 3 nm. An energy barrier of 1.3 eV at the Ta/TaOx interface and 2.4 eV at Al/AlOx interface was found. To distinguish pure electronic conduction from ionical and thermally activated charge transport sample temperatures were varied from 85 K to 510 K. The Ta/TaOx samples were found to withstand this temperature range, while the Al/AlOx samples show a dielectric breakdown at T > 400 K. The temperature dependence of the current through the oxide films suggest an electronic tunnel contribution at T < 350 K and a strong thermally activated charge transport at T > 450 K.