Dresden 2006 – wissenschaftliches Programm
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DF: Dielektrische Festkörper
DF 7: Dielectric and Ferroelectric Thin Films and Nanostructures II
DF 7.1: Vortrag
Mittwoch, 29. März 2006, 14:30–14:50, K{\"O}N Farb
Temperature dependence of elastic electron tunnel currents through thin tantalum oxide films — •Yanka Jeliazova and Detlef Diesing — Institut für Physikalische Chemie, Universität Duisburg Essen
The tunnel process through thin tantalum oxide layers is investigated in tantalum–tantalumoxide–gold thin film tunnel devices. They consist of metal layers (30 nm tantalum, 15 nm gold) separated by a 3.5 nm thick oxide layer. Field strengths up to 1 GV / m were applied to the device and the tunnel current was measured from the 10 pA · cm−2 to 10 mA · cm−2 . At tunnel voltages exceeding the barrier height (e · UT >ϕB) a clear fingerprint of the Fowler-Nordheim tunnel process should be expected in the current voltage plot. This can be barely seen in the experiment with a single current voltage plot at one dedicated temperature. Thereby the band structure of the devices has to be determined by another method. We recorded current voltage plots from 60 K to 500 K and evaluated the temperature dependence of the tunnel current for dedicated tunnel voltages. For tunnel voltages (UT < 1 V ) only a weak increase of the tunnel current of 30 % could be observed while heating the sample from 60 K to 500 K . For tunnel voltages (UT > 1.3 V ) a strong current increase about 4 orders of magnitude was detected. These experimental findings can be rationalized by a thermally induced increase of Fowler Nordheim tunneling processes through a tunnel barrier with 1.8 eV height.