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DS: Fachverband Dünne Schichten
DS 44: Poster III: Focus session: Resistive switching by redox and phase change phenomena
DS 44.12: Poster
Donnerstag, 3. April 2014, 16:00–19:00, P1
TaOx based memristive systems with variable oxygen concentration — •Stefan Niehörster1, Savio Fabretti1, Markus Schäfers1, and Andy Thomas1,2 — 1Bielefeld University, Bielefeld, Germany — 2Mainz University, Mainz, Germany
TaOx based devices show reversible and nonvolatile memristive switching effects for a large number of cycles. This property makes them very interesting for data storage applications or imitating synapses in a neural network. We prepared devices with Pd and Ta electrodes and a TaOx barrier. The electrodes were deposited by magnetron sputtering and the tunnel barrier was fabricated by in-situ oxidation of a thin sputtered Ta film. This approach gives us the possibility to manipulate the oxygen concentration of the barrier compared to sputter deposition of a TaOx target. We varied the bias voltage of the oxygen plasma to regulate the thickness of the barrier by the penetration depth, and we varied the oxidation time to regulate the oxygen concentration. We used optical lithography to define squares of 10x10, 15x15 or 25x25µ m2. The junctions were characterized by transport measurements in two point geometry. The measurements of our devices show memristive switching, where the amplitude and the noise of the switching show a dependence on the oxidation time. In addition, we were able to reach more than two states. The data is compared to our earlier results with MgO based memristive tunnel junctions. Here, the amplitude of the memristive switching was increased by a factor of 3.