Resistive Switching Mechanisms on TaO x and SrRuO3 Thin-Film Surfaces Probed by Scanning Tunneling Microscopy

• Published in: ACS nano Vol. 10; no. 1; pp. 1481 - 1492
• Main Authors: Moors, Marco, Adepalli, Kiran Kumar, Lu, Qiyang, Wedig, Anja, Bäumer, Christoph, Skaja, Katharina, Arndt, Benedikt, Tuller, Harry Louis, Dittmann, Regina, Waser, Rainer, Yildiz, Bilge, Valov, Ilia
• Format: Journal Article
• Language: English
• Published: American Chemical Society 26.01.2016
• Subjects: strontium ruthenate; tantalum oxide; resistive switching; scanning tunneling microscopy; electric field effect
• ISSN: 1936-0851; 1936-086X
• DOI: 10.1021/acsnano.5b07020

The local electronic properties of tantalum oxide (TaO x , 2 ≤ x ≤ 2.5) and strontium ruthenate (SrRuO3) thin-film surfaces were studied under the influence of electric fields induced by a scanning tunneling microscope (STM) tip. The switching between different redox states in both oxides is achieved without the need for physical electrical contact by controlling the magnitude and polarity of the applied voltage between the STM tip and the sample surface. We demonstrate for TaO x films that two switching mechanisms operate. Reduced tantalum oxide shows resistive switching due to the formation of metallic Ta, but partial oxidation of the samples changes the switching mechanism to one mediated mainly by oxygen vacancies. For SrRuO3, we found that the switching mechanism depends on the polarity of the applied voltage and involves formation, annihilation, and migration of oxygen vacancies. Although TaO x and SrRuO3 differ significantly in their electronic and structural properties, the resistive switching mechanisms could be elaborated based on STM measurements, proving the general capability of this method for studying resistive switching phenomena in different classes of transition metal oxides.