No abstract

We have investigated the resistive switching behavior in stoichiometric HfO2 and oxygen-deficient HfO2−x thin films grown on TiN electrodes using reactive molecular beam epitaxy. Oxygen defect states were controlled by the flow of oxygen radicals during thin film growth. Hard X-ray photoelectron spectroscopy confirmed the presence of sub-stoichiometric hafnium oxide and defect states near the Fermi level. The oxygen deficient HfO2−x thin films show bipolar switching with an electroforming occurring at low voltages and low operating currents, paving the way for almost forming-free devices for low-power applications.

Study of polarity effect in SiOx-based resistive switching memory Appl. Phys. Lett. 101, 052111 (2012) Ambipolar operation of hybrid SiC-carbon nanotube based thin film transistors for logic circuits applications Appl. Phys. Lett. 101, 043121 (2012) Non-volatile memory transistor based on Pt nanocrystals with negative differencial resistance J. Appl. Phys. 112, 024319 (2012) Resistive switching by migration of hydrogen ions Appl. Phys. Lett. 101, 043507 (2012) Controllable formation of resistive switching filaments by low-energy H+ irradiation in transition-metal oxides

No abstract

The Ti/HfO2 interface plays a major role for resistance switching performances. However, clear interface engineering strategies to achieve reliable and reproducible switching have been poorly investigated. For this purpose, we present a comprehensive study of the Ti/HfO2 interface by a combined experimental-theoretical approach. Based on the use of oxygen-isotope marked Hf*O2, the oxygen scavenging capability of the Ti layer is clearly proven. More importantly, in line with ab initio theory, the combined HAXPES-Tof-SIMS study of the thin films deposited by MBE clearly establishes a strong impact of the HfO2 thin film morphology on the Ti/HfO2 interface reactivity. Low-temperature deposition is thus seen as a RRAM processing compatible way to establish the critical amount of oxygen vacancies to achieve reproducible and reliable resistance switching performances.