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Role and Optimization of the Active Oxide Layer in TiO 2 -Based RRAM

DOI: 10.1002/adfm.201503522 DOI Help

Authors: Anna Regoutz (University of Southampton) , Isha Gupta (University of Southampton) , Alexantrou Serb (University of Southampton) , Ali Khiat (University of Southampton) , Francesco Borgatti (CNR - ISMN) , Tien-lin Lee (Diamond Light Source) , Christoph Schlueter (Diamond Light Source) , Piero Torelli (Consiglio Nazionale delle Ricerche – Istituto Offi cina dei Materiali (CNR-IOM)) , Benoit Gobaut (Elettra Sincrotrone Trieste) , Mark Light (University of Southampton) , Daniela Carta (University of Southampton) , Stuart Pearce (University of Southampton) , Giancarlo Panaccione (Consiglio Nazionale delle Ricerche – Istituto Offi cina dei Materiali (CNR-IOM)) , Themistoklis Prodromakis (University of Southampton)
Co-authored by industrial partner: No

Type: Journal Paper
Journal: Advanced Functional Materials , VOL 26 (4) , PAGES 507 - 513

State: Published (Approved)
Published: January 2016
Diamond Proposal Number(s): 0240

Open Access Open Access

Abstract: TiO2 is commonly used as the active switching layer in resistive random access memory. The electrical characteristics of these devices are directly related to the fundamental conditions inside the TiO2 layer and at the interfaces between it and the surrounding electrodes. However, it is complex to disentangle the effects of film “bulk” properties and interface phenomena. The present work uses hard X-ray photoemission spectroscopy (HAXPES) at different excitation energies to distinguish between these regimes. Changes are found to affect the entire thin film, but the most dramatic effects are confined to an interface. These changes are connected to oxygen ions moving and redistributing within the film. Based on the HAXPES results, post-deposition annealing of the TiO2 thin film was investigated as an optimisation pathway in order to reach an ideal compromise between device resistivity and lifetime. The structural and chemical changes upon annealing are investigated using X-ray absorption spectroscopy and are further supported by a range of bulk and surface sensitive characterisation methods. In summary, it is shown that the management of oxygen content and interface quality is intrinsically important to device behavior and that careful annealing procedures are a powerful device optimisation technique.

Journal Keywords: Annealing; interfaces; photoelectron spectroscopy; resistive memory; titanium dioxide

Subject Areas: Materials

Instruments: I09-Surface and Interface Structural Analysis