Solid State Communications 150 (2010) 137–141 Contents lists available at ScienceDirect Solid State Communications journal homepage: www.elsevier.com/locate/ssc Improved resistive switching properties in Ti/TiO x /La 0.7 Ca 0.3 MnO 3 /Pt stacked structures X.J. Liu, X.M. Li, Q. Wang ∗ , W.D. Yu, R. Yang, X. Cao, X.D. Gao, L.D. Chen State Key Laboratory of High Performance Ceramics & Superfine Microstructure, Shanghai Institute of Ceramics, Chinese Academy of Sciences, 1295 Ding Xi Road, Shanghai 200050, People’s Republic of China article info Article history: Received 17 June 2009 Received in revised form 14 September 2009 Accepted 18 September 2009 by J. Fontcuberta Available online 23 September 2009 PACS: 73.50.-h 73.40.-c 72.80.-r 75.47.Lx Keywords: A. Manganites A. Thin film D. Resistive switching D. Rectifying properties abstract A TiO x layer (∼20 nm) was designed and introduced by a pulse laser deposition method to simulate the TiO x layer that developed naturally when the Ti top electrode was deposited on a La 0.7 Ca 0.3 MnO 3 (LCMO) film. Comparing Ti/LCMO/Pt structures with those of Ti/TiO x /LCMO/Pt, we found that the inserted TiO x layer between the Ti top electrode and the LCMO film improves the resistive switching (RS) properties. The Ti/TiO x /LCMO/Pt structure shows a large junction resistance (∼32 k), large R HRS /R LRS ratio (∼10), and good endurance (>80 cycles). This improvement of RS properties may be mainly attributed to the modification of the n–p junction barrier width at the TiO x /LCMO interface due to the oxidation/reduction of an interfacial TiO x layer adjacent to the LCMO layer. In addition, the results of pulse measurements also show an improvement of RS properties in Ti/TiO x /LCMO/Pt structures. Crown Copyright © 2009 Published by Elsevier Ltd. All rights reserved. 1. Introduction The electric-pulse-induced resistive switching (EPIR) phenom- ena in metal oxides have recently attracted considerable research interest due to their potential application to resistance random access memory (RRAM), the promising next-generation non- volatile memory with attractive advantages including the dras- tically reduced power consumption, the fast switching speed and nondestructive readout etc [1–3]. Bipolar resistive switch- ing (RS), characterized by different voltage polarities that are needed for write/erase operations, has been observed in perovskite manganites such as Pr 0.7 Ca 0.3 MnO 3 (PCMO) and La 0.7 Ca 0.3 MnO 3 (LCMO) [3–19]. Despite great efforts in exploring the underlying mechanism of the EPIR phenomenon, a general theory which can elucidate all the reported RS behaviors has not been yet developed up to now. According to previous studies, metallic top electrodes (TE) are crucially important for resistance switching. Especially, active ∗ Corresponding author. Tel.: +86 21 52412441; fax: +86 21 52413122. E-mail addresses: liuxj@mail.sic.ac.cn (X.J. Liu), wangqun@mail.sic.ac.cn (Q. Wang), cld@mail.sic.ac.cn (L.D. Chen). metallic electrodes can extract oxygen from neighboring mangan- ites to form metallic oxides. The interfacial MO x layer (M = Ti, Ta, and Al) has already been confirmed by transmission elec- tron microscopy (TEM) in the M/PCMO junctions [15–17]. Due to the occurrence of these oxide layers, the positive bias switches these active-metal-based junctions from a low resistance state (LRS) to a high resistance state (HRS), i.e. the ‘‘negative’’ EPIR phe- nomenon [18,19]. It is a generally accepted consensus for these active-metal-based junctions that the RS originates from oxida- tion/reduction of these metallic oxide layers. Based on the oxi- dation/reduction model, the properties of an active-metal-oxide interlayer such as thickness and degree of oxidation have a cru- cial influence on the motion of oxygen ions and then on the RS property. In this letter, we designed and introduced a TiO x layer by a pulse laser deposition method to clarify the role of the TiO x layer during the RS process. Improved switching properties were observed in the Ti/TiO x /LCMO/Pt stacked structure, which could be attributed to the modification of n–p junction barrier width by electrochemical migration of oxygen at the TiO x /LCMO interface. 2. Experiments Two types of sample were made of LCMO (sample A) and TiO x /LCMO bilayer (sample B) thin films sandwiched between a Ti 0038-1098/$ – see front matter Crown Copyright © 2009 Published by Elsevier Ltd. All rights reserved. doi:10.1016/j.ssc.2009.09.032