Unipolar resistive switching in cobalt titanate thin films

¹ CSIR-National Physical Laboratory - Dr. K. S. Krishnan Marg, New Delhi 110012, India
² Academy of Scientific and Innovative Research (AcSIR), CSIR-National Physical Laboratory (CSIR-NPL) Campus Dr. K. S. Krishnan Road, New Delhi 110012, India
³ Department of Physics, and Institute for Functional Nanomaterials, University of Puerto Rico San Juan, PR 00931-3343, USA

^(a) ashok553@nplindia.org (corresponding author)

Received: 1 February 2017
Accepted: 9 March 2017

Abstract

We report giant resistive switching of the order of 10⁴, long-time charge retention characteristics up to 10⁴ s, non-overlapping SET and RESET voltages, Ohmic in low-resistance state (LRS) and space charge limited current (SCLC) mechanism in high-resistance state (HRS) properties in polycrystalline perovskite cobalt titanate thin films. Impedance spectroscopy study was carried out for both LRS and HRS states which illustrates that only bulk resistance changes after resistance switching, however, there is a small change (<10% which is in the pF range) in the bulk capacitance value in both states. These results suggest that in the LRS state current filaments break the capacitor in many small capacitors in a parallel configuration which, in turn, provides the same capacitance in both states even if there was a 90-degree change in phase angle and an order of change in the tangent loss.