Memristive switching induced by 100 MeV Ag⁷⁺ ion irradiation in Ag/La_0.7Sr_0.3MnO₃/Ag planar structures

Abstract

Resistive random access memory is one of the candidate technologies for the promising next generation non-volatile memories with fast switching speed, low power consumption and non-destructive readout. The swift heavy ion (SHI)-induced resistive switching behavior of Ag/La_0.7Sr_0.3MnO₃/Ag planar structures, grown on SiO₂ substrates by the chemical solution deposition technique, has been investigated. Five identical samples were irradiated by 100 MeV Ag⁷⁺ ions with fluence values ranging from 1×10¹¹ to 5×10¹³ ions/cm² at the Materials Science beamline of the IUAC, New Delhi. Upon irradiation, systematic amorphization and grain elongation was observed in the grazing incidence X-ray diffraction and atomic force microscopy, respectively. Four-terminal I–V curves indicate typical non-ohmic behavior of pristine Ag/La_0.7Sr_0.3MnO₃/Ag planar geometry at room temperature for several voltage-sweeping cycles. On the other hand, well-defined hysteresis loops with sharp on–off transition in the I–V curves were observed for the sample irradiated with 100 MeV Ag⁷⁺ ions at 1×10¹² ions/cm², indicating that the sample possesses low resistance state and high resistance state. A symmetrical resistance ratio (R _high/R _low) of ∼ 330% at−1.7 V has been achieved. The resistance switching is bipolar and may be attributed to SHI-induced defects in the device. Such defect-induced resistive switching has recently been proposed theoretically, and our results are direct evidence of the phenomenon.

Keywords:

• RRAM
• resistance switching
• SHI
• manganite

Acknowledgements

This work was partially supported by the Department of Atomic Energy (DAE-BRNS), India, under the Young Scientist Award (DAE-YSRA), Sanction No. 2006/20/37/1/ BRNS/1020 of USJ and IUAC, New Delhi, under the UFUP Project No. 40302.