Resistive Non-Volatile Memory Effect Enhanced by a Ferroelectric Buffer Layer on Semiconductive Pr0.7Ca0.3MnO3 Film

Abstract

The novel electric-pulse-induced resistance (EPIR) switching effect has been obtained in metal electrode- Pr0.7Ca0.3MnO3 (PCMO)-metal electrode capacitor-like film structures. The EPIR effect encompasses the reversible change of resistance of PCMO under the application of short, low voltage pulses. This reversible resistance switching at room temperature is very attractive for today's computing technology with its wide applications as a resistance random access memory (RRAM) due to its nonvolatility, fast write/read/erase speed, low power-consumption and high radiation-hardness. In this work, a nano-meter thick ferroelectric Pb0.7Zr0.3TiO3(PZT) layer was inserted between the top electrode and PCMO film as a buffer layer in the EPIR device. Such a resistive memory device is comprised of a PCMO epitaxial layer on a c-oriented YBCO bottom electrode layer and a PZT ferroelectric buffer layer grown on top of the PCMO layer with an Ag top electrode. Compared with the Ag/PCMO/YBCO devices, the insertion of the PZT buffer into the Ag/PCMO interface is found to make the EPIR ratio increase greatly and the threshold pulse voltage necessary to switching the resistive device decrease significantly. Since Pr1-xCaxMnO3 is a unique compound oxide, showing semiconductive behavior over the whole composition (x) range, this is attributed to the resistive change of the depletion region at the Ag/PCMO interface including the PZY buffer, in which ferroelectric polarizations play a crucial role in the enhanced EPIR switching effect.