Distinguish and control the multi-level resistive switching for ferroelectric layer and interface in a YMnO3/Nb:SrTiO3 device

Abstract

A YMnO₃/Nb:SrTiO₃ (YMO/NSTO) ferroelectric device with a step was fabricated by pulsed laser deposition. The multi-level resistive switching (RS) properties in the YMO layer and the YMO/NSTO interface were distinguished and studied by impedance spectroscopy, atomic force microcopy, and four-wire measurement. The results showed a large R_HRS/R_LRS ratio (>1000 times), high endurance (>100 cycles), long retention (>14 h at 100 °C) and more than four-level operation. Piezoresponse force microscopy (PFM) images exhibited effective ferroelectric switching, which corresponded to the I–V characteristics. Combined with the energy band structure, the RS behavior in the YMO/NSTO device can be explained on the basis of the polarization reversal induced modification of the width of the depletion region at the p–n interface. These results could pave the way to control the multi-level RS behaviors of the ferroelectric layer and interface in RS devices.