High-performance ferroelectric nonvolatile memory based on Gd-and Ni-codoped BiFeO films.

BiFeO (BFO), BiGdFeO (BGFO) and BiGdFeNiO (BGFNO) films are epitaxially grown on 0.7 wt% Nb-SrTiO (NSTO) substrates. The strong ferroelectric property in BGFNO film is confirmed by piezoresponse force microscopy (PFM) and polarization voltage (-) measurement. It is also found that the Au/BGFNO/NSTO devices possess a ferroelectric resistance switching (RS) effect. Gd- and Ni-codoped BiFeO is found to strongly enhance the resistance on/off ratio. A resistance on/off ratio as large as 3 × 10 is achieved with an applied pulse voltage of -8 V and +4 V. In addition, the devices exhibit excellent retention and anti-fatigue characteristics. The memristor behavior of Au/BGFNO/NSTO is attributed to the switching of polarization states, which modulate the width and height of the barrier at the BGFNO/NSTO interface. The excellent resistive switching properties in Au/BGFNO/NSTO devices indicate the promising application in nonvolatile memory.