Memristive behaviors in Pt/BaTiO3/Nb:SrTiO3 ferroelectric tunnel junctions

We demonstrate memristive behaviors in Pt/BaTiO3/Nb:SrTiO3 metal/ferroelectric/semiconductor ferroelectric tunnel junctions, in which the semiconductor electrode can be switched between the accumulated and the depleted states by polarization reversal in the BaTiO3 barrier via the ferroelectric field effect. An extra barrier, against electron tunneling, forms in the depleted region of the Nb:SrTiO3 electrode surface, which together with the ferroelectric barrier itself modulate the tunneling resistance with the change of effective polarization. Continuous resistance modulation over four orders of magnitude is hence achieved by application of programmed voltage pulses with different polarity, amplitude, and repetition numbers, as a result of the development of the extra barrier.