TY - JOUR
T1 - Strong surface-termination effect on electroresistance in ferroelectric tunnel junctions
AU - Yamada, Hiroyuki
AU - Tsurumaki-Fukuchi, Atsushi
AU - Kobayashi, Masaki
AU - Nagai, Takuro
AU - Toyosaki, Yoshikiyo
AU - Kumigashira, Hiroshi
AU - Sawa, Akihito
N1 - Publisher Copyright:
© 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.
PY - 2015/5/13
Y1 - 2015/5/13
N2 - Tunnel electroresistance in ferroelectric tunnel junctions (FTJs) has attracted considerable interest, because of a promising application to nonvolatile memories. Development of ferroelectric thin-film devices requires atomic-scale band-structure engineering based on depolarization-field effects at interfaces. By using FTJs consisting of ultrathin layers of the prototypical ferroelectric BaTiO3, it is demonstrated that the surface termination of the ferroelectric in contact with a simple-metal electrode critically affects properties of electroresistance. BaTiO3 barrier-layers with TiO2 or BaO terminations show opposing relationships between the polarization direction and the resistance state. The resistance-switching ratio in the junctions can be remarkably enhanced up to 105% at room temperature, by artificially controlling the fraction of BaO termination. These results are explained in terms of the termination dependence of the depolarization field that is generated by a dead layer and imperfect charge screening. The findings on the mechanism of tunnel electroresistance should lead to performance improvements in the devices based on nanoscale ferroelectrics.
AB - Tunnel electroresistance in ferroelectric tunnel junctions (FTJs) has attracted considerable interest, because of a promising application to nonvolatile memories. Development of ferroelectric thin-film devices requires atomic-scale band-structure engineering based on depolarization-field effects at interfaces. By using FTJs consisting of ultrathin layers of the prototypical ferroelectric BaTiO3, it is demonstrated that the surface termination of the ferroelectric in contact with a simple-metal electrode critically affects properties of electroresistance. BaTiO3 barrier-layers with TiO2 or BaO terminations show opposing relationships between the polarization direction and the resistance state. The resistance-switching ratio in the junctions can be remarkably enhanced up to 105% at room temperature, by artificially controlling the fraction of BaO termination. These results are explained in terms of the termination dependence of the depolarization field that is generated by a dead layer and imperfect charge screening. The findings on the mechanism of tunnel electroresistance should lead to performance improvements in the devices based on nanoscale ferroelectrics.
KW - electroresistance
KW - ferroelectric tunnel junctions
KW - metal-oxide interfaces
KW - surface termination
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U2 - 10.1002/adfm.201500371
DO - 10.1002/adfm.201500371
M3 - Article
AN - SCOPUS:84929094360
VL - 25
SP - 2708
EP - 2714
JO - Advanced Functional Materials
JF - Advanced Functional Materials
SN - 1616-301X
IS - 18
ER -