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Name (Title):
Tohru Tsuruoka (MANA Scientist)
Affiliation:
International Center for Materials Nanoarchitectonics (MANA), NIMS
Address:
1-1, Namiki, Tsukuba, Ibaraki 305-0044, Japan
Email: TSURUOKA.Tohru@nims.go.jp
Home Page:
Presentation Title:
Study of the switching mechanism for Ta2O5-based solid electrolyte resistive switch
Abstract:
Resistive switches composed of a solid electrolyte sandwiched between an anode and a
cathode have good potential for use as nonvolatile switches and memories in large-scale
integrated circuits. Resistive switching has previously observed mainly for ionic and electronic
mixed conductors such as Ag2S and Cu2S. 1,2 Recently, another resistive switch, in which Ta2O5 is
used as the solid electrolyte, was demonstrated in order to
increase threshold voltages above the operating voltages of
complementary metal-oxide-semiconductor devices. 3
However, the switching mechanism of this resistive switch
was not fully understood. Here we investigate the electronic
transport of Ta2O5-based resistive switches with different
electrode materials (Cu, Ag, Al, W, Au, and Pt) to reveal the
switch mechanism.
The switch device consists of cross-point structures with
20-µm-wide top (anode) and bottom (cathode) electrodes.
A 30-nm-thick Ta2O5 film was deposited between the two
electrodes. Figure 1 shows typical I-V curves of
Cu/Ta2O5/Pt and Ag/Ta2O5/Au structures. It was found that
switching is occurred at low bias voltages only when Ag and
Cu are used as the anode. The I-V measurements for
switches with Pt, Au, W, and Al contacts indicated that the
bottom interface with Pt and Au is non-ohmic (probably
Schottky-like). From AC impedance measurements, we see
that the difference in turn-on voltage between two switches
of Fig. 1 comes from the difference of conductivity of Cu
and Ag ions in the Ta2O5 film. By combining with these
results and the results of Raman scattering measurements,
we concluded that Cu and Ag metals precipitate in the Ta2O5
film, and the switching behavior is determined by the
electronic properties of two interfaces with the anode and
cathode.
References:
[1] K. Terabe, T. Hasegawa, T. Nakayama, and M. Aono, Nature 433 (2005) 47.
[2] T. Sakamoto et al., Appl. Phys. Lett. 82 (2003) 3032.
[3] T. Sakamoto et al., Appl. Phys. Lett. 91 (2007). 092110.
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Poster Session PS-8
Fig. 1 I-V curves of two switch
structures.