Atomistic Simulations for Understanding
Microscopic Mechanism of Resistive
Switches
S. Watanabe and B. Xiao
Abstract In this chapter, we describe the results of our first-principles simulations
to investigate the switching mechanism of amorphous TaO x (a-TaO x ) based resistive
switching devices. For the Cu/a-Ta 2 O 5 /Pt atomic switch, we first discuss the atomic
structure of the conductive filaments, focusing on the exploration of possible
thinnest filament structure. Then we discuss the structures of interfaces between
metal electrodes and a-Ta 2 O 5 , which are important in understanding Cu ion supply
for the switching. For the Pt/a-TaO x /Pt resistive switch, we discuss the nature of the
conductive filaments and diffusion behaviors of active ions. Here we point out the
importance of Ta-Ta bonding and the non-negligible contribution of Ta diffusion
under certain conditions.
1 Introduction
The resistive switches based on metal oxide have got wide attention because of their
excellent retention, long endurance and low power consumption. Such devices
are composed of an insulator layer (HfO x , TiO x , TaO x , etc.) between two electrodes
[1–3]. On the basis of different switching behaviors, the devices could be divided
into the following two categories: (1) unipolar switches (such as Pt/TaO x /Pt), where
the insulator material is sandwiched between two inert electrodes [4], and the
switching is realized by changing the magnitude of the applied electric field with
keeping its polarity; (2) bipolar switches (including the atomic switches such as
Cu/Ta 2 O 5 /Pt), which have asymmetric structures with inert and oxidizable electrodes [5], and change their states by applying the electric fields with different
polarities.
S. Watanabe (*)
Department of Materials Engineering, The University of Tokyo, Tokyo, Japan
e-mail: watanabe@cello.t.u-tokyo.ac.jp
B. Xiao
School of Chemistry and Chemical Engineering, Yantai University, Yantai, China
© Springer Nature Switzerland AG 2020
M. Aono (ed.), Atomic Switch, Advances in Atom and Single Molecule Machines,
https://doi.org/10.1007/978-3-030-34875-5_6
95
Microscopic Mechanism of Resistive
Switches
S. Watanabe and B. Xiao
Abstract In this chapter, we describe the results of our first-principles simulations
to investigate the switching mechanism of amorphous TaO x (a-TaO x ) based resistive
switching devices. For the Cu/a-Ta 2 O 5 /Pt atomic switch, we first discuss the atomic
structure of the conductive filaments, focusing on the exploration of possible
thinnest filament structure. Then we discuss the structures of interfaces between
metal electrodes and a-Ta 2 O 5 , which are important in understanding Cu ion supply
for the switching. For the Pt/a-TaO x /Pt resistive switch, we discuss the nature of the
conductive filaments and diffusion behaviors of active ions. Here we point out the
importance of Ta-Ta bonding and the non-negligible contribution of Ta diffusion
under certain conditions.
1 Introduction
The resistive switches based on metal oxide have got wide attention because of their
excellent retention, long endurance and low power consumption. Such devices
are composed of an insulator layer (HfO x , TiO x , TaO x , etc.) between two electrodes
[1–3]. On the basis of different switching behaviors, the devices could be divided
into the following two categories: (1) unipolar switches (such as Pt/TaO x /Pt), where
the insulator material is sandwiched between two inert electrodes [4], and the
switching is realized by changing the magnitude of the applied electric field with
keeping its polarity; (2) bipolar switches (including the atomic switches such as
Cu/Ta 2 O 5 /Pt), which have asymmetric structures with inert and oxidizable electrodes [5], and change their states by applying the electric fields with different
polarities.
S. Watanabe (*)
Department of Materials Engineering, The University of Tokyo, Tokyo, Japan
e-mail: watanabe@cello.t.u-tokyo.ac.jp
B. Xiao
School of Chemistry and Chemical Engineering, Yantai University, Yantai, China
© Springer Nature Switzerland AG 2020
M. Aono (ed.), Atomic Switch, Advances in Atom and Single Molecule Machines,
https://doi.org/10.1007/978-3-030-34875-5_6
95