Supplementary Materials for
Formation process of conducting filament in planar organic resistive memory
S. Gao, C. Song,a) C. Chen, F. Zeng, and F. Panb)
Laboratory of Advanced Materials, Department of Materials Science and Engineering,
Tsinghua University, Beijing 100084, People’s Republic of China
1. Plan-view SEM image of the planar device
Fig. S1. Low-magnification plan-view SEM image of the planar device. Both the Pt and
Ag electrodes are 20 μm in width and the distance between these two electrodes is
approximate 1.8 μm.
a)
E-mail: songcheng@mail.tsinghua.edu.cn. Tel.: +861062781275
b)
E-mail: panf@mail.tsinghua.edu.cn. Tel.: +861062772907
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2. I–V curves of a complete switching behavior
Fig. S2. Typical I–V curves of forming process (a) and stable switching cycle (b).
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3. SEM images in Fig. 3 shown on an expanded scale
Fig. S3. (a–d) in this figure are corresponding to Fig. 3 (e–h) in the main text. The arrow
in (a) highlights one of the clusters.
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4. I–t curves and SEM images of pristine devices under 0.5 V constant voltage stress
Fig. S4. (a–d) I–t curves under constant voltage of 0.5 V with different periods of time
and (e–h) corresponding SEM images. The arrow in (e) highlights one of the clusters.
Though the current in (d) does not reach the current compliance of 1 mA due to the small
constant voltage of 0.5 V, the resistance of the device has reduced by one order of
magnitude. According to these figures, it is evident that the CFs grow from the middle of
the device and then extend towards the two electrodes.
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5. EDX analysis near the middle of the device in LRS
Fig. S5. (a) Cross-sectional TEM image near the middle of the device in LRS. (b) EDX
spectra corresponding to the regions denoted by dots as well as numbers with different
colors in (a). The SiO2 substrate, the PEDOT:PSS layer, and the Pt protecting layer are
clearly demonstrated by spectra 1 (red), 2 (green), and 5 (magenta), respectively. The
strong Ag signals in spectra 3 (cyan) and 4 (blue) indicate that the CFs mainly contain Ag
element. The S signals in these two spectra, which can not be ignored when compared to
the Ag signal, imply that the Ag clusters have been partially sulfurized.
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6. A series of schematics on the formation process of CFs
Fig. S6. A series of schematics on the formation process of CFs. (a) Ag cations originate
from anode dissolution and migrate towards cathode electrode. (b)The Ag cations are
initially reduced by the oncoming electrons almost near the middle of the planar device.
(c) With longer voltage stress time, more clusters emerge and the chain of clusters
extends towards both electrodes. (d) When the chain of clusters strong enough, it
short-circuits the electrodes, resulting in the change from HRS to LRS. For clarity and
simplicity, the interaction between Ag and S is omitted and only one filament is
illustrated.
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