Paper title: Multibit memory operation of metal-oxide bi-layer memristors

Authors: Spyros Stathopoulos, Ali Khiat, Maria Trapatseli, Simone Cortese,
  Alex Serb and Themis Prodromakis

Institution: University of Southampton

Department: Electronics and Computer Science

Group: Nanoelectronics and Nanotechnology Research Group

Address: Highfield Campus, Southampton, SO17 1BJ, UK

Corr. author: Themis Prodromakis (t.prodromakis@soton.ac.uk)

Period of data collection: November 2016 to October 2017

Manuscript submitted: 3rd August 2017

Revision submitted: 29th October 2017

Manuscript accepted: 30th November 2017

Journal: Scientific Reports

Data DOI: 10.5258/SOTON/D0329

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Instructions on reading the data provided herein
================================================

The data for each figure presented either in the main manuscript or the
supplementary information is contained within the respective folder. All
figures are accompanied by their corresponding gnuplot script used to generate
it. Gnuplot is open source software available at [1]. The scripts can be used
either by double-clicking on them (provided gnuplot is installed) or loaded
directly through the gnuplot command line (quotes are mandatory).

> load 'FILENAME.gpl'

[1] http://www.gnuplot.info

All data files are in columnar text format separated by one tab (\t or 0x09)
and should be directly importable to any commonly used software package.
Details for each figure can be found below.

Figure 1
--------

`fig01d.dat` contains alternate polarity switching data for the TiO2 sample
`fig01e.dat` contains alternate polarity switching data for the bilayer sample

Figure 2
--------
`fig02.dat` contains comparative data for all the metaloxides that were
investigated. Range data have been extracted from the data presented in
supplementary figure S7 (see below).

Figure 3
--------
`fig03a.dat` contains the CDF data for the sample containing the maximal amount
of resistive states as well as their linear fits. The format of this file
requires some extra details. The file contains multiple datasets that are
separated by TWO blank lines. The contents of each dataset is clearly marked on
the first line it is either a CDF plot (STATE XXX) or a linear fit (Fit of
STATE = XXX).  The fit data are not required for further analysis and are only
used to better visually separate the CDF datasets. For the former the two
columns are "Resistance" and "Cumulative probability" (0 to 1). In the paper
the probabilities are converted into percentages. The raw data are provided in
the `D160_W8_B25.csv` file as received from our characterisation setup. These
data are analysed using the `cdf_regions.py` python script which also generates
the gnuplot script used to plot the data.

`fig03b.dat` are the energy data calculated using the `energy_calc.py` python
script on the `D164_W6_B27.csv` raw dataset.

`fig03c_XX.dat` files contain room temperature retention data, one for each
individual state.

`fig03d_XX.dat` files contain retention data at 85C, one for each individual
state.


Figure 4
--------
`fig04_pulse.dat` contains biasing data. The columns are "Pulse no" and
"Voltage (V)"

`fig04_pw.dat` contains the pulse widths for the above data. The columns are
"Pulse no" and "Pulse width (s)"

`fig04_read.dat` contains the read data. The colums are "Pulse no" and "Read
voltage (V)"

`fig04_res.dat` contains the resistance data. The columns are "Pulse no" and
"Resistance (Ω)

Figure 5
--------
`fig05a.dat` contains number of states recorded for a series of different
metaloxide combinations. The columns are "Metaloxide" and "Number of states".
The data are aggregated into a boxplot using the `fig05a.gpl` gnuplot script.

For the `fig05b.dat` we binned the data from `fig05a.dat` for the Al2O3
bilayer. The data file contains two columns "Minimum number of bits" and
"Percentage of devices"

Figure S1
---------
`figS1.dat` contains the electroforming data. The contents are detailed in the
file itself.

Figure S2
---------
`figS2.dat` is very similar to figs 1d and 1e.

Figure S3
---------
`figS3_pulse.dat` contains the biasing scheme used for this snapshot. The
`STATE_014` and `STATE_013` files contain the resistance evolution for the two
highlighted states.

Figure S5
---------
`figS5_Xsigma.dat` contain data for the multibit assessment using different
tolerances. The columns are detailed in the files themselves.

Figure S6
---------
`figS6X.dat` are the short term retention data for typical devices. They
contain multiple datasets one for each state similar to `fig03a.dat`.

Figure S7
---------
Each `.dat` file contains the resistance of the sampled devices in each state.
They are plotted with the `figS7.gpl` script in respect to their initial
resistance.

Figure S8
---------
A typical I-V in the ~20 kΩ range. Columns for the `.dat` files are "Voltage
(V)" and "Current (A)"

Figure S9
---------
Consecutive state assessments (a, b, c)

Figure S10
----------
Endurance data. `figS10.dat` contains the resistance evolution of the device

Figure S11
----------
Consecutive state assessments after endurance stressing.