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Supplementary Information
Metallic Glass Nano-composite Thin Films for High-performance Functional
Applications
Santanu Das1⌘, Harpreet Singh Arora2, and Sundeep Mukherjee1*
1
Department of Materials Science and Engineering, University of North Texas, Denton Texas 76203
USA.
2
Department of Mechanical Engineering, Shiv Nadar University, Gautam Buddha Nagar, Uttar Pradesh
201314, India.
⌘
Current Affiliation: Department of Ceramic Engineering, Indian Institute of Technology (BHU),
Varanasi, 221005, U.P. India
*Corresponding Author: E-mail: [email protected], Phone: +1-940-565-4170, Fax: +1-940565-4824.
S1. Experimental Procedures
The structure of the films was studied by high-resolution transmission electron microscopy
(HRTEM) and selected-area electron diffraction (SAED) in a Hitachi H-9500 TEM (Hitachi,
USA) operated at 300kV with a point resolution of 0.18 nm. Thin-film x-ray diffraction (XRD)
measurements were conducted on a Bruker D8 Advance diffractometer (Bruker, USA) using Cu
Kα radiation (40kV, 40mA). Films were scanned over a 2θ range of 15° to 60° with a scanning
speed of 0.017°/s. Electrical characterization of Ag-Cu metallic glass thin-films was done using
four point probe technique in an Ecopia HMS 5000 system. Temperature dependent
measurements were performed in the same system from 77 K to 340 K. A high-precision
controller was used to control temperature fluctuations within 1% during each measurement.
Nano-mechanical properties of the thin-films were evaluated using a Hysitron Triboindenter
(Hysitron, Inc., USA) at room temperature using a diamond Berkovich tip. Nano-indentation was
done in displacement control mode. The load cycle used for indentation was 5 second loading, 2
second holding, and 5 second unloading. X-ray photoelectron spectroscopy (XPS) of the thinfilms was carried out using a PHI 5000 Versaprobe x-ray photoelectron spectrometer. The XPS
is equipped with a high-flux X-ray source, which provided a highly focused monochromatic Xray beam for scanning the sample surface. Valence band study of all the thin-films was done by
ultraviolet photoelectron spectroscopy (UPS) using He−Iα 21.22 eV UV light. The samples were
biased at −9 V DC in order to clearly observe the secondary electron cutoff. Pure gold, pure
silver and pure copper specimens were used as references to calibrate the work function of the
spectrometer. The measured Au work function was 5.09 eV and the spectrometer work function
was 8.91 eV. The work function (Φ) was determined according to the relation, Φ = hν −ΔE,
where ΔE is the energy difference between the secondary electron cutoff of the specimen and the
spectrometer work function and hν is the incident beam energy.
1.2E5
Cu2p3
1.0E5
3E4
Cu 2p1/2
2E4
Intensity (CPS)
Intensity (CPS)
4E4
a(a)
Cu 2p3/2
1E4
b(b)
Ag 3d5/2
Ag 3d
Ag 3d3/2
8.0E4
6.0E4
4.0E4
2.0E4
0.0
930
940
950
Binding Energy (eV)
960
360
370
380
Binding Energy (eV)
Figure S1: X-ray photoelectron spectroscopy of the 50 nm thick nanocomposite film showing
(a) Cu 2p and (b) Ag 3d peaks.
50 nm
79.44
80
b 100
60
40
20
6.44
8.71
1-2 nm
2-3 nm
100 nm
92.81
50
5.57
3-6 nm
6-10 nm
Particle Size (nm)
>10 nm
1-2 nm
2-3 nm
3-6 nm
6-10 nm
Particle Size (nm)
100
80
60
40
20
6.21
0.97
0
0
c
Volume Fraction of
Nanocrystallites (%)
100
% Nanocrystallites
% Nanocrystallites
a
>10 nm
50
100
150
200
Film Thickness (nm)
Figure S2: Histograms illustrating the fraction of nanocrystallites present for (a) 50 nm and
(b)100 nm thick Ag-Cu nanocomposite films; (c) Volume fraction of nanocrystallites and plotted
with the nanocomposite film thickness variations.
a
b
Amorphous matrix
Amorphous
5 nm
Crystalline
Amorphous
2 nm
Figure S3: (a) HRTEM image of 200 nm Ag-Cu nanocomposite film shows distribution of
nanocrystallites in an amorphous matrix; (b) Boundary between a nanocrystallite and amorphous
region.