Nano Res.
Electronic Supplementary Material
Enhanced thermoelectric properties of topological
crystalline insulator PbSnTe nanowires grown by vapor
transport
Enzhi Xu1, Zhen Li1, Jaime Avilés Acosta1, Nan Li2, Brian Swartzentruber3, ShiJian Zheng2, Nikolai Sinitsyn4,
Han Htoon2, Jian Wang5, and Shixiong Zhang1 ()
1
Department of Physics, Indiana University, Bloomington, Indiana 47405, USA
Center for Integrated Nanotechnologies, Materials, Physics and Applications Division, Los Alamos National Laboratory, Los Alamos,
New Mexico 87545, USA
3
Center for Integrated Nanotechnologies, Sandia National Laboratories, Albuquerque, New Mexico 87185, USA
4
Theoretical Division, Los Alamos National Laboratory, Los Alamos, New Mexico 87545, USA
5
MST-8, Los Alamos National Laboratory, Los Alamos, New Mexico 87545, USA
2
Supporting information to DOI 10.1007/s12274-015-0961-1
S1 PbTe nanowires and micro-crystals obtained in a vapor transport growth with Au
nanoparticles as catalysts
As shown in the upper panel of Fig. S1, both nanowires (NWs) and micro-crystals of PbTe were obtained in a
single vapor transport growth, in which Au nanoparticles were used as catalysts. Some of the NWs have Au alloy
particles at their tips (lower left panel of Fig. S1), while others do not show clear particles (lower right panel
Fig. S1).
S2
PbSnTe micro-crystals obtained in a growth without Au nanoparticles
A control experiment was performed at the same condition as the growth of PbSnTe nanowires but without the
use of Au catalysts. As shown in Fig. S2, the Au-free growth leads to only PbSnTe microcrystals. This suggests
that the nanowires were indeed grown via a Au-catalyzed vapor-liquid-solid mechanism.
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Nano Res.
Figure S1 Upper panel: a typical scanning electron microscopy (SEM) image showing the coexistence of PbTe nanowires and
micro-crystals. Lower left panel: a typical PbTe NW with an alloy particle at its tip. Lower right panel: a typical PbTe NW that does not
show a clear particle.
Figure S2 A SEM image of PbSnTe micro-crystals grown by vapor transport method without Au catalyst.
S3
Electrical characterization of PbTe and PbSnTe devices
Two-probe current–voltage (I–V) measurements were performed on thermoelectric devices to test the electrical
contacts. Figures S3(a) and S3(b) show typical I–V characteristics of PbTe and PbSnTe devices, respectively.
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Nano Res.
Figure S3 Typical two-probe I–V characteristics of (a) PbTe and (b) PbSnTe devices, respectively.
S4
Thermal voltage versus temperature difference in thermopower measurements
Detailed information about thermopower measurements can be found in Ref. [S1]. Figure S4 shows thermal
voltage ∆V as a function of temperature difference ∆T at variable measurement temperatures for a typical
nanowire device. The thermopower of a device is calculated as S = ∆V/∆T, and the thermopower of nanowire
was determined by subtracting contribution from metal electrodes. For the same batch of fabricated devices,
temperature calibration was performed on one device to avoid burning of devices during measurement (typical
error bar ~ 10% or less).
Figure S4 Thermal voltage ∆V vs. temperature difference ∆T curves of a typical nanowire device. The measurement (cryogenic)
temperature ranges from 25 to 300 K.
References
[S1]
Xu, E. Z.; Li, Z.; Martinez, J. A.; Sinitsyn, N.; Htoon, H.; Li, N.; Swartzentruber, B.; Hollingsworth, J. A.; Wang, J.; Zhang, S. X.
Diameter dependent thermoelectric properties of individual SnTe nanowires. Nanoscale 2015, 7, 2869–2876.
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