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Journal of Chemical Technology and Applications | Volume 2
Annual Spring Conference and Expo on
April 04-05, 2018 | Miami, USA
Chemical Engineering: From
Materials Engineering to Nanotechnology
allied
academies
Electron transport behavior in ZnO-based TCO films embedded with Ag nanoparticles
Po-Shun Huang
and
Jung-Kun Lee
University of Pittsburgh, USA
I
n regime of highly-doped TCOs, their carrier (electron)
concentration strongly depends on the shallow donor
states created by the amount of extrinsic doping impurities.
However, those impurities create equal amount of positively-
charged point defects in the TCO lattice that tend to scatter
electrons, resulting in the degradation of carrier mobility.
Thus, this conundrum between carrier concentration and
carrier mobility limits the development of highly-doped
transparent conducting oxides (TCOs) films. In this study,
we fabricated Ag nanoparticles (NPs) via a surfactant-free
solution method, and pre-mix with Al-doped ZnO sol-gel
(the Al-doping is approx. 0.1 at. %). We report that electrons
can be donated from Ag nanoparticles (NPs) into this ZnO-
based TCO matrix without deteriorating the carrier mobility
significantly. An increasing Ag content (0.7 vol. %) results in
rising electron concentration up to 4×1020 cm
-3
while the
mobility remains 10 to 20 cm
2
/V.s, which is rarely seen in
traditional TCO films prepared by solution methods that
contain such high carrier concentration according to several
electrical properties of TCO films reported historically.
Furthermore, the Hall-effect measurements with function
of temperature suggests us that the energetic barrier for
this electron donation from Ag NPs at room temperature
is synonymous with the Schottky barrier at the metal-oxide
interface. Those evidence suggest us that electrons donated
fromAg NPs can overcome this energetic barrier at themetal-
oxide interface and further transport in the polycrystalline
ZnO-based TCO matrix with relatively less positively-charged
defects. Therefore, the carrier mobility remains as the
same as that of oxide matrix and are eventually collected
by our conductivity measurement tool. It is noted that the
optical transmittance of such composite films in the visible
wavelengths is above 85 % as the electrical resistivity is
slightly less than 10
-3
Ω.cm.
Speaker Biography
Dr. Po-Shun Huang studied metal oxide thin film depositions and low-dimensional
nanomaterials via wet chemistry method during his PhD work with Prof. Jung-kun Lee
in the Department of Mechanical Engineering and Materials Science at the University
of Pittsburgh. Dr. Huang had in-depth knowledge and hangs-on experience in multi-
functional oxides, nano-composites for the application of optoelectronics, and has
develop several thin-film characterization skills. After PhD study, He worked as a R&D
engineer in a startup company affiliated with Lawrence Berkeley National Laboratory
at Berkeley, CA, mainly focusing on the polymeric conformal coating via CVD method
on the AFM cantilevers for the application of liquid AFM. His interest includes low-
dimensional nanomaterials for energy-harvesting devices, photovoltaic materials, and
solution-based methods for electrically active thin-films.
e:
bensonhuang97@gmail.com