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Epitaxial growth of semiconducting LaVO3 thin films
Woong Choia) and Timothy Sands
Department of Materials Science & Mineral Engineering, University of California,
Berkeley, California 94720
Kwang-Young Kim
Display R&D Center, LG Electronics, 16 Woomyeon-Dong, Seocho-Gu, Seoul 137-724, Korea
(Received 26 July 1999; accepted 4 October 1999)
Epitaxial thin films of LaVO3 were grown on (001) LaAlO3 substrates by pulsed laser
deposition from a LaVO4 target in a vacuum ambient at substrate temperatures
ജ500 °C. X-ray diffraction studies showed that epitaxial LaVO3 films consist of mixed
domains of [110] and [001] orientations. Thermoprobe and four-probe conductivity
measurements demonstrated the p-type semiconducting behavior of the epitaxial
LaVO3 films. The temperature dependence of the conductivity is consistent with a
thermally activated hopping mechanism with an activation barrier of 0.16 eV.
There has been increasing interest in growing epitaxial
thin film heterostructures consisting of materials that
have similar crystalline structures but possess remark-
ably different physical properties. Prime emphasis has
been put on perovskite oxides exhibiting wide ranges of
electrical, magnetic, and optical properties since the
combination of such diverse materials offers attractive
possibilities for novel device structures. Although con-
ductive oxide thin films have been extensively investi-
gated due to their potential applications in a number of
different fields,1–3 little attention has been given to semi-
conducting oxide thin films. As components of a ferro-
electric nonvolatile memory device in the ferroelectric
field-effect transistor (FET) configuration, epitaxial thin
films of the semiconducting oxides can enhance the de-
vice performance by improving the interface quality be-
tween the ferroelectric and semiconducting layers.4,5
Moreover, epitaxial thin films of the semiconducting ox-
ides in an FET can be utilized to make optically trans-
parent switches, with potential on-screen display
applications.6
pseudocubic perovskite with a lattice constant of
0.39 nm, revealing the structural compatibility of this
phase with other perovskite-type materials. LaVO3 un-
dergoes an orthorhombic-to-monoclinic structure transi-
tion at about 140 K accompanied by a paramagnetic-to-
antiferromagnetic transition as the temperature
decreases.7 LaVO3 behaves as a p-type semiconductor
with an optical band gap of 1.1 eV.8 The p-type doping
of LaVO3 arises from cation deficiency with an activa-
tion energy for conduction in the range 0.1–0.2 eV.9–12
The resistivity of LaVO3 can be controlled by using its
strontium-doped analogue La1−xSrx VO3, whose electri-
cal properties change from those of a semiconductor to a
metal as the strontium content is increased.12,13
Although the electrical transport and magnetic prop-
erties of bulk LaVO3 have been investigated, there has
been no report on LaVO3 thin films to the authors’
knowledge. In this study, epitaxial LaVO3 thin films
were grown and characterized by structural and electrical
transport measurements.
LaVO3 thin films were deposited on LaAlO3(001)
pseudocubic (a ס
0.3792 nm) single-crystal substrates
by pulsed laser deposition (PLD). The PLD system con-
sisted of a KrF excimer laser (Lambda Physik, Lextra
200) with a 34-ns pulsewidth and wavelength of 248 nm,
external optics, and a vacuum chamber. The laser beam
was focused down at the target to yield an approximate
energy density of 2 J/cm2 and a pulse repetition rate of
5 Hz. The LaVO4 target was purchased from Praxair
Specialty Ceramics. The substrates were mounted with
Among numerous semiconducting oxides, LaVO3
shows many interesting properties. It has a GdFeO3-type
orthorhombic structure (space group Pbnm) with lattice
constants of a ס
0.555548 nm, b ס
0.555349 nm, and
c ס
0.784868 nm.7 The structure can be considered as a
a)Address all correspondence to this author.
e-mail: woongch@uclink4.berkeley.edu
J. Mater. Res., Vol. 15, No. 1, Jan 2000
© 2000 Materials Research Society
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