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Copyright © 2016 American Scientific Publishers
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Article
Journal of
Nanoscience and Nanotechnology
Vol. 16, 12910–12913, 2016
www.aspbs.com/jnn
Properties of Sr(La
093
Nd
007
)
4
Ti
4
O
15
Dielectric
Thin Films by Sol–Gel Method
Yu-Hang Yang, Wen-Shiush Chen, Jen-Chieh Liu, and Cheng-Hsing Hsu
∗
Department of Electrical Engineering, National United University, No. 2 Lien-Da, Nan-Shih Li, Miao-Li 36063, Taiwan
The electrical properties and microstructures of Sr(La
093
Nd
007
4
Ti
4
O
15
thin films prepared by
sol–gel method on n-type Si (100) substrates at different preheating and annealing temperatures
have been investigated. The selected-area diffraction pattern showed that the deposited films exhib-
ited a polycrystalline microstructure. At a preheating temperature of 500
C and an annealing
temperature of 800
C, the Sr(La
093
Nd
007
4
Ti
4
O
15
films possess a dielectric constant of 20, a dis-
sipation factor of 0.12, and a leakage current density of 1.9 × 10
-8
A/cm
2
at an electrical field of
10 kV/cm.
Keywords: Sr(La
093
Nd
007
4
Ti
4
O
15
Thin Film, Sol–Gel Method, Electrical Properties,
Microstructure.
1. INTRODUCTION
New dielectric materials, such as chip capacitors or RF
transistors have increased the importance of research on
the above-mentioned application in recent years.
1–3
Sev-
eral researchers have investigated the electrical prop-
erties of various high dielectric thin films, including
ZrSnTiO
4
, Ta
2
O
5
, (Ba, Sr)TiO
3
and Pb(Ti, Zr)O
3
.
4–9
On the other hand, various cation-deficient hexagonal-
phase (M, La)
n
Ti
n-1
O
3n
(M = Ca, Sr, Ba; n = 5, 6)
ceramics have also been reported due to their excellent
microwave dielectric properties.
10
The SrLa
4
Ti
4
O
15
com-
position has also been widely applied in microwave com-
ponents because it has high dielectric constant (
r
∼
43.8), high quality factor (Q × f ∼ 50000 GHz), and
small temperature coefficient of resonant frequency (
f
∼
-14 ppm/
C).
11
In addition, several studies have been car-
ried out to improve the microwave dielectric properties,
such as the partial replacement of the B-site and the selec-
tion of a compensator in the ceramic systems.
12
As mentioned earlier, it is interesting to study the
influence of microwave dielectric properties on the Nd
4+
substitutions in the B-sites in the SrLa
4
Ti
4
O
15
materials.
Sr(La
093
Nd
007
4
Ti
4
O
15
has excellent characteristics such
as high dielectric constant (∼47) which is much higher
than SiO
2
, low dielectric loss (Q × f ∼ 50000 GHz) and
∗
Author to whom correspondence should be addressed.
high temperature stability (0.54 ppm/
C) as proven in pre-
vious researches.
However, Sr(La
093
Nd
007
4
Ti
4
O
15
thin films fabricated
by sol–gel method have not been yet for dielec-
tric and electrical characteristics. In this article, we
report the electrical, dielectric and physical properties of
Sr(La
093
Nd
007
4
Ti
4
O
15
thin films fabricated by using the
sol–gel deposition method. The effects of the thermal treat-
ment on the microstructure, electrical and dielectric prop-
erties of Sr(La
093
Nd
007
4
Ti
4
O
15
are also investigated.
2. EXPERIMENTAL DETAILS
High-purity stronitum acetate, neodymium(III) nitrate hex-
ahydrate, and lanthanum nitrate hexahydrate were taken
in the suitable molar ratio and dissolved in DI-water at
room temperature. In addition, titanium(IV) isopropoxide
was also dissolved in 2,4-pentanedione and acetic acid.
Two kinds of solutions were mixed with molar ratio and
then the resultant solution was stirred at 60
C for 30 min.
The precursor sol was placed on the n-type Si (100) sub-
strates and spun at 2000 rpm for 10 s and 3000 rpm for
20 s to form precursor thin films. The films were preheated
at a temperature ranging from 300 to 500
C in an air
furnace. The coating and preheating treatment processes
were repeated eight times. Finally, the films were annealed
at 600∼800
C for 30 min in an air furnace for crystal-
lization. The final thickness of the Sr(La
093
Nd
007
4
Ti
4
O
15
films for eight layers was about 500 nm.
12910 J. Nanosci. Nanotechnol. 2016, Vol. 16, No. 12 1533-4880/2016/16/12910/004 doi:10.1166/jnn.2016.13656