Selective polarization of ferroelectrics in functional electronics
The selective polarization technique of ferroelectrics representing sound-conductors and piezoelectric transformers in different devices of functional electronics is described. The feature of the technique is the ability of creating the local polarization regions, with different, in the magnitude an...
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| Опубліковано в: : | Semiconductor Physics Quantum Electronics & Optoelectronics |
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| Дата: | 1999 |
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| Мова: | English |
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Інститут фізики напівпровідників імені В.Є. Лашкарьова НАН України
1999
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| Цитувати: | Selective polarization of ferroelectrics in functional electronics / Ya.I. Lepikh // Semiconductor Physics Quantum Electronics & Optoelectronics. — 1999. — Т. 2, № 3. — С. 38-40. — Бібліогр.: 10 назв. — англ. |
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Lepikh, Ya.I. 2017-06-10T08:05:01Z 2017-06-10T08:05:01Z 1999 Selective polarization of ferroelectrics in functional electronics / Ya.I. Lepikh // Semiconductor Physics Quantum Electronics & Optoelectronics. — 1999. — Т. 2, № 3. — С. 38-40. — Бібліогр.: 10 назв. — англ. 1560-8034 PACS: 77.80.F; 77.84.L https://nasplib.isofts.kiev.ua/handle/123456789/119870 The selective polarization technique of ferroelectrics representing sound-conductors and piezoelectric transformers in different devices of functional electronics is described. The feature of the technique is the ability of creating the local polarization regions, with different, in the magnitude and orientation, polarization vectors and with different electrophysical parameters, in the monolithic ceramic sound-conductor. The examples of specific acousto-electron units based on surface acoustic waves with the essentially improved electrical parameters, simpler construction and higher processibility are presented. The features of the selective polarization process are shown, the recommendations on the usage of the technique are given. en Інститут фізики напівпровідників імені В.Є. Лашкарьова НАН України Semiconductor Physics Quantum Electronics & Optoelectronics Selective polarization of ferroelectrics in functional electronics Article published earlier |
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Selective polarization of ferroelectrics in functional electronics |
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Selective polarization of ferroelectrics in functional electronics Lepikh, Ya.I. |
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Selective polarization of ferroelectrics in functional electronics |
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Selective polarization of ferroelectrics in functional electronics |
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Selective polarization of ferroelectrics in functional electronics |
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Selective polarization of ferroelectrics in functional electronics |
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selective polarization of ferroelectrics in functional electronics |
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Lepikh, Ya.I. |
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Lepikh, Ya.I. |
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1999 |
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English |
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Semiconductor Physics Quantum Electronics & Optoelectronics |
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Інститут фізики напівпровідників імені В.Є. Лашкарьова НАН України |
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Article |
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The selective polarization technique of ferroelectrics representing sound-conductors and piezoelectric transformers in different devices of functional electronics is described. The feature of the technique is the ability of creating the local polarization regions, with different, in the magnitude and orientation, polarization vectors and with different electrophysical parameters, in the monolithic ceramic sound-conductor. The examples of specific acousto-electron units based on surface acoustic waves with the essentially improved electrical parameters, simpler construction and higher processibility are presented. The features of the selective polarization process are shown, the recommendations on the usage of the technique are given.
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1560-8034 |
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https://nasplib.isofts.kiev.ua/handle/123456789/119870 |
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Selective polarization of ferroelectrics in functional electronics / Ya.I. Lepikh // Semiconductor Physics Quantum Electronics & Optoelectronics. — 1999. — Т. 2, № 3. — С. 38-40. — Бібліогр.: 10 назв. — англ. |
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2025-11-25T23:52:48Z |
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2025-11-25T23:52:48Z |
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1850588858967654400 |
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38 © 1999, Institute of Semiconductor Physics, National Academy of Sciences of Ukraine
Semiconductor Physics, Quantum Electronics & Optoelectronics. 1999. V. 2, N 3. P. 38-40.
PACS: 77.80.F; 77.84.L
Selective polarization of ferroelectrics in
functional electronics
Ya.I. Lepikh
Scientific-Technologiccal Center «Phonon», SCTB «Element»
29, pr. Acad. Glushko, 270104 Odessa, Ukraine, Tel. (0484)-66-82-29, Fax.: (0482)-47-02-23
Abstract. The selective polarization technique of ferroelectrics representing sound-conductors and piezo-
electric transformers in different devices of functional electronics is described. The feature of the tech-
nique is the ability of creating the local polarization regions, with different, in the magnitude and orien-
tation, polarization vectors and with different electrophysical parameters, in the monolithic ceramic
sound-conductor. The examples of specific acousto-electron units based on surface acoustic waves with
the essentially improved electrical parameters, simpler construction and higher processibility are pre-
sented. The features of the selective polarization process are shown, the recommendations on the usage
of the technique are given.
Keywords: ferroelectric, domain, sound conductor, polarization, converter, wave, parameter.
Paper received 27.05.99; revised manuscript received 20.09.99; accepted for publication 15.10.99.
One of directions for the efficient improving the charac-
teristics of functional electronic (FE) (acousto-, optoelec-
tronics, acousto-optics, etc.) devices is the development of
new functional materials with controllable properties and
improvement of techniques for the maximum realization of
their potentials. The perspectives of such a direction of stud-
ies are more promising than the design improvement. This
is confirmed by the achievement of high values of specific
parameters of FE devices due to application of ferroelectrics,
AIIBVI structures and other materials [1-4].
The acoustoelectronic devices on surface acoustic waves
(SAW), for example, having evident advantages as compared
to devices based on other physical principles, sometimes are
inferior due to relatively large magnitude of inherent signal
losses. This problem is often solved using complicated design
of interdigital transformers (IDT) or by introduction of supple-
mentary radio devices [4, 5]. In the first case, the one-direc-
tional IDT, multiple-strip couplers, in the second case, the
phase-shifters are used. But in both cases such solutions make
the device construction much more complex, reduce their
processibility and often are not efficient.
The attempts were made [6] to reduce the induced losses
by variation of electrophysical parameters (EPP) of the
sound-conductor piezoelectric material using the additional
polarization of piezoceramics. In this case the complex pro-
cedure of power forming signal generation with a complex
acoustic wave spectrum of a given form.
We suggest a technique for improving the SAW-based
device characteristics by application of selective polariza-
tion of ferroelectrics used as sound-conductors and piezo-
electric transformers. This technique may be also used for
another kinds of FE devices. In the SAW-based sound-
conductor containing the IDT system, the regions are formed
with polarization vectors P
r
with different both amplitude
and orientation in respect to the operation surface of the
sound-conductor (Fig.1). In this case, in the region where
the input IDT is situated the polarization vector 1`P
r
is di-
rected normally to the sound-conductor operation surface,
and in the region where the output IDT is situated, the po-
larization vector 2P
r
is parallel to it, so that |P2|>|P1|. The
part of the sound-conductor between IDT can be non-po-
larized, i.e. 3P
r
= 0.
Fig.1. The block diagram of SAW device with selectively polarized piesoce-
ramic sound-conductor. 1 - region with transverse polarization, 2 - region
with longitudinal polarization, 3 - non-polarized region, 4 - input IDT,
5 - output IDT.
PPP 231
4 1 3 2 5
Ya. I. Lepikh: Selective polarization of ferroelectrics in functional electronics.
39SQO, 2(3), 1999
Thus, in the parts of the piezoceramic sound-conductor
with longitudinal-transverse polarization the regions are
formed with different values of EPP, in particular, of elec-
tromechanical coupling factor KP and dielectric constant ε.
The onset of input and output IDT of the SAW device is
performed in such way that one of summation buses of IDT
and conductive layers situated on inactive surface of the
sound-conductor, are grounded like as in the piezoceramic
transformer. Due to a higher value of KP in the region 2P
r
and due to a greater area from which the signal is collected
by more extended output IDT, the voltage transformation
of the electrical signal generated by the output IDT occurs.
Using this technique the samples of the SAW bandwidth
filters with the mean frequency f0 = 10 MHz were fabri-
cated. The piezoceramics of plumbum zirconat-titanat PZT-
42 was used. In the experimental filter samples the magni-
tude of induced signal losses was less than 2 dB, which can
not be achieved by other techniques.
The possibilities of ferroelectric selective polarization
are not restricted to creation of local parts with different
polarization in the monolithic sound-conductor. By forma-
tion of the polarization regions of different geometrical
shape it is possible, in particular, to form the amplitude-
frequency characteristics of SAW devices. In [7], for ex-
ample, to reduce the distortions of the SAW phase front the
weighing of IDT electrodes with the same overlapping was
performed by setting the polarized region with a definite
shape in the IDT plane. In particular, for the bandwidth
filter the configuration of the region (Fig.2) had the shape
of the envelope of its pulse characteristic h(t) obtained from
its given transfer characteristic H(ω) by the reverse Fourier
transform h(t) = ∫
∞
∞−
Ho(ω) exp (iωt) dω, where ω is the cir-
cular frequency. At the same time, such technique of IDT
apodization allows to increase essentially its processibility,
since it removes the strict requirement imposed on the fab-
rication precision of small IDT electrode bridges, correspon-
ding to calculated weighting functions.
Even greater successes of application of the selective
polarization are expected in acousto-optics, optoelectron-
ics, where the ferroelectric ceramics based on lanthanum
doped PZT (PLZT) with high optical transparency, sensi-
tivity, stability and other advantages [8, 9] is applied more
and more intensively. It is supposed that the method will
enhance also the sensor technology potential.
In this technique all procedures of piezoceramic sub-
strate fabrication from the ferroelectric material (the syn-
thesis of compound, formation, sintering, mechanical treat-
ment) prior to polarization do not differ from the
conventional ones. While using the selective polarization,
which can be carried out using the set-up described in [10]
this process is slightly different.
Omitting the quantum-mechanical aspect of the atom
behaviour in the ferroceramic crystal structure, one should
take into account, that at longitudinal polarization, when the
external electric field E
r
is directed normally to the sponta-
neous polarization vector sP
r
, i.e. along one of directions
[100] or [010], the dipole polarization mechanism is preva-
lent with a 90-degree turn of domains. Since the coercive
field of 90-degree domain turn is higher (the cell deforma-
tion occurs), than that of 180-degree turn, the longitudinal
polarization mode should differ by the polarization field E
r
magnitude, temperature K and polarization time tp. At 90-
degree domain reorientation strong mechanical stresses ap-
pear, which, together with the field accumulated in the near-
electrode space-charge regions, after completing the polar-
ization lead to a greater change of piezoceramic parameters,
than in the case of 180-degree reorientation. It should be
noted that due to different coercive fields of ferroelectrics
with different composition, at the dipole type of polariza-
tion under the external field the qualitatively different po-
larization results are reached. For example, in PZT ceram-
ics the number of domains that are 90-degree reorientable is
by a factor of 3-3.5 greater than in barium titanat (BaTiO3).
These features are manifested in the process of the
piezoceramics aging. This should be taken into account dur-
ing a device calculation, using the stabilized EPP values,
which are reached for the longer time interval, or by artificial
acceleration of aging.
The technique of ferroelectric selective polarization can
be used for the solution of a broad range of problems in
acousto- and optoelectronics, acousto-optics and other di-
rections of functional and solid-state microelectronics.
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4
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Ya. I. Lepikh: Selective polarization of ferroelectrics in functional electronics.
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