ISSN 1063-7397, Russian Microelectronics, 2014, Vol. 43, No. 7, pp. 491–495. © Pleiades Publishing, Ltd., 2014.
Original Russian Text © S.A. Gavrilov, D.G. Gromov, S.V. Dubkov, M.Yu. Nazarkin, M.V. Silibin, S.P. Timoshenkov, A.M. Koz’min, A.S. Shulyat’ev, 2013, published in Izvestiya
Vysshikh Uchebnykh Zavedenii. Elektronika, 2013, No. 4(102), pp. 44–50.
491
1. INTRODUCTION
One-dimensional semiconductor nanostructures
possess unusual properties and therefore are used in
various devices and technologies [1]. The zinc oxide
(ZnO), which is the wide-gap semiconductor with a
peculiar donor-acceptor chemical bond that is close to
an ionic one, is the material for such structures [2].
The piezoelectric properties of thin ZnO films are
used in creating microphones [3] and volume acoustic
resonators [4].
The piezoeffect that occurs when bending a ZnO
nanowire is studied in [5–7]. The ZnO nanowire is
found to be polarized when being bended using the
cantilever of an atomic force microscope. Based on
this phenomenon and using the array of ZnO nanow-
ires, a nanogenerator that operates on ultrasonic waves
is developed [8–10]. In the nanogenerator, mechani-
cal energy is converted into electrical energy via the
difference of potentials in the array of ZnO nanowires
that are deformed under the action of an ultrasound.
The potential difference arises between the bottom
electrode, on which the array of ZnO nanowires is
grown, and the top platinum electrode that touches
upper ends of the nanowires in the array. The devel-
oped nanogenerator is shown to provide only positive
voltage, which is due to the Schottky diode created by
the contact between the platinum electrode and the
ZnO nanowire [11].
The main problem of the device with an array of
piezoelectric wires concerns taking the signal from the
ends of each nanowire at one time. When bending the
piezoelectric wire at the upper end, the positive and
negative charges arise from the polarization [12]. If the
crystal lattice is stretched, the corresponding nanowire
region is charged positively; if the crystal lattice
shrinks, the nanowire region is charged negatively. In
this respect, the top electrode must be commuted only
to that part of the upper end of each piezoelectric wire
which has the same charge. For this purpose, various
designs of the top electrode such as the array of
V-shaped metalized grooves or the array of metallized
spikes are used [7, 13].
In the construction with V-shaped grooves, there
are two obvious disadvantages: expensive photolithog-
raphy is required to form the grooves and, with the
operation of such a construction, the ZnO nanowires
are generally aligned along the groove, which reduces
the generator’s performance.
When using an electrode with an array of spikes,
some piezoelectric ZnO wires in the array are proved
to be nonfunctional due to the closing of the positively
and negatively charged regions of the upper end of the
piezoelectric wire, which is subjected to bending by
the top electrode or due to the loose contact between
them and the second electrode with the length of
piezoelectric wires being different. Another part of the
correctly commutated in-parallel piezoelectric ele-
ments has an unfixed unstable contact with the second
electrode, which results in unavoidable losses of the
electric energy generated by the bending of the piezo-
electric wire.
In this paper, the Al
2
O
3
metallized porous anodic
oxide of aluminum is proposed to be used as the top
electrode. The design of such a device is shown in Fig. 1.
Note that a different number of ZnO nanowires
(bunch) can contact the pores of the top electrode
depending on the diameter of the Al
2
O
3
pore. As a
result, it has the following advantages:
(1) The nanowires placed in the pore fix each
other;
(2) The nanowires contacting the electrode touch
the latter with similarly charged regions;
Study of the Vibration-Sensitive Piezoelectric Element Based
on ZnO Nanowires and Porous Electrode
S. A. Gavrilov, D. G. Gromov, S. V. Dubkov, M. Yu. Nazarkin, M. V. Silibin,
S. P. Timoshenkov, A. M. Koz’min, and A. S. Shulyat’ev
National Research University of Electronic Technology (MIET), Moscow, Russia
e-mail: sv.dubkov@gmail.com
Received February 1, 2013
Abstract—Characteristics of a sensitive element based on the array of ZnO nanowires and Al
2
O
3
metallized
porous anodic oxide are studied. The element is shown to be sensitive to mechanical vibrations. The output
signal of the device is found to have a linear dependence on acceleration. The dependence of the response on
the frequency of mechanical vibrations is investigated.
DOI: 10.1134/S1063739714070075