Query: Piezoelectric Thin Films for Sensors, Actuators, and Energy Harvesting

Candidate papers:

abstract: Piezoelectric microelectromechanical systems (MEMS) offer the opportunity for high sensitivity sensors and large displacement, low voltage actuators. In particular, recent advances in the deposition of perovskite thin films point to a generation of MEMS devices capable of large displacements at complementary metal oxide semiconductor compatible voltage levels. Moreover, if the devices are mounted in mechanically noisy environments, they also can be used for energy harvesting. Key to all of these applications is the ability to obtain high piezoelectric coefficients and retain these coefficients throughout the microfabrication process. This article will review the impact of composition, orientation, and microstructure on the piezoelectric properties of perovskite thin films such as PbZr 1 x Ti x O 3 (PZT) Superior piezoelectric coefficients e 31, f of 18 C/m 2 are achieved in {001} oriented PbZr 0.52 Ti 0.48 O 3 films with improved compositional homogeneity on Si substrates. The advent of such high piezoelectric responses in films opens up a wide variety of possible applications. A few examples of these, including low voltage radio frequency MEMS switches and resonators, actuators for millimeter scale robotics, droplet ejectors, energy scavengers for unattended sensors, and medical imaging transducers, will be discussed.
author_names: Paul Muralt

Ronald Polcawich

Susan E Trolier-McKinstry
title: Piezoelectric Thin Films for Sensors, Actuators, and Energy Harvesting
year: 2009

abstract: Perovskite oxide materials have been widely investigated due to properties related to their spontaneous polarization such as ferroelectricity, piezoelectricity, and pyroelectricity. Often due to high chemical stability, and mechanical robustness with large dielectric constants, ferroelectric and piezoelectric perovskite oxides have become essential components in a wide spectrum of applications such as nonvolatile random access memory, microelectromechanical devices, sensors, actuators, high frequency electrical components, tunable microwave circuits, nanogenerators for energy harvesting, and as potential solar cell absorbers. The realization of miniaturized devices has required these materials to be investigated in thin film forms. However, research in ferroelectric and piezoelectric thin films is limited due to the intrinsic difficulties of structural engineering at the nanoscale. To this end, nanostructured films exhibit uniquely different properties from nontextured homogenous thin films due to the deliberate engineering of nanoscale features into the structure. Moreover, nanostructuring provides new insights into the size, shape, and surface effects on the charge ordering in ferroelectric and piezoelectric perovskite oxide materials. The down scaling effect results in an enhancement of the surface area of materials where surface charges play a dominant role in determining the magnitude and direction of polarization. As polarization properties are the cumulative phenomenon of crystal dimensions, orientation, and ordering, synthesis methodologies that can lead to the manipulation of size and dimensions of ferro and piezoelectric nanostructures can offer great advantages. However, the large scale synthesis and integration of ordered functional nanowires is a challenge, due to their complicated fabrication methodologies, high cost, and difficulties with phase stability in many metastable perovskite compounds. In this chapter we will review how facile solution based synthesis processes can be utilized for fabricating state of the art and novel perovskite nanostructured films where tuning crystallinity and strain engineering due to interfacial effects, dimensional confinement, and domain wall interaction resulting from grain boundaries in nanostructures may enhance the Curie temperature, permittivity, or polarizability, and induce "self poling" effects, eventually enhancing the overall performance of the devices. We will also consider the potential of some of the new ferroelectric nanostructures for photovoltaic applications, proposing pathways for coherent design of next generation sustainable energy devices.
author_names: Anuja Datta

Debarati Mukherjee

Sohini Kar-Narayan
title: Ferroelectric and piezoelectric oxide nanostructured films for energy harvesting applications
year: 2018

abstract: Energy harvesting from ubiquitous ambient vibrations is attractive for autonomous small power applications and thus considerable research is focused on piezoelectric materials as they permit direct inter conversion of mechanical and electrical energy. Nanogenerators (NGs) based on piezoelectric nanowires are particularly attractive due to their sensitivity to small scale vibrations and may possess superior mechanical to electrical conversion efficiency when compared to bulk or thin film devices of the same material. However, candidate piezoelectric nanowires have hitherto been predominantly analyzed in terms of NG output (i.e. output voltage, output current and output power density) Surprisingly, the corresponding dynamical properties of the NG, including details of how the nanowires are mechanically driven and its impact on performance, have been largely neglected. Here we investigate all realizable NG driving contexts separately involving inertial displacement, applied stress T and applied strain S, highlighting the effect of driving mechanism and frequency on NG performance in each case. We argue that, in the majority of cases, the intrinsic high resonance frequencies of piezoelectric nanowires ~tens of MHz) present no barrier to high levels of NG performance even at frequencies far below resonance <1 kHz) typically characteristic of ambient vibrations. In this context, we introduce vibrational energy harvesting (VEH) coefficients eS and eT, based on intrinsic materials properties, for comparing piezoelectric NG performance under strain driven and stress driven conditions respectively. These figures of merit permit, for the first time, a general comparison of piezoelectric nanowires for NG applications that takes into account the nature of the mechanical excitation. We thus investigate the energy harvesting performance of prototypical piezoelectric ceramic and polymer nanowires. We find that even though ceramic and polymer nanowires have been found, in certain cases, to have similar energy conversion efficiencies, ceramics are more promising in strain driven NGs while polymers are more promising for stress driven NGs. Our work offers a viable means of comparing NG materials and devices on a like for like basis that may be useful for designing and optimizing nanoscale piezoelectric energy harvesters for specific applications. S Online supplementary data available from stacks.iop.org/NANO/26/344001/mmedia
author_names: Asif Khan

Zafar Abas

Heung Soo Kim

Il-Kwon Oh
title: Piezoelectric thin films: an integrated review of transducers and energy harvesting
year: 2015

abstract: Abstract Partial substitution of aluminium by scandium in the wurtzite structure of aluminium nitride (AlN) leads to a large increase of the piezoelectric response by more than a factor of 2. Therefore, aluminium scandium nitride (ASN) thin films attracted much attention to improve piezoelectric MEMS devices such as RF filters, sensors, micro actuators and energy harvesting devices. In this work, process microstructure property relationships of ASN thin films containing up to 42% Sc were investigated. Like AlN thin films, ASN films are sputter deposited at 300 350degC with pulsed DC powered magnetrons. The influence of the process parameters on the film structure, the intrinsic stress and the piezoelectric response was investigated in order to achieve optimal piezoelectric coefficients up to high Sc concentrations. X Ray diffraction (XRD) and transmission electron microscopy (TEM) were used to analyse the quality of c axis texture. The films showed exclusively (002) texture with rocking curve widths in the range of 1.3 2deg (FHWM) The films were further analysed by scanning electron microscopy (SEM) The Sc content was determined by energy dispersive X ray spectroscopy (EDX) A good compositional homogeneity in the range of 0.5 1 at. was achieved between border and centre of 200 mm wafers. So far, we obtained ASN films with transversal piezoelectric coefficients of up to e31,f 2.77 C/m2, which is a factor 2.6 higher than in pure AlN thin films.
author_names: Stefan Mertin

Bernd Heinz

Oliver Rattunde

Gabriel Christmann

Marc Dubois

Sylvain Nicolay

Paul Muralt
title: Piezoelectric and structural properties of c axis textured aluminium scandium nitride thin films up to high scandium content
year: 2018

abstract: Aluminium scandium nitride (ASN) exhibits a largely enhanced piezoelectric response as compared to aluminium nitride (AlN) which makes it an upcoming piezoelectric material for next generation RF filters, sensors, actuators and energy harvesting devices. In this work, process microstructure property relationships of such ASN films containing up to 40 at% Sc were investigated. Hereby, the influence of the process parameters on the film structure, the intrinsic stress and the piezoelectric response was carefully investigated.
author_names: Stefan Mertin

Vladimir P Pashchenko

Fazel Parsapour

Cosmin Silviu Sandu

Bernd Heinz

Oliver Rattunde

Gabriel Christmann

Marc Dubois

Paul Muralt
title: Enhanced piezoelectric properties of c axis textured aluminium scandium nitride thin films with high scandium content: Influence of intrinsic stress and sputtering parameters
venue: 2017 IEEE International Ultrasonics Symposium (IUS)
year: 2017

abstract: Aluminium scandium nitride (ASN) exhibits a largely enhanced piezoelectric response as compared to aluminium nitride (AlN) which makes it an upcoming piezoelectric material for use in next generation RF filters, sensors, actuators and energy harvesting devices. In this work, process microstructure property relationships of such sputtered ASN films containing up to 42 at% Sc were investigated. Hereby, the influence of the process parameters on the film structure, the intrinsic stress and the piezoelectric response were carefully investigated. A high piezoelectric response (e31, f 2.67 C/m2 and d33, f 10.3 pm/V) was measured for films with 42 at% and 34 at% Sc, respectively. The results are very promising towards industrial applications.
author_names: Stefan Mertin

Vladimir P Pashchenko

Fazel Parsapour

Clemens Nyffeler

Cosmin Silviu Sandu

Bernd Heinz

Oliver Rattunde

Gabriel Christmann

Marc Dubois

Paul Muralt
title: Enhanced piezoelectric properties of c axis textured aluminium scandium nitride thin films with high scandium content: Influence of intrinsic stress and sputtering parameters
venue: 2017 IEEE International Ultrasonics Symposium (IUS)
year: 2017

abstract: This is a review of a part of the work of the Technological Design Group at Technical University of Sofia, Faculty of Electronic Engineering and Technologies, Department of Microelectronics. It is dealing with piezoelectric polymer materials and their application in different microsystems (MEMS) and Energy Harvesting Devices (EHD) some organic materials and their applications in organic (OLED) displays, some transparent conductive materials etc. The metal oxides Lead Zirconium Titanate (PZT) and Zinc Oxide (ZnO) are used as piezoelectric layers driving part of different sensors, actuators and EHD. These materials are studied in term of their performance in dependence on the deposition conditions and parameters. They were deposited as thin films by using RF Sputtering System. As technological substrates, glass plates and Polyethylenetherephtalate (PET) foils were used. For characterization of the materials, a test structure, based on Surface Acoustic Waves (SAW) was designed and prepared. The layers were characterized by Fourier Transform Infrared spectroscopy (FTIR) The piezoelectric response was tested at variety of mechanical loads (tensile strain, stress) in static and dynamic (multiple bending) mode. The single layered and double layered structures were prepared for piezoelectric efficiency increase. A structure of piezoelectric energy transformer is proposed and investigated.
author_names: Krassimir H Denishev
title: Some metal oxides and their applications for creation of Microsystems (MEMS) and Energy Harvesting Devices (EHD)
year: 2016

abstract: Piezoelectric materials are essential for harvesting energy from mechanical vibrations. Thin films of piezoelectric materials including AlN and binary perovskite compounds PZT are widely studied for a fabrication of energy harvesting MEMS. The piezoelectric materials have held a key position in the energy harvesting devices. Varieties of bulk piezoelectric ceramic materials are studied and used in practice for the piezoelectric sensors and/or actuators. However, piezoelectric properties of the thin film materials are different from bulk properties due to their structural differences. The characters of the thin film piezoelectric materials are not fully understood yet. For making a better energy harvesting device, a fundamental discussion will be necessary for the thin film piezoelectric materials. In this paper, first the fundamentals of thin film piezoelectric materials and the process design are discussed, and then novel piezoelectric thin films of PZT based ternary perovskite compounds are proposed as an example for making the improved energy harvesting MEMS.
author_names: Kiyotaka Wasa

Isaku Kanno

Hidetoshi Kotera
title: FUNDAMENTALS OF THIN FILM PIEZOELECTRIC MATERIALS AND PROCESSING DESIGN FOR A BETTER ENERGY HARVESTING MEMS
year: 2009

abstract: Piezoelectric materials have received considerable attention from the smart structure community because of their potential use as sensors, actuators and power harvesters. In particular, polyvinylidene fluoride (PVDF) has been proposed in recent years as an enabling material for a variety of sensing and energy harvesting applications. In this study, carbon nanotubes (CNT) are included within a PVDF matrix to enhance the properties of PVDF. The CNT PVDF composite is fabricated by solvent evaporation and melt pressing. The inclusion of CNT allows the dielectric properties of the PVDF material to be adjusted such that lower poling voltages can be used to induce a permanent piezoelectric effect in the composite. To compare the piezoelectric characteristics of the CNT PVDF composite proposed, scanning electron microscope (SEM) images were analyzed and ferroelectric experiments were conducted. Finally, the aforementioned composites were mounted upon the surface of a cantilevered beam to compare the voltage generation of the CNT PVDF composite against homogeneous PVDF thin films.
author_names: Junhee Kim

Kenneth J Loh

Jerome P Lynch
title: Piezoelectric polymeric thin films tuned by carbon nanotube fillers
venue: SPIE Smart Structures and Materials Nondestructive Evaluation and Health Monitoring
year: 2008

abstract: Magnetoelectric (ME) thin film composites are attracting a continually increasing interest due to their unique features and potential applications in multifunctional microdevices and integrated units such as sensors, actuators and energy harvesting modules. By combining piezoelectric and highly magnetostrictive thin films, the potentialities of these materials increase. In this paper we report the fabrication of SmFe2 and PZT thin films and the investigation of their properties. First of all, a 400 nm thin SmFe film was deposited on top of Si/SiO2 substrate by magnetron sputter deposition. Afterwards, a 140 nm Pt bottom electrode was sputtered on top of the SmFe film forming a bottom electrode. Spin coating was employed for the deposition of the 150 nm thin PZT layer. A PZT solution with 10 %Pb excess was utilized for this fabrication step. Finally, circular Pt top electrodes were sputtered as top electrodes. This paper focuses on the microstructure of the individual films characterized by X Ray diffractometer (XRD) and scanning electron microscopy (SEM) A piezoelectric evaluation system, aixPES, with TF2000E analyzer component was used for the electric hysteresis measurements of PZT thin films and a vibrating sample magnetometer (VSM) was employed for the magnetic characterization of the SmFe. The developed thin films and the fabricated double layer SmFe PZT exhibit both good ferromagnetic and piezoelectric responses which predict a promising ME composite structure. The quantitative chemical composition of the samples was confirmed by energy dispersive spectroscopy (EDX)
author_names: Ioanna Giouroudi

Mohammed Alnassar

Juergen Kosel
title: Fabrication and properties of SmFe2 PZT magnetoelectric thin films
venue: Microtechnologies for the New Millennium
year: 2013