New Multilayer Architectures for Piezoelectric BaTiO 3 Cantilever Systems
- PDF / 266,255 Bytes
- 6 Pages / 432 x 648 pts Page_size
- 34 Downloads / 202 Views
New Multilayer Architectures for Piezoelectric BaTiO3 Cantilever Systems Giuseppe Vasta1, Timothy J. Jackson1, James Bowen2 and Edward J. Tarte1 1 School of Electronic Electrical and Computer Engineering, University of Birmingham, B15 2TT Birmingham, United Kingdom 2 Department of Chemical Engineering, University of Birmingham, B15 2TT Birmingham, United Kingdom ABSTRACT The fabrication and characterization of released cantilevers in new multilayer thin films architectures is reported. In contrast to previous works, the cantilevers are produced without etching of the substrate and are based on lead free piezoelectric materials. The three architectures are: SrRuO3/BaTiO3/MgO/SrTiO3/YBa2Cu3O7, SrRuO3/BaTiO3/SrRuO3/YBa2Cu3O7 and SrRuO3/BaTiO3/SrRuO3/SrTiO3/YBa2Cu3O7. It is shown that the different architectures allow a choice of the orientation of the polar axis in piezoelectric layers, in plane (d33 mode) or out of plane (d31 mode). Both configurations may be utilized in piezoelectric energy harvesting devices. Released cantilevers with the above layer sequences have been produced with lengths ranging from, 100 ȝm to 250 ȝm. The residual stress after the release of the cantilevers produces an upward bending, the distance between the cantilever tips and the substrate varies between 20 ȝm and 45 ȝm. This distance would allow the sufficient vibration amplitude to enable the cantilevers to be used as micro-generators. Measurements of Young Modulus of the cantilevers and of polarization hysteresis loop are reported. INTRODUCTION Energy scavenging from the surrounding environment represents the key towards the building of autonomous micro-systems. Solar power is the most powerful ambient energy source but not always the most convenient. Another interesting way to harvest energy from the environment is represented by the conversion of the parasitic mechanical vibrations into electrical energy. Piezoelectric materials are the perfect candidate for such conversion because they can efficiently convert mechanical strain into the separation of electrical charge and hence potential difference [1]. Furthermore the simplicity of the piezoelectric micro-generator is particularly attractive for use in MEMS [2]. Studies on energy harvesting devices based on Pb(Zr,Ti)O3 have been widely performed [1,3,4]. Lead-free piezoelectric materials are increasingly of interest. This paper describes the fabrication and characterization of energy harvesting devices based on thin-film architectures using BaTiO3 as piezoelectric layers. The properties of BaTiO3 are well known, making it ideal for exploration of new systems which could then be modified to exploit more recently discovered, higher performance materials. The three multilayer systems investigated were: SrRuO3/BaTiO3/MgO/SrTiO3/YBa2Cu3O7, SrRuO3/BaTiO3/SrRuO3/YBa2Cu3O7 and SrRuO3/BaTiO3/SrRuO3/SrTiO3/YBa2Cu3O7. In these multi-layers, SrRuO3 acts as electrode
111
layer and the YBa2Cu3O7 is the sacrificial layer used to obtain suspended structures through undercutting. EXPERIMENT The mult
Data Loading...
