advanced-materials-nano-engineering-2018-tracks

Page 41

Volume 4

December 10-12, 2018

Rome, Italy

Nano Research & Applications

ISSN: 2471-9838

Advanced Materials 2018

Nano Engineering 2018

JOINT EVENT

International Conference on

Advanced Materials

and Simulation

Edition of International Conference on

Nano Engineering &

Technology

lectromechanical transducers based on the piezoelectric

effect are continuously finding their way into micro-

electromechanical systems (MEMS), typically in the form

of thin films. Piezoelectric transducers feature a linear

voltage response, no snap in behavior and can provide both

attractive and repulsive forces. This removes inherent physical

limitations present in the commonly used electrostatic

transducer approach while maintaining beneficial properties

such as low power operation. Furthermore, piezoelectric

materials can serve for both actuation and sensing purposes,

thus enabling pure electrical excitation and read out of

the transducer element in combination with a compact

design. Based on these outstanding features, piezoelectric

transducers are operated most beneficially in a large variety

of different application scenarios, ranging from resonators

in liquid environment, advanced acoustic devices to sensors

in harsh environments. In order to exploit the full potential of

piezoelectric MEMS in the future, interdisciplinary research

efforts are needed ranging from investigations of advanced

piezoelectric materials over the design of novel piezoelectric

MEMS sensor and actuator devices to the integration of Piezo

MEMS devices into full low-power systems. In this presentation,

we will highlight latest results on the electrical, mechanical

and piezo electrical characterization of sputter-deposited

aluminium nitride (AlN) including the impact of sputter

parameters, film thickness and substrate pre-conditioning.

We will present the impact of doping of AlN with scandium,

which leads to an increase of the moderate piezoelectric

coefficient of AlN upto a factor of four. We will also present

first results on the piezoelectric co-polymer PVDF TrFE. In next

step, these films are implemented into fabrication processes

of cantilever type MEMS devices. In combination with a

tailored electrode design resonators are realized featuring in

liquid Q-factors upto about 300 in the frequency range of 12

MHz. This enables the precise determination of the viscosity

and density of fluids upto dynamic viscosity values of almost

300 mPas. Besides this application, such as high Q factors are

useful when targeting mass sensitive sensors, thus paving the

way, for e.g., particle detection even in highly viscous media.

Given the low increase in permittivity of ScAlN compared to

AlN, another field of application for this functional material

class is vibrational energy harvesters, where the benefit of

ScAlN compared to pure AlN is demonstrated. Finally, we will

present some selected results of ScAlN thin films within SAW

devices ranging from high temperature applications to droplet

manipulation in microfluidics.

Recent Publications

1. PMMayrhofer, C Rehlendt, M Fischeneder, MKucera, E

Wistrela, A Bittner and U Schmid (2017) ScAlN MEMS

cantilevers for vibrational energy harvesting purposes.

Journal of Micro electromechanical Systems 26:102-

112.

2. M Schneider, A Bittner and U Schmid (2015) Improved

piezoelectric constants of sputtered aluminium nitride

thin films by pre-conditioning of the silicon surface.

Journal of Physics D: Applied Physics 48(40):405301.

3. G Pfusterschmied, M Kucera, E Wistrela, T

Manzaneque, V Ruiz-Díez, J L Sánchez-Rojas, A

Bittner and U Schmid (2015) Temperature dependent

performance of piezoelectric MEMS resonators

for viscosity and density determination of liquids.

Journal of Micromechanics and Micro engineering

25(10):105014.

4. W Wang, P M Mayrhofer, X He, M Gillinger, Z Ye, X

Wang, A Bittner, U Schmid and J K Luo (2014) High

performance AlScN thin film based surface acoustic

wave devices with large electromechanical coupling

coefficient. Applied Physics Letters 105(3):133502.

5. M Schneider, A Bittner, F Patocka, M Stöger-Pollach,

E Halwax and U Schmid (2012) Impact of the surface-

near silicon substrate properties on the microstructure

of sputter-deposited AlN thin films. Applied Physics

Letters 101(22):221602.

Piezoelectric MEMS devices from material aspects

to low-power applications

Michael Schneider

and

Ulrich Schmid

Institute of Sensor and Actuator Systems, Austria

Michael Schneider et al., Nano Res Appl 2018, Volume 4

DOI: 10.21767/2471-9838-C7-027