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M. Schneider, U. Schmid:
"Substrate Temperature and Bias Voltage Dependent Properties of Sputtered AlN Thin Films for BAW Applications";
Vortrag: The 18th IEEE International Conferene on Nanotechnology (ieee nano 2018), Cork, Irland; 23.07.2018 - 26.07.2018; in: "Proceedngs of the 18th IEEE International Conferene on Nanotechnology (ieee nano 2018)", IEEE, (2018), ISBN: 978-1-5386-5336-4; S. 420 - 425.

In the last decade, bulk acoustic wave (BAW) devices have almost completely replaced surface acoustic wave (SAW) devices for highly demanding filtering applications such as duplexers in modern electronics [l, 2]. In addition, BAWs offer exciting opportunities as biological or gas sensors, especially when placed on acoustic Bragg reflectors to confine the acoustic energy within the resonator, called solidly mounted BAW resonators (SMRs) [3]-[4][5][6][7]. Most commercially available BAW devices are based on aluminium nitride (A1N) thin films due to its high stiffness and CMOS compatibility [1]. The major drawbacks of A1N are the relatively low piezoelectric coefficients (d33,f=3.9 pm/V) and the relatively low intrinsic electromechanical coupling factor (k2eff=d233,f⋅cE33/ε0ε33=6.5 with the stiffness tensor cEij and the thin film permittivity tensor ε0εij) [8]. The ability to control the properties of the A1N thin film to tailor BAW characteristics such as quality factor Q and electromechanical coupling k2eff is of utmost importance. In this work, we investigate the impact of substrate temperature T and bias voltage Ubias on some fundamental properties of sputter deposited A1N thin films related to these BAW key parameters.

http://dx.doi.org/10.1109/NANO.2018.8626332