16 May 2017 FEM modeling of solidly mounted film bulk acoustic resonator and gas sensor using PIB-sensitive layer
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Abstract
The application of a film bulk acoustic resonator (FBAR) as a gas sensor is presented here. Zinc Oxide is used as a piezoelectric (PZE) material for the resonator and a Bragg reflector is made of Molybdenum and Silicon dioxide in proposed Solidly Mounted FBAR. The structure offers a high quality factor of 1209 at the resonance and shows a coupling coefficient of 7.51% for the 0.7 - μ m -thick PZE layer. To make it capable of working as a gas sensor, an additional sensitive layer for adsorption is used. A 0.51 - μ m -thin film of polymer-sensitive layer (polyisobutylene, PIB) is used on the top electrode. The adsorption of CH 2 Cl 2 (dichloromethane, DCM) prompts the change in density of the PIB layer, which causes the change in resonance frequency of the FBAR. The simulation results have shown the sensitivity of 450    Hz / ppm for gas sensing for the above-mentioned structure. The sensitivity of the sensor depends on the characteristic frequencies of the device, which are further the function of the thickness of the resonating structure. No involvement of a harsh etching process in fabrication, in addition to immense sensitivity and quality factor, makes this sensor relevant for DCM sensing.
© 2017 Society of Photo-Optical Instrumentation Engineers (SPIE)
Raju Patel, Manishkumar Patel, Dharmendar Boolchandani, Kamaljit Rangra, "FEM modeling of solidly mounted film bulk acoustic resonator and gas sensor using PIB-sensitive layer," Journal of Micro/Nanolithography, MEMS, and MOEMS 16(2), 025002 (16 May 2017). https://doi.org/10.1117/1.JMM.16.2.025002 . Submission: Received: 21 December 2016; Accepted: 24 April 2017
Received: 21 December 2016; Accepted: 24 April 2017; Published: 16 May 2017
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