SEMINAR LMGP - September 20, 2022 - Masoud AKBARI

Masoud AKBARI

PhD student,
Univ. Grenoble Alpes, CNRS, Grenoble INP, LMGP, Grenoble, France
Univ. Grenoble Alpes, CNRS, Grenoble INP, TIMA, Grenoble, France
Dept. Mechanical and Mechatronics Engineering, University of Waterloo, Waterloo, Canada

Abstract

  
   Gas sensors have a vast variety of applications such as toxic gas detection, air quality monitoring, and early disease detection. Among the different gas sensing platforms, cantilever-based sensors have attracted considerable interest in recent years thanks to their ultra-sensitivity and high-speed response. The gas sensing mechanism in a dynamic cantilever sensor is based on its resonance frequency shift upon adsorption of a gas molecule on the sensor.[1] Metal oxides such as ZnO, SnO₂, etc. are commonly used as the sensing material to sense a variety of gases such as ethanol, acetone, hydrogen, methane, etc.[2][3]

   The aim of the research is to fabricate high-sensitivity/selectivity dynamic cantilever gas sensors by developing freestanding oxide-based cantilevers. Reducing the size of the cantilever and the number of layers on the cantilever allows for larger sensitivities.[4] The oxide layer is deposited using Atmospheric Pressure-Spatial Atomic Layer Deposition (AP-SALD), with tuned composition and properties for targeted sensing applications. This deposition technique is capable of producing high-quality metal oxide thin films with precise thickness control, up to 2 orders of magnitude faster than ALD and of occurring in open atmospheric conditions.[5] Accordingly, first we study deposition of oxides by AP-SALD and characterize the properties of the films. Next, a gas sensing bench setup is developed to investigate sensing response of the oxides using silicon cantilevers as transducer. The cantilevers are also simulated in COMSOL environment. Eventually, the oxide-based freestanding cantilevers will be fabricated and their frequency response to several analytes will be measured.

   In this presentation, the study on the deposition of SnO₂ thin films by AP-SALD using Sn(acac)₂ and water will be explained and the structural, optical, chemical, and electrical properties of the SnO₂ thin films will be discussed in detail. Growth rates of about 0.15 nm/min/cm² are achieved at low-temperature (< 220 °C) and open-air conditions. Amorphous films deposited at 220 °C present low resistivity values of 0.005 Ωcm. Frequency response of silicon cantilevers sensitized by metal oxides, as well as metal organic frameworks will be shown. We observed that the devices show fast and reliable sensitivity to several analytes. Finally, our recent progress in fabrication of the freestanding cantilevers will be presented, and the fabrication challenges and future plans will be discussed.

References

[1] H. Debéda and I. Dufour, “Resonant microcantilever devices for gas sensing,” Adv. Nanomater. Inexpensive Gas Microsens., pp. 161–188, 2020.

[2] Y. Deng, Semiconducting Metal Oxides for Gas Sensing. 2019.

[3] A. Gaskov, M. Rumyantseva, and A. Marikutsa, Tin oxide nanomaterials: Active centers and gas sensor properties. Elsevier Inc., 2020.

[4] K. Mistry et al., “Highly Sensitive Self-Actuated Zinc Oxide Resonant Microcantilever Humidity Sensor,” Nano Lett., vol. 22, no. 8, pp. 3196–3203, 2022.

[5] D. Muñoz-Rojas and J. Macmanus-Driscoll, “Spatial atmospheric atomic layer deposition: A new laboratory and industrial tool for low-cost photovoltaics,” Mater. Horizons, vol. 1, no. 3, pp. 314–320, 2014.