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We have introduced design, technology as well as measurement of physical parameters of antenna-coupled microbolometer, used for broadband detection of terahertz electromagnetic spectrum. This microbolometer features an application of La0.67Sr0.33MnO3 layer (shortened LSMO) grown on multilayered material stack ensuring lattice matching of the sensing LSMO layer to silicon. By virtue of bulk micromachining of silicon-on-insulator substrates, the sensing structure is built on thin suspended membrane to provide weak thermal link, increasing thermal response, thus sensitivity. Additionally, it helps suppressing excitation of in-plane guided surface modes that will otherwise deteriorate the antenna radiation diagram and affect the spectral responsivity of the sensor. Finally, the operation of sensor is demonstrated using a molecular laser setup at 762 GHz (and also 1.4 THz) emission line. The parameters of the fabricated microbolometers are analyzed in terms of response and time constant. Optimal working temperature of the detectors is about 65 °C.
Figure 1. Pictorial view of antenna-coupled microbolometer, featuring a bolometer disk placed in the center of circular drum membrane defined on SOI substrate. This disk is electrically connected to log-periodic antenna and converts the incident electromagnetic energy to Joule heat. The temperature of the bolometric disk is measured electrically through its resistance, accessible on the extended pads in the corners of the chip.
Figure 2. Photograph of the antenna-coupled microbolometer chip used in the tests.
Figure 3. x-y scan of 762-GHz laser beam over antenna-effective area; color-coded is the normalized lock-in amplifier signal magnitude.
Outputs:
Lalinský, T., Dzuba, J., Vanko, G., Kutiš, V., Paulech, J., Gálik, G., Držík, M., Chromik, Š., and Lobotka, P.:Thermo-mechanical analysis of uncooled La0.67Sr0.33MnO3 microbolometer made on circular SOI membrane. Sensors Actuators A 265 (2017) 321–328.
Kutiš, V., Paulech, J., Gálik, G., Lalinský, T., Vanko, G., Hrabovský, J., Jakubec, J., : Thermal analysis of microbolometer In: Proc. 23th Inter. Conf. on Applied Phys. of Cond. Matter (APCOM 2017). Eds. J. Vajda and I. Jamnický. Bratislava: FEI STU 2017. ISBN 978-80-227-4699-1. P. 267-271.