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Open AccessArticle

Switchable Piezoresistive SmS Thin Films on Large Area

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Lumilab, Department of Solid State Sciences, Ghent University, Krijgslaan 281/S1, 9000 Ghent, Belgium
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Cocoon, Department of Solid State Sciences, Ghent University, Krijgslaan 281/S1, 9000 Ghent, Belgium
*
Author to whom correspondence should be addressed.
Sensors 2019, 19(20), 4390; https://doi.org/10.3390/s19204390
Received: 12 September 2019 / Revised: 8 October 2019 / Accepted: 9 October 2019 / Published: 11 October 2019
(This article belongs to the Section Sensor Materials)
Samarium monosulfide (SmS) is a switchable material, showing a pressure-induced semiconductor to metal transition. As such, it can be used in different applications such as piezoresistive sensors and memory devices. In this work, we present how e-beam sublimation of samarium metal in a reactive atmosphere can be used for the deposition of semiconducting SmS thin films on 150 mm diameter silicon wafers. The deposition parameters influencing the composition and properties of the thin films are evaluated, such as the deposition rate of Sm metal, the substrate temperature and the H2S partial pressure. We then present the changes in the optical, structural and electrical properties of this compound after the pressure-induced switching to the metallic state. The back-switching and stability of SmS thin films are studied as a function of temperature and atmosphere via in-situ X-ray diffraction. The thermally induced back switching initiates at 250 °C, while above 500 °C, Sm2O2S is formed. Lastly, we explore the possibility to determine the valence state of the samarium ions by means of X-ray photoelectron spectroscopy. View Full-Text
Keywords: SmS; switchable materials; semiconductor to metal transition (SMT); optical properties; structural properties SmS; switchable materials; semiconductor to metal transition (SMT); optical properties; structural properties
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MDPI and ACS Style

Sousanis, A.; Poelman, D.; Detavernier, C.; Smet, P.F. Switchable Piezoresistive SmS Thin Films on Large Area. Sensors 2019, 19, 4390.

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