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Switchable Piezoresistive SmS Thin Films on Large Area

Authors
  • Sousanis, Andreas1
  • Poelman, Dirk1
  • Detavernier, Christophe
  • Smet, Philippe F.1
  • 1 (D.P.)
Type
Published Article
Journal
Sensors
Publisher
MDPI AG
Publication Date
Oct 11, 2019
Volume
19
Issue
20
Identifiers
DOI: 10.3390/s19204390
PMID: 31614444
PMCID: PMC6832629
Source
PubMed Central
Keywords
License
Green

Abstract

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.

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