Hysteresis in As-Synthesized MoS2 Transistors: Origin and Sensing Perspectives
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AuthorSalazar, Norberto; Galdón, José Carlos; Gity, Farzan; Navarro Moral, Carlos; Márquez González, Carlos; Sampedro Matarín, Carlos; Gámiz Pérez, Francisco Jesús; Hurley, Paul; Chang, Edward Yi
two-dimensional materialslight sensormolybdenum disulfideMoS2trappingreliability
Marquez, C.; Salazar, N.; Gity, F.; Galdon, J.C.; Navarro, C.; Sampedro, C.; Hurley, P.K.; Chang, E.Y.; Gamiz, F. Hysteresis in As-Synthesized MoS2 Transistors: Origin and Sensing Perspectives. Micromachines 2021, 12, 646. https://doi.org/10.3390/mi12060646
SponsorshipEuropean Union’s Horizon 2020 Research and Innovation Programme under the Marie Skłodowska-Curie grant agreement No 895322; Spanish Government under Juan de la Cierva Formacion grant number FJC2018-038264-I; Spanish Ministry of Economy, Industry and Competitivity under grant TEC2017-89800-R; ASCENT (EU Horizon 2020 GRANT 654384); Science Foundation Ireland through the AMBER 2 project (12/RC/2278-P2); UGR-MADOC CEMIX 2D-EDEX
Two-dimensional materials, including molybdenum disulfide (MoS2), present promising sensing and detecting capabilities thanks to their extreme sensitivity to changes in the environment. Their reduced thickness also facilitates the electrostatic control of the channel and opens the door to flexible electronic applications. However, these materials still exhibit integration difficulties with complementary-MOS standardized processes and methods. The device reliability is compromised by gate insulator selection and the quality of the metal/semiconductor and semiconductor/insulator interfaces. Despite some improvements regarding mobility, hysteresis and Schottky barriers having been reported thanks to metal engineering, vertically stacked heterostructures with compatible thin-layers (such as hexagonal boron nitride or device encapsulation) variability is still an important constraint to sensor performance. In this work, we fabricated and extensively characterized the reliability of as-synthesized back-gated MoS2 transistors. Under atmospheric and room-temperature conditions, these devices present a wide electrical hysteresis (up to 5 volts) in their transfer characteristics. However, their performance is highly influenced by the temperature, light and pressure conditions. The singular signature in the time response of the devices points to adsorbates and contaminants inducing mobile charges and trapping/detrapping carrier phenomena as the mechanisms responsible for time-dependent current degradation. Far from being only a reliability issue, we demonstrated a method to exploit this device response to perform light, temperature and/or pressure sensors in as-synthesized devices. Two orders of magnitude drain current level differences were demonstrated by comparing device operation under light and dark conditions while a factor up to 105 is observed at vacuum versus atmospheric pressure environments.