Ultrathin calcium fluoride insulators for two-dimensional field-effect transistors

Two-dimensional semiconductors could be used to fabricate ultimately scaled field-effect transistors and more-than-Moore nanoelectronic devices. However, these targets cannot be reached without appropriate gate insulators that are scalable to the nanometre range. Typically used oxides such as SiO 2...

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Veröffentlicht in:Nature electronics 2019-06, Vol.2 (6), p.230-235
Hauptverfasser: Illarionov, Yury Yu, Banshchikov, Alexander G., Polyushkin, Dmitry K., Wachter, Stefan, Knobloch, Theresia, Thesberg, Mischa, Mennel, Lukas, Paur, Matthias, Stöger-Pollach, Michael, Steiger-Thirsfeld, Andreas, Vexler, Mikhail I., Waltl, Michael, Sokolov, Nikolai S., Mueller, Thomas, Grasser, Tibor
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Sprache:eng
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Zusammenfassung:Two-dimensional semiconductors could be used to fabricate ultimately scaled field-effect transistors and more-than-Moore nanoelectronic devices. However, these targets cannot be reached without appropriate gate insulators that are scalable to the nanometre range. Typically used oxides such as SiO 2 , Al 2 O 3 and HfO 2 are, however, amorphous when scaled, and 2D hexagonal boron nitride exhibits excessive gate leakage currents. Here, we show that epitaxial calcium fluoride (CaF 2 ), which can form a quasi van der Waals interface with 2D semiconductors, can serve as an ultrathin gate insulator for 2D devices. We fabricate scalable bilayer MoS 2 field-effect transistors with a crystalline CaF 2 insulator of ~2 nm thickness, which corresponds to an equivalent oxide thickness of less than 1 nm. Our devices exhibit low leakage currents and competitive device performance characteristics, including subthreshold swings down to 90 mV dec −1 , on/off current ratios up to 10 7 and a small hysteresis. High-performance MoS 2 transistors can be created using 2-nm-thick CaF 2 as a gate insulator, which forms a quasi van der Waals interface with the 2D semiconductor.
ISSN:2520-1131
2520-1131
DOI:10.1038/s41928-019-0256-8