Quantum confinement-induced semimetal-to-semiconductor evolution in large-area ultra-thin PtSe2 films grown at 400 °C

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Ansari, Lida
Monaghan, Scott
McEvoy, Niall
Ó Coileáin, Cormac
Cullen, Conor P.
Lin, Jun
Siris, Rita
Stimpel-Lindner, Tanja
Burke, Kevin F.
Mirabelli, Gioele
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In this work, we present a comprehensive theoretical and experimental study of quantum confinement in layered platinum diselenide (PtSe2) films as a function of film thickness. Our electrical measurements, in combination with density functional theory calculations, show distinct layer-dependent semimetal-to-semiconductor evolution in PtSe2 films, and highlight the importance of including van der Waals interactions, Green’s function calibration, and screened Coulomb interactions in the determination of the thickness-dependent PtSe2 energy gap. Large-area PtSe2 films of varying thickness (2.5–6.5 nm) were formed at 400 °C by thermally assisted conversion of ultra-thin platinum films on Si/SiO2 substrates. The PtSe2 films exhibit p-type semiconducting behavior with hole mobility values up to 13 cm2/V·s. Metal-oxide-semiconductor field-effect transistors have been fabricated using the grown PtSe2 films and a gate field-controlled switching performance with an ION/IOFF ratio of >230 has been measured at room temperature for a 2.5–3 nm PtSe2 film, while the ratio drops to <2 for 5–6.5 nm-thick PtSe2 films, consistent with a semiconducting-to-semimetallic transition with increasing PtSe2 film thickness. These experimental observations indicate that the low-temperature growth of semimetallic or semiconducting PtSe2 could be integrated into the back-end-of-line of a silicon complementary metal-oxide-semiconductor process.
Electronic devices , Two-dimensional materials , Quantum confinment , Confinement-induced-semimetal-to-semiconductor , Evolution , PtSe2
Ansari, L., Monaghan, S., McEvoy, N., Ó Coileáin, C., Cullen, C. P., Lin, J., Siris, R., Stimpel-Lindner, T., Burke, K. F., Mirabelli, G., Duffy, R., Caruso, E., Nagle, R. E., Duesberg, G. S., Hurley, P. K. and Gity, F. (2019) 'Quantum confinement-induced semimetal-to-semiconductor evolution in large-area ultra-thin PtSe2 films grown at 400 °C', npj 2D Materials and Applications, 3(1), 33 (8pp.). DOI: 10.1038/s41699-019-0116-4