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

• Published in: NPJ 2D materials and applications Vol. 3; no. 1
• Main Authors: Ansari, Lida, Monaghan, Scott, McEvoy, Niall, Coileáin, Cormac Ó, Cullen, Conor P., Lin, Jun, Siris, Rita, Stimpel-Lindner, Tanja, Burke, Kevin F., Mirabelli, Gioele, Duffy, Ray, Caruso, Enrico, Nagle, Roger E., Duesberg, Georg S., Hurley, Paul K., Gity, Farzan
• Format: Journal Article
• Language: English
• Published: London Nature Publishing Group UK 03.09.2019; Nature Publishing Group
• Subjects: 639/301/1005/1007; 639/301/357/1018; 639/925/357/1018; 639/925/927/1007; Chemistry and Materials Science; Density functional theory; Electrical measurement; Energy gap; Evolution; Field effect transistors; Film thickness; Hole mobility; Low temperature; Materials Science; MOSFETs; Nanotechnology; P-type semiconductors; Platinum; Quantum confinement; Room temperature; Semiconductor devices; Silicon dioxide; Silicon substrates; Surfaces and Interfaces; Thick films; Thickness measurement; Thin Films
• DOI: 10.1038/s41699-019-0116-4
• ISSN: 2397-7132

In this work, we present a comprehensive theoretical and experimental study of quantum confinement in layered platinum diselenide (PtSe 2 ) 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 PtSe 2 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 PtSe 2 energy gap. Large-area PtSe 2 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/SiO 2 substrates. The PtSe 2 films exhibit p -type semiconducting behavior with hole mobility values up to 13 cm 2 /V·s. Metal-oxide-semiconductor field-effect transistors have been fabricated using the grown PtSe 2 films and a gate field-controlled switching performance with an I ON / I OFF ratio of >230 has been measured at room temperature for a 2.5–3 nm PtSe 2 film, while the ratio drops to <2 for 5–6.5 nm-thick PtSe 2 films, consistent with a semiconducting-to-semimetallic transition with increasing PtSe 2 film thickness. These experimental observations indicate that the low-temperature growth of semimetallic or semiconducting PtSe 2 could be integrated into the back-end-of-line of a silicon complementary metal-oxide-semiconductor process.