Ultrathin platinum diselenide synthesis controlling initial growth kinetics: Interfacial reaction depending on thickness and substrate

Abstract

Platinum diselenide (PtSe2) is an emerging transition-metal dichalcogenide showing both strong interlayer coupling and remarkable electrical properties. Because field-effect transistors (FETs) recently fabricated using PtSe2 films grown by various methods have not shown the high mobilities and on–off ratios compared with exfoliated PtSe2 and predicted by theoretical calculations, the PtSe2 growth mechanism must be better understood to prevent the degradation of electrical properties and improve the electrical performances of PtSe2-based devices. Therefore, molecular beam epitaxy is used in the current study to grow PtSe2 films, and a correlation is demonstrated between the initial PtSe2 growth kinetics and the electrical performances of PtSe2-based devices. X-ray photoelectron spectroscopy and annular dark field–scanning transmission electron microscopy show that metallic Platinum (Pt) is present in the thin PtSe2 films, as explained by the density functional theory calculations comparing Pt–Pt bond with Pt–Se bond. Electrical measurements of the PtSe2-based FETs show that the electrical performances are closely correlated with the initial growth kinetics of the PtSe2 films, indicating that removing Pt (which degrades device performance) is the most important aspect of growing thin PtSe2 films to optimize device performance.