Perpustakaan Digital ITB

Two-dimensional (2D) transition-metal dichal-cogenides (2D TMDs) in the form of MX2(M: transitionmetal, X: chalcogen) exhibit intrinsically anisotropic layeredcrystallinity wherein their material properties are determinedby constituting M and X elements. 2D platinum diselenide(2D PtSe2) is a relatively unexplored class of 2D TMDs withnoble-metal Pt as M, offering distinct advantages overconventional 2D TMDs such as higher carrier mobility andlower growth temperatures. Despite the projected promise,much of its fundamental structural and electrical propertiesand their interrelation have not been clarified, and so its fulltechnological potential remains mostly unexplored. In thiswork, we investigate the structural evolution of large-areachemical vapor deposition (CVD)-grown 2D PtSe2layers of tailored morphology and clarify its influence on resulting electricalproperties. Specifically, we unveil the coupled transition of structural?electrical properties in 2D PtSe2layers grown at a lowtemperature (i.e., 400°C). The layer orientation of 2D PtSe2grown by the CVD selenization of seed Ptfilms exhibitshorizontal-to-vertical transition with increasing Pt thickness. While vertically aligned 2D PtSe2layers present metallic transports,field-effect-transistor gate responses were observed with thin horizontally aligned 2D PtSe2layers prepared with Pt of smallthickness. Density functional theory calculation identifies the electronic structures of 2D PtSe2layers undergoing the transitionof horizontal-to-vertical layer orientation, further confirming the presence of this uniquely coupled structural-electricaltransition. The advantage of low-temperature growth was further demonstrated by directly growing 2D PtSe2layers ofcontrolled orientation on polyimide polymeric substrates and fabricating their Kirigami structures, further strengthening theapplication potential of this material. Discussions on the growth mechanism behind the horizontal-to-vertical 2D layer transitionare also presented