Growth of ultrathin Pt layers and selenization into PtSe2 by molecular beam epitaxy

Among the high-mobility two-dimensional transition metal dichalcogenides PtSe2 is of particular interest due to its record high carrier mobility of 1,000 cm2/Vs, sizeable band gap and air stability to address the current need for low-power, high-performance and ultra-thin body electronics. A scalable fabrication process with highly precise thickness control on ultra-smooth insulating gate oxides however has not been achieved to date. This work is addressing this gap by presenting ultra-thin growth of Pt layers on insulating Al2O3 and the subsequent conversion into PtSe2 by direct selenization in molecular beam epitaxy.
Due to the chosen growth technique, the approach is scalable and offers precise control over Pt and thus PtSe2 layer thickness. We engineered deposition parameters to fabricate smooth, single crystal Pt films in the mono-/few-layer limit and optimized selenization conditions to convert a maximum amount of Pt into PtSe2. A post selenization anneal in Se proved essential to enhance crystal quality of the PtSe2 layers.