Formation of In-Plane Semiconductor–Metal Contacts in 2D Platinum Telluride by Converting PtTe<sub>2</sub> to Pt<sub>2</sub>Te<sub>2</sub>
Kinga Lasek, Jing‐Feng Li, Mahdi Ghorbani‐Asl, Salma Khatun, Onyedikachi Alanwoko, Vimukthi Pathirage, Arkady V. Krasheninnikov, Matthias Batzill
Abstract
Monolayer PtTe2 is a narrow gap semiconductor while Pt2Te2 is a metal. Here we show that the former can be transformed into the latter by reaction with vapor-deposited Pt atoms. The transformation occurs by nucleating the Pt2Te2 phase within PtTe2 islands, so that a metal–semiconductor junction is formed. A flat band structure is found with the Fermi level of the metal aligning with that of the intrinsically p-doped PtTe2. This is achieved by an interface dipole that accommodates the ∼0.2 eV shift in the work functions of the two materials. First-principles calculations indicate that the origin of the interface dipole is the atomic scale charge redistributions at the heterojunction. The demonstrated compositional phase transformation of a 2D semiconductor into a 2D metal is a promising approach for making in-plane metal contacts that are required for efficient charge injection and is of particular interest for semiconductors with large spin–orbit coupling, like PtTe2.