Formation of In-Plane Semiconductor-Metal Contacts in 2D Platinum Telluride by Converting PtTe2to Pt2Te2

Funding Information: Financial support through NSF Grant No. 2140038 is acknowledged. In addition, we acknowledge funding from the German Research Foundation (DFG), Project KR 4866/6-1, and through the collaborative research center “Chemistry of Synthetic 2D Materials” SFB-1415-417590517. We further thank the Gauss Centre for Super-computing e.V. ( www.gauss-centre.eu ) for providing computing time on the GCS Supercomputer HAWK at Höchstleistungsrechenzentrum Stuttgart ( www.hlrs.de ) and also TU Dresden (Taurus cluster) for generous grants of CPU time. Publisher Copyright: © 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 â¼0.2 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.