Formation of In-Plane Semiconductor-Metal Contacts in 2D Platinum Telluride by Converting PtTe2 to Pt2Te2

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 similar to 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 semi-conductor 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.

Automated summary

The study shows that monolayer PtTe2 can be transformed into the metal Pt2Te2 by reacting with vapor-deposited Pt atoms. The transformation occurs by nucleating the Pt2Te2 phase within PtTe2 islands, forming a metal-semiconductor junction. The alignment of the Fermi levels of the metal and the p-doped PtTe2 is achieved by an interface dipole that accommodates the difference in the work functions of the two materials.