Stoichiometry‐Controlled Growth of 2D PtSe x Films for n‐PtSe 1.7 /p‐PtSe 2 Mid‐Wave Infrared Photodetectors Toward Scalable Integration

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Abstract
2D heterostructures have promising potential for applications in mid‐infrared (MWIR) photodetection but often suffer from transfer‐induced interfacial defects and limited micrometer‐scale active areas. In this study, PtSe x thin films are synthesized via a scalable thermally assisted conversion (TAC) method that enables precise stoichiometry control and carrier‐type conversion from Se‐deficient n ‐type to Se‐rich p ‐type phases. Structural and spectroscopic analyses confirm layered structures and defect‐induced mid‐gap states that improve infrared absorption and facilitate bandgap engineering. Functional 2D/2D photodetectors are fabricated via a two‐step TAC approach that leads to vertically stacked n‐PtSe 1.7 /p‐PtSe 2 junctions. The top n ‐type layer is rapidly synthesized without disturbing the underlying p ‐type film because n ‐type PtSe 1.7 forms within tens of seconds, whereas the formation of p ‐type PtSe 2 requires several minutes. This kinetic selectivity preserves pristine interfaces, yielding reproducible rectification and robust MWIR photoresponse with a specific detectivity of 3.8 × 10 9 Jones across centimeter‐scale active areas. This study establishes PtSe x as a scalable material platform, with the transfer‐free growth approach and uniform film quality highlighting its strong potential for wafer‐scale integration of layered heterojunction devices.
Funding Information
  • Defense Acquisition Program Administration (912903601)

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