Chemical vapor deposition of epitaxial chromium nitride thin films

Chromium nitride (CrN) is a thermoelectric transition metal nitride whose properties are strongly influenced by stoichiometry, substrate choice, and defect chemistry. CrN is routinely synthesized by physical vapor deposition (PVD); its growth by chemical vapor deposition (CVD) has been limited by the lack of suitable chromium precursors capable of producing carbon-, oxygen-, and chlorine-free films. CVD of contamination-free Cr compounds is notoriously difficult, with carbon-free Cr compounds thought unattainable below 1000 °C. Here, we report epitaxial, carbon- and chlorine-free CrN thin films synthesized by thermal CVD. Single-phase CrN films were deposited on c-plane α-Al₂O₃ using in-situ generated chromium chlorides. Films exhibit n-type conduction with a maximum Seebeck coefficient of −51 μV K −1 , comparable to PVD-grown CrN. These results present a route to highly crystalline rock-salt CrN films suitable for defect engineering, doping, and alloying, while avoiding the ion-bombardment-induced damage often associated with PVD-based growth techniques.