Chemical Vapor Deposition of Epitaxial Chromium Nitride Thin Films

Abstract

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 (~110 nm) were deposited on c-plane alpha-Al2O3 using in-situ generated chromium chlorides. Films exhibit n-type conduction with a Seebeck coefficient of -36 uV/K, comparable to PVD-grown CrN. These results present a routeto highly crystalline rock-salt CrN films for defect engineering, doping, and alloying with reduced implantation-related damage capabilities previously largely confined to PVD-based techniques.