Chemical Vapor Deposition of Epitaxial Chromium Nitride Thin Films

TL;DR

This paper demonstrates the successful chemical vapor deposition of high-quality, contamination-free epitaxial chromium nitride thin films, expanding the methods available for their synthesis and potential applications in thermoelectrics and materials engineering.

Contribution

It introduces a novel CVD process for producing single-phase, epitaxial CrN films free of carbon and chlorine contaminants, previously thought unattainable below 1000°C.

Findings

CrN films exhibit n-type conduction with a Seebeck coefficient of -36 μV/K

Films are approximately 110 nm thick and grown on alpha-Al2O3 substrates

The process enables defect engineering and doping with reduced damage risk.

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.