Synthesis and structure of chromium nitride films by evaporation in an ammonia plasma

Abstract

Chromium nitride films were deposited by activated reactive evaporation of chromium in an ammonia plasma. The structure, crystallite size, composition, and surface morphology of the films have been investigated and correlated to the deposition parameters. The nitrogen-to-chromium ratio in the films is found to increase with the substrate temperature, leading to a gradual transition from Cr-N solid solution to Cr₂N and CrN phases. A mixture of these phases is formed at substrate temperatures below 773 K and a single-phase CrN is formed above 773 K. The nitrogen incorporation in the films decreases the grain size of the films whereas the reaction between chromium and nitrogen resulting in Cr₂N and CrN phases increases the grain size.