Low-temperature CVD of η-Mn3N2−x from bis[di(tert-butyl)amido]manganese(II) and ammonia

Manganese nitride films are grown by low-pressure chemical vapor deposition from the novel precursor bis[di(tert-butyl)amido]manganese(II) and ammonia. Mixed-phase films containing crystalline manganese nitride can be grown on substrates at temperatures as low as 80 °C. Above 200 °C, the films consist entirely of crystalline manganese nitride. The crystalline material has the same tetragonal unit cell as η-Mn3N2, but composition analysis of the Mn:N suggests that the material is best denoted as η-Mn3N2−x with x ∼ 0.7. Both oxygen and carbon contamination in the bulk of the films are <1 at. %. Deposition rates of up to 10 nm/min are observed. The growth of crystalline films of a ceramic material at such low temperatures and high rates is highly unusual. The authors attribute this outcome to the presence of high-moment manganese atoms in mixed valence states and to vacancies in the nitrogen sublattice; both features lower the energies needed to break and reform metal-nitrogen bonds and thus allow the deposited atoms to settle more easily into a low-energy ordered arrangement.