Growth of α´ nitrogen martensite and Fe16N2 films using (001) silicon substrates

In this work, epitaxial, single-phase (001) textured α´ nitrogen-martensite films have been grown successfully on (001) Si substrates with a Ag reaction-barrier layer using conventional reactive sputtering. The growth orientation was obtained by X-ray φ-scans: Si(001)||Ag(001)||α´(001)//Si[100]||Ag[100]|| α´[110]. In addition, (001) textured Fe₁₆N₂ or α´´ nitrogen-martensite which forms from an ordering of the N atoms in the α´, was detected in the films after ex-situ annealing. High resolution electron microscopy studies reveal that α´ martensite has good epitaxy with the Ag underlayer. Single-crystal formation of the martensites, however, is impeded by the intersection of Ag twins with the Ag/Fe-N interface. Single phase α´ was not detected in any of the as-deposited films grown under various substrate temperatures (10-150°C) and pressures (2-5 mTorr)