Growth of /spl alpha/' nitrogen martensite and Fe/sub 16/N/sub 2/ films using [001] silicon substrates

In this work, epitaxial, single-phase [001] textured /spl alpha/' 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 /spl phi/-scans: Si[001]/spl par/Ag[001]/spl par//spl alpha/'[001]//Si[100]/spl par/Ag[100]/spl par//spl alpha/'[110]. In addition, [001] textured Fe/sub 16/N/sub 2/ or /spl alpha/'' nitrogen-martensite which forms from an ordering of the N atoms in the /spl alpha/', was detected in the films after ex-situ annealing. High resolution electron microscopy studies reveal that /spl alpha/' 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 /spl alpha/' was not detected in any of the as-deposited films grown under various substrate temperatures (10-150/spl deg/C) and pressures (2-5 mTorr).