Epitaxial Fe₁₆N₂ films grown on Si(001) by reactive sputtering

We present a crystallographic template for the growth of the range of Fe-N phases on Si(001) by lattice matching on selected underlayers. Epitaxial films of pure γ′-Fe, γ′-Fe4N, and α′-Fe8N (N martensite) were grown individually by the optimization of reactive N2 sputtering parameters. The orientation relation of the Fe-N phases was Fe-N(001)||Ag(001)||Si(001) and Fe-N[100]||Ag[110]||Si[100]. Annealing the α‴-Fe8N films resulted in the formation of α′-Fe8N/α″-Fe16N2 mixtures. In addition to the crystallographic and structural analysis, quantification of x-ray diffraction peak intensities confirmed that the α′/α″ mixtures contained as much as 46 vol % α″ (remaining α′). Vibrating sample magnetometry and SQUID magnetometry measurements of the α× and α′ (54%)/α″(46%) mixture, respectively, indicate enhanced magnetic moments for both the α′ and α′ phases with respect to pure Fe. © 1996 American Institute of Physics.