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 alpha-Fe, gamma'-Fe4N, and alpha'-Fe8N (N martensite) were grown individually by the optimization of reactive Nz Sputtering parameters. The orientation relation of the Fe-N phases was FeN(001)\\Ag(001)\\Si(001) and Fe-N[100]\\Ag[110]\\Si[100]. Annealing the alpha'-Fe8N films resulted in the formation of alpha'-Fe8N/alpha ''-Fe16N2 mixtures. In addition to the crystallographic and structural analysis, quantification of x-ray diffraction peak intensities confirmed that the alpha'/alpha '' mixtures contained as much as 46 vol % alpha '' (remaining alpha'). Vibrating sample magnetometry and SQUID magnetometry measurements of the alpha' and alpha'(54%)/alpha ''(46%) mixture, respectively, indicate enhanced magnetic moments for both the alpha' and alpha '' phases with respect to pure Fe. (C) 1996 American Institute of Physics.