Growth and microstructure of r.f. sputtered Fe/Ti multilayers

Fe/Ti multilayers with different modulation wavelengths (Lambda) prepared b y r.f. sputtering has been investigated by using cross sectional transmissi on electron microscopy (XTEM). It was observed that the columnar structure, interface morphology, and metastable phase presented at the interface of t he multilayer system strongly depend on the bilayer thickness (Lambda). For high period multilayers, the waviness wavelength of interfaces is about tw o times broader than the column diameter. For a sample with Lambda =30 nm, its column width and waviness wavelength was about 80, and 190 nm, respecti vely. Both of them decreased with the reduction of Lambda, so as to nearly equal values of column diameter and waviness wavelength were obtained. The Fe and Ti grains of both 30 nm and 6 nm multilayers are polycrystalline, an d have a textured structure. In short bilayer thickness (Lambda =6 nm), the intermetallic compound Fe2Ti was presented at the interfaces due to solid state reaction; for Lambda =2 nm, amorphous phase Ti-rich layer was formed at the interfaces, resulting in a sharp interface multilayer structure.