ATOMIC TRANSPORT AND PHASE-FORMATION IN THE SB AL SYSTEM INDUCED BY HEAVY-ION BOMBARDMENT/

Antimony/aluminium films in bilayer and multilayer geometries were irr adiated at liquid-nitrogen temperature with 50-900 keV ion beams rangi ng in mass from Ne-20 to Pb-208. Depth profiling of the element concen trations was carried out via Rutherford backscattering spectroscopy. T he formation of intermetallic phases and phase segregation was analyze d by means of x-ray diffraction, cross-section transmission electron m icroscopy, and scanning electron microscopy. From the low-dose irradia tion data, the mixing rates k were obtained and found to depend linear ly on the energy density F-D deposited at the interface. The mixing ef ficiency of Sb/A1 bilayers, k/F-D=296(30) Angstrom(5)/eV, supports the local thermal spike model. After high-fluence irradiations of Sb/Al b ilayers with 550 keV Xe++ ions, a reacted layer of crystalline SbAl (B -3 phase) at the interface was observed. Sb/Al multilayers irradiated with 900 keV Xe++ ions were found to become amorphous. Phase formation was studied as a function of the ion fluence, irradiation energy, and ion mass, and was found to start at that fluence, where cracking and shrinking of the Sb top layer and an increase of the sputtering yield were also observed. (C) 1995 American Institute of Physics.