Irradiation effects in Ag-Fe bilayers: Ion-beam mixing, recrystallization, and surface roughening
Por:
Crespo-Sosa A., Schaaf P., Bolse W., Lieb K., Gimbel M., Geyer U.
Publicada:
1 ene 1996
Resumen:
Ag/Fe bilayers deposited onto (Formula presented)/Si substrates were irradiated at 20, 77, and 300 K with 300-750 keV Ar and Xe ions in order to study the ion-beam-induced mixing and phase formation in this thermally immiscible system. A combination of Rutherford backscattering spectroscopy (RBS), channeling, conversion electron Mössbauer spectroscopy (CEMS), and scanning tunneling microscopy (STM) was used to analyze the atomic transport at the interface and the resulting microstructure and morphology changes of the samples. In the CEMS measurements, a 13 nm thin (Formula presented) marker layer at the Ag/Fe interface was introduced in order to enhance the sensitivity to alterations of the interfacial composition. From the small amount of Ag atoms found to be dissolved in Fe and from the sharpness of the element profiles at the interface, we derived a very small mixing efficiency, which is significantly smaller than the prediction of the ballistic model. Since ballistic mixing is expected in any case, we argue that demixing and phase separation occur in the relaxation stage or thermal spike phase of the collision cascade, as a consequence of the positive heat of mixing. On the other hand, ion irradiation induces a large surface roughening of the Ag top layer as proven by STM. This effect is obviously due to recrystallization of Ag, which results in grain growth and texture formation along the direction of the impinging ion, as demonstrated by RBS/channeling measurements. © 1996 The American Physical Society.
Filiaciones:
Crespo-Sosa A.:
II. Physikalisches Institut and Sonderforschungsbereich 345, Universität Göttingen, Bunsenstrase 7/9, D-37073 Göttingen, Germany
Schaaf P.:
II. Physikalisches Institut and Sonderforschungsbereich 345, Universität Göttingen, Bunsenstrase 7/9, D-37073 Göttingen, Germany
Bolse W.:
II. Physikalisches Institut and Sonderforschungsbereich 345, Universität Göttingen, Bunsenstrase 7/9, D-37073 Göttingen, Germany
Lieb K.:
II. Physikalisches Institut and Sonderforschungsbereich 345, Universität Göttingen, Bunsenstrase 7/9, D-37073 Göttingen, Germany
Gimbel M.:
I. Physikalisches Institut and Sonderforschungsbereich 345, Universität Göttingen, Bunsenstrase 9, D-37073 Göttingen, Germany
Geyer U.:
I. Physikalisches Institut and Sonderforschungsbereich 345, Universität Göttingen, Bunsenstrase 9, D-37073 Göttingen, Germany
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