In situ RBS measurements for the effect of swift heavy ion irradiation on metal-insulator interfaces

We have studied the effect of 200 MeV Xe ion irradiation on Bi-Al2O3 and Au-Al2O3 interfaces by means of in situ Rutherford backscattering spectrometry (RBS). For the Bi-Al2O3 interface, we could observe a systematic change in RBS spectrum as a function of Xe ion fluence or the irradiation time. On the other hand, for Au-Al2O3 system, we could not observe any change in RBS spectrum. The experimental result confirmed our previous result that atomic mixing at Bi-Al2O3 interface surely occurs by the Xe ion irradiation. We analyzed the RBS spectra by the simulation software SIMNRA, and discussed the Bi-Al2O3 mixing quantitatively. From the irradiation time dependence of the mixing layer thickness, we estimated the effective diffusion constant for the atomic mixing at Bi-Al2O3 interface. Its value corresponds to the self-diffusion near the melting temperature of Al2O3. The result implies that Bi and Al2O3 are in molten forms during the ion irradiation, resulting in the atomic mixing at Bi-Al2O3 interface. (C) 2013 Published by Elsevier B.V.