Depth dependence of atomic mixing by ion beams

Abstract

Ion backscattering spectrometry has been used to investigate the depth dependence of atomic mixing induced by ion beams. Samples consisting of a thin Pt (or Si) marker a few tens of angstroms thick buried at different depths in a deposited Si (or Pt) layer were bombarded with Xe+ of 300 keV at 2×1016 cm−2 dose and Ar+ of 150 keV at 5×1015cm−2 dose. Significant spreading of the marker was observed as a result of ion irradiation. The amount of spreading was measured as a function of depth of the marker, which was then compared with the deposited energy distribution. Measurements of this kind promise new insight into the nature of the interaction between ion beams and solids.

Recollections of fifty years with sputtering

“…It became obvious immediately that such treatments also were applicable to interface mixing under ion bombardment, a phenomenon of great importance in micro-and nanoscience and technology. This phenomenon could be studied experimentally by means of nondestructive techniques such as Rutherford backscattering [133].…”

“…I had been active in other areas at that time, but stimulated by the two theoretical papers mentioned above as well as experimental studies following ref. [133] I looked into the matter together with a clever postdoc, A. Gras-Marti. We noticed that the theory of ion-beam mixing could be mapped on a theoretical scheme that had been available for some time, established by Nobel Laureate W. Bothe to treat multiple scattering of ion beams [134], utilized by Nobel Laureate L. Landau to treat energy-loss spectra of swift charged particles [135] and generalized further by J. Lindhard [136].…”

“…Controlled mixing experiments were performed on thin impurity layers embedded in a matrix (usually silicon). Broadening of this layer as a function of ion fluence was then measured by Rutherford backscattering [133]. Results of such experiments were conveniently interpreted in terms of the formulas given in refs.…”