Formation mechanisms of amorphous clusters in Mn + implanted thin Al films

Abstract

The amorphization process of thin Al films by successive implantation with Mn + ions at RT and LNT was studied by X-ray diffraction and Rutherford backscattering. For each Mn concentration strain and crystallite size were determined from X-ray line broadening. For RT implantation amorphization sets in at approximately 1 at % Mn by thermally activated local atomic rearrangements which lead to the formation of amorphous clusters. At LNT, a supersaturated solid solution is formed at mean Mn concentrations below 5 at %. At higher Mn concentrations amorphous clusters are formed throughout the sample in regions where the local strain level has reached a threshold value which occurs at a critical local Mn concentrations of 8.5 at %. The results indicate a preferential short-range migration of Mn atoms from the remaining crystalline material toward the amorphous clusters formed at LNT causing a Mn depletion and partial recovery of the crystalline regions.