Allotaxy in the Ni-Si system

Allotaxy is a special method to grow epitaxial heterostructures. An importa nt role in this process is the distribution of the crystallites of the comp ound AB(X) in the matrix A. This study concerns the first step of allotaxy in the Ni-Si system, that is, the preparation of the precipitate distributi on. To investigate the influence of the deposition conditions on the growth and arrangement of the precipitates the substrate temperature as well as t he deposition rate have been varied. RES measurements revealed the redistri bution of the deposited Ni already during the deposition process resulting in precipitate coarsening. This effect increases with increasing substrate temperature and decreasing deposition rate. A strong diffusion of Ni atoms towards the sample surface has been observed. The TEM analysis shows that o riented cubic NiSi2 is grown. Under appropriate deposition conditions self- assembling of the NiSi2 precipitates has been observed. (C) 1998 Elsevier S cience S.A. All rights reserved.