EXPERIMENTAL-STUDY AND MODELING OF STRUCTURE FORMATION IN BURIED LAYERS AT ION-BEAM SYNTHESIS

During ion beam synthesis of SIMOX structures a redistribution process is responsible for the modification of the implanted O+ profile towards a homogeneous buried layer of SiO2. This is known to be mainly due to Ostwald ripening. The first approach of our study of this highly complex system, both experimentally and theoretically, is devoted to the substoichiometric concentration range representing the wings of stoichiometric layers. Our experiment shows that Ostwald ripening starts from precipitates of comparable size, homogeneously distributed throughout the substoichiometric implanted layer. A computer simulation of Ostwald ripening of such an initial distribution of precipitates results in the self-organisation of structure in the precipitate distribution which can be related to the experimentally observed two band structure of precipitates. Thus it has been proven experimentally: (i) that the two band structure of precipitates must not originate from preferred precipitation in certain regions as proposed so far, and (ii) theoretically that a structure formation in the precipitate distribution may arise from self-organisation during Ostwald ripening.