INVESTIGATION OF INHOMOGENEOUS STRUCTURES OF NEAR-SURFACE-LAYERS IN ION-IMPLANTED SILICON

The ion implantation as a subject of investigations attracts increasin g interest because of its technological applications. For example, the ion implantation and the adequate thermal treatment are the basic pro cesses for fabrication of a new so-called delta-BSF solar cell. In thi s silicon solar cell, the continuous sub-structure of modified materia l (planar amorphous-like layer of nanometric thickness with very thin transition zones) is inserted into the single-crystal emitter. From ea rlier high resolution electron microscopy studies, it is evident that these two Si phases coexist in the form of well-defined layers separat ed by sharp heterointerfaces [Z.T. Kuznicki, J. Thibault, F. Chautain- Mathys, S. De Unamuno, Towards ion beam processed single-crystal Si so lar cells with a very high efficiency, E-MRS Spring Meeting, Strasbour g, France, First Polish-Ukrainian Symposium, New Photovoltaic Material s for Solar Cells, October 21-22, Krakow, Poland, 1996.]. The aim of t his paper is the further structural characterisation of silicon single crystal with buried 'amorphous' layer. The non-destructive X-ray diff raction methods as well as the transmission electron microscopy were u sed to investigate the quality of the a-Si/c-Si heterointerfaces, stru ctural homogeneity of the layers and distribution of the stress field. The measurements were carried out on an initial, as-implanted and ann ealed material. The [100]-oriented Si single crystals were implanted w ith 180 keV energy P ions at room temperature. (C) 1998 Published by E lsevier Science S.A.