Regensburg 2002 – wissenschaftliches Programm
DS 21.2: Vortrag
Donnerstag, 14. März 2002, 14:15–14:30, HS 31
Synthesis and size-control of Si nanocrystals by SiO/SiO2 superlattices — •Johannes Heitmann1, Roland Scholz1, Michael Schmidt2, and Margit Zacharias1 — 1MPI für Mikrostrukturphysik, Weinberg 2, D-06120 Halle, Germany — 2Otto-von-Guericke Universität Magdeburg, Inst. für Experimentelle Physik, PF 4120, D-39016 Magdeburg, Germany
Todays Silicon nanocrystal research is focused on preparation of nanocrystals embedded in oxide host. Different processes for the synthesis of nanocrystalline Si like Si ion implantation into high-quality oxides, sputtering of Si-rich oxides or reactive evaporation of Si-rich oxides are known. Within these methods the Si crystal size is controlled by the Si content in the SiO2 matrix. Therefore, crystal size and density cannot be controlled independently. We present a new approach of reactive evaporation of SiO/SiO2 superlattices for nc-Si synthesis which allows independent control of these properties by adjusting the crystal size by the SiO layer thickness. TEM investigations confirm the thermal induced phase separation of the SiO layers in SiO2 and Si nanocrystals and the correlation between SiO layer thickness and crystal size. A size-dependent blue shift of the luminescence from 900 to 750 nm and a luminescence intensity comparable to porous Si are observed. Temperature and power dependence of the luminescence intensity are reported. The nearly size-independent PL intensity observed in our SiO/SiO2 superlattices indicates the accomplishment of an independent control of crystal size and density.