Dresden 2011 – wissenschaftliches Programm
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KR: Fachgruppe Kristallographie
KR 6: Poster: Crystallography in Materials Science
KR 6.2: Poster
Mittwoch, 16. März 2011, 15:00–17:30, P1
Modeling of Defects in Silicon Nitride — •Torsten Weißbach, Steve Schmerler, and Jens Kortus — Institut für Theoretische Physik, TU Bergakademie Freiberg, 09596 Freiberg
Si3N4 and Oxynitrides play an important role in todays flash memory technology because of their ability to trap charge and retain it for long time. The long-time trapping occurs in deep centers, electronic states within the large bandgap of the basic materials, which are caused by local impurities and defects. In memory chips, these materials are contained in very thin layers which are assumed to be amorphous. DFT methods are frequently applied to model defects within these materials, but have to be carried out on periodic structure models. One approach is to create large supercells with a nearly amorphous arrangement of atoms. In this case, the crystal structure is strongly disturbed, and local defects are not evident. In another method, defects are modeled by manipulating single atoms in a large supercell of bulk-structure material. Here, we show complex defect models obtained by relocation of several atoms in bulk Si3N4, and compare their properties to simpler models as a N vacancy or an O substitutional.
The financial support of the Cluster of Excellence "Structure Design of Novel High-Performance Materials via Atomic Design and Defect Engineering (ADDE)" through the European Union and the Ministry of Science and Art of Saxony (SMWK) is gratefully acknowledged.