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O: Fachverband Oberflächenphysik

O 96: Poster Session VII: Poster to Mini-Symposium: Frontiers of electronic-structure theory IV

O 96.1: Poster

Donnerstag, 4. März 2021, 10:30–12:30, P

Electronic structure of β-SiAlON: effect of Al/O doping and of finite temperature — •Saleem Ayaz Khan¹, Ondrej Sipr², Jiri Vackar², Robin Niklaus³, Peter J Schmidt⁴, Wolfgang Schnick³, and Jan Minar¹ — ¹University of West Bohemia, Czech Republic — ²Institute of Physics of the Czech Academy of Sciences — ³LMU Munich, Germany — ⁴Lumileds Development Center, Aachen, Germany

Electronic structure of a series of ordered and disordered β-Si_6−zAl_zO_zN_8−z systems is investigated by means of ab initio calculations, using the FLAPW method as implemented in the wien2k code and Green function KKR method as implemented in the spr-kkr code. Finite temperature effects are included within the alloy analogy model. We found that the trends with the Al/O doping are similar for ordered and disordered structures. The electronic band gap decreases with increasing z by about 1 eV when going from z=0 to z=2. The optical gap decreases analogously as the electronic band gap. The changes in the density of states (DOS) at Si and N atoms introduced by doping β-Si₃N₄ with Al and O are comparable to the DOS at Al and O atoms themselves. The bottom of the conduction band in β-Si_6−zAl_zO_zN_8−z is formed by extended states residing on all atomic types. Increasing the temperature leads to a shift of the bottom of the conduction band to lower energies. The amount of this shift increases with increasing doping z.