Dresden 2026 – wissenschaftliches Programm

Bereiche | Tage | Auswahl | Suche | Aktualisierungen | Downloads | Hilfe

HL: Fachverband Halbleiterphysik

HL 1: Optical Properties I

HL 1.10: Vortrag

Montag, 9. März 2026, 12:00–12:15, POT/0006

Quantum-engineered CaAlSiN3 via terbium substitution: coupling spin, optical, and lattice responses in a rare-earth nitride host — •Sikander Azam and Jan Minar — University of West Bohemia New Technologies - Research Centre Univerzitní 8 301 00 Plzeň Czech Republic

Rare-earth nitrides attract interest because they link optical activity, magnetism, and mechanical stability. CaAlSiN3 is a robust wide-gap host, but the microscopic role of terbium substitution is not well established. We study pristine and Tb-doped CaAlSiN3 (8.5 and 17 percent) using spin-polarized density functional theory within GGA+U and spin-orbit coupling in WIEN2k. Tb narrows the bandgap and introduces 4f-derived mid-gap states that enhance visible-range absorption. The densities of states show hybridization between Tb 4f levels and the surrounding network. The optical response shows higher absorption, a larger refractive index, and shifts in dielectric features that follow these electronic changes. Simulated Tb L*-edge X-ray absorption spectra display white-line shifts and peak broadening with increasing Tb content, consistent with the modified unoccupied 4f states. Tb carries a strong local moment, raising the total moment to about 11.8 μB at higher doping. All compositions remain mechanically stable, and bulk and shear moduli increase moderately. The piezoelectric response also strengthens, with d33 and e33 roughly doubling compared to the undoped host. These results show that Tb substitution tunes the electronic, magnetic, optical, and mechanical behaviour of CaAlSiN*, supporting its potential in photonic and spin-related applications.

Keywords: Terbium doping CaAlSiN₃; Electronic structure (DFT); Optical properties; Bandgap engineering; GGA+U