Előadó:Bezerra Morais, Sarah (Wigner FK SZFI)
Előadásának címe: Study of solid-state photon emitters in- SiC (PhD házivédés, Témavezető Beke Dávid)
Dátum: 2026. május 28. csütörtök, 10 óra
Helyszín: 1-es épület tanácsterem
Összefoglaló:
In this doctoral thesis, I investigate the controlled chemical synthesis of photon-emitting point defects—commonly known as color centers—in silicon carbide (SiC), with the aim of providing an alternative to irradiation-based methods using scalable thermal and mechanochemical approaches. The optically active defects I focused on are the negatively charged silicon vacancy and the neutral divacancy, which offer near-infrared emission and long spin coherence times relevant to quantum sensing and communication applications.
I generated colour centres through combustion-assisted thermal synthesis from silicon and carbon precursors, using induction and tube furnaces to systematically vary heating rate, temperature, and dwell time. I identified a critical synthesis window between 1050–1150 °C, within which defect-related photoluminescence signatures are preserved. I found that rapid heating favours non-equilibrium conditions conducive to vacancy formation, while slow heating promotes structural relaxation and reduces defect density.
I achieved silicon vacancy densities exceeding 10¹⁷ spins/cm³ — comparable to irradiation-based benchmarks. Through multivariate statistical analysis, I further established that hexagonal polytype fraction and stacking-fault density are the dominant structural predictors of optically active defect concentration, providing a new framework for defect engineering in wide-bandgap semiconductors.
