Regensburg 2025 – wissenschaftliches Programm

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HL: Fachverband Halbleiterphysik

HL 29: Poster II

HL 29.47: Poster

Dienstag, 18. März 2025, 18:00–20:00, P1

Investigating the optical pumping of silicon vacancies in 4H-SiC to increase the maser output — •Emilian Eisermann, Vladimir Dyakonov, and Andreas Sperlich — Experimental Physics 6, University of Würzburg, 97074 Würzburg, Germany

A major breakthrough in the realization of a continuous-wave maser at room temperature was achieved with the utilization of nitrogen vacancies in diamond. However, diamond is a comparatively expensive material. For this reason, silicon carbide (SiC), a material used commercially in electrical systems, has received attention in recent years. Only recently, our group has demonstrated the first room temperature continuous-wave SiC maser. Despite innovative microwave feedback loop engineering, only a low output could be achieved. In an effort to boost the maser output, we investigate the fundamental pumping behavior of silicon vacancy defects in SiC in dependence of the optical pump wavelength, the temperature and their density. Using electron paramagnetic resonance spectroscopy, we resolve microwave absorption and emission signals due to the optical polarisation of Zeeman-split states. By analyzing these features, we calculate the population inversion in the gain material. This crucial parameter allows us to quantitatively evaluate the pump efficiency. It turns out that an excitation with an energy of the zero-phonon line of the silicon vacancy is particularly efficient. Furthermore, we examine to what extent excitation with an energy lower than that of the zero-phonon line is possible if thermally driven phonons are used to compensate the missing energy. First results are presented on the poster, which we are discussing here.

Keywords: Maser; 4H-SiC; Si vacancy; Zero-phonon line; EPR