Regensburg 2022 – wissenschaftliches Programm
HL 21.4: Vortrag
Mittwoch, 7. September 2022, 15:45–16:00, H32
Ultra-fast change of the absorption onset in undoped cubic GaN — •Elias Baron1, Martin Feneberg1, Rüdiger Goldhahn1, Michael Deppe2, Donat J. As2, Shirly Espinoza3, and Martin Zahradník3 — 1Institut für Physik, Otto-von-Guericke-Universität Magdeburg, Germany — 2Department Physik, Universität Paderborn, Germany — 3ELI Beamlines, Institute of Physics, Czech Academy of Science, Dolní Břežany, Czech Republic
Nitride semiconductors are essential for modern applications, which means that an example for nitride research is necessary. For this, the cubic zincblende phase is predestined on account of isotropic properties. We present our investigation of thin film zincblende GaN, deposited by plasma-assisted molecular beam epitaxy on 3C-SiC/Si substrates in (001) orientation, by time-resolved spectroscopic ellipsometry, based on a pump-probe approach in the visible and ultra violet spectral range. The 266nm pump beam excites the cubic GaN far above the band gap and therefore creates up to ≈ 5×1020cm−3 electron-hole pairs, which influence the dielectric function due to many-body effects like band gap renormalization and Burstein-Moss shift. By varying the delay time between pump and probe beam from femto- to nanoseconds, a time-resolved change of the absorption onset due to the relaxation and recombination of electron-hole pairs in the context of many-body effects is observed and concur with comparable steady-state measurements of highly n-type doped GaN.