Regensburg 2022 – scientific programme

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HL: Fachverband Halbleiterphysik

HL 21: Optical Properties 1

HL 21.4: Talk

Wednesday, September 7, 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.