Berlin 2024 – scientific programme

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HL: Fachverband Halbleiterphysik

HL 1: Nitrides: Preparation and characterization I

HL 1.1: Talk

Monday, March 18, 2024, 09:30–09:45, EW 015

Time-resolved ellipsometry on degenerately doped cubic GaN — •Elias Baron¹, Rüdiger Goldhahn¹, Michael Deppe², Donat J. As², Shirly Espinoza³, Martin Zahradník³, and Martin Feneberg¹ — ¹Institut für Physik, Otto-von-Guericke-Universität Magdeburg, Germany — ²Department Physik, Universität Paderborn, Germany — ³ELI Beamlines, ELI ERIC, Dolní Břežany, Czech Republic

The interest in ultra-fast processes in semiconductors has steadily increased in recent years, as modern technologies require faster and faster electronics and optics. Highly sensitive measurement techniques are essential for researching these phenomenons. In this context, time-resolved spectroscopic ellipsometry (TRSE) proved to be an excellent technique for determining the transient optical properties. Additionally, the metastable cubic phase of the well-known GaN offers advantageous properties for investigating fundamental processes in excited semiconductors. We present our analysis of thin film cubic GaN, deposited by plasma-assisted molecular beam epitaxy on 3C-SiC/Si substrates in (001) orientation and doped by either Ge or Si up to 9×10¹⁹ cm⁻³. TRSE measurements, based on a pump-probe approach in the UV spectral range are performed using a 266 nm pump-beam. The electron-hole pairs generated by this pump-beam influence the optical properties due to many-body effects like band gap renormalization and Burstein-Moss shift. The impact of these effects vary depending on the doping concentration. Furthermore, a free-carrier profile from top to bottom has to be considered for an accurate description.