Berlin 2024 – wissenschaftliches Programm
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HL: Fachverband Halbleiterphysik
HL 1: Nitrides: Preparation and characterization I
HL 1.1: Vortrag
Montag, 18. März 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.
Keywords: Cubic GaN; Spectroscopic ellipsometry; Doped semiconductors; Ultra-fast phenomenons; Optical properties