Dresden 2020 – scientific programme

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HL: Fachverband Halbleiterphysik

HL 68: Nitrides: Preparation and characterization II

HL 68.1: Talk

Thursday, March 19, 2020, 15:00–15:15, POT 112

Impact of high free-carrier concentrations on optical properties of cubic GaN — •Elias Baron¹, Rüdiger Goldhahn¹, Michael Deppe², Donat J. As², and Martin Feneberg¹ — ¹Institut für Physik, Otto-von-Guericke-Universität Magdeburg, Germany — ²Department Physik, Universität Paderborn, Germany

The zincblende III-nitrides are possible candidates for replacing the wurtzite phase nitrides in certain applications such as quantum-dot-based devices. Despite their metastable nature, several improvements concerning control and quality have been reported. Free-electron concentrations n above 10²⁰cm⁻³ are achievable by using Ge as a donor in zincblende GaN and AlGaN. We present a characterization of thin film zincblende GaN, deposited by plasma-assisted molecular beam epitaxy on 3C-SiC/Si substrates in (001) orientation. The complex dielectric functions (DF) in the mid-infrared are obtained by spectroscopic ellipsometry, from which the transverse-optical phonon and plasma frequencies are determined. These results are corroborated by Raman experiments. Utilizing Kane’s model for the band structure in the vicinity of the Γ-point of the Brillouin zone, taking into account many-body effects like band-gap renormalization and Burstein-Moss shift, and the optical effectice electron mass determined by the plasma frequency, an all-optical determination of the free-carrier concentration of zincblende GaN is achieved.