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HL: Fachverband Halbleiterphysik

HL 51: Nitrides: Preparation and Characterization

HL 51.10: Vortrag

Freitag, 31. März 2023, 12:00–12:15, POT 112

Temperature dependent spectroscopic ellipsometry on cubic GaN — •Jonas Rose¹, 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

Cubic Galliumnitride (c-GaN) is a promising material for designing and fabricating efficient optoelectronic devices, such as green LEDs, and can potentially replace hexagonal GaN for certain applications due to its lack of internal polarization fields. Therefore, the knowlegde and control of the optical properties is essential. Recently, several breakthroughs regarding crystal quality of c-GaN have been achieved by utilizing 3C-SiC as a substrate material. We present our investigation of thin film c-GaN deposited by plasma-assisted molecular beam epitaxy on 3C-SiC/Si substrates in (001) orientation. Temperature dependent spectroscopic ellipsometry between 80 and 300 K yields the optical properties (dielectric function, DF) in this temperature range. Hereby, the influence of the excitonic contribution to the DF is of special interest. Using Elliott’s model, we describe the lineshape of the DF around the absorption onset. The obtained transition energies follow Pässler’s temperature dependent model. Degenerately doped samples up to 10²⁰ cm⁻³ are investatigated as well. A free-carrier dependent behaviour of the absorption onset is observed and explained for different temperatures.