Berlin 2024 – scientific programme

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HL: Fachverband Halbleiterphysik

HL 36: Poster III

HL 36.58: Poster

Wednesday, March 20, 2024, 18:00–20:30, Poster E

Temperature dependent free carrier concentration in GaN:Si — •Christina Harms, Jona Grümbel, Rüdiger Goldhahn, and Martin Feneberg — Institut für Physik, Otto-von-Guericke-Universität Magdeburg, Germany

GaN is already commercialized in a variety of different applications. Nevertheless, still fundamental questions remain to be answered. Here, we focus on the temperature dependence of the free carrier concentration of doped GaN. We investigate the Raman excitations of hexagonal bulk GaN:Si from 80 K to 300 K. Six samples with carrier concentrations ranging from 10¹² to 10¹⁹ cm⁻³ were measured using laser excitation at 532 nm. Our results reveal that at room temperature, both coupled phonon-plasmon modes (LPP_±) are visible and agree with Hall-effect experiments. Under temperature variation, the LPP₊ mode shows a weak frequency shift or remains even unaffected. Surprisingly, the LPP₋ mode exhibits a frequency shift towards higher frequencies with decreasing temperatures for all samples, contradicting previous assumptions. To shed light onto this shift, photoluminescence spectra are taken into account as well. The combination of both experimental data sets allows to better understand the evolution of temperature dependence of the free carrier concentration.

Keywords: GaN; Raman spectroscopy; photoluminescence; temperature dependent