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HL: Fachverband Halbleiterphysik
HL 7: Transport properties I
HL 7.1: Vortrag
Montag, 18. März 2024, 15:00–15:15, ER 325
Challenges of mapping transport parameters of N-doped 4H-SiC by Raman spectroscopy — •Hannes Hergert1,2, Matthias T. Elm1,2,3, and Peter J. Klar1,2 — 1Center for Materials Research, Giessen, Germany — 2Instituten of Experimental Physics I, Giessen, Germany — 3Institute of Physical Chemistry, Giessen, Germany
We assess Raman spectroscopy as a tool for fast and non-invasive mapping of charge carrier density and carrier mobility in inhomogeneously doped 4H-SiC. For this purpose, we compare values of these transport parameters obtained by magneto-transport and Raman measurements of N-doped 4H-SiC. The effective charge density and mobility, which are obtained from resistivity and Hall measurements by employing the commonly used effective one-band model, deviate from the values extracted by applying the established line-shape models for describing the longitudinal optical phonon coupled (LOPC) modes in the Raman spectra. Differentiating between free and localized carriers in the framework of a three-band transport model confirms that only the free charge carriers in the conduction band of N-doped 4H-SiC contribute to the LOPC Raman signal and their density agrees well with that obtained by the line shape analysis. The agreement of the mobility values is reasonable keeping in mind that different frequencies of the applied electric fields are used in the two approaches. Moreover, the excitation of electrons into the conduction band by the laser causes differences in the temperature dependence of the carrier density compared with the electrical transport data.
Keywords: 4H-SiC; LOPC line shape analysis; temperature dependent; Hall measurements; Raman spectroscopy