Regensburg 2010 – wissenschaftliches Programm

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HL: Fachverband Halbleiterphysik

HL 45: Group-III-Nitrides: Optical Properties II

HL 45.1: Vortrag

Mittwoch, 24. März 2010, 14:30–14:45, H15

Determination of the Faust-Henry Coefficient of GaN by Raman Scattering — •Christian Röder, Gert Irmer, and Cameliu Himcinschi — TU Bergakademie Freiberg, Institute for Theoretical Physics, Leipziger Str. 23, 09596 Freiberg, Germany

In order to specify the charge carrier concentration n and mobility µ in GaN by Raman spectroscopy the Faust-Henry coefficient C should be determined with good precision. Unfortunately, the values for this parameter found in literature differ significantly. Using the standard dielectric approach we calculated the Raman lineshape of coupled phonon-plasmon modes (CPPM) depending on the Faust-Henry coefficient and scattering mechanisms respectively.
Raman intensity measurements on the A1(TO) and A1(LO) phonons of undoped GaN specimen were carried out from room temperature down to 77 K to determine the Faust-Henry coefficient. Additionally we investigated several doped GaN samples with the goal to compare the ascertained free-carrier concentrations with those derived from the Raman lineshape fitting using the previously determined value of C. The comparison gives good agreement confirming the determined Faust-Henry coefficient. Furthermore the analysis of the lineshape reveals the deformation-potential and electro-optic mechanisms as dominant scattering mechanisms in gallium nitride.
The authors would like to thank the European Union (EFRE) as well as the Free State of Saxony for financial support.