Regensburg 2022 – wissenschaftliches Programm
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HL: Fachverband Halbleiterphysik
HL 25: Poster 1
HL 25.95: Poster
Mittwoch, 7. September 2022, 18:00–20:00, P2
Thermal Transport in c-plane GaN Membranes Characterized by Raman Thermometry — •Wilken Seemann1, Joachim Ciers2, Isabell Hüllen1, Mahmoud Elhajhasan1, Jean-François Carlin3, Nicolas Grandjean3, Åsa Haglund2, and Gordon Callsen1 — 1Institute of Solid State Physics, University of Bremen, Germany — 2Department of Microtechnology and Nanoscience, Chalmers University of Technology, Gothenburg, Sweden — 3Institute of Physics, École Polytechnique Fédérale de Lausanne (EPFL), Switzerland
Excess heat often limits the lifetime or stability of semiconductor devices, like laser strcutures, e.g. by affecting the refractive index or defect formation. It is therefore vital to understand how thermal energy is dissipated from the active region. In this contribution, we analyze the in-plane thermal transport in GaN-based membranes which can be applied in UV-visible light emission. The temperature of the material is probed by the shift and width of Raman modes under heating with a UV laser. This method allows for a contactless characterization without the need for additional processing steps often needed for alternative thermometry. We find, that the thermal conductivity, κ, is significantly reduced compared to bulk GaN due to the finite thickness of the analyzed membranes. Phonon scattering due to roughness and porosity of the membrane is found to further reduce κ. Studying in-plane thermal transport lays the foundation for subsequent thermal studies on entire device structures; exploiting a subtle balance of in- and cross-plane thermal transport which could improve device designs.