SKM 2023 – scientific programme
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HL: Fachverband Halbleiterphysik
HL 51: Nitrides: Preparation and Characterization
HL 51.5: Talk
Friday, March 31, 2023, 10:30–10:45, POT 112
Thermal Transport in c-plane GaN Membranes Studied 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
Heating during operation often limits the lifetime or stability of semiconductor devices, like laser structures, e.g., via defect formation or by affecting the refractive index. Understanding how thermal energy is dissipated from the active region of such structures is therefore an important step towards device optimization.
We analyze the in-plane thermal transport in GaN-based membranes. The temperature is probed by the shift and width of Raman modes under heating with a UV laser. This allows for a non-contact characterization without the need for additional processing steps.
By varying the membrane underetching process, we can tune the membrane bottom facet roughness and porosity to study their impact on thermal conductivity κ, due to phonon boundary scattering. A reduction of κ is a sign of phonon frequency filtering, which is a first step towards engineering the phonon dispersion relation in GaN membranes. Controlling this effect, e.g., via the position and sizes of pores, might enable thermal concepts to locally reduce temperature rises.