Regensburg 2022 – wissenschaftliches Programm
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HL: Fachverband Halbleiterphysik
HL 37: Thermal Properties
HL 37.3: Vortrag
Donnerstag, 8. September 2022, 17:00–17:15, H34
Anisotropy in the c-plane thermal conductivity of Gallium Nitride — •Mahmoud Elhajhasan1, Isabell Hüllen1, Wilken Seemann1, Ian Rousseau2, Nicolas Grandjean2, and Gordon Callsen1 — 1Institute of Solid State Physics, University of Bremen, Germany — 2Institute of Solid State Physics, École Polytechnique Fédérale de Lausanne (EPFL), Switzerland
The thermal characterization of modern semiconductor membranes commonly employed for photonic devices like nanobeam lasers (1D) or photonic crystals (2D), often lacks spatial resolution and appropriate quantification. However exactly these two points are relevant for the detection of e.g., thermal anisotropies, heat spots, and interfaces providing thermal resitance.
In this contribution, Raman thermometry employing one laser beam (1LRT) is used to quantify the thermal conductivity κ of 250-nm-thick state-of-the-art, c-plane GaN membranes. The same membranes are then probed by two laser Raman thermometry (2LRT) to map the temperature distribution caused by a heating laser via a second probe laser. As a result, κ is determined for all in-plane crystal directions. A particular thermal anisotropy is revealed in c-plane GaN via this direct thermal imaging technique with sub-µm spatial resolution, which compares well to ab-initio calculations.
Consequently, we outline first potential routes towards thermal optimizations of photonic nanostructures.