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HL: Fachverband Halbleiterphysik
HL 8: Nitrides: Devices
HL 8.6: Vortrag
Montag, 16. März 2020, 10:45–11:00, POT 51
Thermal management of ultraviolet LEDs and VCSELs: computer-aided multiphysics optimization — •Giulia Cardinali1,2, Filip Hjort2, Michael Alexander Bergmann2, Johan Gustavsson2, and Åsa Haglund2 — 1Department of Electronics and Telecommunications, Politecnico di Torino, Turin, Italy — 2Department of Microtechnology and Nanoscience, Chalmers University of Technology, Gothenburg, Sweden
Thermal management is crucial to push the power conversion efficiency above the current limit of 10% in UV LEDs and to enable lasing in UV VCSELs. Numerical simulations have been used to study thermal transport in AlGaN-based vertical-cavity surface-emitting lasers (VCSELs) with dielectric distributed Bragg reflectors (DBRs) and thin-film flip-chip LEDs. The VCSELs technology suffers from poor thermal dissipation through to the DBRs: AlN or diamond heat spreading layers showed to be the most effective way to reduce the internal temperature while maintaining a short optical cavity length. Transfer matrix simulations show a resonance wavelength shift rate with temperature of 6 × 10−3 nm/K, one order of magnitude lower than the value reported for GaN VCSELs with thermally conductive bottom epitaxial DBR. In UVB LEDs to enhance the vertical heat transport the mesa should be in contact with the carrier over the whole area by avoiding air gaps. In that way, thermal performance becomes less dependent upon the exact alignment during the flip-chip bonding process.