Recombination mechanisms and thermal droop in AlGaN-based UV-B LEDs
Photonics Res., vol. 5, no. 2, pp. A44-A51 (2017).
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This paper reports a comprehensive analysis of the origin of the electroluminescence (EL) peaks and of the thermal droop in UV-B AlGaN-based LEDs. By carrying out spectral measurements at several temperatures and currents, (i) we extract information on the physical origin of the various spectral bands, and (ii) we develop a novel closed-form model based on the Shockley-Read-Hall theory and on the ABC rate equation that is able to reproduce the experimental data on thermal droop caused by non-radiative recombination through deep levels. In the samples under test, the three EL bands are ascribed to the following processes: band-to-band recombination in the quantum wells (main EL peak), a parasitic intra-bandgap radiative transition in the quantum well barriers, and a second defect-related radiative process in the p-AlGaN superlattice.
1 Department of Information Engineering, University of Padova, via Gradenigo 6/B, Padova 35131, Italy
2 Ferdinand-Braun-Institut, Leibniz-Institut für Höchstfrequenztechnik, Gustav-Kirchhoff-Str. 4, 12489 Berlin, Germany
3 Technische Universität Berlin, Institut für Festkörperphysik, Hardenbergstr. 36, EW 6-1, 10623 Berlin, Germany
(230.3670) Light-emitting diodes; (230.0250) Optoelectronics; (250.5590) Quantum-well, -wire and -dot devices.