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HL: Fachverband Halbleiterphysik
HL 68: Nitrides: Preparation and characterization II
HL 68.6: Vortrag
Donnerstag, 19. März 2020, 16:15–16:30, POT 112
100% quantum efficiency in III-nitride quantum wells at low temperatures: experimental verification by time-resolved photoluminescence — •Philipp Henning, Savutjan Sidik, Philipp Horenburg, Heiko Bremers, Uwe Rossow, and Andreas Hangleiter — Institut für Angewandte Physik & Laboratory for Emerging Nanometrology, Technische Universität Braunschweig, 38106 Braunschweig, Germany
Using time-resolved photoluminescence (PL) measurements, we present an experimental verification for 100% internal quantum efficiency (IQE) of III-N quantum wells at low temperatures. Conventional IQE measurements, such as temperature- and power-dependent PL, require a low-temperature normalization, where usually an IQE of 100% is assumed. This assumption neglects remaining nonradiative recombination processes, such as tunneling to nonradiative centers, that may be present even at low temperatures. From time-resolved PL measurements, charge carrier lifetimes for radiative and nonradiative recombination can be evaluated separately. We state that the low-temperature IQE corresponds to 100%, whenever the effective charge carrier decay is dominated only by radiative recombination. In this case, the temperature-dependent measurements show a synchronous rise of the effective lifetimes together with the radiative lifetimes, since only the radiative lifetime increases with temperature in a 2D system, while nonradiative processes are thermally activated. Thereby, absolute IQE measurements become possible, since we provide a robust indicator for nonradiative recombination at low temperatures.