On the temperature dependence of the efficiency of electroluminescence

Abstract

Electroluminescent cooling (ELC) of light-emitting diodes (LEDs) generally requires very high light emission efficiency. Earlier studies of electro-and photoluminescence suggest that temperature strongly affects the light emission efficiency and therefore it is useful to explore the temperature range below room temperature (RT) where ELC might be easier to observe. With that purpose in mind, we electrically characterised four differently sized (0.2, 0.5 and 1 mm diameter) test devices, consisting of LEDs coupled with integrated photodetectors (PDs), at temperatures ranging from 100 K to 300 K to investigate how the temperature affects the efficiency of the structures in practice. We found that, for the studied devices, both the quantum efficiency (QE) and the overall efficiency indeed increase for low temperatures and reach peak values at temperatures clearly below RT. We also found that the temperature at which the peak efficiency occurs shifts towards higher values as the absolute value of the efficiency increases.

Near‐Unity External Quantum Efficiency in GaAs|AlGaAs Heterostructures Grown by Molecular Beam Epitaxy

“…[8,9] This disparity has been largely attributed to the interface recombination velocity, being nearly two orders of magnitude higher at room temperature for a GaAs|AlGaAs than for a GaAs|GaInP DHS, [10] leading to nonradiative decay of the photocarriers. Although more complex structures have been studied for ELC, [11] to our knowledge, a detailed and systematic temperature-dependent investigation of the EQE in a GaAs|AlGaAs DHS below room temperature-most pertinent for cooling applications-has not been reported until now. Such a temperature-dependent characterization has become more relevant with the recent demonstration of a high-EQE GaAs|AlGaAs DHS at low temperatures.…”