Temperature-Dependent Internal Quantum Efficiency of Blue High-Brightness Light-Emitting Diodes

Abstract

Internal quantum efficiency (IQE) of a blue highbrightness InGaN/GaN LED was evaluated from the external quantum efficiency measured as a function of current at various temperatures ranged between 13 K and 440 K. Processing the data with a novel evaluation procedure based on the ABC-model, we have determined the temperature dependent IQE of the LED structure and light extraction efficiency of the LED chip. Separate evaluation of these parameters is helpful for further optimization of the heterostructure and chip designs. The data obtained enable making a guess on the temperature dependence of the radiative and Auger recombination coefficients, which may be important for identification of dominant mechanisms responsible for the efficiency droop in III-nitride LEDs. Thermal degradation of the LED performance in terms of the emission efficiency is also considered.

Towards quantification of the crucial impact of auger recombination for the efficiency droop in (AlInGa)N quantum well structures

“…from IQE fits at room temperature of a SQW emitting at 540 nm [20]. To account qualitatively for the cryogenic temperature we increase the SRH recombination lifetimes by a factor of 100 whereas the B and C coefficients were not changed due to discordant temperature trends found in literature [19,21]:…”

Efficiency of True-Green Light Emitting Diodes: Non-Uniformity and Temperature Effects<strong> </strong>

“…Recently, implication of composition fluctuations in InGaN to the LED effi-324 ciency reduction in the "green gap" has been also demonstrated [22,23,24]. products of both sw-and lw-emission peaks are found to be nearly independent of temperature, similar to the case of blue LED [5]. This is evidence for the fact that both radiative and Auger recombination coefficients in the green LED, like in the blue one, have qualitatively similar temperature dependence: either ascending or descending.…”

“…Data for blue LED reported in [5] 366 are also shown for comparison by small circles and dash-dotted line. the difference between the wavelengths of sw-and lw-emission, (ii) the sequence of sw-and lw-peaks appearance in the emission spectrum with the operating current, (iii) the difference in the recombina-tion volumes associated with sw-and lw-emission, and (iv) the difference in the Q-factors or IQEs of the sw-and lw-emission.…”

“…Maximum IQE of the green LED was found to decrease from ~91% at 13 K to 473 ~70% at 300 K and controlled by the lw-emission from the main part of the active region. Remarkable 474 deviation of the IQE maximum from 100% at cryogenic temperatures indicates that non-radiative re-475 combination does not vanish in the green LED, in contrast to blue one where it was ~97% [5]. This 476 makes doubtful the method of IQE determination based on comparison of EL intensity at cryogenic 477 and room temperatures.…”

AlGaInP red-emitting light emitting diode under extremely high pulsed pumping

“…In order to estimate CW light extraction efficiency (LEE) and IQE of blue LEDs from the measured EQE(I) dependence, a special procedure based on the ABC recombination model has been suggested elsewhere 18 . Direct application of the procedure to red LEDs fails because of (i) small contribution of Auger recombination to the total recombination rate in the range of the current densities of interest and (ii) interfering the recombination processes with the electron leakage producing the efficiency decrease at high currents.…”