Abstract
In this work, a GaN-based multiple quantum well (MQW) sample has a much higher IQE although it has a stronger non-radiative recombination. Through experimental verification, the higher IQE is attributed to the suppressed carrier leakage mechanism, which is normally neglected under optical excitation. To achieve a more reasonable IQE expression in a GaN MQW structure, leakage factor m is introduced into the ABC-models. Meanwhile, by analyzing the Arrhenius fitting of the plot of IQE-temperature and leakage factor m, the key temperature and excitation power turning on the carrier leakage mechanism was roughly determined to be below 220 K and 10 mW, respectively. Such a low turn-on temperature and excitation power indicates a much easier carrier leakage mechanism in GaN-based MQW, which may be caused by the small effective electron mass of InGaN (0.11–0.22 m*) and the narrow thickness of quantum well via the model calculation of energy band structure via simulation software LASTIP. Moreover, higher IQE can be achieved by suppressing the carrier leakage mechanism via structural optimization (such as electron block layer) in GaN-based MQW.
Highlights
There is a high lattice and thermal mismatch between the InN and GaN, the InGaN/GaN multiple quantum well (MQW) active region is widely applied in highefficiency laser diodes (LDs) [1,2,3,4,5] and light-emitting diodes (LEDs) [6,7,8] due to its unexpected high internal quantum efficiency (IQE)
The IQE increases with increasing excitation power, which is mainly caused by increased carrier concentration
The key factor is the carrier leakage mechanism which was normally neglected under optical excitation
Summary
There is a high lattice and thermal mismatch between the InN and GaN, the InGaN/GaN multiple quantum well (MQW) active region is widely applied in highefficiency laser diodes (LDs) [1,2,3,4,5] and light-emitting diodes (LEDs) [6,7,8] due to its unexpected high internal quantum efficiency (IQE). To get a higher IQE, the techniques to suppress the non-radiative recombination are widely studied [16,17,18]. According to ABCmodels, the IQE will strongly increase with the increasing carrier concentration in MQW due to the enhanced radiative recombination [11]. To provide a balance between the current flowing through the LED structure and integral recombination rate, the effect of carrier leakage on IQE is neglected, especially under optical excitation due to the low photogenerated carrier density [10,12,19,20]. Considering the great impact of carrier concentration on LED luminescence efficiency, a further investigation on the carrier leakage mechanism and its effect on IQE is necessary. The structural optimization is another powerful way to achieve higher IQE in GaN-based photoelectric device
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