Investigation of Carrier Recombination Dynamics of Light-Emitting Diode Based on InGaN Quantum Dots
CAO Jie-hua1, 2, TIAN Ming1, 2, LIN Tao1, 2*, FENG Zhe-chuan1, 2
1. College of Physical Science and Engineering Technology, Guangxi University, Nanning 530004, China
2. Center on Nanoenergy Research, Guangxi University, Nanning 530004, China
Abstract：InGaN semiconductor materials are widely used In a new generation of optoelectronic devices because of their adjustable bandgap width by changing In components. However,the green LED still has a “green gap” problem to be solved. In this paper, the carrier recombination mechanism is studied in depth to provide a new idea for solving a “green gap”. The photoluminescence spectrum (PL) and time-resolved photoluminescence spectrum (TRPL) were used for investigating the carrier recombination processes of InGaN quantum dots (QDs) LED devices with different photon energies at temperatures. The transient photoluminescence properties of InGaN QDs and the transient life of radiative/nonradiative recombination were obtained. In the temperature range from 15 to 300 K, the peak value of the steady-state photoluminescence spectrum has its first blue shift and then red shift (s-shaped). The blue shift of the emission peak is about 4.2 meV, reaching its maximum value at 60 K, followed by the red shift of the emission peak, forming an s-shaped change with temperature. This change indicates that carrier localization behavior in QDs structure, and exciton recombination is the main reason for green light emission of InGaN QDs. By fitting the normalized PL integral intensity at different temperatures, the activation energy Eact was about 204.07 meV, with high activation energy, which proved that the InGaN QDs have strong carrier limiting effect and can better suppress the transitions to the nonradiative recombination centers. The internal quantum efficiency was estimated at 35.1%. Free carrier in the InGaN QDs composite average composite life τrad=73.85 ns. The energy boundary value Eme=2.34 eV is much higher than the local depth E0=62.55 meV, and it can be seen that the energy level is completely lower than the mobility edge, so the decay of InGaN QDs life is attributed to carrier local state recombination. In this study, the improved spectral data analysis method was used to study the fluorescence device based on the new structure of embedded QDs, and meaningful conclusions were obtained. It provides a reference for further understanding of the internal luminescence mechanism of InGaN quantum dots and the development of a new generation of lighting devices, indicating that the introduction of InGaN quantum dots plays a good role in promoting the development of photoelectric devices.
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