Abstract
This paper reports the transient photoluminescence (PL) properties of an InGaN/GaN multiple quantum well (MQW) light-emitting diode (LED) with green emission. Recombination of localized excitons was proved to be the main microscopic mechanism of green emission in the sample. The PL dynamics were ascribed to two pathways of the exciton recombination, corresponding to the fast decay and the slow decay, respectively. The origins of slow decay and fast decay were assigned to local compositional fluctuations of indium and thickness variations of InGaN layers, respectively. Furthermore, the contributions of two decay pathways to the green PL were found to vary at different emission photon energy. The fraction of fast decay pathway decreased with decreasing photon energy. The slow radiative PL from deep localized exciton recombination suffered less suppression from non-radiative delocalization process, for the higher requested activation energy. All these results supported a clear microscopy mechanism of excitation-emission process of the green MQW LED structure.
Highlights
InGaN/GaN multiple quantum well (MQW) lightemitting diodes (LEDs) have attracted much attention for the potential application in generation solidstate lighting
Many efforts have been performed to analyze the dynamic properties of green emission point by point to each wavelength involved in emission band, giving the conclusion that the whole emission band may contributed by exciton localization [20, 21], few attention has been paid to the existence of multiple PL pathways for green emission
In summary, temperature-dependent SSPL and time-resolved PL (TRPL) spectra were studied for the green emission from InGaN/GaN MQW LED structure
Summary
InGaN/GaN multiple quantum well (MQW) lightemitting diodes (LEDs) have attracted much attention for the potential application in generation solidstate lighting. The internal quantum efficiency (IQE) of the green emission from MQW structure has suffered from a dramatical decrease compared with that from blue emission [1,2,3,4]. This drawback strongly hindered their full-color applications. For a typical blue MQW LED, exciton localization effect has been proposed to improve the IQE, which was related to several structural imperfections [10,11,12,13], such as compositional fluctuations of indium within InGaN wells [14, 15], formation of dot-like In-rich clusters [16,17,18] and well-width fluctuations in the activated layers [19], all of which were dependent on indium fractions in the wells. Many efforts have been performed to analyze the dynamic properties of green emission point by point to each wavelength involved in emission band, giving the conclusion that the whole emission band may contributed by exciton localization [20, 21], few attention has been paid to the existence of multiple PL pathways for green emission
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