Enhanced localisation effect and reduced quantum-confined Stark effect of carriers in InGaN/GaN multiple quantum wells embedded in nanopillars

Xu, Xinglian; Wang, Qiang; Li, Changfu; Ji, Ziwu; Xu, M.; Yang, Huai; Xu, Xiangang

doi:10.1016/j.jlumin.2018.06.024

Cited by 13 publications

(11 citation statements)

References 37 publications

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“…5(a)) is also related to the stronger carrier localization effect, in addition to smaller electron leakage under these conditions. The injection current-dependent reduction of the carrier localization effect induced by composition fluctuation can be attributed to the fact that, when the IC gradually increases, corresponding to the gradual increase of the external electric field, in addition to the localization centers being gradually filled by the increasing injection carrier, the QW profile gradually inclines, resulting in the carrier easily escaping from the localization centers 14,26,27 .…”

Section: Resultsmentioning

confidence: 99%

Wave-shaped temperature dependence characteristics of the electroluminescence peak energy in a green InGaN-based LED grown on silicon substrate

et al. 2020

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This study aimed to investigate temperature dependencies at different injection currents (ICs) of the electroluminescence (EL) spectra from a green InGaN/GaN light-emitting diode (LED) based on multiple quantum wells (MQWs) grown on a Si substrate in a wide range of ICs (0.001-350 mA) and temperatures (6-350 K). The results show that the temperature-changing characteristic of the EL peak energy gradually evolves from an approximately V-shaped temperature dependence into a wave-shaped (three-step blueshift) dependence with increasing IC. Finally, it emerges as an approximately inverted V-shaped temperature dependence. The behavior reflects the fact that the emission related to InGaN is significantly influenced by the changing recombination dynamics of carriers with rising temperature or IC. This is attributed to the presence in the MQW active region of a stronger carrier localization effect across three zones with different average In contents. Moreover, with the decline of the temperature at lower ICs, the temperature behavior of the external quantum efficiency (EQE) value is dominated by the deactivated non-radiative centers. This phenomenon occurs not only in the higher temperature range but also at lower temperatures due to more In-content-induced structural defects, which are confirmed by measurements of the integrated EL intensity as well as the EQE dependence on IC.

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Section: Resultsmentioning

confidence: 99%

Wave-shaped temperature dependence characteristics of the electroluminescence peak energy in a green InGaN-based LED grown on silicon substrate

et al. 2020

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“…Due to the fact that the density-of-states of the tails is much lower, the occupation of the higher energy states of the tails is more obvious than the occupation in regular energy bands with the increasing T j [24]. In the temperature range of~120-175 K, thermalized bound excitons occupy higher energy states, and the effect of the blueshift is stronger than the effect of the temperature-induced band gap shrinkage with temperature increasing, leading to the blueshift of the emission peak energy [22,27]. Using Equation (1) to fit the blue LED data, the fitting curve is presented in Figure 8a and shows good agreement with the experimental data.…”

Section: Emission Peak Energy Vs Tjmentioning

confidence: 99%

“…This relationship is attributed to the electric field formed by the increased carrier concentration that decreases the impact of the quantum-confined Stark effect (QCSE) [26,34] and the energy band filling effect [35,36]. The excitons' lifetime decreased in the high-temperature range, and therefore, as the current increased the excitons could not occupy the lower energy state prior to the recombination, leading to the blue shift of the emission peak [27]. Since many higher energy extended states may be present, this kind of recombination will be accompanied by the linewidth broadening, as shown in Figure 9c, which is derived from Figure 5a.…”

Section: Emission Peak Energy Vs Tjmentioning

confidence: 99%

Investigation of the Electroluminescence Mechanism of GaN-Based Blue and Green Light-Emitting Diodes with Junction Temperature Range of 120–373 K

et al. 2020

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Junction temperature (Tj) and current have important effects on light-emitting diode (LED) properties. Therefore, the electroluminescence (EL) spectra of blue and green LEDs were investigated in a Tj range of 120–373 K and in a current range of 80–240 mA based on accurate real-time measurements of Tj using an LED with a built-in sensor unit. Two maxima of the emission peak energy with changing Tj were observed for the green LED, while the blue LED showed one maximum. This was explained by the transition between the donor-bound excitons (DX) and free excitons A (FXA) in the green LED. At low temperatures, the emission peak energy, full width at half maximum (FWHM), and radiation power of the green LED increase rapidly with increasing current, while those of the blue LED increase slightly. This is because when the strong spatial potential fluctuation and low exciton mobility in the green LED is exhibited, with the current increasing, more bonded excitons are found in different potential valleys. With a shallower potential valley and higher exciton mobility, excitons are mostly bound around the potential minima. The higher threshold voltage of the LEDs at low temperatures may be due to the combined effects of the band gap, dynamic resistance, piezoelectric polarization, and electron-blocking layer (EBL).

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“…In general, the InGaN well layers are considered the pivotal factor in determining the luminescence properties of InGaN/GaN MQWs, since the nonequilibrium electrons and holes mainly recombine radiatively and emit photons in InGaN QWs. Due to the growth of InGaN/GaN MQWs along the polar GaN [0001] direction, in InGaN QWs the polarization-induced quantum-confined Stark effect (QCSE), reducing the luminescence efficiency of InGaN QWs as well as the energy of emitted photons, plays a crucial role in the luminescence characteristics of light-emitting devices, which has attracted high research interest [14][15][16]. Nevertheless, the GaN quantum barriers also affect the QCSE in InGaN QWs as well as the transport of carriers in the whole MQW active region, which may strongly influence the performance of the optoelectronic devices based on the InGaN/GaN MQWs [17,18].…”

Section: Introductionmentioning

confidence: 99%

Reduction in the Photoluminescence Intensity Caused by Ultrathin GaN Quantum Barriers in InGaN/GaN Multiple Quantum Wells

et al. 2022

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The optical properties of InGaN/GaN violet light-emitting multiple quantum wells with different thicknesses of GaN quantum barriers are investigated experimentally. When the barrier thickness decreases from 20 to 10 nm, the photoluminescence intensity at room temperature increases, which can be attributed to the reduced polarization field in the thin-barrier sample. However, with a further reduction in the thickness to 5 nm, the sample’s luminescence intensity decreases significantly. It is found that the strong nonradiative loss process induced by the deteriorated crystal quality and the quantum-tunneling-assisted leakage of carriers may jointly contribute to the enhanced nonradiative loss of photogenerated electrons and holes, leading to a significant reduction in photoluminescence intensity of the sample with nanoscale ultrathin GaN quantum barriers.

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Enhanced localisation effect and reduced quantum-confined Stark effect of carriers in InGaN/GaN multiple quantum wells embedded in nanopillars

Cited by 13 publications

References 37 publications

Wave-shaped temperature dependence characteristics of the electroluminescence peak energy in a green InGaN-based LED grown on silicon substrate

Wave-shaped temperature dependence characteristics of the electroluminescence peak energy in a green InGaN-based LED grown on silicon substrate

Investigation of the Electroluminescence Mechanism of GaN-Based Blue and Green Light-Emitting Diodes with Junction Temperature Range of 120–373 K

Reduction in the Photoluminescence Intensity Caused by Ultrathin GaN Quantum Barriers in InGaN/GaN Multiple Quantum Wells

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