“…As can be seen in the figure, the decay curves show single-exponential behaviors at low-energy region (2.30 eV) but deviate from single-exponential decay at high-energy region (2.58 eV). As our previous work [ 26 ], this phenomenon indicates that multiple PL pathways may exist in the high-energy region of PL. Fig.…”
Section: Resultssupporting
confidence: 77%
“…PL decay curves of high-energy region were fitted by bi-exponential decay function (Eq. (1)), where two decay time were obtained [ 26 ], where I 0 represents the PL intensity at t = 0, τ 1 and τ 2 represent the slow decay lifetime and the fast decay lifetime, respectively. A 1 and A 2 are related to the initial PL intensities of slow and fast decay process.…”
Section: Resultsmentioning
confidence: 99%
“…5 , guided by the broad SSPL peak. The origins of slow PL process and fast PL process can be assigned to local compositional fluctuations of indium and thickness variation of InGaN layers, respectively [ 26 ]. It can be seen that the values of PL lifetime increase with decreasing photon energy for both fast and slow decays, which is ascribed to the energy transfer from a higher localized energy state to lower one.…”
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.
“…As can be seen in the figure, the decay curves show single-exponential behaviors at low-energy region (2.30 eV) but deviate from single-exponential decay at high-energy region (2.58 eV). As our previous work [ 26 ], this phenomenon indicates that multiple PL pathways may exist in the high-energy region of PL. Fig.…”
Section: Resultssupporting
confidence: 77%
“…PL decay curves of high-energy region were fitted by bi-exponential decay function (Eq. (1)), where two decay time were obtained [ 26 ], where I 0 represents the PL intensity at t = 0, τ 1 and τ 2 represent the slow decay lifetime and the fast decay lifetime, respectively. A 1 and A 2 are related to the initial PL intensities of slow and fast decay process.…”
Section: Resultsmentioning
confidence: 99%
“…5 , guided by the broad SSPL peak. The origins of slow PL process and fast PL process can be assigned to local compositional fluctuations of indium and thickness variation of InGaN layers, respectively [ 26 ]. It can be seen that the values of PL lifetime increase with decreasing photon energy for both fast and slow decays, which is ascribed to the energy transfer from a higher localized energy state to lower one.…”
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.
“…It is worth noted that not all decay curve can be perfectly fitted by above single exponential decay function. This has been widely discussed by several groups [ 31 – 34 ]. A reasonable assumption was that there exist multiple recombination centers in the system.…”
This paper reports the photoluminescence (PL) properties of InGaN/GaN multiple quantum well (MQW) light-emitting diodes grown on silicon substrates which were designed with different tensile stress controlling architecture like periodic Si δ-doping to the n-type GaN layer or inserting InGaN/AlGaN layer for investigating the strain-controlled recombination mechanism in the system. PL results turned out that tensile stress released samples had better PL performances as their external quantum efficiencies increased to 17%, 7 times larger than the one of regular sample. Detail analysis confirmed they had smaller nonradiative recombination rates ((2.5~2.8)×10−2 s−1 compared to (3.6~4.7)× 10−2 s−1), which was associated with the better crystalline quality and absence of dislocations or cracks. Furthermore, their radiative recombination rates were found more stable and were much higher ((5.7~5.8) ×10−3 s−1 compared to [9~7] ×10−4 s−1) at room temperature. This was ascribed to the suppression of shallow localized states on MQW interfaces, leaving the deep radiative localization centers inside InGaN layers dominating the radiative recombination.
“…And some company have also prepared blue GaN based LED used ECR-PEMOCVD on conductive glass substrate in Australia, which could not stand high temperature [14][15][16][17]. Many study proved that the PE can be used to prepare the GaN based LED at low temperature, then operating apparatus at low temperature and using cheap substrate can reduce the LED's production cost.…”
GaN-based solar cells fabricating greatly depends on the using of cheap substrate and the high quality of the as-grown GaN films. The high c-axis preferred orientation GaN films were prepared on amorphous quartz glass substrate using self developed electron cyclotron resonance plasma enhanced metal-organic chemical vapor deposition (ECR-PEMOCVD) system. The properties of the GaN films were characterized by in situ Reflection High Energy Electron Diffraction (RHEED), X-ray diffraction (XRD), Transmission Spectra and photo-luminescence (PL) spectra. The results show that concentric diffraction RHEED rings demonstrated the successful nitriding of conventional amorhpous quartz glass substrates at low temperature of the 430℃, and the temperature is far below the strain point of glass. And the nitridation with as-grown GaN films deposition exhibited stronger c-axis orientation
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