Investigation of optical and electrical properties of GaN-based blue light-emitting diodes with various quantum well thicknesses

Lin, Yingwen; Wang, Chun-Kai; Chiou, Yu−Zung; Chang, Hui-Ming; Chang, Shoou‐Jinn

doi:10.1117/1.jpe.5.057612

Cited by 6 publications

(2 citation statements)

References 33 publications

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“…With the increase of W‐T, peak IQE first increases and then decreases, showing the maximum value (IQE = 94.53 %) obtained at W‐T = 2.5 nm. That can be attributed to the following reasons: 1) a thin W‐T may cause the electron overflow, which could be suppressed by a thicker QW structure, confining more carriers in the active region [ 23 ] to facilitate the radiation recombination rate in the MQW; 2) when the QW thickness is keeping on increasing, the spontaneous and piezoelectric polarization in the GaN/InGaN heterostructures are stronger, which makes the potential profile of the QW tilt to a triangular shape and the separation of electron and hole wave‐functions. In addition, as the polarization field enhances, the quantum‐confined Stark effect (QCSE) becomes more severe in the epitaxy layer.…”

Section: Resultsmentioning

confidence: 99%

Advanced Design of a III‐Nitride Light‐Emitting Diode via Machine Learning

Jiang,

Chen

et al. 2023

Laser & Photonics Reviews

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Gallium nitride (GaN)‐based light‐emitting diodes (LEDs) have obtained great market success in the past 20 years. However, the traditional research paradigm, i.e., experimental trial‐and‐error method, no longer adapts to the industry development. In this work, an efficient approach is demonstrated to design and optimize GaN‐based LED structures via machine learning (ML). By using the dataset of GaN‐based LED structures over the past decade to train four typical ML models, it is found that the convolutional neural network (CNN) provides the most accurate prediction, with a root mean square error (RMSE) of 1.03% for internal quantum efficiency (IQE) and 11.98 W cm−2 for light output power density (LOPD). Based on the CNN model, 1) the feature importance analysis is adopted to reveal the critical features for LED performance; 2) the predicted trends of IQE and LOPD match well with the physical mechanism, being consistent with the experimental and simulation results; and 3) a high‐throughput screening is demonstrated to predict the properties of over 20 000 structures within seconds to obtain high efficiency LED structures. This ML‐based LED design method enables direct guiding of the LED structure optimization in terms of key parameter selection during manufacturing and greatly accelerates the development cycle of GaN‐based LEDs.

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Section: Resultsmentioning

confidence: 99%

Advanced Design of a III‐Nitride Light‐Emitting Diode via Machine Learning

Jiang,

Chen

et al. 2023

Laser & Photonics Reviews

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“…In addition to the width of the QW, it was noted the SRH lifetime also can be pointedly increased by increasing the number of QWs. A thick QW structure (width > 2.5 nm) [92][93][94][95] grown on a c-plane shows better efficiency than a thin wall. However, the oscillator strength in thick polar QW is reduced via polarization, which implies a substantially extended radiative lifetime of thick c-plane QWs.…”

Section: Shockley-read-hall Recombination Lifetime In Ingan Quantum W...mentioning

confidence: 99%

Recent Research on Indium-Gallium-Nitride-Based Light-Emitting Diodes: Growth Conditions and External Quantum Efficiency

Jafar,

Jiang,

et al. 2023

Crystals

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The optimization of the synthesis of III-V compounds is a crucial subject in enhancing the external quantum efficiency of blue LEDs, laser diodes, quantum-dot solar cells, and other devices. There are several challenges in growing high-quality InGaN materials, including the lattice mismatch between GaN and InGaN causing stress and piezoelectric polarization, the relatively high vapor pressure of InN compared to GaN, and the low level of incorporation of indium in InGaN materials. Furthermore, carrier delocalization, Shockley–Read–Hall recombination, auger recombination, and electron leakage in InGaN light-emitting diodes (LEDs) are the main contributors to efficiency droop. The synthesis of high-quality III-V compounds can be achieved by optimizing growth parameters such as temperature, V/III ratios, growth rate, and pressure. By reducing the ammonia flow from 200 sccm to 50 sccm, increasing the growth rate from 0.1 to 1 m/h, and lowering the growth pressure from 250 to 150 Torr, the external quantum efficiency of III-V compounds can be improved at growth temperatures ranging from 800 °C to 500 °C. It is crucial to optimize the growth conditions to achieve high-quality materials. In addition, novel approaches such as adopting a microrod crystal structure, utilizing the piezo-phototronic effect, and depositing AlN/Al2O3 on top of the P-GaN and the electron-blocking layer can also contribute to improving the external quantum efficiency. The deposition of a multifunctional ultrathin layers of AlN/Al2O3 on top of the P-GaN can enhance the peak external quantum efficiency of InGaN blue LEDs by 29%, while the piezo-phototronic effect induced by a tensile strain of 2.04% results in a 183% increase in the relative electroluminescence intensity of the LEDs. This paper also discusses conventional and inverted p-i-n junction structures of LEDs.

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Total-InGaN-thickness dependent Shockley-Read-Hall recombination lifetime in InGaN quantum wells

Zhou

Ikeda

Zhang

et al. 2020

Journal of Applied Physics

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The mechanism behind the quantum-well-width dependent Shockley-Read-Hall (SRH) recombination lifetime is investigated in the InGaN/GaN quantum wells (QWs). According to the literature, the strong dependence of SRH lifetime on QW width is proposed to originate from the electron-hole separation in c-plane QWs, just as the radiative recombination. However, in this work, by temperature dependent steady-state time-resolved photoluminescence experiment, it is found that besides the QW width, the SRH lifetime also increases significantly with increasing QW number, which cannot be explained by the electron-hole separation. The two kinds of dependences of SRH lifetime can be attributed to the same source, judging from their similar activation energies, which is the existence of indium atoms compensating the SRH recombination centers generated during the epitaxy and thereby prolonging the SRH lifetime. The density of SRH centers deduced from our analysis decreases with the total thickness of the InGaN layer in a consistent manner for both the QW-width dependent and QW-number dependent sets of samples.

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Investigation of optical and electrical properties of GaN-based blue light-emitting diodes with various quantum well thicknesses

Cited by 6 publications

References 33 publications

Advanced Design of a III‐Nitride Light‐Emitting Diode via Machine Learning

Advanced Design of a III‐Nitride Light‐Emitting Diode via Machine Learning

Recent Research on Indium-Gallium-Nitride-Based Light-Emitting Diodes: Growth Conditions and External Quantum Efficiency

Total-InGaN-thickness dependent Shockley-Read-Hall recombination lifetime in InGaN quantum wells

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