Shape designing for light extraction enhancement bulk-GaN light-emitting diodes

Sun, Bo; Zhao, Lixia; Wei, Tongbo; Yi, Xiaoyan; Liu, Zhiqiang; Li, Jinmin

doi:10.1063/1.4812464

Cited by 18 publications

(12 citation statements)

References 28 publications

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“…We believe that it is due to an enhanced light extraction due to geometric effects. The light generated and trapped in the structure due to the high refractive index contrast can escape more easily at the corners than the centre of the pixel due to the angle formed by the shape of the corners [16].…”

Section: Resultsmentioning

confidence: 99%

Investigation of sidewall damage induced by reactive ion etching on AlGaInP MESA for micro-LED application

Boussadi

Rochat

Barnes

et al. 2021

Journal of Luminescence

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Previous reports have studied the impact of sidewall defects on AlGaInP micro light emitting diode (µLED) only by Current-Voltage-Luminescence (I-V-L) measurements. In this work, we propose an alternative approach to investigate these defects directly after MESA formation, by coupling optical characterization techniques together with Time-of-flight secondary ion mass spectrometry (TOF-SIMS) on AlGaInP square shaped pixels of different sizes formed by BCl3-based Reactive Ion Etching (RIE). It is found that for a 6×6 µm² pixel, the light emission homogeneity is largely impacted by the sidewall defects. From emission efficiency map deduced by temperature-dependent cathodoluminescence measurements, we estimate that 86% of the 6×6 µm² pixel exhibit a lower efficiency than the center. The carriers lifetime extracted from time-resolved photoluminescence (TRPL) measurements on larger pixel begins to decrease gradually at 3 µm from the sidewall due to non-radiative recombinations. On the other hand, the TOF-SIMS analysis shows that residues of boron and chlorine remain on the surface and sidewalls of the pixel after BCl3 etching. These results show the importance to characterize the µLEDs at the MESA step and the necessity to optimize the etching process and the passivation.

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Section: Resultsmentioning

confidence: 99%

Investigation of sidewall damage induced by reactive ion etching on AlGaInP MESA for micro-LED application

Boussadi

Rochat

Barnes

et al. 2021

Journal of Luminescence

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“…For instance, lasers serve as a heat source for rapid annealing, and forming ohmic contact of low contact resistance for Micro-LEDs. [57,58] Laser induced heating, ablation and decomposition are utilized for Micro-LED dicing, [59] chip shaping [60,61] and surface texturing. [62] Substrate removal by LLO is another well-established technique for making high power LEDs for general lighting [63] and are now extended for making thin film Micro-LEDs by exploiting the UV laser irradiating at the GaN/sapphire interface through a transparent sapphire substrate and laser-induced GaN decomposition under high temperature.…”

Section: Introductionmentioning

confidence: 99%

Laser‐Based Micro/Nano‐Processing Techniques for Microscale LEDs and Full‐Color Displays

Gong

2022

Adv Materials Technologies

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Micro light‐emitting diode (Micro‐LED) display is an emerging display technology thanks to its high brightness, fast switching speed, and low power consumption. The commercialization of this technique is being explored by developing advanced processing techniques on an industrial scale. Recent ground‐breaking advances in the manufacture of Micro‐LEDs are mainly based on powerful laser micro/nano‐processing techniques with the unique ability to fabricate materials, structures and devices with the advantages of non‐contacting processing, high efficiency, adjustable coverage from micro‐ to macroscale and the compatibility with organic and inorganic materials. This paper categorizes, reviews and analyzes the main challenges and technical solutions in the Micro‐LED displays by various laser manufacturing processes, covering chip dicing, geometry shaping, laser annealing, laser lift‐off (LLO), laser‐based Micro‐LED transfer, laser‐assist bonding (LAB) and laser repair. The fundamental principles of these techniques are discussed along with their basic mechanisms, followed by an exploration of the latest progress in the field. Finally, a detailed analysis of the advantages and disadvantages of these techniques is given, and the future research directions of laser techniques in Micro‐LED display are discussed.

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“…In III–V compound semiconductors, control of the surface structures is essential to improve the functionality of the optical devices. For example, high‐aspect‐ratio tapered pillar array changes the refractive indices gradually from air to semiconductor, providing excellent antireflection of high‐efficiency solar cells 5; cone‐shaped structures enhance light extraction efficiency of the light‐emitting diodes (LEDs) 6; holes with smooth and vertical sidewalls reduce the propagation loss of the photonic crystal waveguide 7, 8. Moreover, the use of microstructures with refractive index matched to substrate is important for enabling optimum light extraction efficiency in LEDs 9.…”

Section: Introductionmentioning

confidence: 99%

Formation of three‐dimensional GaAs microstructures by combination of wet and metal‐assisted chemical etching

Lee

Kim

Choi

et al. 2014

Physica Rapid Research Ltrs

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Previously, plasma‐enhanced dry etching has been used to generate three‐dimensional GaAs semiconductor structures, however, dry etching induces surface damages that degrade optical properties. Here, we demonstrate the fabrication method forming various types of GaAs microstructures through the combination etching process using the wet‐chemical solution. In this method, a gold (Au)‐pattern is employed as an etching mask to facilitate not only the typical wet etching but also the metal‐assisted chemical etching (MacEtch). High‐aspect‐ratio, tapered GaAs micropillars are produced by using [HF]:[H2O2]:[EtOH] as an etching solution, and their taper angle can be tuned by changing the molar ratio of the etching solution. In addition, GaAs microholes are formed when UV light is illuminated during the etching process. Since the wet etching process is free of the surface damage compared to the dry etching process, the GaAs microstructures demonstrated to be well formed here are promising for the applications of III–V optoelectronic devices such as solar cells, laser diodes, and photonic crystal devices. (© 2014 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)

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Shape designing for light extraction enhancement bulk-GaN light-emitting diodes

Cited by 18 publications

References 28 publications

Investigation of sidewall damage induced by reactive ion etching on AlGaInP MESA for micro-LED application

Investigation of sidewall damage induced by reactive ion etching on AlGaInP MESA for micro-LED application

Laser‐Based Micro/Nano‐Processing Techniques for Microscale LEDs and Full‐Color Displays

Formation of three‐dimensional GaAs microstructures by combination of wet and metal‐assisted chemical etching

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