Effects of Mesa Size on Current Spreading and Light Extraction of GaN-Based LEDs

Horng, Ray−Hua; Chen, Ken-Yen; Tien, Ching-Ho; Liao, Jung-Chuan

doi:10.1109/jdt.2015.2461015

Cited by 10 publications

(7 citation statements)

References 12 publications

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“…In order to enhance the current spreading, vertical LEDs have been adopted to suppress the current crowding effect . Moreover, the mesa area size is also found to have strong impact on the current distribution . Other approaches to reduce the current crowding effect include purposely increasing the vertical resistivity by generating energy barriers in the hole injection layer and reducing the lateral resistivity by using the tunnel junction or the polarization tunnel junction .…”

Section: Introductionmentioning

confidence: 99%

“…[23,24] Moreover, the mesa area size is also found to have strong impact on the current distribution. [25] Other approaches to reduce the current crowding effect include purposely increasing the vertical resistivity by generating energy barriers in the hole injection layer [26] and reducing the lateral resistivity by using the tunnel junction or the polarization tunnel junction. [22,27,28] Here, it is worth defining the polarization tunnel junction in which the polarization induced electric field in the polarization tunnel junction is along the same direction as the built-in electric field, and thus the coupled electric field possesses the enhanced intensity.…”

Section: Introductionmentioning

confidence: 99%

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Numerical Investigations on the n⁺‐GaN/AlGaN/p⁺‐GaN Tunnel Junction for III‐Nitride UV Light‐Emitting Diodes

Zhang

Tian

et al. 2017

Physica Status Solidi (a)

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In this report, a parametric investigation on the n+‐GaN/AlGaN/p+‐GaN tunnel junction is made for III‐nitride based ultraviolet light emitting diodes (UV LEDs). It is found that, on one hand, by using various Al compositions and AlGaN layer thicknesses, the n+‐GaN/AlGaN/p+‐GaN tunnel junction can modify the electric field therein, which will affect the carrier tunneling probability and the current‐voltage characteristics. On the other hand, the Al composition and the AlGaN layer thickness also have a strong impact on the tunnel region width, which will affect the current flowing path and then influence the hole distribution apart from the p‐type ohmic contact. This work conducts a comprehensive analysis and presents an in‐depth understanding regarding the n+‐GaN/AlGaN/p+‐GaN tunnel junction, so that the hole concentration and the internal quantum efficiency can be significantly improved for III‐nitride UV LEDs.

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Numerical Investigations on the n⁺‐GaN/AlGaN/p⁺‐GaN Tunnel Junction for III‐Nitride UV Light‐Emitting Diodes

Zhang

Tian

et al. 2017

Physica Status Solidi (a)

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“…However, the diminished dimension in the y- direction increases the ratio of perimeter-to-area. The increased ratio of perimeter-to-area in the smaller LEDs leads to improved heat dissipation and reduced self-heating, hence the temperature in the LED device is decreased ( Kim et al, 2012 ; Horng et al, 2015 ). Moreover, the light extraction through the sidewalls is improved with diminished LED size, which contributes to the improvement of the LED performance ( Stark et al, 2011 ).…”

Section: Resultsmentioning

confidence: 99%

Experimental and Modeling Investigations of Miniaturization in InGaN/GaN Light-Emitting Diodes and Performance Enhancement by Micro-Wall Architecture

Zhang

Qiu³

et al. 2021

Front. Chem.

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The recent technological trends toward miniaturization in lighting and display devices are accelerating the requirement for high-performance and small-scale GaN-based light-emitting diodes (LEDs). In this work, the effect of mesa size-reduction in the InGaN/GaN LEDs is systematically investigated in two lateral dimensions (x- and y-directions: parallel to and perpendicular to the line where p-n directions are) both experimentally and numerically. The role of the lateral size-reduction in the x- and y-directions in improving LED performance is separately identified through experimental and modeling investigations. The narrowed dimension in the x-direction is found to cause and dominate the alleviated current crowding phenomenon, while the size-reduction in the y-direction has a minor influence on that. The size-reduction in the y-orientation induces an increased ratio of perimeter-to-area in miniaturized LED devices, which leads to improved thermal dissipation and light extraction through the sidewalls. The grown and fabricated LED devices with varied dimensions further support this explanation. Then the effect of size-reduction on the LED performance is summarized. Moreover, three-micro-walls LED architecture is proposed and demonstrated to further promote light extraction and reduce the generation of the Joule heat. The findings in this work provide instructive guidelines and insights on device miniaturization, especially for micro-LED devices.

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“…However, there will be more difficulties and challenges in fabricating the vertical LEDs. In order to improve the current spreading and suppress the current crowding effect, some approaches, such as improving the design of the hole injection layer [27], optimization of the mesa area size to adjust the current distribution [28], enhancing the conductivity of the contact layer with the p-electrode [27], transparent p-side electrode fabrication [7,29], and use of a tunnel junction (TJ) or a polarization TJ (PTJ) [30][31][32][33][34][35][36][37][38][39][40][41] have been proposed.…”

Section: Introductionmentioning

confidence: 99%

Calculating the Effect of AlGaN Dielectric Layers in a Polarization Tunnel Junction on the Performance of AlGaN-Based Deep-Ultraviolet Light-Emitting Diodes

et al. 2021

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In this work, AlGaN-based deep-ultraviolet (DUV) light-emitting diodes (LEDs) with AlGaN as the dielectric layers in p+-Al0.55Ga0.45N/AlGaN/n+-Al0.55Ga0.45N polarization tunnel junctions (PTJs) were modeled to promote carrier tunneling, suppress current crowding, avoid optical absorption, and further enhance the performance of LEDs. AlGaN with different Al contents in PTJs were optimized by APSYS software to investigate the effect of a polarization-induced electric field (Ep) on hole tunneling in the PTJ. The results indicated that Al0.7Ga0.3N as a dielectric layer can realize a higher hole concentration and a higher radiative recombination rate in Multiple Quantum Wells (MQWs) than Al0.4Ga0.6N as the dielectric layer. In addition, Al0.7Ga0.3N as the dielectric layer has relatively high resistance, which can increase lateral current spreading and enhance the uniformity of the top emitting light of LEDs. However, the relatively high resistance of Al0.7Ga0.3N as the dielectric layer resulted in an increase in the forward voltage, so much higher biased voltage was required to enhance the hole tunneling efficiency of PTJ. Through the adoption of PTJs with Al0.7Ga0.3N as the dielectric layers, enhanced internal quantum efficiency (IQE) and optical output power will be possible.

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Effects of Mesa Size on Current Spreading and Light Extraction of GaN-Based LEDs

Cited by 10 publications

References 12 publications

Numerical Investigations on the n⁺‐GaN/AlGaN/p⁺‐GaN Tunnel Junction for III‐Nitride UV Light‐Emitting Diodes

Numerical Investigations on the n⁺‐GaN/AlGaN/p⁺‐GaN Tunnel Junction for III‐Nitride UV Light‐Emitting Diodes

Experimental and Modeling Investigations of Miniaturization in InGaN/GaN Light-Emitting Diodes and Performance Enhancement by Micro-Wall Architecture

Calculating the Effect of AlGaN Dielectric Layers in a Polarization Tunnel Junction on the Performance of AlGaN-Based Deep-Ultraviolet Light-Emitting Diodes

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Effects of Mesa Size on Current Spreading and Light Extraction of GaN-Based LEDs

Cited by 10 publications

References 12 publications

Numerical Investigations on the n+‐GaN/AlGaN/p+‐GaN Tunnel Junction for III‐Nitride UV Light‐Emitting Diodes

Numerical Investigations on the n+‐GaN/AlGaN/p+‐GaN Tunnel Junction for III‐Nitride UV Light‐Emitting Diodes

Experimental and Modeling Investigations of Miniaturization in InGaN/GaN Light-Emitting Diodes and Performance Enhancement by Micro-Wall Architecture

Calculating the Effect of AlGaN Dielectric Layers in a Polarization Tunnel Junction on the Performance of AlGaN-Based Deep-Ultraviolet Light-Emitting Diodes

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Numerical Investigations on the n⁺‐GaN/AlGaN/p⁺‐GaN Tunnel Junction for III‐Nitride UV Light‐Emitting Diodes

Numerical Investigations on the n⁺‐GaN/AlGaN/p⁺‐GaN Tunnel Junction for III‐Nitride UV Light‐Emitting Diodes