Matrix-Addressable Micropixellated InGaN Light-Emitting Diodes With Uniform Emission and Increased Light Output

Gong, Zheng; Zhang, H.X.; Gu, Erdan; Griffin, C.; Dawson, Martin D.; Poher, V.; Kennedy, Gordon T.; French, Paul M. W.; Neil, Mark A. A.

doi:10.1109/ted.2007.904991

Cited by 72 publications

(52 citation statements)

References 17 publications

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“…Clearly, further improvement of spatial resolution and simulation accuracy will enable a much better understanding of the mechanism of strain relaxation in the micro-GaN pillars, which is critically important to the design of novel micro/nano pixellated LED devices for a wide range of applications. 4,[16][17][18][19] This study focuses on the strain relaxation process in micro-pillars fabricated from an LED wafer optimized for emission at yellow-green wavelengths ($560 nm). These micro-pillars had a fixed height of 1.1 lm, and diameters systematically varied from 2 to 150 lm.…”

Section: Introductionmentioning

confidence: 99%

Strain relaxation in InGaN/GaN micro-pillars evidenced by high resolution cathodoluminescence hyperspectral imaging

Xie

Chen

Edwards

et al. 2012

Journal of Applied Physics

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This version is available at https://strathprints.strath.ac.uk/40400/ Strathprints is designed to allow users to access the research output of the University of Strathclyde. Unless otherwise explicitly stated on the manuscript, Copyright © and Moral Rights for the papers on this site are retained by the individual authors and/or other copyright owners. Please check the manuscript for details of any other licences that may have been applied. You may not engage in further distribution of the material for any profitmaking activities or any commercial gain. You may freely distribute both the url (https://strathprints.strath.ac.uk/) and the content of this paper for research or private study, educational, or not-for-profit purposes without prior permission or charge.Any correspondence concerning this service should be sent to the A size-dependent strain relaxation and its effects on the optical properties of InGaN/GaN multiple quantum wells (QWs) in micro-pillars have been investigated through a combination of high spatial resolution cathodoluminescence (CL) hyperspectral imaging and numerical modeling. The pillars have diameters (d) ranging from 2 to 150 lm and were fabricated from a III-nitride light-emitting diode (LED) structure optimized for yellow-green emission at $560 nm. The CL mapping enables us to investigate strain relaxation in these pillars on a sub-micron scale and to confirm for the first time that a narrow ( 2 lm) edge blue-shift occurs even for the large InGaN/GaN pillars (d > 10 lm). The observed maximum blue-shift at the pillar edge exceeds 7 nm with respect to the pillar centre for the pillars with diameters in the 2-16 lm range. For the smallest pillar (d ¼ 2 lm), the total blue-shift at the edge is 17.5 nm including an 8.2 nm "global" blue-shift at the pillar centre in comparison with the unetched wafer. By using a finite element method with a boundary condition taking account of a strained GaN buffer layer which was neglected in previous simulation works, the strain distribution in the QWs of these pillars was simulated as a function of pillar diameter. The blue-shift in the QWs emission wavelength was then calculated from the strain-dependent changes in piezoelectric field, and the consequent modification of transition energy in the QWs. The simulation and experimental results agree well, confirming the necessity for considering the strained buffer layer in the strain simulation. These results provide not only significant insights into the mechanism of strain relaxation in these micro-pillars but also practical guidance for design of micro/nano LEDs.

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Section: Introductionmentioning

confidence: 99%

Strain relaxation in InGaN/GaN micro-pillars evidenced by high resolution cathodoluminescence hyperspectral imaging

Xie

Chen

Edwards

et al. 2012

Journal of Applied Physics

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“…In recent years, matrix-addressed and individually addressed CMOS-controlled GaN microdisplays with a luminance on the order of 10 4 cd/m 2 have been demonstrated [3], [13]. This is already one order of magnitude higher than alternative technologies, such as organic LED displays [3].…”

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confidence: 99%

Active-Matrix GaN Micro Light-Emitting Diode Display With Unprecedented Brightness

Herrnsdorf

McKendry

Zhang

et al. 2015

IEEE Trans. Electron Devices

129

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Displays based on microsized gallium nitride light-emitting diodes possess extraordinary brightness. It is demonstrated here both theoretically and experimentally that the layout of the n-contact in these devices is important for the best device performance. We highlight, in particular, the significance of a nonthermal increase of differential resistance upon multipixel operation. These findings underpin the realization of a blue microdisplay with a luminance of 10 6 cd/m 2 .

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“…Active matrix displays have been developed for decades such as active matrix liquid crystal displays (AMLCDs), active matrix organic light emitting diode displays (AMOLEDs) and active matrix light emitting diode displays (AMLEDs) 7 . Compared with passive matrix (PM) addressing mechanism, active matrix (AM) mechanism has obvious advantages [8][9][10][11][12] . Firstly, active components such as metal-oxide-semiconductor (MOS) and thin field transistors (TFTs) promise superior controllability.…”

Section: Current Driving Circuitsmentioning

confidence: 99%

25.3: Current Driving Active Matrix Micro‐LED Display

Zhang

Liu

Kwok

2018

Symp Digest of Tech Papers

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Micro‐LED display is a quite new technology which has developed only about a decade and been attracting tremendous attention in recent years. It was regarded as a great candidate for many applications, especially a new generation display technology. Here we report a design of active matrix Micro‐LED display including Micro‐LED array fabrication, AM driving circuit and flip‐chip integration. 4T2C (4 transistors and 2 capacitors) driving circuits with a configuration of current control current source (CCCS) was used for better pixels uniformity and display quality.

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Matrix-Addressable Micropixellated InGaN Light-Emitting Diodes With Uniform Emission and Increased Light Output

Cited by 72 publications

References 17 publications

Strain relaxation in InGaN/GaN micro-pillars evidenced by high resolution cathodoluminescence hyperspectral imaging

Strain relaxation in InGaN/GaN micro-pillars evidenced by high resolution cathodoluminescence hyperspectral imaging

Active-Matrix GaN Micro Light-Emitting Diode Display With Unprecedented Brightness

25.3: Current Driving Active Matrix Micro‐LED Display

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