Ultra-bright green InGaN micro-LEDs with brightness over 10M nits

Zhanghu, Mengyuan; Hyun, Byung‐Ryool; Jiang, Fulong; Liu, Zhaojun

doi:10.1364/oe.451509

Cited by 23 publications

(16 citation statements)

References 40 publications

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“…As illustrated in Figure b, the R region of region 2 is higher than that of region 1 when the current ranges from 10 to 3000 μA. As illustrated in Figure c, the peak energy of region 1 is obviously higher than that of region 2, indicating that the minimum energy of the local potential in region 1 is higher than those in the inner region of mesa, which is mainly attributed to the reduction of band bending and polarization originating from the strain relaxation at the edge of mesa. , …”

Section: Resultsmentioning

confidence: 88%

“…As illustrated in Figure 9c, the peak energy of region 1 is obviously higher than that of region 2, indicating that the minimum energy of the local potential in region 1 is higher than those in the inner region of mesa, which is mainly attributed to the reduction of band bending and polarization originating from the strain relaxation at the edge of mesa. 33,34 The separation between peak energies among selected regions decreases with increasing current due to the bandfilling effect. Nevertheless, as shown in Figure 9d, the FWHM of region 2 is larger than that of region 1.…”

Section: Acs Photonicsmentioning

confidence: 99%

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Origin of the Inhomogeneous Electroluminescence of GaN-Based Green Mini-LEDs Unveiled by Microscopic Hyperspectral Imaging

et al. 2022

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Although high quantum efficiency has been achieved in large-sized InGaN/GaN LEDs operating at relatively high current densities (above 35 A/cm 2 ), the operating current density of mini-LEDs (around 1 A/cm 2 ) is far less than that of traditional large-sized LEDs. The low external quantum efficiency (EQE) of mini-LEDs at small current densities seriously hinders their practical applications, highlighting the importance of investigating the radiative recombination mechanisms of mini-LEDs at small current densities. By using microscopic hyperspectral imaging, the cryogenic electroluminescence (EL) of GaN-based green mini-LEDs mainly originating from localized excitons was demonstrated experimentally. Based on the dependence of electron−phonon coupling on current and temperature, Coulomb screening of the polarization field weakens the electron−phonon coupling, whereas the band-filling effect enhances the coupling. Coulomb screening of the polarization field can also reduce the deviation of the localization. The EL from edge regions of the mesa adjacent to the sidewall possesses relatively higher peak energy due to the strain relaxation. Results of this work also suggest that optimization of the chromatic characteristics and efficiency can be achieved by strain engineering of GaN-based green mini-LEDs.

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Section: Resultsmentioning

confidence: 88%

Section: Acs Photonicsmentioning

confidence: 99%

Origin of the Inhomogeneous Electroluminescence of GaN-Based Green Mini-LEDs Unveiled by Microscopic Hyperspectral Imaging

et al. 2022

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“…We measured peak external quantum efficiency (EQE) of our uLEDs to be ∼7% by placing a 70mm 2 photodiode (Thorlabs S120VC) against the sapphire substrate and measuring the bottom-emitted output power (Figure 1g). Since GaN-based µLED efficiency has been reported as high as 15% EQE for comparable µLEDs 47, 64 , additional process development is likely to yield further improvements in efficiency.…”

Section: Resultsmentioning

confidence: 99%

A thin-film optogenetic visual prosthesis

Knudsen

Zappitelli

Brown

et al. 2023

Preprint

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Retinitis pigmentosa and macular degeneration lead to photoreceptor death and loss of visual perception. Despite recent progress, restorative technologies for photoreceptor degeneration remain largely unavailable. Here, we describe a novel optogenetic visual prosthesis (FlexLED) based on a combination of a thin-film retinal display and optogenetic activation of retinal ganglion cells (RGCs). The FlexLED implant is a 30 um thin, flexible, wireless uLED display with 8,192 pixels, each with an emission area of 66 um2. The display is affixed to the retinal surface, and the electronics package is mounted under the conjunctiva in the form factor of a conventional glaucoma drainage implant. In a rabbit model of photoreceptor degeneration, optical stimulation of the retina using the FlexLED elicits activity in visual cortex. This technology is readily scalable to hundreds of thousands of pixels, providing a route towards an implantable optogenetic visual prosthesis capable of generating vision by stimulating RGCs at near-cellular resolution.

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“…For μLEDs, its EQE decreases as the mesa size decreases due to sidewall defects and surface recombination. Even if we assume that all the produced light from μLEDs can be coupled into the AR/VR imaging system, in comparison with blue 25,26 and green InGaN μLEDs 25,[27][28][29] in which EQE is size dependent, our blue nanowire LED still has a higher EQE than μLED whose mesa size is smaller than 10 μm as shown in Figure 7. The advantage of nanowire is pronounced for green light emission and the effective LEE of green nanowire LEDs is even higher than that of 80-μm μLED.…”

Section: Performancementioning

confidence: 99%

High‐efficiency nanowire light‐emitting diodes for augmented reality and virtual reality displays

et al. 2023

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Through 3D dipole cloud model, RGB (red, green, and blue) nanowire light‐emitting diode (LED) structures are geometrically optimized to exhibit a narrower radiation pattern, weaker angular color shift, and higher optical efficiency. In comparison with micro‐LEDs whose external quantum efficiency is dependent on the mesa size, these RGB nanowire LEDs are more efficient than micro‐LEDs when the chip size is below 20, 80, and 10 μm, respectively. As a result, nanowire LED is a promising candidate for augmented reality and virtual reality displays where high‐resolution density and efficient directional light emission are desired.

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Ultra-bright green InGaN micro-LEDs with brightness over 10M nits

Cited by 23 publications

References 40 publications

Origin of the Inhomogeneous Electroluminescence of GaN-Based Green Mini-LEDs Unveiled by Microscopic Hyperspectral Imaging

Origin of the Inhomogeneous Electroluminescence of GaN-Based Green Mini-LEDs Unveiled by Microscopic Hyperspectral Imaging

A thin-film optogenetic visual prosthesis

High‐efficiency nanowire light‐emitting diodes for augmented reality and virtual reality displays

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