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Design and Simulation of Low Circadian Action Micro-LED Displays with Four Primary Colors
摘要： Nowadays, displays are ubiquitous in our daily lives. Long-time exposure to a display’s unnatural light could influence the user’s circadian rhythm, especially at night. Here, we propose a four-color micro-light-emitting diode (LED) display to achieve low circadian action for nighttime uses. Specifically, we evaluate the RGBW-type (red, green, blue, and white) and RYGB-type (red, yellow, green, and blue) micro-LED displays in terms of circadian effect and color gamut coverage. With the addition of an extra white subpixel, it was found that the circadian effect at night can be reduced dramatically, but the color gamut remains unchanged. However, with an additional yellow subpixel, both the circadian effect and color gamut were found to improve. Finally, we simulated the circadian illuminance of real image contents for different displays. In comparison with existing liquid crystal displays, organic LED displays, and RGB (red, green, blue) micro-LED displays, the proposed four-primary-color micro-LED displays can significantly reduce the circadian effect at night.
关键词： micro-LEDs,circadian action,four primary colors
更新于2025-09-23 15:21:01
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High performance GaN-based hybrid white micro-LEDs integrated with quantum-dots
摘要： Hybrid white micro-pillar structure light emitting diodes (LEDs) have been manufacture utilizing blue micro-LEDs arrays integrated with 580 nm CIS ((CuInS2-ZnS)/ZnS) core/shell quantum dots. The fabricated hybrid white micro-LEDs have good electrical properties, which are manifested in relatively low turn-on voltage and reverse leakage current. High-quality hybrid white light emission has been demonstrated by the hybrid white micro-LEDs after a systemic optimization, in which the corresponding color coordinates are calculated to be (0.3303, 0.3501) and the calculated color temperature is 5596 K. This result indicates an effective way to achieve high-performance white LEDs and shows great promise in a large range of applications in the future including micro-displays, bioinstrumentation and visible light communication.
关键词： hybrid white micro-LEDs,GaN,quantum dots
更新于2025-09-23 15:19:57
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Nanoscale Characterization of Surface Plasmon-Coupled Photoluminescence Enhancement in Pseudo Micro Blue LEDs Using Near-Field Scanning Optical Microscopy
摘要： The microcave array with extreme large aspect ratio was fabricated on the p-GaN capping layer followed by Ag nanoparticles preparation. The coupling distance between the dual-wavelength InGaN/GaN multiple quantum wells and the localized surface plasmon resonance was carefully characterized in nanometer scale by scanning near-field optical microscopy. The effects of coupling distance and excitation power on the enhancement of photoluminescence were investigated. The penetration depth was measured in the range of 39–55 nm depending on the excitation density. At low excitation power density, the maximum enhancement of 103 was achieved at the optimum coupling distance of 25 nm. Time-resolved photoluminescence shows that the recombination life time was shortened from 5.86 to 1.47 ns by the introduction of Ag nanoparticle plasmon resonance.
关键词： near-field scanning optical microscopy,micro-LEDs,localization surface plasmon
更新于2025-09-23 15:19:57
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Investigation of Electrical Properties and Reliability of GaN-Based Micro-LEDs
摘要： In this paper, we report high-performance Micro-LEDs on sapphire substrates, with pixel size scaling to 20 μm and an ultra-high current density of 9902 A/cm2. The forward voltages (VF) of the devices ranged from 2.32 V to 2.39 V under an injection current density of 10 A/cm2. The size and structure-dependent effects were subsequently investigated to optimize the device design. The reliability of Micro-LED devices was evaluated under long-aging, high-temperature, and high-humidity conditions. It was found that Micro-LED devices can maintain comparable performance with an emission wavelength of about 445 nm and a full width at half maximum (FWHM) of 22 nm under extreme environments. Following this, specific analysis with four detailed factors of forward voltage, forward current, slope, and leakage current was carried out in order to show the influence of the different environments on different aspects of the devices.
关键词： GaN-based micro-LEDs,micro-LED display,reliability test
更新于2025-09-19 17:13:59
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Performance analysis of GaN-based micro light-emitting diodes by laser lift-off process
摘要： In this study, a monochromatic GaN-based micro-light-emitting-diode (μLED) array was fabricated using flip-chip technology. The laser lift-off (LLO) process was employed to decrease the light divergence caused by the differing refractive indexes of sapphire (n = 1.77) and GaN (n = 2.4). The LLO-μLEDs considerably improve light collimation, compared with conventional flip-chip μLEDs containing a sapphire substrate. We highlight, in particular, the importance of the optical characteristics before and after LLO. Collimation of light was discovered to be 12% higher after removal of the sapphire substrate. The results are of high importance for understanding the optical properties of μLED arrays after LLO.
关键词： Light-emitting diodes,Micro-LEDs,Laser lift-off,GaN
更新于2025-09-19 17:13:59
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[IEEE 2019 41st Annual International Conference of the IEEE Engineering in Medicine & Biology Society (EMBC) - Berlin, Germany (2019.7.23-2019.7.27)] 2019 41st Annual International Conference of the IEEE Engineering in Medicine and Biology Society (EMBC) - A wearable phototherapy device utilizing micro-LEDs
摘要： A conformable device for wearable phototherapy applications is presented. The device consists of a 1mm thick elastomeric membrane edge-lit by specially fabricated micro-sized LEDs. Nanoparticle based scattering films are utilized to extract light and a uniform emission of 15μW/cm2 is reported over an area of 2cm2.
关键词： micro-LEDs,elastomeric membrane,light extraction,wearable phototherapy,uniform emission
更新于2025-09-16 10:30:52
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Strategy toward ultra-high-resolution micro-LED displays by bonding interface-engineered vertical stacking and surface passivation
摘要： In this paper, we have proposed the strategy to fulfill the vertically stacked subpixel (VSS) micro-light-emitting diodes (μ-LEDs) for future ultra-high resolution microdisplays. At first, to vertically stack the LED with different colors, we have successfully adopted the bonding interface engineered monolithic integration method by using SiO2/SiNx distributed Bragg reflectors (DBRs). It was found that an intermediate DBR structure can be performed as the bonding layer and the color filter, which can reflect and transmit desired wavelengths the bonding interface. Furthermore, the optically pumped μ-LEDs array with 0.4 μm pitch corresponding to ultra-high-resolution of 63500 PPI was successfully fabricated by using typical semiconductor processing, including electron-beam lithography. Compared with pick-and-place with the limitation of the machine alignment accuracy, there is a significant improvement for fabricating the high-density μ-LEDs. Finally, we have systematically investigated the effects of surface traps by using time-resolved photoluminescence (TRPL) and two-dimensional simulation. These results clearly demonstrated that performance improvements could be possible by employing the optimal passivation techniques according to diminishing the pixel size for low power and highly-efficient microdisplays.
关键词： ultra-high-resolution,micro-LEDs,wafer bonding,distributed Bragg reflectors,surface passivation
更新于2025-09-11 14:15:04
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30.2: <i>Invited Paper:</i> A RGB chip Full Color Active Matrix Micro‐LEDs Transparent Display with IGZO TFT Backplane
摘要： In this paper, the first time reported the full color active matrix micro-LEDs (AMLEDs) display with high transparent over 40% which is based on top gate IGZO TFT (Thin film transistor) backplane. This AMLEDs display was successfully developed with flip chip RGB micro-LEDs that can achieve more than 108% NTSC gamut, while the display is also brighter than 400nits.
关键词： micro-LEDs,Active Matrix,High Transparent,Full Color,IGZO TFT backplane
更新于2025-09-11 14:15:04
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Light Extraction Enhancement of InGaN Based Micro Light-Emitting Diodes with Concave-Convex Circular Composite Structure Sidewall
摘要： We demonstrate that the concave-convex circular composite structure sidewall prepared by inductively coupled plasma (ICP) etching is an effective approach to increase the light efficiency without deteriorating the electrical characteristics for micro light-emitting diodes (LEDs). The saturated light output power of the device using the concave-convex circular composite structure sidewalls with a radius of 2 μm is 39.75 mW, an improvement of 7.2% compared with that of the device using flat sidewalls. The enhanced light output characteristics are primarily attributed to the increased photon emitting due by decreasing the total internal reflection without losing the active region area.
关键词： ICP,micro-LEDs,light extraction efficiency,InGaN/GaN,concave-convex circular composite structure sidewall
更新于2025-09-11 14:15:04
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Omnidirectional optogenetic stimulation
摘要： Omnidirectional optogenetic stimulation. A wireless, low-power optoelectronic platform, which is based on micro-LEDs, can provide multimodal programmable control over optogenetic stimulation parameters. Optogenetics is a powerful tool for perturbing populations of specific cell types. Here, individual cell types of the central and peripheral nervous systems are tagged with light-sensitive opsins. Specific wavelengths of light can then be used to turn the cells off and on, allowing complex neural circuitry to be dissected. For example, blue light can be used to activate neurons and green light can be used to deactivate neurons depending on the expression of either channelrhodopsin-2 (ChR) or halorhodopsins (Halo), respectively. The technique has been important in elucidating new neural pathways in many preclinical models of disease (including those related to memory, depression, sleep, anxiety, and restoration of vision) and could lead to potential new disease targets.
关键词： wireless,micro-LEDs,optogenetics,disease models,neural circuitry
更新于2025-09-04 15:30:14