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Coupled thermoa??electrical analysis of highly scaled GaN micro-LEDs with meshed hybrid conductors
摘要： Display technology with ultrafine pixels for near-eye application is a rapidly growing field due to the recent emergence of augmented/mixed reality. With the constant demand for high energy efficiency, long lifetime, and high luminosity, micro-LED displays based on compound semiconductors are promising candidates for such applications. However, miniaturizing LEDs results in significant drawbacks in terms of their quantum efficiency, current injection efficiency, and heat extraction. With relatively low device resistance compared to that of liquid crystals or organic LEDs, micro-LEDs are also more susceptible to the effects of parasitic resistance. In this study, gallium nitride based micro-LED displays with very small pixels (5 μm pixel, 10 μm pitch) are fabricated to study the thermal–electrical effect of meshed hybrid conductors on the optical emission efficiency. In situ thermographic imaging with I–V measurement confirms a significant trade-off among heat transfer, electrical conductivity, and light extraction efficiency. An increase of 37.9 % in the emission efficiency (2,540 PPI, 5 μm pixels, 1 mm2 display, at 49.2 ℃) is achieved by optimizing the thermal and electrical conduction paths. This study experimentally confirms the importance of thermal management and multi-physics analysis in designing ultra-small-pixel micro-LEDs with high energy efficiency.
关键词： hybrid transparent conductor,Thermo–electrical analysis,gallium nitride,micro-LED
更新于2025-09-23 15:21:01
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High-quality nanodisk of InGaN/GaN MQWs fabricated by neutral-beam-etching and GaN regrowth: Towards directional micro-LED in top-down structure
摘要： A nanodisk array of blue InGaN/GaN multiple quantum wells was made using neutral beam etching (NBE) followed by GaN regrowth. The NBE-fabricated nanodisk presented a vertical and highly smooth sidewall surface where the InGaN well layers were easily distinguished even with a scanning electron microscope. A high interface quality without any voids or obvious defects was obtained between the nanodisk and the regrown-GaN layer. The nanodisk after regrowth presented a smaller blueshift of photoluminescence emission energy (12 meV) and a substantially higher and almost constant internal quantum efficiency of ~50% over three orders of magnitude of excitation laser power when compared to the nanodisk before regrowth. This study shows that the process of NBE nanodisk etching followed by GaN regrowth represents a promising step forward in the development of truncated cone-shaped directional micro-LEDs with a buried active region in a top-town structure.
关键词： Regrowth,InGaN/GaN MQWs,Directional micro-LED,Nanodisk,Neutral beam etching
更新于2025-09-23 15:21:01
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A discrete core-shell-like micro-light-emitting diode array grown on sapphire nano-membranes
摘要： A discrete core-shell-like micro-light-emitting diode (micro-LED) array was grown on a 100 nm-thick sapphire nano-membrane array without harmful plasma etching for chip singulation. Due to proper design for the sapphire nano-membrane array, an array of multi-faceted micro-LEDs with size of 4 μm × 16 μm was grown. threading dislocation density in the micro-LeD formed on sapphire nano-membrane was reduced by 59.6% due to the sapphire nano-membranes, which serve as compliant substrates, compared to GaN formed on a planar substrate. Enhancements in internal quantum efficiency by 44% and 3.3 times higher photoluminescence intensity were also observed from it. Cathodoluminescence emission at 435 nm was measured from c-plane multiple quantum wells (MQWs), whereas negligible emissions were detected from semi-polar sidewall facets. A core-shell-like MQWs were formed on all facets, hopefully lowering concentration of non-radiative surface recombination centers and reducing leakage current paths. This study provides an attractive platform for micro-LEDs by using sapphire nano-membrane.
关键词： internal quantum efficiency,photoluminescence,threading dislocation density,micro-LED,sapphire nano-membrane,core-shell-like,cathodoluminescence
更新于2025-09-23 15:21:01
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Improving the leakage characteristics and efficiency of GaN-based micro-light-emitting diode with optimized passivation
摘要： We investigated the effect of atomic layer deposition (ALD) Al2O3 (50 nm)/plasma-enhanced chemical vapour deposition (PECVD) SiO2 (250 nm) and PECVD SiO2 (300 nm) passivation layers on the leakage current and efficiency of InGaN-based micro-LEDs with different sizes. The micro-LEDs with the single passivation layer gave the ideality factors of about 2.0, while that with the double layer exhibited values smaller than 2.0. The micro-LEDs with the double passivation layer exhibited external quantum efficiency peaks at lower current density compared to those with the single layer. It was shown that smaller micro-LEDs were more sensitively dependent on the types of the passivation layers. These results exhibit that the ALD-Al2O3/PECVD-SiO2 passivation layer is more effective in suppressing the sidewall damage-induced current than the PECVD-SiO2 layer.
关键词： Atomic layer deposition,Micro-LED,Passivation,GaN
更新于2025-09-23 15:21:01
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Thermal and optical properties of high-density GaN micro-LED arrays on flexible substrates
摘要： Flexible GaN-based micron-size light-emitting diodes (μLEDs) with high brightness and low power-consumption are a promising technology for next-generation wearable displays. While, integrating GaN μLEDs onto flex can provide more functionality, the bending-induced strain and potential self-heating of the device are the challenges that degrade the device performance on plastic platforms. Here, a novel “paste-and-cut” approach to selectively transfer GaN μLEDs from sapphire substrates onto flexible platforms demonstrated the effectiveness of various intermediate metallic-bonding layers and LED geometries on the optical properties and performance of the flexible devices. Computational thermal simulation of the flexible μLEDs showed effective heat dissipation for devices mounted on plastic platforms bonded using a 0.5 μm thick Cu metallic pad to create stable optical emission (λ = 450 nm) under current densities of > 1 A/cm2. Through a finite-element analysis (FEA), it was determined that the applied stress-induced strain near the quantum wells of the μLEDs can be negligible for devices with diameters smaller than 20 microns. Experimental verification supported the simulation results; the diodes were found to be electrically and thermally stable when copper electrode layers > 600 nm thick was used to bond the LEDs onto the plastic platforms. The I-V characteristics of the μLEDs showed no measurable degradation after transfer onto the flexible substrate with a turn-on voltage of 2.5 V. Commensurate to the FEA simulations, no measurable optical wavelength shift was observed for LED having a diameter of 20 microns when driven at a current density of 1 A/cm2 under different mechanical strain.
关键词： Flexible Display,Heat Transfer,Invariant Emission,GaN Micro-LED
更新于2025-09-23 15:21:01
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High-Performance Color-Converted Full-Color Micro-LED Arrays
摘要： Color-converted micro-LED displays consisting of mono-blue-colored micro LED arrays and color-conversion materials have been used to achieve full color while reliving the transfer and epitaxial growth of three di?erent-colored micro LEDs. An e?cient technique is suggested to deposit the color-conversion layers on the blue micro LEDs by using a mixture of photo-curable acrylic and nano-organic color-conversion materials through the conventional lithography technique. This study attempts to provide a solution to fabricate full-color micro-LED displays.
关键词： full color,color-conversion,micro LED,GaN,light-emitting diode
更新于2025-09-23 15:19:57
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Analysis of Factors Affecting Optical Performance of GaN-Based Micro-LEDs with Quantum Dots Films
摘要： Optical performance in terms of light efficiency, color crosstalk and ambient contrast ratio were analyzed for blue GaN-based micro-light emitting diodes (micro-LEDs) combined with red/green quantum dots (QDs)-polymethyl methacrylate (PMMA) films. The thickness and mass ratio of QDs films are two critical factors in affecting the performance of micro-LEDs. Firstly, the precise optical modeling of QDs-PMMA films is established based on the double integrating sphere (DIS) testing system and inverse adding doubling algorithm (IADA) theory. Red and green QDs-PMMA films are composed of ZnCdSe/ZnS QDs and green ZnCdSeS/ZnS QDs, respectively. The fundamental optical parameters of QDs-PMMA films, including scattering, absorption and anisotropy coefficients, are obtained successfully. Secondly, based on these optical parameters, the Monte Carlo ray tracing method is applied to analyze the effect of a QDs-PMMA film’s thickness and mass ratio on the optical performance of micro-LEDs. Results reveal that the light efficiency first increases and then decreases with the increase of a QDs film's thickness or mass ratio, owing to the scattering characteristics of QDs. Different from the variation tendencies of light efficiency, the crosstalk between adjacent pixels increases as the QDs-PMMA film's thickness or mass ratio increases, and the ambient contrast ratio is kept stable when the thickness increases. The mass ratio variation of QDs film can change the optical performance of micro-LEDs more effectively than thickness, which demonstrates that mass ratio is a more important factor affecting the optical performance of micro-LEDs.
关键词： micro-LED,quantum dot,optical modeling,light efficiency
更新于2025-09-23 15:19:57
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Growth, transfer printing and colour conversion techniques towards full-colour micro-LED display
摘要： Micro light-emitting diode (micro-LED) display, mainly based on inorganic GaN-based LED, is an emerging technique with high contrast, low power consumption, long lifetime and fast response time compared to liquid crystal display (LCD) and organic light-emitting diode (OLED) display. Therefore, many research institutes and companies have conducted in-depth research on micro-LED in the full-colour display, gradually realizing the commercialization of micro-LED. And the current research results of micro-LED indicate that it can be widely used in display, visible light communication (VLC), biomedicine and other fields. Although micro-LED has broad commercial prospects, it still faces great challenges, such as the effect of size reduction on performance, the realization of high-density integration on a single wafer for independent addressing of full-colour micro-LED display, the improvement of repair technique and yield, et al. This paper reviews the key solutions to the technical difficulties of the full-colour micro-LED display. Specifically, this review analyzes and discusses a variety of advanced full-colour micro-LED display techniques with a focus on three aspects: growth technique, transfer printing technique and colour conversion technique. This review demonstrates the opportunities, progress and challenges of these techniques, aiming to guide the development of full-colour micro-LED display.
关键词： full-colour,growth,transfer printing,Micro-LED display,colour conversion
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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P‐9.14: High transparent Active matrix Mini‐LED Full Color Display with IGZO TFT Backplane
摘要： In this paper, we presented a active matrix Mini LED full color display with high transmittance over 60%. A 8-inch display with RGB Mini-LED with IGZO TFT backplane was demonstrated, which is 46 PPI pixel resolution and 256 grayscales and the pixel pitch is less than 0.55mm. It is the first time to realized the full color display based on RGB Mini-LEDs and chip on glass with top gate structure IGZO TFT backplane. We believe that it is a good breakthrough and demonstration for developing large-size Micro LED backplane and displays.
关键词： High transparent,Full Color,IGZO Glass Backplane,Active Matrix,Transparent,Active matrix,Micro LED,RGB Mini-LED Chip
更新于2025-09-19 17:13:59