Optical Modules for Micro-LED Displays

Abstract InGaN red micro-LEDs were fabricated with indium tin oxide (ITO) and metal n-electrode designs. Micro-LEDs ITO electrodes achieved a peak on-wafer external quantum efficiency of 2.1% (at 1.25 A/cm2) wall-plug 1.7% 0.64 A/cm2), representing 1.6 times 1.5 improvements compared to metal-based electrodes. Improved performance was attributed the transparency ITO, enabling light extraction, while block emission. Both configurations low leakage current density ( 107 high emission wavelength around 650 nm. These results represent strong potential for low-power consumption required/area-limited AR/VR applications.

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Anti-aliasing technique for microLED displays that improves image smoothness by adjusting brightness levels within individual pixels. The technique uses microLED displays with each pixel containing a group of three differently colored microLEDs covered by a scattering plate. By controlling the brightness of the individual microLEDs inside a pixel, it allows gradual color transitions between pixels for smoother images compared to using fixed color filters.

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Transferring micro-LEDs using a stamp with shape memory polymer nanotips to pick up and release the devices. The stamp has nanotips that can selectively adhere to the micro-LEDs due to shape memory properties. The nanotips heat to a critical temperature, contact the LED, press to attach, cool below critical temp, align on substrate, then heat again to transfer. This allows precise pickup, placement, and repair of micro-LEDs.

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Using microLED arrays in applications beyond just displays, like augmented reality (AR) and virtual reality (VR) devices, by integrating compact light sources made of microLED arrays into these devices. The microLED arrays provide smaller, more efficient light sources compared to traditional light sources. This allows for improved AR/VR devices with better display brightness, contrast, and power efficiency.

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MicroLED display to prevent crosstalk and improve brightness by inserting blocking regions between each color conversion region. The blocking regions prevent light from one subpixel leaking into adjacent subpixels, reducing crosstalk. This is achieved by forming the microLED structure with separate pores for the color conversion regions and additional blocking regions in between. The color conversion material is filled in the color conversion pores and the blocking regions are left empty. This prevents light from one subpixel leaking into adjacent subpixels, reducing crosstalk.

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An allGaNbased monolithic activematrix microLED system that integrates metalinsulatorsemiconductor highelectronmobility transistors (MIS HEMTs) with lightemitting diodes (LEDs) is demonstrated. The proposed structure employs direct electron injection from the 2D gas (2DEG) in a HEMT, serving as ntype layer, into quantum wells of LEDs. A 2HEMT1LED pixel configuration fabricated one epitaxial growth, enabling precise control LED light output through combination select and drive HEMTs. achieved maximum optical density 0.5 Wcm 2 . 2 matrix constructed row column lines connected via HEMTs, demonstrating capability for individual control.

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Abstract Microlight emitting diode (LED) based LED on silicon (LEDoS) is a promising candidate for nextgeneration AR and VR displays due to superior pixel performance potential high resolution. Traditional RGB pixels are placed single plane, which limits the To overcome this, vertically stacked using heterogeneous monolithic 3D integration (M3D) have been explored. However, previously reported vertical LED not considered heat dissipation capability of pixels, indeed important in future micro displays, utilized materials incompatible with standard CMOS processes, further limiting their practicality LEDoS. The critical regions constraint, bonding medium, typically organic polymer materials. Therefore, handle issue, fullcolor LEDs demonstrated oxide (SiO 2 ) yttrium (Y O 3 ), as mediums. These CMOScompatible offer thermal conductivity at least 10 times higher than conventional polymers. InGaN/GaN blue bonded oxides show improved management, leading external quantum efficiency (EQE) better color characteristics, including narrower full width half maximum (FWHM) purity. ... Read More

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Display apparatus with a pixel structure that allows combined light emission and light sensing in each subpixel. The pixel has subpixels, at least one of which has a light-emitting and light-receiving device instead of a regular light-emitting device. This allows the display to emit light and also detect light in the same subpixel. This enables multifunctionality like displaying an image and sensing light simultaneously. The light-emitting and light-receiving device has a structure with electrodes for emitting and sensing light.

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Display device with integrated components in the display area and an opening for other components. The display has a substrate with an opening surrounded by a display area. Grooves are formed between the opening and display using a layer with different etch selectivity compared to the main insulating layer. This allows etching grooves without damaging the display elements. It enables integrating components like sensors or cameras into the display while preventing contamination of the display area.

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A light-emitting element transfer stamp and manufacturing method for pickup and placement of micro-LEDs without complex spring structures or high voltages. The stamp has adhesive layers in grooves that protrude above the stamp. This allows selective picking up of micro-LEDs from a growth substrate by adhesion force, then releasing to transfer onto a target substrate. A passivation layer prevents sticking between layers. The stamp material has thermal expansion matching the LED substrate. The stamp has a buffer layer with thermal conductivity between the stamp and a heater wire. This enables local heating for stamp deformation and release of the LEDs. The stamp structure allows micro-LED transfer without complex springs or high voltages.

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Packaging design for optical interconnects that allows vertical transmission between stacked optical components using integrated lenses and reflectors. The packaging involves bonding optical interposers and optical packages vertically aligned with lenses between them. The reflectors in each interposer are aligned vertically to transmit light between the packages. This enables vertical optical transmission between stacked optical components using integrated lenses and reflectors instead of through-the-substrate techniques.

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Arrangement and method for simplified assembly of compact optoelectronic devices like microLED displays with improved uniformity and reduced tilt. The devices have small-sized semiconductor components with side walls insulated and absorbing to prevent tilt. They are mounted on a carrier with a transparent output element and connected via an insulating layer. The components' contacts are electrically accessed from the rear. This allows easier assembly of small-pitch arrays with uniform radiation and reduced crosstalk. The method involves applying the components, insulation, and output element on a carrier, then connecting the contacts.

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Micro LED display panel design to improve display quality by reducing aberrations and crosstalk between subpixels. The key idea is to surround the LED chip with a symmetrical void in the prism layer. This ensures equal distances between the LED and void in the transverse and oblique directions. The symmetry allows the light rays to reflect identically in both directions, preventing asymmetric focal planes and reducing astigmatism. It also prevents light crosstalk between subpixels by reflecting the rays back into the LED instead of spreading them.

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Light emitting module with reduced stray light on the irradiation surface. The module has a lens over the light source, and a cover over the lens. The cover has three regions: an inner region where light from the lens enters, a middle region around the inner region with higher diffusion, and an outer region. This configuration reduces stray light by having the cover's middle region with higher diffusion surrounding the inner region where light from the lens enters, preventing light from escaping sideways.

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Micro LED display panel with integrated micro lenses to simplify manufacturing. Each micro LED structure has a first type epitaxial layer, a light emitting layer, and a second type epitaxial layer. The second type epitaxial layer has an integrated structure containing both a micro lens and a bottom layer. This eliminates the need for a separate micro lens manufacturing step.

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An optical laminate with improved light extraction. The laminate has a light extraction layer with recessed areas, covered by two sheets separated by adhesive. The recessed areas form air gaps between the sheets. The laminate also optionally has a thin porous layer between the light extraction layer and the adhesive. The air gaps and porous layer lower the refractive index in certain regions, improving light extraction compared to solid adhesive.

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Transparent display device with improved resolution and repair capability. The display has sub-pixels containing red, green, and blue LEDs, along with a reserve sub-pixel with stacked red, green, and blue LEDs. If any LED in a normal sub-pixel fails, the reserve LEDs can replace them. Stacking the reserve LEDs reduces area compared to parallel LEDs. The reserve LED electrodes are transparent to allow light from lower LEDs to escape. This allows repair and area savings while maintaining light output.

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Optical stack and backlight design for high dynamic range displays using blue LEDs instead of white backlights. The optical stack reflects blue light with a specific polarization and transmits orthogonal polarization. This allows collimated blue light with low divergence to be used in displays with blue-only backlights. The stack has high reflection in the blue range for one polarization and high transmission for the orthogonal polarization. This preserves blue light while suppressing cross-talk between pixels in blue-only displays. The collimated blue light can be generated by blue LEDs and reduces the need for color filters in the display.

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MicroLED displays with containers for color conversion materials like quantum dots that have varying diameter profiles along their length. This shape provides better light coupling efficiency compared to cylindrical containers. The containers have a waist section with a smaller diameter than the end faces. This design helps collect more emitted light from the LED into the display's acceptance angle. It balances couplings between LED, quantum dots, microlens, and display acceptance cone for improved overall display performance.

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Display module with micro-lenses to improve brightness of microLED displays. The display module has a color filter layer with light-filtering sections, and a micro-lens layer with converging lenses. Each micro-lens is aligned with a color filter section. Gaps are provided between adjacent micro-lenses. Additional converging lenses are placed in these gaps to capture light from the gaps and focus it. This improves brightness by reducing light spread and improving convergence.

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