Epitaxial Growth for Micro-LED Manufacturing

A manufacturing method for improving the uniformity of micro LED epitaxial layers. This method helps to ensure a consistent thickness and wavelength of the epitaxial layer. The method involves using a patterned substrate with receiving grooves. These grooves are strategically placed to catch the excess epitaxial material as it is grown. This prevents the uneven thickness caused by centrifugal forces during rotation. The grooves are also positioned to gradually increase the density away from the center. The epitaxial layer is grown on the grooved substrate, which helps to retain the excess material in the grooves. This results in a more uniform layer thickness and wavelength. The groove pattern can be checked to verify the effectiveness of the manufacturing method.

Source

This patent covers a micro LED chip design that is optimized for efficient red light emission. The chip is built using a GaAs epitaxial structure, which has a tunneling junction layer sandwiched between N-type and P-type layers. This structure enhances electron-hole recombination in the light-emitting layer, resulting in efficient red light emission. The chip has electrodes on one side and features a concave platform that exposes the N-type window layer. The tunneling junction layer is also doped for optimal electron tunneling. This helps to further improve the efficiency of the chip.

Source

A method for manufacturing micro-LEDs that increases LED efficiency. Micro-LEDs are typically manufactured by cutting the wafer into individual chips. This process can cause bond breakage, which reduces the efficiency of the LED. This patent describes a method to avoid this problem. The method involves growing vertical epitaxial walls around each micro-LED chip before cutting the wafer. This effectively isolates the chips, preventing bond breakage. As a result, the LED efficiency is improved.

Source

This patent describes a micro LED device and a method for manufacturing it. The device is composed of an epitaxial layer stack with a support layer, n-type semiconductor, an active layer, and p-type semiconductor. Electrical contact is made to the n-type and p-type semiconductors through electrodes. The method for manufacturing the device involves growing the epitaxial layer stack using techniques like MOCVD. After this, the n-type and p-type electrodes are formed separately on the exposed surfaces of the semiconductors. This process ensures that the device is manufactured with the highest level of precision and accuracy.

Source

Preparing high quality LED epitaxial structures by stepwise growth of the P-type AlGaN barrier layer to reduce defects and improve efficiency. The growth rate and Al composition are incrementally increased in multiple stages instead of abruptly changing. This allows time for indium atoms to desorb before growing the barrier, preventing surface roughness. It also reduces growth time compared to a single high rate stage. The stepwise growth improves epitaxial structure quality and yield.

Source

A method to grow GaN-based LEDs on sapphire substrates with improved crystal quality and reduced defects. The method involves growing an initial AlxGa1-xN layer on the sapphire substrate, followed by a GaN layer. This two-step process reduces the lattice mismatch between the GaN and sapphire compared to direct GaN growth. The AlxGa1-xN layer acts as an interlayer to mitigate strain and defects. The AlxGa1-xN composition is optimized to balance lattice match and electrical properties for the LED application.

Source

Epitaxial structure, manufacturing method, and light-emitting device to reduce the impact of lattice mismatch on luminescence in microLEDs grown on heterogeneous substrates. The method involves dividing the substrate into regions along a parallel direction, growing sacrificial layers in some regions, and alternating semiconductor layers in the remaining region. This creates isolated epitaxial stacks with sacrificial layers between. After growth, the sacrificial layers are removed to separate the stacks. This reduces lattice strain accumulation during growth and improves crystal quality compared to sequential growth.

Source

A method for growing high quality LED epitaxial structures with improved internal quantum efficiency. The method involves a specific sequence of layer growth steps in an MOCVD reactor. It involves inserting multiple AlN layers with varying temperatures between the InGaN quantum wells. This creates potential barriers to confine holes and prevent leakage. It also uses pulsed NH3 feeds during AlN growth to reduce dislocations. This enhances hole concentration and recombination probability within the quantum wells, improving LED efficiency.

Source

LED epitaxial structure and growth method to improve LED brightness. The method involves growing the LED structure in steps where alternate layers of Si-doped and Si-undoped GaN are used in the superlattice layers. The doping alternation in the superlattices increases the electron concentration and extraction efficiency from the core light-emitting layer. This leads to higher LED brightness compared to continuous doping. The optimal number of alternating doping cycles in the superlattices was found to be 6-20.

Source

This patent describes a method to reduce non-radiative recombination in micro-LEDs. Non-radiative recombination occurs when electrons and holes recombine without emitting light. This reduces the efficiency of the LED. The method involves repairing defects on the sidewalls of the mesa structures and passivating them to prevent non-radiative recombination. After etching the mesas, the repair and passivation are achieved by performing two stages of atomic layer deposition (ALD) on the etched LED epitaxial wafer. The first ALD repairs any dangling bonds or defects on the sidewalls. The second ALD deposits a passivation layer on the repaired sidewalls to reduce non-radiative recombination. This helps to increase the efficiency of the LED and reduce non-radiative recombination.

Source

A method to improve LED efficiency by reducing stacking faults and improving crystallization quality in LED epitaxy. The method involves introducing a stress release layer between the n-type GaN layer and the light-emitting layer. The stress release layer has a first superlattice section with lower In content compared to a second superlattice section. The lower In content in the first section reduces stacking faults compared to direct growth of the second section. This prevents defects caused by lattice mismatch between GaN and InGaN. The gradual In content increase in the second section still provides strain relief.

Source

A method for manufacturing microLEDs with improved efficiency and reliability. It involves depositing a support layer, first-type semiconductor layer, active layer, and second-type semiconductor layer on a substrate. This forms the epitaxial layered structure of the LED. Then electrodes are formed on the first and second semiconductor layers. The LEDs are then separated from the substrate and packaged. The key aspect of this method is the use of a support layer beneath the first-type semiconductor layer. This layer provides mechanical stability during the separation step. This prevents damage to the LED structure and maintains performance. This layer is the key to the improved efficiency and reliability of the microLEDs produced using this method.

Source

A method for preparing epitaxial wafers with higher LED chip brightness by improving the crystal quality of the epitaxial layer. The method involves growing the GaN layer in steps, with selective etching of poor quality regions using chlorine gas. This involves growing the GaN layers as normal, but then feeding chlorine gas at a low rate for a short time after the initial growth of the 3D GaN. This removes defective GaN areas while leaving the better quality GaN intact. The process is repeated several times to improve the overall crystal quality of the epitaxial layer.

Source

Growing high-efficiency LED epitaxial wafers for applications like mini and micro LED displays. The method involves a growth sequence for the active layer that reduces the current density required for peak external quantum efficiency. It involves pre-doping In into the reaction chamber before growing the barrier layers, then alternately stacking InGaN wells and GaN barriers with the GaN barrier growth rate higher than the InGaN. This provides a lattice match, reduces defects, and improves carrier confinement compared to just stacking InGaN wells.

Source

LED epitaxial structure with reduced dislocations for improved device performance. The structure has a transition layer between the substrate and the two-dimensional growth layer. The transition layer alternates between undoped and silicon-doped gold nitride layers. The growth conditions are controlled to minimize dislocation generation. This reduces dislocations compared to growing directly from substrate to two-dimensional layer. The silicon doping helps electron injection. The transition layer improves crystal quality before transitioning to the two-dimensional structure for better device performance.

Source

A method to prepare Micro LED epitaxial wafers with reduced dislocation density for improving the electrical consistency and performance of Micro LED devices. The method involves secondary growth of an aluminum nitride buffer layer on the substrate followed by cyclical growth of 3D-type nitride using varying temperatures, pressures, and rotation speeds. This allows annihilation of threading dislocations between the substrate and nitride layers, resulting in Micro LED epitaxial wafers with lower dislocation density compared to conventional methods.

Source

Epitaxially growing a gallium nitride (GaN) light-emitting diode (LED) structure on silicon without significant compressive stress that degrades material quality. The method involves depositing a GaN layer sequence on silicon followed by an LED structure. But instead of growing the LED directly on the GaN, a masking layer is inserted between the GaN and LED layers. This masks the underlying GaN from the LED growth, preventing stress transfer. The masking layer can have windows to allow LED current flow. The LED is then detached from the GaN for use.

Source

Epitaxial growth method for LEDs that improves brightness under high current injection. The method involves inserting a graded p-type AlGaN layer before the quantum wells, controlling the Al composition to gradually increase and then decrease during growth. This forms a built-in polarization voltage inside the quantum wells that reduces activation energy for hole injection. It also involves using alternate growth of InxGa(1-x)N/GaN layers with gradually increasing Alx to improve crystal quality and reduce roughness of the quantum wells.

Source

GaN-based LED epitaxial growth method to improve crystal quality by reducing dislocation density and improving LED performance. The method involves a process called pre-spreading Al on the sapphire substrate before GaN growth. This involves coating a thin layer of aluminum nitride (AlN) on the substrate, followed by annealing to spread the Al into the sapphire. This modified substrate is then used for the LED epitaxial growth. The Al pre-spreading reduces dislocation density in the GaN layers, improving crystal quality and LED performance.

Source

A manufacturing method for silicon-based GaN-HEMT epitaxial structures that improves growth uniformity, device performance, and reliability. The method involves using optimized carrier gas ratios during metal organic chemical vapor deposition (MOCVD) growth. The nitrogen source gas ratio is adjusted to 1.75-2.5 with hydrogen carrier gas. This improves growth rate uniformity, thickness uniformity, Al component uniformity, and 2DEG mobility in the epitaxial layers. Additionally, partitioning the showerhead gas outlets into central and edge areas and independently controlling them maintains growth uniformity from the center to edge of the wafer.

Source