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

LED epitaxial structure with improved uniformity and reduced warpage for higher yield and efficiency. The structure grows an AlGaN/AlN nucleation layer on a sapphire substrate followed by undoped GaN, n-type GaN, multiple quantum wells, p-type AlGaN, and p-type GaN. The key is growing a thin AlN layer on sapphire before GaN to reduce warpage during high-temperature GaN growth. The AlN layer promotes nucleation and adhesion of GaN on sapphire, reducing stress and warpage compared to direct GaN growth. The thin AlN layer can be 1-5 nm thick.

Source

A fabrication method for Micro-LEDs that reduces the Quantum-Confined Stark Effect (QCSE) and improves the quantum efficiency. QCSE is a phenomenon caused by the internal electric field in the active region of the LED. This field can cause the LED to lose its efficiency and brightness. To prevent this, the method described in this patent grows a buried p-GaN layer on a semi-polar III-nitride substrate before the active layers and n-GaN layer. This configuration opposes the strain-induced piezoelectric field with the built-in depletion field in the active region. This minimizes the internal electric field, thus reducing the QCSE and improving the quantum efficiency of the LED.

Source

Method for growing miniature LED epitaxial wafers with reduced warpage and improved consistency to meet requirements of high consistency of various parameters of the micro LED. The method involves alternately growing a thicker, high-temperature doped N-type layer and a thinner, lower-temperature undoped N-type layer multiple times. This repeatedly releases stress in the N-type layer to reduce warpage compared to growing a single thick N-type layer. Lowering the growth temperature for the thinner N-type layer also offsets some of the high-temperature layer's stress.

Source

A method for growing Micro LED epitaxial wafers with improved uniformity and reduced defects compared to conventional methods. The method involves stopping gas feed into the growth chamber, adjusting growth conditions in multiple stages, then introducing gas to grow each layer. This allows controlled environment adjustments before growth. It improves consistency of layers like the active region with quantum wells and barriers, reduces surface particles, and meets Micro LED requirements.

Source

A method for growing miniature LED epitaxial wafers that reduces particle generation during growth to improve LED quality. The method involves optimizing the amount of purge gas used in the reaction chamber cover based on factors like MO source usage, gas flow rates, layer thickness, doping concentration, and growth stage. This prevents byproducts from accumulating on the sidewalls and falling onto the wafer. By tailoring the purge gas for each layer, it ensures impurities are discharged instead of depositing on the growing LED.

Source

Reducing dislocation density in microLED epitaxial wafers to improve device performance and reliability. The method involves growing a nanopatterned nitrogen-rich layer on top of the epitaxial structure. This layer has a rough surface with nano-scale protrusions and recesses. The nanopatterned nitrogen-rich layer is sandwiched between the active LED layer and the bottom nitride layer. The nanopatterned layer acts as a stress relief layer that reduces dislocation propagation from the substrate into the LED layers. The nanopatterned layer promotes dislocation accumulation and annihilation at the protrusions and recesses, thus reducing dislocations in the LED layers.

Source

An LED epitaxial growth method suitable for AlN substrates that aims to improve the quality and yield of LED chips grown on AlN substrates by reducing dislocations and defects. The method involves starting with an AlN-coated sapphire substrate, growing a low-temperature buffer layer, followed by undoped GaN, N-type GaN, P-type AlGaN, and Mg-doped P-type GaN layers. This gradual improvement of lattice matching reduces dislocation density and improves crystal quality.

Source

A method for growing a light-emitting diode (LED) epitaxial wafer with improved crystal quality and reduced defects to boost LED efficiency. The method involves dividing the growth of the three-dimensional nucleation layer into multiple stages, alternating between low temperature and high temperature stages. This reduces stress and defects caused by lattice mismatch compared to continuous growth. The temperature is increased gradually, starting low to avoid damaging the low-temperature buffer layer, then gradually increasing to improve the nucleation layer and active layer crystal quality.

Source

A method to improve the quality of LED epitaxial wafers, particularly in the edge areas, by dividing the high-temperature GaN layer into two stages with optimized growth conditions. The first stage is grown at high temperature and speed to fill in the layer and prevent warpage. The second stage is grown at lower temperature and speed to reduce turbulence and improve crystal quality. This allows better distribution of airflow during growth to improve edge quality. The higher speed first stage fills in faster but generates more stress, while the lower speed second stage releases some stress and improves crystal quality.

Source

Growing a light-emitting diode (LED) epitaxial wafer with higher hole concentration in the P-type semiconductor layer to improve LED efficiency. The method involves dividing the P-type layer into multiple sublayers, activating magnesium doping in each sublayer, and matching the magnesium doping concentration, growth temperature, and thickness between adjacent sublayers to increase the hole concentration in the P-type layer. The activation involves pre-introducing magnesium and nitrogen sources before growing each sublayer to form vacancies that promote magnesium doping. This prevents self-compensation effects limiting hole injection.

Source

A method for growing an LED epitaxial structure that improves the cold-to-heat ratio and reduces luminous flux attenuation at high temperatures. The method involves growing the active region MQW light-emitting layer on the N-type GaN layer at a temperature of 600-650°C for 20-30 minutes, then rapidly cooling it to room temperature. This rapid cooling step improves the crystal quality and reduces defects in the active region compared to slower cooling. This results in better thermal stability and reduced luminous flux attenuation at elevated temperatures.

Source

LED epitaxial growth method to improve crystal quality by reducing dislocations and warping in GaN-on-sapphire wafers. The method involves growing an AlN buffer layer on the sapphire substrate first, followed by a undoped GaN layer, then an N-type GaN layer, P-type AlGaN layer, and Mg-doped P-type GaN layer. This sequence reduces the lattice mismatch and stress compared to directly growing GaN on sapphire. The AlN buffer layer also helps reduce dislocations. The periodic growth of active MQW layers further improves crystal quality.

Source

Method for growing high-quality LED epitaxial wafers with reduced dislocation density and improved crystal quality compared to traditional sapphire substrates. The method involves growing an LED epitaxial structure on a sapphire substrate that has an AlN buffer layer. The AlN buffer reduces dislocation density in the subsequent GaN layers compared to growing directly on sapphire. The steps include: coating AlN on sapphire, growing a low-temperature buffer layer, undoped GaN, doped N-type GaN, and doped P-type GaN. This sequence on the AlN-coated sapphire reduces dislocations and warping compared to growing directly on sapphire.

Source

Growing LED epitaxial structures with improved luminous efficiency and reduced warpage. The method involves growing an LED epitaxial structure with a multiple quantum well (MQW) layer by controlling dopant concentrations, temperature, and growth sequence. The MQW is formed using a gradient capacitance structure with low-temperature and high-temperature alternate MQW growth. This limits current and improves efficiency. Changing dopant concentrations and temperature improves lattice matching. Using TEGa instead of TMGa reduces impurities.

Source

LED epitaxial growth method to improve antistatic behavior and reduce defects in LED structures. The method involves growing a composite N-type layer instead of a single N-type layer. The composite N-type layer has six distinct layers grown in specific steps. This multilayer structure helps mitigate defects like dislocations and improves antistatic properties compared to a single N-type layer.

Source

Method to grow high-brightness LED epitaxial wafers that improves luminous efficiency by reducing electron recombination. The method involves a multi-quantum well structure with controlled Al composition in the barrier layers. The steps are: 1) Grow basic GaN buffer on sapphire substrate using MOCVD. 2) High-temperature, low-pressure MOCVD growth to form GaN crystals. 3) Multi-quantum well structure growth: Keep low-temperature well unchanged, pass Al through barrier in 3 cycles with increasing ratio to form AlGaN. This high-to-low barrier reinforcement reduces electron transition excess.

Source

This method improves the efficiency of light-emitting diodes (LEDs). It involves inserting a granular layer during the epitaxy process. This layer forms V-shaped pits in the superlattice layer. These pits are then filled with a multi-quantum well layer. The V-shaped pits act as channels for hole injection into the quantum wells, increasing hole utilization and LED lighting efficiency. This method can be used to create LEDs that are more efficient and brighter than traditional LEDs.

Source

Process for growing high quality, low cracking AlGaN layers in deep ultraviolet LEDs by gradual composition, temperature, and pressure adjustments in the superlattice buffer layer. The composition of the AlxGa1-xN/AlYGa1-YN superlattice is gradually changed during growth, starting with a high Al composition at the bottom and decreasing toward the top. This reduces stress and improves matching between the AlN and AlGaN layers. The growth temperature and pressure are also gradually decreased. Additionally, a silane doping concentration gradient is used in the n-type AlGaN layer, with a low concentration growth layer followed by a high concentration growth layer. This improves the crystal quality and reduces cracking.

Source

Growing LED epitaxial wafers with reduced blue shift to improve display quality. The method involves inserting AlInGaN and InGaN layers between the barrier layer and well layer in the active region. This reduces lattice mismatch between the layers and prevents internal electric fields. The AlInGaN matches the barrier layer and the InGaN matches the well layer. The growth temperatures and rates are adjusted to transition smoothly. This reduces the piezoelectric polarization and stress in the active region compared to direct well-barrier transitions.

Source

A method for preparing high-quality semipolar (11-22) gallium nitride (GaN) epitaxial wafers using metal-organic chemical vapor deposition (MOCVD) technology. The method involves growing GaN islands on a silicon nitride (SiNx) thin layer on an m-plane sapphire substrate. The GaN islands are grown at high temperature, followed by GaN layer growth at lower temperature. This step sequence reduces defect density and improves surface quality compared to direct GaN growth on the sapphire substrate.

Source

A method for preparing a light-emitting diode (LED) epitaxial wafer with improved efficiency by optimizing the P-type semiconductor layer. The method involves growing a low-temperature P-type layer at lower temperature than the high-temperature P-type layer. The low-temp layer has a superlattice structure with indium gallium nitride and magnesium nitride sublayers. The indium gallium nitride is treated with ammonia and carrier gas before adding magnesium nitride. This reduces gallium incorporation, creates hole vacancies, and allows magnesium doping to increase hole concentration. The low-temp P-type layer with optimized superlattice provides better hole concentration compared to conventional P-type layers, improving LED efficiency.

Source

LED epitaxial growth method to improve LED efficiency and reduce wafer warping. The method involves growing an LED structure with a specific sequence of layers and gradual composition changes in certain layers. The sequence is substrate, low-temperature GaN buffer, undoped GaN, Si-doped N-type GaN, multiple quantum wells (MQW), AlGaN electron barrier, Mg-doped P-type GaN. The gradual changes are in the molar ratio of nitrogen to gallium in the high-temperature GaN barrier, and the molar ratio of indium to gallium in the InGaN wells. This composition grading improves lattice matching between layers, reducing stress and warping, and improving LED efficiency.

Source

Reducing dislocations and improving surface morphology in non-polar GaN grown on sapphire substrates using a two-step growth process with an intermediate InGaN/GaN superlattice layer. The process involves growing a three-dimensional GaN layer on the sapphire, followed by a two-dimensional GaN layer. But in between, an InGaN/GaN superlattice layer is inserted. This intermediate layer helps relieve strain and reduce dislocations caused by the lattice mismatch between the sapphire and GaN. It also blocks threading dislocations from the substrate. This improves the quality of the non-polar GaN epitaxial layer by reducing dislocations and improving surface morphology compared to a conventional two-step growth process.

Source

Growing light-emitting diode (LED) epitaxial wafers with improved internal stress relief and lattice matching to enhance LED efficiency. The method involves inserting a stress relief layer between the buffer layer and active region. This layer has alternating high and low temperature N-type GaN sublayers. The low-temperature sublayers reduce stress during growth. Additional layers with staggered Al and In compositions further relieve stress. A GaN cap layer between the stress relief and active regions prevents damage. The layers decrease in thickness towards the P-type region. This gradual stress relief and matching improves LED efficiency compared to abrupt transitions.

Source

Reducing the operating voltage and increasing brightness of LED chips by matching the contact layer material with the transparent conducting oxide (TCO) layer used for current spreading. The LED epitaxial growth method involves growing an InxGa1-xN:Si/AlyGa1-yN:Si superlattice structure as the contact layer to match the TCO layer like AZO. This adjusts the barrier height difference and reduces contact resistance compared to using just GaN contacts. It lowers LED voltage and improves brightness.

Source

A method to improve the efficiency of light emitting diodes (LEDs) by growing the active layer in stages with varying temperatures to increase the indium (In) content and reduce crystal defects. The active layer is divided into three sub-layers with alternating InGaN wells and GaN barriers. The growth temperature of the GaN barriers in the first sub-layer matches the wells to prevent In decomposition. The temperature is gradually increased in the second and third sub-layers to enhance In composition. Growing the GaN barriers under mixed H2 gas avoids defects at low temperatures. This results in an active layer with higher In-rich regions for better electron-hole recombination and LED efficiency.

Source

A method for growing an LED epitaxial structure that reduces dislocation defects and improves light output, aging, and electrical performance. The method involves two key steps: 1) growing a nitride line buffer layer at medium temperature and low pressure to reduce lattice mismatch between the substrate and the LED layers. 2) Growing a three-dimensional structure layer at the bottom of the LED stack. This three-dimensional layer is grown in segments at increasing temperature and flow rate using trimethyl gallium. It consists of a thin layer of small dense islands, a thick layer that grows into larger islands, and a healing layer that connects the large islands. This three-dimensional structure reduces dislocations at the bottom of the LED, improves warpage, releases stress, and protects the crystal sequence.

Source

Growing a light-emitting diode (LED) epitaxial wafer with improved crystal quality in the buffer layer to reduce defects and improve LED efficiency and reliability. The method involves inserting a second gallium nitride (GaN) layer with higher growth temperature into a first GaN layer with lower growth temperature. This higher quality GaN crystal improves overall buffer layer quality, reduces defect propagation, and prevents composite non-radiative recombination. The second GaN layer is thinner and grows faster to minimize temperature impact on the lower layer. It also facilitates lattice matching with the undoped GaN layer.

Source

LED epitaxial growth method to reduce warpage of the LED wafers during manufacturing. The method involves a controlled growth sequence of layers with specific composition gradations. The layers grown are: AlxGa1-xN, AlN, MgAlyGa1-yN, Si-doped N-type GaN, InxGa1-xN/GaN (x=0.20-0.25), P-type AlGaN, Mg-doped P-type GaN. The graded composition of these layers promotes regular atomic arrangement, resulting in a flatter epitaxial wafer surface and reduced warpage compared to conventional growth methods.

Source

LED epitaxial layer growth method that reduces warpage, improves yield, and enhances efficiency of LED wafers. The method involves growing an LED structure on a substrate by alternating layers of doped InxGa(1-x)N/InyMg(1-y)N with gradually increasing Mg doping concentration. This gradual Mg doping helps control stress and improve crystalline quality of the layers, reducing warpage of the epitaxial wafer and improving yield. The Mg doping also improves LED efficiency and antistatic properties.

Source