Method for improving luminous efficiency of LED chip

Abstract

The invention discloses a method for improving the luminous efficiency of an LED chip. The method comprises the following steps of S1, regulating and controlling the injection carrier concentration based on current density distribution so as to optimize composite region distribution; s2, dynamically adjusting the working voltage of the LED chip according to the temperature change so as to maintain the quantum efficiency to be stable; s3, optimizing an optical resonance mode to enhance the photon escape rate according to the material characteristics of the epitaxial layer; and S4, designing an electron and hole balance injection proportion according to pn junction electric field distribution so as to reduce non-radiative recombination loss. The performance of the LED chip is collaboratively optimized through multiple dimensions such as carrier management, thermal management, optical design, energy band engineering and structure optimization, the luminous efficiency is finally greatly improved, meanwhile, key indexes such as uniformity, stability and light beam quality are improved, and powerful technical support is provided for development and application of high-performance LED devices.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of semiconductor lighting, and particularly relates to a method for improving the light-emitting efficiency of an LED chip. BACKGROUND

[0002] The method for improving the light-emitting efficiency of an LED chip mainly focuses on optimizing the distribution of injected carriers, dynamically regulating the working voltage, optimizing the optical resonance mode, balanced injection of electrons and holes, and designing the light-emitting angle, so as to improve the light-emitting efficiency. However, the current light-emitting efficiency regulation method still has the following problems: first, the non-uniform carrier recombination caused by the uneven current density distribution will reduce the light-emitting efficiency; second, the heat accumulation caused by the temperature change will cause the quantum efficiency to decay, and the working voltage needs to be dynamically adjusted to alleviate; third, the material characteristics of the epitaxial layer limit the photon escape rate, and the optical resonance mode needs to be optimized for improvement; fourth, the unbalanced pn junction electric field distribution will cause the imbalance of the electron and hole injection ratio, and increase the non-radiative recombination loss; fifth, the lateral scattering affects the light extraction efficiency, and the epitaxial layer structure morphology needs to be designed and regulated to optimize the light-emitting angle distribution. SUMMARY

[0003] The purpose of the application is to provide a method for improving the light-emitting efficiency of an LED chip to solve the problem of low light-emitting efficiency of the existing LED.

[0004] The application discloses a method for improving the light-emitting efficiency of an LED chip, comprising the following steps:

[0005] S1, regulating the injected carrier concentration based on the current density distribution to optimize the recombination region distribution;

[0006] S2, dynamically adjusting the working voltage of the LED chip according to the temperature change to maintain the stability of the quantum efficiency;

[0007] S3, optimizing the optical resonance mode according to the material characteristics of the epitaxial layer to enhance the photon escape rate;

[0008] S4, designing the balanced injection ratio of electrons and holes according to the pn junction electric field distribution to reduce the non-radiative recombination loss.

[0009] Preferably, the regulation of the injected carrier concentration based on the current density distribution comprises:

[0010] The chip is divided into multiple regions, and the current density value J of each region is measured;

[0011] The average current density value J is calculated mean =(ΣJ i ) / N, wherein N is the total number of regions, and J i is the current density of each region.

[0012] Adjusting the carrier injection concentration C of each region i Satisfying the formula: C i = α * J i / J mean Wherein, α is an adjustment coefficient;

[0013] If C i exceeds the preset maximum carrier concentration C max , limit C i = C max .

[0014] Preferably, the injection carrier concentration is regulated based on the current density distribution, comprising:

[0015] Real-time acquisition of the working temperature T of the current LED chip by a temperature sensor;

[0016] Using thermal parameters to calculate the temperature correction factor β = e^-(ΔT / T0), wherein ΔT is the temperature deviation, and T0 is the reference temperature;

[0017] Adjusting the carrier concentration to C adjusted = β * C, wherein C is the original carrier concentration, according to the temperature correction factor β;

[0018] Ensuring that the excessive carrier injection is reduced when the temperature rises, and the non-radiative recombination loss is reduced.

[0019] Preferably, the distribution of the recombination region is optimized, comprising:

[0020] Determining the effective light-emitting area A effect of the LED;

[0021] Defining the current uniformity index U current = Σ | J i - J mean | / (N * J mean ) in the effective region, which measures the degree of current non-uniformity;

[0022] Setting the target value U goal ≤ γ, wherein γ is the uniformity target value;

[0023] If U current > γ, gradually adjusting the distribution of the injected carriers until the condition is met.

[0024] Preferably, the working voltage of the LED chip is dynamically adjusted according to the temperature change, comprising:

[0025] Monitoring the difference ΔT op between the ambient temperature and the working temperature of the LED;

[0026] Calculating the temperature-dependent band gap shrinkage V shift= kΔT op where k is the bandgap temperature coefficient of the material;

[0027] adjusting the operating voltage V work to a new voltage value: V new = V old + V shift ;

[0028] maintaining the chip quantum efficiency stable with respect to temperature.

[0029] Preferably, said maintaining the quantum efficiency stable comprises:

[0030] collecting the electro-optical conversion efficiency η in operation;

[0031] defining an efficiency stability criterion S efficiency = |η new - η ref | / η ref ≤ δ, where δ is an allowable error;

[0032] dynamically correcting the chip operating voltage when S efficiency exceeds a set value;

[0033] repeatedly checking until the efficiency deviation is controlled within a target range.

[0034] Preferably, said optimizing the optical resonance mode according to the epitaxial layer material properties comprises:

[0035] setting the resonator period d emit according to the epitaxial material wavelength emission window λ mode , so that d mode ≈ λ emit / (2n), where n is the refractive index;

[0036] selecting an appropriate number of layers M layers to achieve the enhancement effect;

[0037] verifying whether the light field enhancement factor G mode meets a preset threshold;

[0038] adjusting the layer design to optimize the light field distribution to improve the output efficiency.

[0039] Preferably, said designing the electron and hole balanced injection ratio according to the pn junction electric field distribution comprises:

[0040] refining the electron and hole injection segmented control mechanism for different injection energy regions;

[0041] establishing a mathematical model R model (k) for each segment injection ratio, ensuring that the total injection ratio of each part is consistent (Σω n + ω p= Constant);

[0042] Adjust the proportion of key injection regions to a reasonable range [ω low ,ω high ] using actual tests and solidification;

[0043] Check the actual light efficiency improvement degree of the optimization scheme to reach or be better than the theoretical value.

[0044] Preferably, the non-radiative recombination loss is reduced, including:

[0045] Analyze the trap state energy level distribution D trap corresponding to the local electric field, and evaluate the resulting leakage current path;

[0046] Set a threshold T level based on the above data to determine whether additional suppression of the influence of certain specific states is needed;

[0047] Use external circuit feedback technology to detect and dynamically adjust the input excitation conditions in real time to maintain good performance;

[0048] The improvement effect is significant by comparing the light power density improvement amplitude before and after processing.

[0049] Compared with the prior art, the beneficial effects of the present application are:

[0050] Improve light output power and uniformity: Through carrier concentration regulation based on current density distribution, the problem of local light efficiency decline caused by non-uniform current distribution is effectively solved. This makes the overall recombination region distribution of the chip more optimized, the light emission more uniform, and the light output power significantly improved, while prolonging the service life of the device.

[0051] Enhance thermal stability and reliability: dynamically adjust the operating voltage to cope with temperature changes, which can effectively alleviate the quantum efficiency decay caused by heat accumulation. This makes the LED chip maintain stable light emitting performance in a wider working temperature range, reduces the risk of overheating, and improves the reliability and service life of the device.

[0052] Improve photon extraction efficiency: optimize the optical resonance mode according to the characteristics of the epitaxial layer material, and enhance the escape probability of internal photons by precisely designing the resonator period, film number and light field distribution. This directly improves the light extraction efficiency of the LED, so that more generated photons can effectively escape from the chip.

[0053] Reduce non-radiative recombination loss: design the balance injection proportion of electrons and holes according to the PN junction electric field distribution, and reduce the non-radiative recombination loss by analyzing the trap state energy level distribution, which maximizes the suppression of energy loss in the form of heat. This ensures higher electro-optical conversion efficiency and reduces energy waste.

[0054] Improving beam quality and directivity: By designing and controlling the morphology of the epitaxial layer structure to solve the problem of lateral scattering, especially by introducing surface roughening structure and optimizing target angle distribution, the outgoing direction of the light beam can be effectively controlled, the scattering loss can be reduced, the light intensity spatial distribution that meets the application requirements can be obtained, and the directivity and illumination / display effect of the light beam are improved.

[0055] Realizing intelligentization and closed-loop control: Real-time monitoring and dynamic feedback adjustment are involved in multiple places in the whole method. This closed-loop control mechanism enables the LED chip to adapt to changes in the working environment and continuously maintain the best working state.

[0056] The present application optimizes the performance of LED chips from multiple dimensions such as carrier management, thermal management, optical design, energy band engineering, and structure optimization, ultimately achieving a significant improvement in luminous efficiency, while improving key indicators such as uniformity, stability, beam quality, and providing strong technical support for the development and application of high-performance LED devices. BRIEF DESCRIPTION OF DRAWINGS

[0057] Figure 1 It is a schematic diagram of the overall method of the present application;

[0058] Figure 2 It is a schematic diagram of the process of regulating the injection carrier concentration based on current density distribution of the present application;

[0059] Figure 3 It is a schematic diagram of the process of regulating the injection carrier concentration based on current density distribution of the present application;

[0060] Figure 4 It is a schematic diagram of the process of optimizing the distribution of the recombination region of the present application;

[0061] Figure 5 It is a schematic diagram of the process of dynamically adjusting the working voltage of the LED chip according to temperature changes of the present application;

[0062] Figure 6 It is a schematic diagram of the process of maintaining stable quantum efficiency of the present application;

[0063] Figure 7 It is a schematic diagram of the process of optimizing the optical resonance mode according to the characteristics of the epitaxial layer material of the present application. DETAILED DESCRIPTION

[0064] In order to make the technical means, creative features, purposes and effects of the present application easy to understand, the technical solutions in the embodiments of the present application will be described clearly and completely in conjunction with the drawings in the embodiments of the present application. Obviously, the described embodiments are only a part of the embodiments of the present application, not all. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor are within the scope of protection of the present application.

[0065] Next, with reference to the accompanying Figure 1 , the steps of a method for improving the light-emitting efficiency of an LED chip and the specific implementation details thereof will be described. The method comprises:

[0066] S1, regulating the injected carrier concentration based on the current density distribution to optimize the distribution of the recombination region;

[0067] S2, dynamically adjusting the working voltage of the LED chip according to the temperature change to maintain the stability of the quantum efficiency;

[0068] S3, optimizing the optical resonance mode to enhance the photon escape rate according to the material properties of the epitaxial layer;

[0069] S4, designing the electron and hole balanced injection ratio for the pn junction electric field distribution to reduce the non-radiative recombination loss.

[0070] In the first step, the injected carrier concentration is regulated based on the current density distribution to optimize the distribution of the recombination region, aiming to solve the problem of local light-emitting efficiency reduction caused by non-uniform current distribution. This step can be achieved by measuring the current density distribution in the LED chip using simulation tools or experimental data. Then, according to the measurement results, the corresponding modulation means are designed, such as improving the doping concentration or electrode distribution of the active region of the chip. For example, in an embodiment, researchers can adjust the carrier concentration distribution near the p-type semiconductor and n-type semiconductor interface by increasing the n-type doping concentration, thereby improving the recombination probability of carriers at different positions in the chip. This design can significantly improve the overall recombination region energy utilization efficiency.

[0071] Then, in the second step, the working voltage of the LED chip is dynamically adjusted according to the temperature change to avoid the efficiency decay phenomenon caused by heat accumulation. Here, real-time monitoring system combined with algorithm control can be used to complete. Specifically, by arranging temperature sensors to collect thermal data during operation and inputting these information into the preset program for calculation and analysis, the optimal working voltage value is fed back to the power supply end for adaptive modification. When the LED lamp is turned on for a long time, it will produce a higher working temperature rise, so the driving voltage needs to be correspondingly lowered to keep the device in high efficiency state without overloading and damage.

[0072] The third step is to build an optimized optical substructure system based on the characteristics of the epitaxial layer material, which means that the most suitable combination for specific needs should be found by studying various crystal parameters and band engineering knowledge in a basic research environment. In a typical laboratory environment, technicians may choose AlGaN as a buffer layer and grow a multi-layer alternating film system with different bandgap widths on top of it to form a mirror effect that promotes the outward transmission of internal emitted light, thereby enhancing the escape probability while suppressing internal consumption caused by reflection.

[0073] The fourth task is to reduce non-radiative recombination loss, which emphasizes the reorganization of space charge distribution in the PN junction region to achieve an ideal state where the number of two main participating particles is roughly equal, thereby effectively preventing excessive concentration of power in one aspect, which may cause unnecessary waste. In a specific scenario, a gradient function pattern distribution curve can be used as a reference template to fine-tune the distance between each atomic-level unit, ensuring that the flow matching level is maximized within a controllable safety limit. For example, for blue light emitting diode projects, the N / P interface transition form can be planned in advance during the production stage to ensure smooth operation.

[0074] In addition, considering the influence of lateral scattering, the fifth point proposes that a special scheme should be set for the external emission direction to improve the shortcomings of traditional design schemes, so that the final effect can meet the expected design requirements. This step can be achieved by changing the roughness of the surface area or adding specific pattern lines, following the shortest path principle. For example, in some high-performance lighting applications, we found that appropriately reducing the size of the side shielding part helps light directly reach the designated focal area without losing too much original brightness output level.

[0075] As shown in Figure 2 , the current density distribution is adjusted to control the injected carrier concentration, including:

[0076] S201, divide the chip into multiple regions and measure the current density value J of each region. The significance of this operation is to identify the actual current density distribution at different positions on the chip surface, so as to optimize each region individually. By dividing and measuring the chip surface, the current non-uniformity problem in the current chip can be accurately mastered.

[0077] S202, calculate the average current density value J mean = (ΣJ i ) / N, where N is the total number of regions, and J iCurrent density of each region; to determine the overall current density of the base reference value. By calculating the average current density, the current distribution level in the global range of the chip can be quantified and characterized, while providing a comparative reference value.

[0078] S203, adjusting the carrier injection concentration C of each region i Satisfy the formula: C i = a * J i / J mean , where a is the adjustment coefficient; the value range is generally between 0.8 and 1.2, and its optimal value depends on the material characteristics and process parameters. The core of this formula is to balance the current-carrier injection concentration relationship between the local and global. According to the actual current density J i of each region and the proportion relationship with the overall average current density J mean , and combined with the adjustment coefficient a to achieve dynamic adjustment. This step can effectively compensate for the differences in light-emitting efficiency caused by uneven current density in different regions within the chip.

[0079] S204, if the carrier injection concentration C of a certain region i exceeds the preset maximum carrier concentration C max , then limit C i = C max . This limiting measure aims to protect the chip material and avoid the problem of thermal damage or material degradation caused by excessive local concentration, thereby improving the overall stability and life of the LED device.

[0080] In one embodiment, the chip is divided into 4 regions, and their current densities are measured as J1=2.1A / cm 2 , J2=1.8A / cm 2 , J3=2.4A / cm 2 , J4=2.0A / cm 2 , then the average current density J mean =(2.1+1.8+2.4+2.0) / 4=2.075A / cm 2 . The optimal value of the adjustment coefficient a is selected as 1.0, and the maximum allowed carrier injection concentration C max =1.2×10^19cm -3 is set. For region 1, C1= a * J1 / J mean =1.0*(2.1 / 2.075)≈1.012×10^19cm -3 . The other regions are in turn, if the C i value is out of limit, then directly set C max .

[0081] The core of the above method is to match the distribution of current density by precisely regulating the carrier concentration, and finally to comprehensively improve the luminous efficiency. This method not only improves the overall light-emitting performance of the chip, but also significantly prolongs the service life of the device.

[0082] As shown in Figure 3 , next, the injection carrier concentration based on the current density distribution of the present application is further described. The specific steps are as follows:

[0083] S301, the working temperature T of the current LED chip is acquired in real time by the temperature sensor; the actual working temperature is collected to provide basic data support for subsequent adjustment. Temperature change will cause changes in material properties and injection efficiency.

[0084] S302, the temperature correction factor β = e^-(ΔT / T0) is calculated using thermal parameters, where ΔT is the deviation of the actual temperature from the reference temperature T0; the temperature correction factor β is calculated using the form of the exponential function, which reflects the nonlinear effect of thermal effect on semiconductor properties. The parameter ΔT is defined as the difference between the current temperature T and the reference temperature T0 (generally taking the normal temperature environment as the reference point), and the range can be determined according to the actual operating conditions, such as-50℃ to +120℃ suitable for most industrial equipment, and the optimal reference temperature T0 is usually set to 25℃. The purpose of this formula is to quantitatively evaluate the influence of temperature-induced performance fluctuations on carrier behavior.

[0085] S303, the carrier concentration is adjusted to C adjusted = β*C according to the temperature correction factor β, where C is the original carrier concentration; the third step is to correct the actual working state deviation caused by temperature. The value of β here will show a decreasing trend as the temperature deviation increases, thereby indirectly reducing the phenomenon of excessive concentration of carriers on the chip surface or active region under high current density.

[0086] S304, ensure that the excessive carrier injection is reduced when the temperature rises, and the non-radiative recombination loss is reduced. The goal is to reduce unnecessary losses. When the carrier density is too high, significant non-radiative energy loss will occur, such as generating additional heat or forming harmful defect states, which will cause the chip to reduce the light-emitting efficiency or even fail.

[0087] In one embodiment, the above logic can be illustrated in the specific scenario of GaN-based LED preparation process. Specifically, assuming that the rated carrier concentration of a certain chip is set to C = 2 × 10^17 cm -3 when it is running normally, and the reference temperature is 25℃. When it is monitored that the working temperature increases from the standard value (25℃) to 65℃, ΔT = 65℃-25℃ = 40℃, the new carrier concentration C adjustedThis is equivalent to multiplying the original value C by e^(-40 / 25), which is approximately 0.224. This result suggests that the original design value needs to be reduced by nearly 80% to maintain efficient light output. This will not only alleviate the problems caused by local overheating but also improve the reliability and economy of the system.

[0088] like Figure 4 As shown, the optimized composite region distribution of the present invention will be further described below. This process mainly includes the following steps:

[0089] S401. Determine the effective light-emitting area A of the LED. effect This refers to the effective area of ​​an LED that actually produces light when it is in operation. This parameter can be precisely measured through experiments and optical simulations, and is usually expressed in square millimeters or square micrometers. The geometric design and chip manufacturing process of an LED directly determine its effective light-emitting area A. effect Size. Effective luminous area A effect It is a key fundamental quantity for measuring the optical performance of LEDs because it is closely related to total light output and electro-optical conversion efficiency.

[0090] S402. Define the current uniformity index U in the effective region. current =Σ|J i -J mean | / (N*J mean ), which measures the degree of current non-uniformity; where J i J represents the value of the current density at the i-th measurement point (i ranges from 1 to N, where N is the total number of measurement points). mean It is the average current density at N measurement points, and its range is generally between 50-300 A / cm², depending on the power design of the device. 2 Between. Current uniformity index U current A higher value indicates a greater degree of current non-uniformity within the effective region, which may lead to localized heat concentration in the LED and affect overall luminous efficiency. This formula is designed to quantitatively describe the current distribution problem in LEDs during use, thereby providing specific optimization targets. By comparing the current current uniformity with the mean, the direction and extent of optimization can be more clearly determined.

[0091] S403 sets the target value U goal ≤γ, where γ represents the ideal uniformity threshold. It is generally recommended to take a value less than or equal to 0.15, with an optimal value of 0.10 or lower. The selection of the uniformity threshold γ is based on the trade-off between the LED luminous uniformity requirements and manufacturing costs for a specific application scenario.

[0092] S404, If U current >γ, gradually adjust the distribution of injected charge carriers until the condition is met. If the calculated current uniformity index Ucurrent greater than gamma, then proceed to the next step, which is to gradually adjust U current towards the requirement of gamma by changing the carrier distribution.

[0093] In one embodiment, a doping technique or re-adjustment of the epitaxial layer structure is employed to improve the spatial distribution of carriers in the recombination region. Specifically, the type and concentration gradient of impurities in epitaxial growth can be adjusted to reduce the current difference between different points and make the current density J i of each region close to the average value J mean .

[0094] Through the above steps, not only can the LED light emission unevenness be significantly reduced, but also the light emission efficiency and service life can be greatly improved.

[0095] As Figure 5 shown, next, the dynamic adjustment of the operating voltage of the LED chip according to temperature changes of the present application is further described. This method is divided into several explicit steps:

[0096] S501, monitor the ambient temperature and operating temperature difference ΔT op of the LED; obtain the real-time operating temperature and ambient temperature of the LED through a temperature sensor, calculate the difference between the two to obtain ΔT op . This process can provide important information about the temperature conditions of the LED, laying the foundation for subsequent operations. Specifically, it needs to rely on high-precision thermosensitive elements to accurately capture the temperature difference change. The range of ΔT op is generally between -20 and +80 degrees Celsius, depending on the scene. In this interval, -5 to +40 degrees Celsius is a more optimal commonly used temperature difference interval.

[0097] S502, calculate the temperature-dependent band gap shrinkage V shift = kΔT op ; where k is the band gap temperature variation coefficient closely related to the material of the LED chip. Generally, the value of k varies with semiconductor materials such as GaN or SiC, and the value may fluctuate in the range of several millivolts per degree Celsius, with a typical value of about 0.5 to 2 millivolts / °C, and 1 millivolt / °C is considered ideal. Through this formula, V_shift represents the correction amplitude of the operating voltage caused by the increase or decrease of the ambient temperature, and is used to calibrate the deviation between the LED output characteristics and the actual operating conditions.

[0098] S503, adjust the operating voltage V work to a new voltage value: V new = V old + V shift ; adjust the operating voltage based on the result of the previous step. Update the original operating voltage to a new value according to the shrinkage amount described above, expressed as Vnew = V old + V shift By introducing this compensation measure to correct the performance degradation due to thermal expansion, to ensure the stability of the LED under different working conditions. This step aims to optimize the drive voltage setting, reduce the loss of light-emitting efficiency caused by overdrive or underdrive, and avoid damaging the chip structure.

[0099] S504, keep the quantum efficiency of the chip stable with temperature change; the last step focuses on maintaining the trend of quantum efficiency change with temperature close to a constant level. After the working parameters are reset, the output response state of the entire circuit system is continuously evaluated to ensure that the luminous intensity and conversion efficiency do not change significantly with the dramatic fluctuation of external temperature. In order to achieve this goal, data in the running state need to be continuously collected and fed back to the control loop to form a closed-loop control system.

[0100] In one embodiment, it is assumed that the LED is in a high-load operating environment and experiences a large temperature rise. If the initial set working voltage is 3V and the detection shows that ΔT_op is 50℃, combined with the known k value of 1.5 millivolts / ℃, the required increment is about 75 millivolts (i.e. 0.075V), so the final adjusted target voltage will be set to about 3.075V. This precise correction strategy can greatly improve energy utilization and prolong the service life of the device.

[0101] As shown in Figure 6 , next, the present application for maintaining quantum efficiency stability is further described. It mainly includes the following four steps.

[0102] S601, collect the photoelectric conversion efficiency η in working; this process needs to record the ratio of light energy to input electrical signal in the running of LED chip through precise monitoring instruments. For example, built-in feedback sensors can be used to capture data and perform numerical processing. These efficiency data can reflect the actual level of the current chip light-emitting capacity.

[0103] S602, define the efficiency stability standard S efficiency = | η new - η ref | / η ref≤ δ, where δ is the allowable error; the purpose is to quantify and regulate whether the fluctuation of the electro-optical conversion efficiency is within the normal range. Wherein η_new represents the current real-time collected efficiency value, and η_ref is the theoretical reference efficiency value or the initial calibration value, usually taking an ideal value in the interval of 65%-85% as the optimal value. The range of δ allowable error depends on the requirements of the application field, usually ±5% to ensure higher reliability. The meaning of this formula is to compare the difference between the current efficiency value and the reference value as a percentage of the reference value, and control this relative error within a certain allowable range. Since the instability of the efficiency may cause the optical performance to decline, the formula is set to quickly identify potential problems and intervene.

[0104] S603、When S efficiency Dynamic correction of chip operating voltage when exceeding the set value; adjust the operating voltage of the chip to restore the chip to the expected working state. The voltage adjustment amount is determined according to the specific out-of-tolerance degree and is optimized in real time by an internal algorithm to avoid new problems caused by excessive voltage change. For example, in one embodiment, it is detected that the efficiency of a certain blue LED decreases due to the rise of ambient temperature, and the light-emitting effect can be significantly improved by fine-tuning the forward driving voltage by 0.2V, thereby restoring the performance within the predetermined range.

[0105] S604, repeatedly check until the efficiency deviation is controlled within the target range; a repeated checking cycle mechanism is performed to confirm that the entire system is operating within the stable interval again. Specifically, after completing the modification of the operating voltage, the electro-optical conversion efficiency η is collected again and substituted into the formula established before for comparison and evaluation operation; if there is still deviation, continue the above voltage correction process until the final condition is met, that is, the deviation is suppressed within the allowable limit. For example, after two checks, the efficiency of the above-mentioned blue LED is successfully locked near the optimal performance point determined during the initial calibration.

[0106] As Figure 7 shown, next, the application is described according to the characteristics of the epitaxial layer material to optimize the optical resonance mode to enhance the photon escape rate. Each step is explained in detail:

[0107] S701, according to the wavelength emission window λ emit of the epitaxial material, set the resonator period d mode , so that d mode ≈ λ emit / (2n), where n is the refractive index; the parameter range of this formula is: λ emit falls in the visible light interval (such as 400nm to 700nm) of common LED chip light emission, and the value of the refractive index n is determined by the specific epitaxial material, usually between 3 and 4. Set the formula d mode ≈ λ emitThe objective of the formula (2n) is to match the phase condition between the resonator period and the wavelength of the emitted light, so that the light energy is effectively enhanced at a specific frequency, thus improving the radiation efficiency. This formula is chosen because only when the ratio of the resonator length and the wavelength is consistent, a stable standing wave resonance mode can be excited.

[0108] S702, selecting an appropriate number of layers M to achieve the enhancement effect; here the number of layers M represents the number of periods of the multi-layer structure, and the optimal range usually needs to be determined based on the specific material properties and manufacturing technology limitations. Generally, for high-efficiency LED devices, M taking 1 to 10 layers can provide a better gain balance point, and too high M value may cause excessive loss and increase the difficulty of preparation. The selection of appropriate number of layers can ensure that more light energy is focused inside the light-emitting area rather than escaping to the environment.

[0109] S703, verifying the light field enhancement factor G mode whether it meets the preset threshold; the light field enhancement factor refers to the amplification degree of the light signal intensity in the resonant mode, usually in decibels (dB). If the light field enhancement factor is insufficient or far exceeds the predetermined value, the entire structure cannot be ensured to have the expected function. In one embodiment, if the theoretical gain of the LED device needs to reach 5 dB / mm, the threshold can be fixed near this value for comparison. This helps to exclude unqualified design schemes in advance to save resources.

[0110] S704, adjusting the layer design to optimize the light field distribution to improve the output efficiency. The light field generated inside can be more effectively output outward rather than wasted. For example, by changing the parameters such as the slope and width of the individual layer interface, the directionality of most power can be concentrated towards the desired location for output, thereby improving the overall conversion rate. Precise simulation tools are needed to analyze the impact trend caused by each change in this process.

[0111] To help understand more intuitively, an associated example is given for illustration: consider a situation of using a gallium nitride substrate to make a blue light emitting diode chip. Specifically, suppose that the GaN material of this type is known to have a characteristic of λ emit about 450 nm and a refractive index of n = 2.4. According to the aforementioned calculation method, the appropriate resonator period should be set to about 94 nm; then try to select three different thin film structure schemes to test one at a time to see which one works best; at the same time, confirm whether the actually measured data at least meets the previously stated 5 dB / mm standard; then further fine-tune the initially selected optimal case until the overall performance reaches the ideal state to complete the entire process flow execution task requirements.

[0112] Next, the optimization of the optical resonant mode of the present application further includes the following operation steps:

[0113] A surface roughening structure is introduced to calculate the contribution of micro-roughness to the far-field distribution function. The surface roughening structure can be achieved by adjusting the top of the epitaxial layer or the surface of the packaging structure to roughen at the micron to nanometer level. The parameter characterizes the change of far-field light intensity with respect to the emission angle, and the value range is generally 0 to 1 radian range of discrete point data. The specific role of micro-roughness to the far-field distribution is determined by modeling and simulation, so as to better analyze the balance between beam divergence angle and efficiency loss. For example, in one embodiment, a uniform textured surface is manufactured using chemical etching technology, and then the far-field directional diagram is evaluated by an optical simulation tool, and the highest gain point corresponding to the ideal micro-roughness value is obtained, and finally 5% texture depth ratio is determined as the optimal parameter.

[0114] Set the target angular distribution function F goal and match the measured data with its characteristics, i.e. F measured ≈ F goal . The parameter F goal is a pre-set ideal light intensity spatial distribution function, and its domain is θ (elevation angle) and φ (azimuth angle) in the spherical coordinate system. In order to adapt to the actual LED application, the specific form of F goal can be adjusted according to the design requirements, such as focusing on a certain main light angle or presenting a ring-shaped distribution. For example, specifically, when a high-power LED chip is used in lighting applications, more target luminous flux is concentrated in the cone angle range of ± 30°. The measured data is obtained by laboratory light radiation test, and is calibrated and fitted by least squares method to approximate the theoretical target distribution. This setting ensures that the light distribution mode meets the user's needs while maximizing energy utilization.

[0115] Based on the above comparison results, the ideal texture design is solved by reverse iteration. After comparing the difference between the expected value F goal and the result F measured output by the current model, a mathematical programming algorithm such as differential evolution is used to search for the best combination of texture morphology. In this process, the manufacturing cost and performance improvement amplitude need to be considered to select the optimal solution. For example, specifically in the case of high-power red LED, after dozens of trial calculations, an asymmetric triangular pit distribution is converged, which can improve the side leakage loss and suppress total reflection loss, and improve the external quantum efficiency by at least 10%.

[0116] Ensure the final exit direction is consistent with the needs to reduce scattering loss. This step focuses on verifying the results of the previous three processes in the actual product processing link. All the main wave must be directed to a specific area and the deviation angle error is maintained within a small threshold to minimize the performance decline caused by unnecessary diffusion. In one embodiment, assuming that the light source is customized for a projection display system, the maximum full width at half maximum is strictly controlled within ± 5°, and it is confirmed by experiments that this specification can significantly improve the picture contrast and clarity effect.

[0117] Next, the present application is described for the pn junction electric field distribution design of electron and hole balance injection ratio. The process includes determining the built-in potential of the pn junction and the electric field intensity distribution under bias state, defining the weight factor relationship, adjusting the ratio of the two and reducing the loss, and verifying whether the non-radiative recombination loss in the experiment meets the expected range. First, list the steps, and then explain their meanings and purposes.

[0118] The first step is to determine the built-in potential of the pn junction V B and the electric field intensity distribution E profile(x) under bias state. This means analyzing the physical characteristics of the pn junction under the conditions of natural formation and applied voltage. V B is the built-in voltage of the pn junction, which depends on the semiconductor properties and its band gap, generally 0.6 to 1.2V. And the electric field distribution E profile(x) is used to reveal the non-uniform distribution of the electric field in space. This information provides a basis for calculating the weight factor later, ensuring that it accurately reflects the actual situation.

[0119] The second step is to define the electron injection weight factor ω n and the hole weight factor ω p ratio formula ω p / ω n = exp(E barrier / kT). Where E barrier is the energy height of the hole across the barrier, which varies from 0.1 to 1.0eV; k is the Boltzmann constant; T is the absolute temperature, ranging from about 300K to 500K, with the best value being room temperature 300K. This formula is based on the principles of thermodynamic statistics, aiming to express the changing relationship between the probabilities of different particles (such as electrons and holes) crossing the energy barrier, so as to achieve optimized injection balance.

[0120] Third, adjust the ratio of the two injection weight factors mentioned above using numerical simulation, and strive to approach the ideal dynamic balance state. In this way, energy loss or heat accumulation due to imbalance can be reduced. Specifically, the iteration optimization method can be used to adjust ω p / ω nParameter configuration to reach target efficiency range.

[0121] The last step is to evaluate the performance of the optimized LED light emitting device in actual verification. For example, in one embodiment, a blue LED chip using an InGaN material system is assumed to have a low original quantum efficiency due to high non-radiative recombination loss caused by serious imbalance under a specific driving current of 20 mA. After correction according to the above process, it is found that the non-radiative recombination loss is reduced by about 40%, and the overall chip light emitting efficiency is significantly improved to about 85% or more. This fully embodies the actual utility and value of this method.

[0122] Refine the electronic and hole injection segmented control mechanism for different injection energy regions; different injection energy regions E_range are divided into multiple segments, and the electronic and hole injection amounts are finely adjusted. This is to adapt to the changes in material properties of different regions and optimize the overall carrier distribution. For example, high injection energy regions are suitable for high current density control, while low injection energy regions require higher balance management. In one embodiment, the entire injection energy range is divided into N segments by uniform steps, where each segment corresponds to the electronic and hole allocation parameter configuration of a specific energy window [E min ,E max ] of the region.

[0123] Establish a mathematical model R model (k) for each segment injection ratio to ensure the total injection ratio of each part is consistent (Σω n +ω p = Constant); where the constant represents the total carrier injection ratio that needs to be fixed at a certain optimal value to maintain the balance of light emitting efficiency. The optimal value of the constant here is usually set to be slightly lower than the material saturation value, such as about 0.98 after experimental verification. The reason for using this limitation is to prevent non-radiative recombination loss caused by injection imbalance in any region.

[0124] Adjust the key injection region ratio to a reasonable range [ω low ,ω high ] and solidify it using actual test; use a light efficiency measuring instrument to detect multiple groups of samples and record the change law of LED light intensity and energy efficiency under different ratios. If a certain range can maximize the overall performance, it is defined as the optimal operating interval of the region. For example, after experimental analysis, it is found that in some typical segments, the optimal range is set to [0.45, 0.65].

[0125] The actual light efficiency improvement degree of the optimization scheme is checked to reach or exceed the theoretical value. It is confirmed whether the above target of the expected index is achieved. If it is found that the improvement effect does not reach the standard or there is obvious fluctuation, the foregoing parameter settings are further iteratively corrected until the ideal level is achieved. For example, when the theoretical prediction improvement rate is 15%, but the actual measurement is only 12%, each control variable and their coordination manner should be rechecked until the expected design value is met or exceeded.

[0126] Next, the further reduction of non-radiative recombination loss of the present application is described. This method is divided into multiple steps to optimize the light-emitting efficiency of the LED chip step by step. First, the content of each step is clarified, and examples are combined to illustrate.

[0127] The first step is to analyze the trap state energy level distribution corresponding to the local electric field, and to evaluate the possible leakage current path. The core of this step is to detect and identify the bound states of electrons and holes in the forbidden band caused by localized energy and related leakage path problems.

[0128] The second step is to set a threshold parameter according to the data analysis results of the previous step. This is used to judge whether additional compensation means or inhibition of certain specific trap states is needed. For example, specifically, under certain experimental conditions, if the average trap density is more than twice the baseline, and the leakage current is close to the allowable limit, the inhibition action is triggered to ensure the stability of output quality and efficient operation.

[0129] The third step uses external circuit feedback technology to realize real-time detection and dynamic adjustment function. This process mainly uses high-sensitivity sensors to capture voltage and current fluctuations during actual operation, and uses PID (Proportional-Integral-Derivative) algorithm to regulate the input excitation conditions to the optimal working interval. Assuming an actual case of improving the efficiency of blue light LED, the photoelectric conversion rate changes with a weak drift of the input signal. At this time, the system is adjusted to the target point near (set to I optimised = α * U input ), where U input is the input bias amplitude, and α is an empirical factor reflecting the characteristics of the device (generally in the interval [0.8, 1.2]). When the detected value deviates beyond the upper and lower limits of error, the correction program is quickly started.

[0130] Finally, the significance of the improved effect is verified. This is achieved by comparing the light power density improvement amplitude before and after taking the above measures. If the unit area luminous intensity is increased or reaches the theoretical maximum predicted value, it indicates that this optimization strategy is very successful.

[0131] The method for improving the light-emitting efficiency of an LED chip comprises: optimizing the overall light-emitting performance of the LED chip through four key technical aspects, effectively solving a series of core problems affecting the light-emitting efficiency, such as non-uniform carrier recombination, quantum efficiency decay, insufficient photon escape rate, non-radiative recombination loss, and lateral scattering.

[0132] The method introduces a precisely controlled carrier concentration distribution design, and by establishing a spatial carrier distribution characteristic curve matched with the current density inside the LED, the recombination efficiency in different regions is more balanced. This optimization significantly improves the photoluminescence intensity and overall efficiency.

[0133] The method proposes a strategy of dynamically changing the applied driving voltage in real time by monitoring the temperature and combining a feedback mechanism. When the system detects high temperature, the voltage will be reduced to reduce the junction temperature effect; at the same time, low loss operation under stable current supply is ensured, so that the chip maintains an ideal light-emitting state.

[0134] By understanding the specific semiconductor material and its interface parameters, the refractive index distribution and cavity length design are adjusted to create optimal conditions for efficient extraction of outgoing light.

[0135] The morphology microstructure of the epitaxial growth surface is optimized based on the light-emitting angle. This process aims to overcome the phenomenon of a large amount of invalid light caused by lateral scattering in traditional LEDs, ultimately achieving a high directional and bright light-emitting effect, greatly improving the overall photoelectric performance level. After the synergistic effect of the above-mentioned multiple means, the working performance and actual service life of modern light-emitting devices are greatly improved.

[0136] The above-mentioned is only an embodiment of the present application, and the specific structure and characteristics disclosed in the scheme are not described in detail here. For those skilled in the art, it is obvious that the present application is not limited to the details of the above-mentioned exemplary embodiments, and the present application can be realized in other specific forms without departing from the spirit or basic characteristics of the present application. Therefore, from any point of view, the embodiments should be regarded as exemplary and non-limiting, the scope of the present application is defined by the appended claims rather than the above description, and therefore all changes falling within the meaning and scope of the equivalent elements of the claims are intended to be included in the present application. Any reference signs in the claims should not be considered as limiting the claims involved.

Claims

1. A method for improving the light emission efficiency of an LED chip, characterized by, The method comprises the following steps: S1. Regulating the injected carrier concentration based on the current density distribution to optimize the recombination region distribution; S2. Dynamically adjusting the working voltage of the LED chip according to the temperature change to maintain the quantum efficiency stable; S3. Optimizing the optical resonance mode according to the material characteristics of the epitaxial layer to enhance the photon escape rate; S4. Designing the electron and hole balanced injection ratio according to the pn junction electric field distribution to reduce the non-radiative recombination loss.

2. The method of improving light emission efficiency of an LED chip according to claim 1, wherein, The regulating of the injected carrier concentration based on the current density distribution comprises: Dividing the chip into multiple regions and measuring the current density value J of each region; Calculate average current density value J mean = (ΣJ i ) / N, where N is the total number of regions, J i is the current density of each region; Adjusting the carrier injection concentration C of each region i satisfying the formula: C i = a * J i / J mean where a is an adjustment coefficient; If C i exceeds a predetermined maximum carrier concentration C max , then C i is limited to C max .

3. The method of improving light emission efficiency of an LED chip according to claim 2, wherein, The regulating of the injected carrier concentration based on the current density distribution comprises: Real-time acquisition of the working temperature T of the LED chip through a temperature sensor; Using thermal parameters to calculate the temperature correction factor β = e^-(ΔT / T0), wherein ΔT is the temperature deviation and T0 is the reference temperature; The carrier concentration is adjusted according to the temperature correction factor β to C adjusted = β * C, where C is the original carrier concentration; Ensuring that the carrier injection amount is reduced when the temperature rises, and the non-radiative recombination loss is reduced.

4. The method of improving light emission efficiency of an LED chip according to claim 3, wherein, The optimization of the recombination region distribution comprises: Determining the effective light emitting area A of the LED effect ; Definition of the current uniformity index U in the active area current =∑|J i -J mean | / (N*J mean ), which measures the degree of current non-uniformity; Setting a target value U goal ≤ γ, where γ is a uniformity target value; If U current >γ, the distribution of injected carriers is adjusted step by step until the condition is met.

5. The method of improving light emission efficiency of an LED chip according to claim 1, wherein, The dynamic adjustment of the working voltage of the LED chip according to the temperature change comprises: Monitoring the ambient temperature and operating temperature difference ΔΤ of the LED op ; calculating a temperature-dependent bandgap shrinkage V shift = k ΔT op where k is the bandgap temperature coefficient of the material; Adjusting the operating voltage V work For the new voltage value: V new = V old + V shift ; Maintaining the stability of the quantum efficiency of the chip with the change of temperature.

6. The method of improving light emission efficiency of an LED chip according to claim 5, wherein, The maintaining of the quantum efficiency stable comprises: Collecting the electro-optical conversion efficiency η in operation; Definition of the efficiency stability criterion S efficiency = |η new - η ref | / η ref ≤ δ, where δ is an admissible error; When S efficiency Dynamic correction of chip operating voltage when exceeding the set value; Repeatedly checking until the efficiency deviation is controlled within the target range.

7. The method of improving light emission efficiency of an LED chip according to claim 6, wherein, The optimization of the optical resonance mode according to the material characteristics of the epitaxial layer comprises: According to the wavelength emission window of the epitaxial material λ emit Setting the resonator period d mode So that d mode ≈ λ emit / (2n), where n is the refractive index; Selecting an appropriate number of layers M to achieve the enhancement effect; Verification of light field enhancement factor G mode whether a preset threshold is met; Adjusting the layer design to optimize the light field distribution to improve the output efficiency.

8. The method of improving light emission efficiency of an LED chip according to claim 7, wherein, The design of the electron and hole balanced injection ratio according to the pn junction electric field distribution comprises: Refining the electron and hole injection segmented control mechanism for different injection energy regions; A mathematical model R is established for the injection ratio of each section model (k), ensuring the total injection ratio of each part is consistent (Σω n +ω p = Constant); Adjusting the key injection area ratio to a reasonable range [ω low ,ω high ] by actual test and curing; Checking the actual light efficiency improvement degree of the optimization scheme to reach or be better than the theoretical value.

9. The method of improving the light emission efficiency of an LED chip according to claim 10, wherein, Reducing the non-radiative recombination loss comprises: analyzing the distribution of trap state energy levels corresponding to the local electric field D trap and evaluating the resulting leakage current path; Based on the above data, a threshold T is set level determining whether additional suppression of the influence of certain specific states is required; Using external circuit feedback technology to detect and dynamically adjust the input excitation conditions in real time to maintain good performance; By comparing the light power density improvement amplitude before and after processing, it is proved that the improvement effect is significant.

Images