A si-based nanoporous gaN structure micro-led device enhanced by ag mirror

Abstract

The application relates to a Si-based nanoporous GaN structure Micro-LED device enhanced by an Ag mirror, and belongs to the technical field of semiconductor optoelectronic devices. The device comprises, from top to bottom, a p-GaN layer, an electron blocking layer, an InGaN multi-quantum well, a superlattice layer, an n-GaN layer, nanoporous GaN, a buffer layer and an Ag mirror arranged on a Si substrate in sequence; and a dipole source arranged in the InGaN multi-quantum well; the nanoporous GaN contains a periodic nanoporous structure array. The application introduces the periodic nanoporous structure array and the Ag mirror, can break the interface total reflection, promotes the radiation of photons from the escape cone, and further improves the Purcell factor and the light extraction efficiency.

Description

Technical Field

[0001] This invention belongs to the field of semiconductor optoelectronic device technology, specifically to the field of Si-based GaN optoelectronic devices, and more specifically to an Ag mirror-enhanced Si-based nanoporous GaN structure Micro-LED device. Background Technology

[0002] In recent years, GaN, as a third-generation wide-bandgap semiconductor, has become a preferred material for fabricating high-performance optoelectronic devices due to its advantages such as wide bandgap, good stability, radiation resistance, and high-temperature resistance. Among them, GaN-based Micro-LEDs, with their advantages of small size, long lifespan, low power consumption, high response speed, and high brightness, have been widely used in optical interconnects, visible light communication, high-density displays, AR / VR, and near-eye displays, and are core devices for next-generation display and optical communication systems. However, its low luminous efficiency has become a major factor restricting its development. Since the luminous efficiency of Micro-LEDs is equal to the product of its external quantum efficiency and voltage efficiency, and the external quantum efficiency is equal to the product of its internal quantum efficiency and light extraction efficiency, and the internal quantum efficiency has already reached a relatively high value, the key to improving the luminous efficiency of Micro-LEDs lies in improving the light extraction efficiency. Because the refractive index difference between GaN and air causes severe interfacial total internal reflection, photons are trapped within the chip, forming waveguide losses, resulting in light extraction efficiency and luminous brightness far below theoretical values. Conventional methods such as surface roughening and patterned substrates have limited effect on suppressing total internal reflection, and the absorption of back-facing photons by the Si substrate will further exacerbate the loss of light extraction efficiency.

[0003] The Purcell factor is the ratio of the radiative power of dipoles in an optical microcavity to the emission power of dipoles in a semiconductor material; it is also the ratio of the lifetimes of spontaneously radiating carriers in the microcavity and the semiconductor material. Furthermore, the Purcell factor is closely related to the local density of states in optics, and the resulting spontaneous emission enhancement effect is a local effect. The lifetimes of radiative and non-radiative recombination carriers play a decisive role in the carrier lifetime of Micro-LED devices. In optical microcavities, the Purcell factor is inversely proportional to the ratio of radiative recombination carrier lifetime; the spontaneous emission rate increases with increasing Purcell factor, while the radiative recombination carrier lifetime decreases. Current conventional Micro-LED devices have limited ability to control the local density of states, resulting in insufficient improvement in the Purcell factor and limited spontaneous emission enhancement effects.

[0004] Therefore, there is an urgent need for a new GaN structure Micro-LED device to solve the problem of luminous efficiency of existing Micro-LED devices. Summary of the Invention

[0005] In view of this, the purpose of this invention is to provide a Si-based nanoporous GaN structure Micro-LED device enhanced by an Ag mirror. By introducing a periodic nanoporous structure array and an Ag mirror (the nanoporous GaN structure can suppress total internal reflection at the interface by means of the photon bandgap effect and multi-level diffraction, expand the range of photon emission angles, and effectively enhance the Purcell effect; at the same time, combined with the Ag mirror for the recovery and utilization of back-emitting light, it can simultaneously improve the light extraction efficiency and radiative recombination efficiency), it can break the total internal reflection at the interface, promote the radiation of photons from the escape cone, and thus improve the Purcell factor and light extraction efficiency.

[0006] To achieve the above objectives, the present invention provides the following technical solution: An Ag mirror-enhanced Si-based nanoporous GaN structure Micro-LED device utilizes the novel GaN nanoporous structure. Coulomb binding significantly enhances the exciton binding energy of the GaN heterostructure, increasing the probability of free electrons and holes combining to form excitons and generating photons through radiative recombination. The nanoporous GaN has a periodic lattice arrangement structure, belonging to the grating structure, which can form a photonic bandgap and generate corresponding diffraction effects. This breaks the total internal reflection limitation inside the Micro-LED chip, thereby effectively improving the Purcell factor and light extraction efficiency.

[0007] The device specifically includes a p-GaN layer 1, an electron blocking layer 8, an InGaN multiple quantum well 2, a superlattice layer 10, an n-GaN layer 3, a nanoporous GaN 4, a buffer layer 5, an Ag mirror 6, a Si substrate 7, a dipole source 9, and may also include a PML (perfectly matched) boundary 11 and a monitor 12.

[0008] The p-GaN layer 1, electron blocking layer 8, InGaN multiple quantum well 2, superlattice layer 10, n-GaN layer 3, nanoporous GaN 4, buffer layer 5, and Ag reflector 6 are sequentially arranged on the Si substrate 7 from top to bottom.

[0009] The dipole source 9 is located within the InGaN multiple quantum well 2.

[0010] Nanoporous GaN4 is a periodic nanoporous structure array.

[0011] The p-GaN layer 1, InGaN multiple quantum well 2, n-GaN layer 3, nanoporous GaN 4, buffer layer 5, Ag mirror 6, Si substrate 7, electron blocking layer 8, superlattice layer 10 and monitor 12 are placed within the PML boundary 11.

[0012] Within the PML boundary 11, the upper and side surfaces of the p-GaN layer 1, the electron blocking layer 8, the InGaN multiple quantum wells 2, the superlattice layer 10, the n-GaN layer 3, the nanoporous GaN 4, and the side surfaces of the buffer layer 5, as well as the internal gaps of the nanoporous GaN 4, are all filled with air 13.

[0013] The monitor 12 is located above the p-GaN layer 1, inside the InGaN multiple quantum well 2, and outside the electron blocking layer 8, the superlattice layer 10, the n-GaN layer 3, the nanoporous GaN 4, or the buffer layer 5.

[0014] Preferably, the nanopore radius of the nanoporous GaN4 is less than or equal to 100 nm.

[0015] Preferably, the period of the nanoporous GaN4 is less than or equal to 160 nm, and the etching depth is less than or equal to 1000 nm.

[0016] The aforementioned nanopore radius, along with the corresponding period and etching depth, not only break the total internal reflection at the interface and promote the radiation of photons from the escape cone, thereby improving the Purcell factor and light extraction efficiency, but also enable the device to have better light emission directionality and light field intensity.

[0017] Preferably, the thicknesses of the p-GaN layer 1, InGaN multiple quantum well 2, n-GaN layer 3, buffer layer 5, Ag mirror 6, Si substrate 7, electron blocking layer 8 and superlattice layer 10 are 100 nm, 84.5 nm, 100 nm, 1 μm, 100 nm, 2 μm, 40 nm and 46 nm, respectively.

[0018] Preferably, the refractive indices of the p-GaN layer 1, n-GaN layer 3, buffer layer 5, Ag mirror 6, Si substrate 7, electron blocking layer 8 and air 13 are 2.375, 2.375, 2.3, 0.135+4.01i, 3.88+0.0186i, 2.27 and 1, respectively.

[0019] Preferably, the InGaN multiple quantum well 2 has In 0.44 Ga 0.56 N-potential well layer and In 0.3 Ga 0.7 The refractive indices of the N barrier layers are 2.52 and 2.48, respectively.

[0020] Preferably, the In of the superlattice layer 10 0.1 Ga 0.9 The refractive indices of the N layer and the GaN layer are 2.39 and 2.378, respectively.

[0021] Preferably, the monitor 12 includes six power monitors, three field distribution monitors, one refractive index monitor, and four time monitors.

[0022] The beneficial effects of this invention are as follows: 1) The device of this invention operates under TE mode dipole source conditions. By introducing a GaN nanoporous structure array, the total internal reflection effect of the device interface can be effectively broken, promoting efficient radiation of photons from the escape cone and significantly enhancing the spontaneous emission effect of charge carriers, thus achieving a simultaneous improvement in Purcell factor and light extraction efficiency. By controlling the period and radius of the nanoporous GaN structure in the Micro-LED device, the optimal device structure model is obtained. By comparing the light field intensity distribution under different nanopore radii, through the superposition and coupling effect of the complex optical path inside the nanopore structure, a device structure with better light emission directionality and higher light field intensity is obtained. By setting an Ag reflector on the Si substrate, the downward-propagating back-facing photons can be reflected to the light emission surface, further recovering light energy and greatly improving the light extraction efficiency, ultimately achieving high brightness and high efficiency light emission performance of the Micro-LED device.

[0023] 2) This invention introduces a p-AlGaN electron blocking layer (EBL) into the device, which effectively blocks electron leakage to the p-side, improves hole injection efficiency, and reduces device leakage current, thereby enhancing the radiative recombination efficiency of charge carriers in the multi-quantum-well region. By employing an InGaN multi-quantum-well (MQWs) structure and controlling the In composition and thickness of the well / barrier layers, efficient light emission in the red light band is achieved, while mitigating the adverse effects of the quantum confinement Stark effect (QCSE) on charge carrier recombination and improving internal quantum efficiency. The InGaN / GaN superlattice (SLs) structure in the device effectively alleviates the lattice stress mismatch between the n-GaN layer and the active region, reduces dislocation defect density, and serves as a gradient buffer layer to improve interface quality, further enhancing the reliability and luminous efficiency of the device.

[0024] Other advantages, objectives, and features of the invention will be set forth in part in the description which follows, and in part will be apparent to those skilled in the art from the following examination, or may be learned from practice of the invention. The objectives and other advantages of the invention can be realized and obtained through the following description. Attached Figure Description

[0025] To make the objectives, technical solutions, and advantages of the present invention clearer, the preferred embodiments of the present invention will be described in detail below with reference to the accompanying drawings, wherein: Figure 1 This is a schematic diagram of the structure of the Si-based nanoporous GaN structure Micro-LED device enhanced by Ag mirrors according to the present invention; Figure 2The effect of different radii, periods and nanopore etching depths on the Purcell factor of the Si-based nanoporous GaN structure Micro-LED device enhanced by Ag mirrors of the present invention; Figure 3 The effect of different radii, periods, and nanopore etching depths on the light extraction efficiency (LEE) of the Si-based nanoporous GaN structure Micro-LED device enhanced by Ag mirrors according to the present invention. Figure 4 for Figure 2 and Figure 3 A schematic diagram of the optical field intensity distribution in the XY plane corresponding to the better results of the structure as a function of nanopore etching depth; Figure 5 for Figure 2 and Figure 3 A schematic diagram of the optical field intensity distribution in the XZ plane corresponding to the better results of the structure as a function of nanopore etching depth; in, Figures 2 to 5 In the figure, (a), (b), (c) and (d) represent nanopore radii of 25 nm, 50 nm, 75 nm and 100 nm, respectively.

[0026] Figure reference numerals: 1-p-GaN layer; 2-InGaN multiple quantum well; 3-n-GaN layer; 4-nanoporous GaN; 5-buffer layer; 6-Ag mirror; 7-Si substrate; 8-electron blocking layer; 9-dipole source; 10-superlattice layer; 11-PML boundary; 12-monitor; 13-air. Detailed Implementation

[0027] The following specific examples illustrate the implementation of the present invention. Those skilled in the art can easily understand other advantages and effects of the present invention from the content disclosed in this specification. The present invention can also be implemented or applied through other different specific embodiments, and various details in this specification can be modified or changed based on different viewpoints and applications without departing from the spirit of the present invention. It should be noted that the illustrations provided in the following embodiments are only schematic representations of the basic concept of the present invention. Unless otherwise specified, the following embodiments and features can be combined with each other.

[0028] The accompanying drawings are for illustrative purposes only and are schematic diagrams, not actual pictures. They should not be construed as limiting the invention. To better illustrate the embodiments of the invention, some parts in the drawings may be omitted, enlarged, or reduced, and do not represent the actual product dimensions. It is understandable to those skilled in the art that some well-known structures and their descriptions may be omitted in the drawings.

[0029] In the accompanying drawings of the embodiments of the present invention, the same or similar reference numerals correspond to the same or similar components. In the description of the present invention, it should be understood that if terms such as "upper," "lower," "left," "right," "front," and "rear" indicate the orientation or positional relationship based on the orientation or positional relationship shown in the drawings, they are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, the terms used to describe positional relationships in the drawings are only for illustrative purposes and should not be construed as limiting the present invention. For those skilled in the art, the specific meaning of the above terms can be understood according to the specific circumstances.

[0030] Example 1: This embodiment provides a Si-based nanoporous GaN structure Micro-LED device enhanced by an Ag mirror. The GaN nanoporous structure array breaks interface total internal reflection, promotes photon radiation from the escape cone, and more easily excites the spontaneous emission effect of charge carriers, thereby improving the Purcell factor and light extraction efficiency. Simultaneously, the Ag mirror reflects downward-propagating photons back to the light-emitting surface, further enhancing light extraction efficiency and achieving high brightness and high-efficiency light emission performance in the Micro-LED device. The specific structure of this device is as follows... Figure 1 As shown, it includes a p-GaN layer 1, an electron blocking layer 8, an InGaN multiple quantum well 2, a superlattice layer 10, an n-GaN layer 3, a nanoporous GaN 4, a buffer layer 5, an Ag mirror 6, a Si substrate 7, and a dipole source 9.

[0031] Among them, p-GaN layer 1, electron blocking layer 8, InGaN multiple quantum well 2, superlattice layer 10, n-GaN layer 3, nanoporous GaN 4, buffer layer 5, and Ag reflector 6 are arranged sequentially on Si substrate 7 from top to bottom.

[0032] The dipole source 9 is located within the InGaN multiple quantum well 2.

[0033] Nanoporous GaN4 contains a periodic array of nanoporous structures. This embodiment employs a periodic array of nanoporous GaN structures, which can significantly enhance the exciton binding energy and increase the probability of electron-hole recombination to generate photons. This structure not only forms a photonic bandgap but also exhibits a related diffraction effect. This effect can break the total internal reflection limitation within the Micro-LED chip, thereby improving the Purcell factor and light extraction efficiency.

[0034] The Micro-LED device in this embodiment has a double heterojunction structure, mainly composed of p-GaN and InGaN multiple quantum wells (5 pairs of InGaN). 0.44 Ga 0.56 N / In 0.3 Ga 0.7InGaN (InGaN multiple quantum wells) and n-GaN are combined. InGaN multiple quantum wells are inserted into the depletion region of the pn junction and form a well-like structure in the energy band. This strongly binds carriers within the wells and enhances the overlap of electron and hole wave functions to increase the radiative recombination probability. Furthermore, a p-AlGaN electron blocking layer (p-Al...) is also present. 0.3 Ga 0.7 N EBL can effectively block electron leakage into the p-type region and improve hole injection efficiency, while the InGaN / GaN superlattice layer (7 pairs of n-type In) can effectively block electron leakage into the p-type region and improve hole injection efficiency. 0.1 Ga 0.9 N / GaN SLs can alleviate lattice stress mismatch, reduce defect density, and improve carrier transport characteristics. The synergistic effect of these three factors can significantly improve the radiative recombination efficiency and luminous efficiency of Micro-LED devices.

[0035] The nanopore radius of the nanoporous GaN4 is preferably less than or equal to 100 nm, and more preferably less than or equal to 25 nm. The period of the nanoporous GaN4 is less than or equal to 160 nm, and the etching depth is less than or equal to 1000 nm. For example, the nanopore radius of the nanoporous GaN4 is 25 nm, the period is 140 nm, and the etching depth is 500 nm.

[0036] Example 2: Please see Figure 1 This embodiment provides an Ag mirror-enhanced Si-based nanoporous GaN structure Micro-LED device, which, based on the device structure of Embodiment 1, also includes a PML boundary 11 and a monitor 12.

[0037] The p-GaN layer 1 is located on the upper surface of the electron blocking layer 8, with air contact between its left and right sides and the PML boundary 11. The p-GaN layer 1 has a thickness of 100 nm and a refractive index of 2.375. The electron blocking layer 8 is located between the p-GaN layer 1 and the InGaN multiple quantum well 2, with air contact between its left and right sides and the PML boundary 11. The electron blocking layer 8 has a thickness of 40 nm and a refractive index of 2.27.

[0038] The InGaN multiple quantum well 2 is located between the electron blocking layer 8 and the superlattice layer 10, with air between its left and right sides and the PML boundary 11. The InGaN multiple quantum well 2 has a thickness of 84.5 nm, in which In 0.44 Ga 0.56 N-potential well layer and In 0.3 Ga 0.7 The refractive indices of the N barrier layers are 2.52 and 2.48, respectively.

[0039] The superlattice layer 10 is located between the InGaN multiple quantum well 2 and the n-GaN layer 3, with air between its left and right sides and the PML boundary 11. The superlattice layer 10 has a thickness of 46 nm, in which In... 0.1 Ga 0.9 The refractive indices of the N layer and the GaN layer are 2.39 and 2.378, respectively.

[0040] The n-GaN layer 3 is located between the superlattice layer 10 and the nanoporous GaN 4, with air between its left and right sides and the PML boundary 11. The thickness of the n-GaN layer 3 is 100 nm, and its refractive index is 2.375. The buffer layer 5 is located between the nanoporous GaN 4 and the Ag mirror 6, with air between its left and right sides and the PML boundary 11. The buffer layer 5 (Al) 0.1 Ga 0.9 The thickness of the N Buffer is 1 μm and the refractive index is 2.3.

[0041] The Si substrate 7 with Ag mirror 6 is located on the lower surface of the buffer layer 5, and its left and right sides and lower surface are in contact with the PML boundary 11. The thicknesses of Ag mirror 6 and Si substrate 7 are 100 nm and 2 μm, respectively, and their refractive indices are 0.135+4.01i and 3.88+0.0186i, respectively.

[0042] The dipole source 9 is located in the center of the InGaN multiple quantum well 2, and the operating wavelength of the dipole source 9 is 635nm.

[0043] Monitor 12 is located above the p-GaN layer 1, inside the InGaN multiple quantum well 2, and outside the electron blocking layer 8, superlattice layer 10, n-GaN layer 3, nanoporous GaN 4, or buffer layer 5. Because monitor 12 has a large number of cells and is distributed around the perimeter, it is... Figure 1 Only one monitor is labeled in the diagram; specifically, the monitors include six power monitors, three field distribution monitors, one refractive index monitor, and four time monitors. The power monitors and field distribution monitors are placed on the periphery of the device, while the refractive index monitors and time monitors are placed inside the material layers of the device.

[0044] The PML boundary 11 is filled with air 13 in the upper part of the p-GaN layer 1 and in the internal gaps of the nanoporous GaN 4. The refractive index of air 13 is 1.

[0045] In this embodiment, left and right are relative to each other. Figure 1 In other words.

[0046] Comparative experiment: The performance of the Si-based nanoporous GaN structure Micro-LED device enhanced by the Ag mirror of this invention was compared and analyzed under device structures with different nanopore radii, periods, and etching depths.

[0047] like Figure 2 As shown, simulation results of the Purcell factor varying with etching depth (z_span) for different nanopore radii and periods reveal significant differences in the variation trends of the Purcell factor with etching depth for the four groups of different nanopore radii. Figure 2 As shown in (a), when the radius is 25 nm, the Purcell factor generally shows an upward trend with slight oscillations before the etching depth reaches 2000 nm. After reaching a peak near 500 nm, it shows a significant downward trend in the 500 nm-2500 nm range, and the peak value of the Purcell factor for some small cycles appears near 2000 nm; Figure 2 As shown in (b), when the radius is 50 nm, the Purcell factor exhibits dramatic periodic fluctuations throughout the entire etching depth range, with peak values ​​mainly concentrated in the 1000-1500 nm range, showing no obvious monotonic trend; Figure 2 As shown in (c), when the radius is 75 nm, the Purcell factor increases slowly in the 0-1000 nm range, then enters a plateau and decreases slowly, with a relatively small overall change. Figure 2 As shown in (d), when the radius is 100 nm, the Purcell factor exhibits relatively small fluctuations in the 0-2000 nm range, showing slight periodic fluctuations, with the value consistently hovering around 1. All four simulation results show certain oscillating characteristics, and the overall fluctuation amplitude gradually decreases as the nanopore radius increases. The results indicate that when the nanopore radius is 25 nm, and the period and etching depth are 140 nm and 2000 nm respectively, Micro-LED reaches the maximum peak value of the Purcell factor, as shown in (d). Figure 2 As shown in (a), when the nanopore radius is 50 nm, and the period and etching depth are 120 nm and 200 nm respectively, the Micro-LED reaches the maximum peak value of the Purcell factor, as shown in (a). Figure 2 As shown in (b), when the nanopore radius is 75 nm, and the period and etching depth are 160 nm and 1000 nm respectively, the Micro-LED reaches the maximum peak of the Purcell factor, as shown in (b). Figure 2 As shown in (c), when the nanopore radius increases to 100 nm, and the period and etching depth are 240 nm and 2200 nm respectively, the Micro-LED reaches the maximum peak of the Purcell factor, as shown in (c). Figure 2 As shown in (d), it can be observed that, for different nanopore radii, the maximum peak of the Purcell factor mainly occurs in structures with smaller nanopore periods. This is mainly because, under the current simulation conditions, the smaller the period of the nanopore structure, the easier it is to form a strong local light field, thereby effectively enhancing the spontaneous emission effect of charge carriers.

[0048] Figure 3 The figure shows the simulation results of light extraction efficiency (LEE) as a function of etching depth (z_span) under different nanopore radii and periods. Figure 3 (a)-(d) correspond to the periodic nanopore radii of 25 nm, 50 nm, 75 nm, and 100 nm, respectively. Each curve represents the variation of light extraction efficiency (LEE) under different nanopore periods (120~320 nm). Figure 3 As shown in (a), the light extraction efficiency of a nanopore with a radius of 25 nm reaches its peak at a shallow etching depth (less than 500 nm), then decreases overall with increasing etching depth, and tends to level off and fluctuate slightly in the later stages (greater than 1500 nm). The light extraction efficiency over a larger period maintains a monotonically decreasing trend and shows peaks at the light extraction efficiency curves corresponding to shallower etching depths. The light extraction efficiency attenuation and fluctuations are most pronounced at smaller periods, making it more sensitive to periodic changes. When the nanopore radius is 50 nm, as... Figure 3 As shown in (b), the light extraction efficiency peaks near an etching depth of 500 nm. When the etching depth exceeds 1000 nm, the light extraction efficiency curves for smaller periods exhibit a fluctuating downward trend, while the curves for larger periods show a characteristic of first slowly rising and then monotonically decreasing, exhibiting a similar trend to the structure with a nanopore radius of 25 nm. When the etching depth continues to increase to 2500 nm, the light extraction efficiency rapidly decreases by about 10%, and the light extraction efficiency for some periods oscillates within the etching depth range of 2000-2500 nm. When the nanopore radius is 75 nm, as... Figure 3 As shown in (c), when the etching depth is less than 1000 nm, the light extraction efficiency generally shows a rapid decline trend, with some periods exhibiting a slow plateau. However, when the etching depth is greater than 1000 nm, the light extraction efficiency fluctuates within a small range and no longer changes significantly with the period. When the nanopore radius is 100 nm, as... Figure 3 As shown in (d), the light extraction efficiency decreases rapidly in the etching depth range of less than 500 nm, while it remains relatively stable with small fluctuations when the etching depth is greater than 1000 nm. Some periods correspond to oscillations in the light extraction efficiency within the etching depth range of 2000-2500 nm, exhibiting a similar trend to structures with a nanopore radius of 75 nm. When the etching depth exceeds 1000 nm, the change in light extraction efficiency remains within a relatively small range. This is because when the refractive index difference between the two materials is large, Bragg scattering occurs at the interface, forming a photonic bandgap that prevents light from propagating within it.

[0049] A comparative analysis of the four sets of simulation results clearly shows that as the nanopore radius increases, the impact of changes in the nanopore period on the light extraction efficiency decreases. When the nanopore radius changes, the location of the peak point of the light extraction efficiency also changes. With a smaller aperture radius of 25 nm, the maximum peak point of the light extraction efficiency occurs at a nanopore period of 160 nm and an etching depth of 100 nm; with an aperture radius of 50 nm, the maximum peak point occurs at a nanopore period of 140 nm and an etching depth of 500 nm; with an aperture radius of 75 nm, the maximum peak point occurs at a nanopore period of 320 nm and an etching depth of 200 nm; and with a larger aperture radius of 100 nm, the maximum peak point occurs at a nanopore period of 320 nm and an etching depth of 200 nm. The location of the peak point of the light extraction efficiency shows a pattern where, as the nanopore radius increases, the nanopore period corresponding to the peak point also increases, but the etching depth decreases. When the nanopore radius varies within the range of 25nm-100nm, the light extraction efficiency generally decreases gradually with increasing etching depth. Furthermore, the larger the nanopore radius, the smaller the degree of light extraction efficiency decay, the slower the rate of decrease, and the more stable the light extraction efficiency becomes at a relatively small value. The light extraction efficiency shows a continuous decreasing trend, and the larger the pore radius, the faster the rate of decrease and the weaker the fluctuation amplitude of the light extraction efficiency with etching depth. This is because as the nanopore radius increases, its ability to restrict and control the dipole radiation mode inside the device weakens, resulting in more radiated energy leaking laterally into the device, reducing the upward emitted light field energy. Simultaneously, the coupling effect of the radiation modes inside the device intensifies, leading to fluctuations in the light extraction efficiency and an overall decrease in efficiency. Through comparative analysis of simulation results, it was finally concluded that when the nanopore radius is 25nm, the period is 140nm, and the etching depth is 500nm, both the Purcell factor and the light extraction efficiency are at optimal values. The Purcell factor is 1.22, and the light extraction efficiency reaches 22.86%, which is a significant improvement compared to other structures.

[0050] Figure 4 The image shows the XY plane optical field intensity distribution at etching depths (z_span) of 100nm, 500nm, 1000nm, and 2000nm, under the optimal structure with a nanopore radius of 25nm and a period of 140nm, when the emission wavelength λ is 635nm. Figure 4 As can be seen from (a)-(d), the optical field intensity at different nanopore etching depths exhibits a centrally symmetrical distribution along the origin of the XY axis. Figure 4 As shown in (a), at an etching depth of 100 nm, the light energy emitted by the radiative recombination of the Micro-LED mainly propagates from the side edges. With increasing etching depth, the energy of photons radiated from the top of the Micro-LED device gradually increases, as... Figure 4 As shown in (a)-(d), when the etching depth reaches 2000 nm, the energy of photons radiated from the top is the largest, and the uniformity of the light field intensity distribution is the best. The energy of photons radiated from the side of the device is relatively small. This effectively avoids excessive loss of light field energy and improves the effective light propagation efficiency. The reason why the effective light propagation efficiency is better when the etching depth reaches 2000 nm is mainly because the directionality of light emission is better at this etching depth (most of the light is radiated from the top of the device to the outside), and the photons radiated from the sidewalls are relatively small.

[0051] Figure 5 for Figure 4 The XZ cross-section light field intensity distribution diagram under the structure shows that, through comparative analysis of the light field intensity distribution of four different device structures, it can be seen that after introducing the nanoporous GaN structure, the light energy emitted downward from the dipole source is transmitted along the nanopores. The downward-propagating photons are absorbed and wasted by the Si substrate, while the Ag mirror reflects all of this light back to the top light-emitting surface. Finally, the light energy is radiated from the top and sidewalls of the Micro-LED device into the external environment. The nanoporous GaN structure can break the total internal reflection limitation, expand the photon escape cone, directly improve the light extraction efficiency and Purcell factor, enhance the local light field and spontaneous emission, and optimize the light emission direction and uniformity. After the dipole source radiates, it passes through multiple nanopores along the perimeter, that is, it needs to penetrate the GaN / air / GaN dielectric material multiple times, resulting in multiple refraction and reflection phenomena. Therefore, compared with the planar structure model, the optical path superposition and coupling effects inside the nanoporous GaN structure are relatively more complex. Figure 5 As can be seen, the comparative analysis of the light field intensity at four different nanopore etching depths further verifies that as the nanopore etching depth increases, the energy of photons radiated from the top of the Micro-LED device increases, while the number of photons escaping from the sides decreases. Therefore, the research and optimization of this invention contributes to improving the luminous efficiency and light emission uniformity of Micro-LED devices.

[0052] The Micro-LED device of this invention operates under a dipole source in TE mode. Due to the nanoporous GaN structure array, total internal reflection at the interface is broken, promoting photon radiation from the escape cone and more easily exciting the spontaneous emission effect of charge carriers, thereby improving the Purcell factor and light extraction efficiency. Simultaneously, the Ag mirror reflects downward-propagating photons back to the light-emitting surface, further enhancing light extraction efficiency and achieving high-brightness, high-efficiency Micro-LED light-emitting performance.

[0053] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit it. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of the present invention without departing from the spirit and scope of the present invention, and all such modifications or substitutions should be covered within the scope of the claims of the present invention.

Claims

1. A Si-based nanoporous GaN structure Micro-LED device reinforced with Ag mirrors, characterized in that, The device includes a p-GaN layer (1), an electron blocking layer (8), an InGaN multiple quantum well (2), a superlattice layer (10), an n-GaN layer (3), a nanoporous GaN (4), a buffer layer (5), an Ag mirror (6), a Si substrate (7), and a dipole source (9). The p-GaN layer (1), electron blocking layer (8), InGaN multiple quantum well (2), superlattice layer (10), n-GaN layer (3), nanoporous GaN (4), buffer layer (5), and Ag mirror (6) are sequentially disposed on the Si substrate (7) from top to bottom; The dipole source (9) is disposed within the InGaN multiple quantum well (2); The nanoporous GaN(4) is a periodic nanoporous structure array.

2. The Ag-reflector-enhanced Si-based nanoporous GaN structure Micro-LED device according to claim 1, characterized in that, The device also includes a PML boundary (11) and a monitor (12); where PML stands for perfect match; The p-GaN layer (1), InGaN multiple quantum well (2), n-GaN layer (3), nanoporous GaN (4), buffer layer (5), Ag mirror (6), Si substrate (7), electron blocking layer (8), superlattice layer (10) and monitor (12) are placed within the PML boundary (11); Within the PML boundary (11), the upper and side surfaces of the p-GaN layer (1), the electron blocking layer (8), the InGaN multiple quantum well (2), the superlattice layer (10), the n-GaN layer (3), the nanoporous GaN (4), and the buffer layer (5), as well as the internal gaps of the nanoporous GaN (4), are all filled with air (13). The monitor (12) is located above the p-GaN layer (1), inside the InGaN multiple quantum well (2), and outside the electron blocking layer (8), superlattice layer (10), n-GaN layer (3), nanoporous GaN (4) or buffer layer (5).

3. The Ag-reflector-enhanced Si-based nanoporous GaN structure Micro-LED device according to claim 1 or 2, characterized in that, The nanopore radius of the nanoporous GaN(4) is less than or equal to 100 nm.

4. The Ag-reflector-enhanced Si-based nanoporous GaN structure Micro-LED device according to claim 1 or 2, characterized in that, The period of the nanoporous GaN (4) is less than or equal to 160 nm, and the etching depth is less than or equal to 1000 nm.

5. The Ag-reflector-enhanced Si-based nanoporous GaN structure Micro-LED device according to claim 1 or 2, characterized in that, The thicknesses of the p-GaN layer (1), InGaN multiple quantum well (2), n-GaN layer (3), buffer layer (5), Ag mirror (6), Si substrate (7), electron blocking layer (8) and superlattice layer (10) are 100nm, 84.5nm, 100nm, 1μm, 100nm, 2μm, 40nm and 46nm, respectively.

6. The Ag-reflector-enhanced Si-based nanoporous GaN structure Micro-LED device according to claim 1 or 2, characterized in that, The refractive indices of the p-GaN layer (1), n-GaN layer (3), buffer layer (5), Ag mirror (6), Si substrate (7), electron blocking layer (8) and air (13) are 2.375, 2.375, 2.3, 0.135+4.01i, 3.88+0.0186i, 2.27 and 1, respectively.

7. The Ag-reflector-enhanced Si-based nanoporous GaN structure Micro-LED device according to claim 1 or 2, characterized in that, The InGaN multiple quantum well (2) has In 0.44 Ga 0.56 N-potential well layer and In 0.3 Ga 0.7 The refractive indices of the N barrier layers are 2.52 and 2.48, respectively.

8. The Ag-reflector-enhanced Si-based nanoporous GaN structure Micro-LED device according to claim 1 or 2, characterized in that, In of the superlattice layer (10) 0.1 Ga 0.9 The refractive indices of the N layer and the GaN layer are 2.39 and 2.378, respectively.

9. The Ag-reflector-enhanced Si-based nanoporous GaN structure Micro-LED device according to claim 2, characterized in that, The monitor (12) includes six power monitors, three field distribution monitors, one refractive index monitor and four time monitors.

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