Near-eye display and method for forming a near-eye display

Abstract

A color conversion resonator system (100) comprising a partially reflective region (114) configured to transmit light of a first dominant peak wavelength and reflect light of a second dominant peak wavelength, a further partially reflective region (116) configured to at least partially reflect light having the second dominant peak wavelength, and a color conversion resonator cavity including at least one quantum well (105a-d), wherein the color conversion resonator cavity receives input light having the first dominant peak wavelength through the partially reflective region and converts at least a portion of the received input light into a second dominant peak wavelength by the at least one quantum well. and providing light of a second dominant peak wavelength, whereby the light of the second dominant peak wavelength resonates within the cavity and the light having the resonant second dominant peak wavelength is output through a further partially reflective region, wherein the at least one quantum well is positioned to coincide with an antinode of a standing wavelength of the color conversion resonator cavity for light of the second dominant peak wavelength, thereby improving at least one of the intensity, spectral width, and directionality of the output light having the second dominant peak wavelength.

Description

[Technical Field]

[0001] The present invention relates to a color conversion resonator system and a method for forming a color conversion resonator system. More specifically, but not limited to, the present invention relates to a color conversion resonator for a high color purity light-emitting diode structure. [Background technology]

[0002] Light-emitting diode (LED) devices are known to provide efficient light sources for a wide range of applications. LED light sources are used to provide conventional white light and / or multicolor light emission. For example, multicolor light emission can be red, green, and / or blue light emission, among other colors of light, which are particularly suitable for display applications. The desired wavelength of light provided by the LED is typically achieved using a combination of a pump-source LED and a color conversion material, such as a phosphor or quantum dot (QD). Such a pump-source LED generates light with a dominant peak wavelength output, stimulating the emission of light of different wavelengths in the color conversion material. For example, a blue photonitride material LED (emitting light with a dominant peak wavelength of approximately 450 nm) is used to provide white light conversion LED emission. Blue nitride material LEDs are also used to provide red light conversion LED emission and green light conversion LED emission. When QD is used as the color conversion material, the thickness of the QD material layer is typically required to be 20 μm in order to completely absorb the input light. This creates limitations on the size and pixel pitch of light-emitting pixels within an array of light-emitting diode-based pixels.

[0003] Pump-source LEDs, such as those made from blue nitride-based materials, are available with high-quality, efficient emission. However, the application of color conversion materials to achieve a desired color of light typically results in a color conversion LED with reduced luminous efficiency compared to the source LED used to pump the color conversion material. This reduced efficiency is due, for example, to the absorption of light generated by the source LED within the color conversion material. Furthermore, color conversion using known methods such as quantum dots and phosphor materials typically results in emission with a broad full width at half maximum (FWHM) spectrum relative to the peak dominant wavelength of the converted light. In addition, known native nitride light-emitting diodes that emit green or red light (e.g., based on indium gallium nitride (InGaN) quantum wells) typically have broad FWHM spectra for the emitted green and red light. As a result, the color gamut is reduced.

[0004] A further potential difficulty arises in implementing LEDs for waveguide-type augmented reality (AR) display applications, due to the relatively wide beam angle. Therefore, in LED arrays, such as micro-LED arrays, where a narrow beam angle may be required, collimators and / or lenses are typically used for each pixel to narrow the beam angle and light distribution. However, the monolithic integration of collimators and lenses is a complex process and requires high aspect ratio pixels. In addition, the use of such structures reduces light efficiency.

[0005] Therefore, it would be beneficial to enable more efficient light extraction in color-converting LEDs using color conversion techniques to provide light-emitting pixels that emit light of a desired wavelength while providing a narrow beam angle. [Overview of the project] [Means for solving the problem]

[0006] To mitigate at least some of the problems mentioned above, the following is provided:

[0007] A chromatic conversion resonator system comprising: a partial reflection region configured to transmit light of a first principal peak wavelength and reflect light of a second principal peak wavelength; a further partial reflection region configured to at least partially reflect light having a second principal peak wavelength; and a chromatic conversion resonator cavity including at least one quantum well, wherein the chromatic conversion resonator cavity is configured to receive input light having a first principal peak wavelength through the partial reflection region and to convert at least a portion of the received input light by at least one quantum well to provide light of a second principal peak wavelength, thereby resonating within the cavity and providing light having the second principal peak wavelength of the resonance through the further partial reflection region, wherein at least one quantum well is positioned to coincide with a wave antinode of the standing wavelength of the chromatic conversion resonator cavity for light of the second principal peak wavelength, thereby improving at least one of the intensity, spectral width, and directivity of the output light having the second principal peak wavelength.

[0008] Furthermore, a method for forming a chromatic conversion resonator system is provided, comprising: a chromatic conversion resonator cavity including at least one quantum well, wherein the chromatic conversion resonator system comprises: a partial reflection region configured to transmit light of a first principal peak wavelength and reflect light of a second principal peak wavelength; a further partial reflection region configured to at least partially reflect light having a second principal peak wavelength; and the chromatic conversion resonator cavity is configured to receive input light having a first principal peak wavelength through the partial reflection region and to convert at least a portion of the received input light by at least one quantum well to provide light of a second principal peak wavelength, thereby providing light of a second principal peak wavelength resonating within the cavity and light having the second principal peak wavelength of the resonance being output through the further partial reflection region, wherein at least one quantum well is positioned to coincide with a wave antinode of the standing wavelength of the chromatic conversion resonator cavity for light of a second principal peak wavelength, thereby improving at least one of the intensity, spectral width, and directivity of the output light having a second principal peak wavelength.

[0009] Advantageously, improved optical output is achieved, enabling narrow beam angles and narrow spectra for use in near-eye displays, for example. Advantageously, the color conversion resonator system enables the formation of wide color gamut displays and high-resolution micro-LED arrays. Advantageously, the optical color conversion resonator system enables wafer-level processing, and narrow beam angle emission without collimators, and compressed emission spectra with reduced efficiency losses.

[0010] Preferably, the partial reflection region and further partial reflection regions are λ in (N+1). converted / 2n(λ converted The distances are separated by the product of ), where N is a positive integer and λ converted This is the second main peak wavelength, n(λ) converted ) is the effective refractive index of the material that separates the partial reflection region and further partial reflection regions, thereby defining the length of the chromatic conversion resonator cavity. Advantageously, careful tuning of the chromatic conversion resonator cavity allows for improved output emission.

[0011] Preferably, the chromatic conversion resonator cavity includes at least one absorbing layer configured to absorb input light having a first principal peak wavelength, thereby enabling energy transfer from the input light of the first principal peak wavelength into at least one quantum well, preferably the absorbing layer comprising a material having an energy bandgap lower than the energy of the input light of the first principal peak wavelength. Advantageously, the absorbing layer facilitates a process that allows carriers to recombine within the quantum well layer, and thus enables improved resonance of the converted light emitted by at least one quantum well.

[0012] Preferably, the system comprises at least one diffusion barrier configured to reduce the diffusion of carriers from the chromatic conversion cavity. Advantageously, the use of a diffusion barrier reduces carrier diffusion and therefore improves radiative recombination within the chromatic conversion cavity.

[0013] Preferably, the color conversion resonator cavity includes multiple quantum wells. Preferably, the multiple quantum wells form a portion of a multiple quantum well structure arranged to coincide with the antinode of the standing wave wavelength of the color conversion resonator cavity for light of the second main peak wavelength, and / or the separation of at least one quantum well layer and a further quantum well layer is N multiplied by λ converted / 2n(λ converted ), where N is a positive integer, λ converted is the second main peak wavelength, and n(λ converted ) is the effective refractive index of the material between at least one quantum well and a further quantum well at the second main peak wavelength. Advantageously, careful adjustment of the color conversion resonator cavity enables improvement of the output emission.

[0014] Preferably, the color conversion resonator system includes an input pump LED. Preferably, the input pump LED is a micro LED. More preferably, the input pump LED is directly bonded to the color conversion resonator system. Even more preferably, the input pump LED is bonded to a partial reflection region. Advantageously, the combination of the LED structure and the color conversion resonator cavity results in improved coupling and improved emission. Advantageously, an LED structure (such as a blue light emitting nitride-based LED) is used as an input light source for light emitting pixels of different colors, thereby resulting in improved emission that can be implemented in an array of light emitting pixels.

[0015] Preferably, the color conversion resonator system is bonded onto the input pump LED using a dielectric bond or a polymer bond. Advantageously, such a bond enables high-quality coupling between the color conversion resonator cavity system and the input pump LED, thereby reducing losses and improving the efficiency of the resulting device.

[0016] Preferably, at least one of the partial reflection region and the further partial reflection region includes a distributed Bragg reflector, preferably, the distributed Bragg reflector is at least one of a dual-band distributed Bragg reflector, a conventional distributed Bragg reflector, and a vertical laminate of two distributed Bragg reflectors, and more preferably, the partial reflection region includes a low-Herpin refractive index DBR centered on a blue wavelength, or a low-Herpin refractive index DBR centered on a green wavelength, or a low-Herpin refractive index DBR centered on a red wavelength. Advantageously, the partial reflection region is made to optimize which wavelength is emitted by the light-emitting pixel formed by the combination of the color conversion resonator cavity system and the LED device. Advantageously, in order to improve the conversion efficiency from input light having a main peak wavelength to output light having a different main peak wavelength, light of a predetermined wavelength is reused within the color conversion resonator cavity.

[0017] Preferably, the input light is at least one of UV light and visible light, preferably, the input light has a wavelength of 340 nm to 560 nm. Advantageously, a high-quality established input LED source having a wavelength shorter than the wavelength of the further visible light color required for the optical display is used to provide an input pump source for color conversion within the color conversion resonator cavity.

[0018] Preferably, at least one of the partial reflection region and the color conversion resonator cavity includes a group III-V semiconductor material and / or a dielectric material. Advantageously, the partial reflection region is formed using a technique that enables seamless integration of the functional layers within the color conversion resonator cavity.

[0019] Preferably, the partial reflection layer has a reflectivity of less than 20% of the light of the first main peak wavelength and a reflectivity of more than 80% of the light of the second main peak wavelength, or the partial reflection layer has a reflectivity of less than 10% of the light of the first main peak wavelength and a reflectivity of more than 90% of the light of the second main peak wavelength, or the partial re flection layer has a reflectivity of less than 5% of the light of the first main peak wavelength and a reflectivity of more than 95% of the light of the second main peak wavelength. Advantageously, the partial reflection region is adjusted to provide improved output quality in different situations.

[0020] Furthermore, an array of pixels equipped with a color conversion resonator system is provided. Advantageously, a light-emitting pixel based on a composite of a light-emitting device, such as an LED device, and a color conversion resonator cavity means that high-purity color light-emitting pixels can be formed on a scale that means they can be implemented within a high-resolution microscale array.

[0021] Preferably, the first pixel is configured to emit light of a different wavelength than the second pixel, and preferably, the array comprises a third pixel configured to emit light of a different wavelength than the first and second pixels. Advantageously, the multicolor array of light-emitting pixels is formed using a color conversion resonator cavity.

[0022] Preferably, the method comprises one or more of the following steps: growing a color conversion resonator cavity on a substrate, preferably the substrate including a buffer structure; depositing or growing a partial reflection region and / or further partial reflection regions on the substrate; depositing a bonding material; bonding the color conversion resonator system to an LED structure; removing the substrate and / or buffer structure by etching; insulating the color conversion resonator cavity and forming one or more pixels.

[0023] Advantageously, forming a color conversion resonator cavity on a substrate allows for the large-scale formation of color conversion resonator cavities for integration with light-emitting devices. Advantageously, known growth and fabrication techniques can be applied to form the structure using high-quality, low-defect-density materials that provide efficient light input and conversion for use in light-emitting pixels.

[0024] Further aspects of the present invention will become apparent from the description and the appended claims.

[0025] A detailed description of embodiments of the present invention will be given only by reference to the figures. [Brief explanation of the drawing]

[0026] [Figure 1]Figure 1 shows a cross-sectional view of a color conversion resonator cavity with a reflector. [Figure 2] Figure 2 shows a cross-sectional view of the fabricated color conversion resonator cavity from Figure 1, joined to the light-emitting device. [Figure 3A] Figure 3A shows a comparison of the angular light distribution from an LED without a color conversion resonator cavity bonded to the light-emitting device in Figure 2, and from an LED with a color conversion resonator cavity bonded to the light-emitting device in Figure 2. [Figure 3B] Figure 3B shows a comparison of the emission spectra of an LED without a color conversion resonator cavity bonded to the light-emitting device in Figure 2, and an LED with a color conversion resonator cavity bonded to the light-emitting device in Figure 2. [Figure 4] Figure 4 shows a cross-sectional view of a fabricated color conversion resonator cavity bonded to a light-emitting device with an additional lens. [Modes for carrying out the invention]

[0027] Advantageous and sophisticated implementation forms of high-color-purity, narrow-beam-angle color-conversion resonator systems formed in combination with light-emitting devices such as light-emitting diode (LED) devices are described with reference to Figures 1 to 4. The figures show how the color-conversion resonator system is formed and how it interacts with the light-emitting device, using cross-sectional views of individual structures based on a single light-emitting device. However, alternatively, or in addition, the concept is to use high-resolution monoliths having a pixel pitch of 10 μm or less, and preferably 5 μm or less. This technology is applicable to two-dimensional arrays of light-emitting devices, such as high-resolution micro-LED arrays, including micro-LED arrays.

[0028] As described above, in micro-LED display applications, a narrow beam angle and narrow spectrum are desirable for waveguide-type AR display applications and wide color gamut displays, respectively. However, current micro-LED devices using color conversion materials such as phosphors or quantum dots, as well as natural III-N materials, can make it difficult to achieve such wide color gamut and narrow spectrum, and when these are used, the size that can be achieved is limited by the required thickness of the quantum dots. Collimators or lens structures are usually used to reduce the beam angle, but these are difficult to implement on all pixels and can be bulky. Furthermore, filters are usually inserted to cut wavelengths in order to narrow the emission spectrum, but this reduces the efficiency of the pixels. Advantageously, the color conversion resonator cavities described herein enable wafer-level processing and a compressed spectrum with improved narrow beam angles without the use of collimators and reduced efficiency losses.

[0029] Figure 1 shows a cross-sectional view of the color conversion resonator cavity system 100. The color conversion resonator cavity system 100 is a stack of epitaxial crystalline compound semiconductor layers. The epitaxial crystalline compound semiconductor layers are provided by the sequential growth of epitaxial layers on a growth substrate 101a. The growth substrate 101a, for example, silicon, silicon carbide, sapphire, gallium nitride, or other suitable growth substrate is used as a base for the subsequent growth of the epitaxial crystalline compound semiconductor layers. A buffer layer 101b is grown on the substrate 101a. The buffer layer 101b contains gallium nitride (GaN). In further examples, additional and / or alternative buffer layers 101b are included in the growth process. The growth substrate 101a and buffer layer 101b are removed when the final color conversion resonator cavity system 100 is grown and bonded to its optical input source, as described herein. In a further example, the substrate 101a and buffer layer 101b are removed after the epitaxial compound semiconductor crystal layer has been formed. Advantageously, the growth of such an epitaxial compound semiconductor crystal layer can be controlled with high precision to result in a high-quality material with a low defect density, a well-controlled layer thickness, and efficient radiative recombination of carriers at a controlled wavelength of light.

[0030] The chromatic conversion resonator cavity system 100 is designed to receive input light from an input light source, convert the input light having a primary peak wavelength from the input light source, and provide output light having a different, converted primary peak wavelength. The chromatic conversion resonator cavity system 100 is designed so that the converted primary peak wavelength light resonates within the cavity, and the resonant converted light is output from the chromatic conversion resonator cavity system 100.

[0031] Figure 1 shows the color conversion resonator cavity system 100 in the orientation that will later be joined to the input LED. Thus, the layer growth sequence is practically from the substrate 101a shown at the top of Figure 1 to the partial reflection region 114 shown at the bottom of Figure 1.

[0032] The color conversion resonator cavity system 100 is shown in a specific orientation, and those skilled in the art will understand that the sequence of layer growth on the substrate 101a is such that a partial reflection region 116 is grown on the buffer layer 101b before the sequential growth of a first type barrier layer 110 (described later), a second type barrier layer 102e (described later), an absorption layer 106d, a quantum well layer 105d, an absorption layer 104d, a second type barrier layer 102d, an absorption layer 106c, a quantum well layer 105c, an absorption layer 104c, a second type barrier layer 102c, an absorption layer 106b, a quantum well layer 105b, an absorption layer 104b, a second type barrier layer 106a, a quantum well layer 105a, an absorption layer 104a, a second type barrier layer 102a, a first type barrier layer 108, and a partial reflection region 114.

[0033] Advantageously, the substrate 101a is used to position the color conversion resonator cavity system 100 relative to the input optical device in order to bond the color conversion resonator cavity system 100 to the input optical device, and is then removed. In further examples, the epitaxial layers of the color conversion cavity system 100 are provided in a different order.

[0034] Therefore, Figure 1 shows the color conversion resonator cavity system inverted to show a partial reflection region, which is a first partial reflection region 114 formed on the substrate 101a and is a reflector of the color conversion resonator cavity system 100. A first type of barrier layer 108 is shown on the first partial reflection region 114. A second type of barrier layer 102a is shown on the first type of barrier layer 108, and an absorption layer 104a is shown on top of that. The first type of barrier layer has a higher band gap than the absorption layer 104a. The second type of barrier layer 102a has a band gap greater than or equal to that of the absorption layer 104a and a lower band gap than that of the first type of barrier layer 108. A quantum well layer 105a is shown on the absorption layer 104a. A further absorption layer 106a is shown on the quantum well layer 105a. The sequence is repeated with a second type of further barrier layer 102b shown on the absorption layer 106a, followed by an absorption layer 104b shown on the second type of barrier layer 102b, then a quantum well layer 105b, and then another absorption layer 106b. The sequence is then repeated with a second type of further barrier layer 102c shown on the absorption layer 106b, another absorption layer 104c shown on the second type of barrier layer 102c, another quantum well layer 105c grown on the absorption layer 104c, another absorption layer 106c shown on the quantum well layer 105c, another second type of barrier layer 102d shown on the absorption layer 106c, another absorption layer 104d shown on the second type of barrier layer 102d, another quantum well layer 105d shown on the absorption layer 104d, and another absorption layer 106d shown on the quantum well layer 105d. A second type of further barrier layer 102e is shown on the absorption layer 106d. Above the structure, a first type of further barrier layer 110 is shown. A further partial reflection region 116 is shown on the first type of barrier layer 110. The further partial reflection region 116 is a reflector that forms part of the color conversion resonator cavity system 100.

[0035] The first type of barrier layers 108, 110 are diffusion barriers designed to prevent carriers generated within the color conversion resonator cavity system 100 from diffusing outside the color conversion resonator cavity system 100. The first type of barrier layers 108, 110 have a thickness on the order of 1 to 100 nm. In one example, the first type of barrier layers 108, 110 are AlGaN barriers. In further examples, the first type of barrier layers 108, 110 may be formed from different materials or omitted.

[0036] Those skilled in the art will understand that the epitaxial layer forming the color-converting resonator cavity system 100 is a planar layer grown on a substrate 101a. Once the color-converting resonator cavity system 100 is formed, the substrate 101a is used to position the color-converting resonator cavity system 100 relative to its optical input, after which the substrate 101a (along with any buffer layer 101b) is removed, resulting in a freestanding color-converting resonator cavity system 100. In further examples, the substrate 101a is removed at an earlier stage in the process before the color-converting resonator cavity system 100 is fixed to the input LED. The color-converting resonator cavity system 100 is described as being grown in a specific step sequence in relation to the substrate 101a. Those skilled in the art will understand that in further examples, alternatively or in addition, the color-converting resonator cavity system 100 is provided in the reverse order before the removal of the substrate 101a and / or buffer layer 101b. Furthermore, the chromatic conversion resonator cavity system 100 is shown to comprise certain layers. In further examples, alternative or additional layers are used to form the chromatic conversion resonator cavity system 100. For example, in further examples, the chromatic conversion resonator cavity system comprises further quantum well layers and / or absorption layers and intervening layers, or fewer quantum well layers and / or absorption layers and intervening layers. In further examples, layers are omitted while retaining the concepts described herein. It can be done.

[0037] The color conversion resonator cavity system 100 shown in Figure 1 is formed using epitaxial compound semiconductor growth techniques such as metal-organic chemical vapor deposition (MOCVD) and molecular beam epitaxy (MBE). In addition, or alternatively, the color conversion resonator cavity system 100 may be formed using any suitable technique.

[0038] The color conversion resonator cavity system 100 described with respect to Figure 1 is formed from a nitride-based material. Specifically, the epitaxial crystalline compound semiconductor layer is a gallium nitride (GaN)-based material. Although the structure described with respect to Figure 1 relates to nitride-based semiconductor compound materials, those skilled in the art will understand that the concepts described herein are also applicable to other materials, in particular to other semiconductor materials, such as other III-V compound semiconductor materials or II-VI compound semiconductor materials.

[0039] The quantum well layers 105a, 105b, 105c, and 105d are designed to allow carriers to recombine, thereby enabling radiative recombination to produce output light with a dominant peak wavelength different from the wavelength of the input light that gives rise to the emission of output light. To enable the emission of output light, the input light is absorbed by the absorption layers 104a, 104b, 104c, 104d, 106a, 106b, 106c, and 106d. In one example, the input light is blue light with a wavelength of approximately 450 nm. The wavelength of the light output by the quantum well layers 105a, 105b, 105c, and 105d is longer than the wavelength input. The output wavelength of the light is the converted wavelength of the light. The input light is blue light, but in further examples, additional or alternative wavelengths of the input light are used.

[0040] The color conversion resonator cavity system 100 shows four quantum well layers 105a, 105b, 105c, 105d. Each of the quantum well layers 105a, 105b, 105c, 105d is associated with an absorption layer. Each of the quantum well layers 105a, 105b, 105c, 105d includes at least one quantum well. The first quantum well layer 105a is associated with two absorption layers 104a, 106a. The second quantum well layer 105b is associated with two absorption layers 104b, 106b. The third quantum well layer 105c is associated with two absorption layers 104c, 106c. The fourth quantum well layer 105d is associated with two absorption layers 104d, 106d. Thus, the color conversion resonator cavity system 100 includes multiple quantum wells. In a further example, additional or alternative quantum well structures are implemented within the color conversion resonator cavity system 100. For example, one or more of the quantum well layers 105a, 105b, 105c, 105d include multiple quantum wells, whereby one or more of the quantum well layers 105a, 105b, 105c, 105d include multiple quantum wells (MQW (multiple quantum well)).

[0041] Careful positioning of the quantum well structure (single and / or multiple QW) results in improved output of light. The quantum well layers 105a, 105b, 105c, 105d are arranged to coincide with the antinode of the standing wave wavelength of the color conversion resonator cavity for light of the second main peak wavelength (i.e., the converted light), thereby improving at least one of the intensity, spectral width, and directivity of the output light having the second main peak wavelength. The separation between the first partial reflection region 114 and the first quantum well layer 105a is shown to be separated by a separation 112 between the transverse planes of λ converted / 2n(λ converted ). Here, λ converted is the main peak wavelength of the converted light within the color conversion resonator cavity system 100, and n(λ converted) is the effective refractive index of the material separating the partial reflection region and the first quantum well layer 105a. Further quantum well layers 105b, 105c, and 105d are spaced apart from each other with the same separation 112. Here, the separation 112 indicates the distance perpendicular to the transverse plane formed by the epitaxial layers in the color conversion resonator system 100. Quantum well layer 1 The positioning of 05a, 105b, 105c, and 105d is such that they coincide with the wave antinodes of the resonant standing waves of the primary peak wavelength of the converted light within the chromatic conversion cavity system, thereby improving at least one of the intensity, spectral width, and directivity of the output light having a second primary peak wavelength, as described herein. If the quantum well layers 105a, 105b, 105c, and 105d each contain multiple quantum wells (MQWs), the MQWs are positioned to coincide with the wave antinodes of the resonant standing waves of the primary peak wavelength of the converted light within the chromatic conversion cavity system, thereby improving at least one of the intensity, spectral width, and directivity of the output light having a second primary peak wavelength.

[0042] To enable efficient resonance within the color conversion resonator cavity system 100, the color conversion resonator cavity system 100 is formed between two reflector layers, a first partial reflection region 114 and a second further partial reflection region 116. The first reflection region 114 and the second reflection region 116 are layers configured to selectively reflect and transmit light so that they have at least partial reflectivity.

[0043] Advantageously, the first and second reflective regions 114, 116 are formed during the same process that provides the chromatic conversion resonator cavity system 100. Advantageously, a continuous growth process is used to form the chromatic conversion resonator cavity system 100, resulting in a high-quality, low-defect-density material with precise control over the layer thickness and, consequently, the separation of the transverse planes that form the epitaxial structure. In further examples, alternatively or in addition, the partial reflective regions 114, 116 are deposited separately in a physical vapor deposition (PVD) reactor or evaporator.

[0044] The chromatic conversion resonator cavity system 100 is designed to receive input light through a first partial reflection region 114. The input light has a main peak wavelength. The input light is absorbed within the chromatic conversion resonator cavity system 100 by absorption layers 104a, 106a, 104b, 106b, 104c, 106c, 104d, 106d and quantum well layers 105a, 105b, 105c, 105d. The absorption of the input light results in the generation of electron-hole pairs within the absorption layers 104a, 106a, 104b, 106b, 104c, 106c, 104d, 106d and quantum well layers 105a, 105b, 105c, 105d. Electron-hole pairs generated in absorption layers 104a, 106a, 104b, 106b, 104c, 106c, 104d, and 106d move to quantum well layers 105a, 105b, 105c, and 105d. The electron-hole pairs recombine and emit light having a wavelength determined by the composition of quantum well layers 105a, 105b, 105c, and 105d. The light emitted by quantum well layers 105a, 105b, 105c, and 105d has a principal peak wavelength longer than the principal peak wavelength of the input light absorbed in the color conversion resonator cavity system 100. The principal peak wavelength of the light converted from the input light is determined by the transition wavelength. If the input light is blue light, quantum well layers 105a, 105b, 105c, and 105d are designed to emit green light, and the quantum well material is Al x In y Ga 1-x-y When it is N, it has a spectral range (full width at half maximum (FWHM)) of approximately 30 nm. When the quantum well layers 105a, 105b, 105c, and 105d are designed to emit red light, the spectral range is approximately 50 nm. Generally, when the quantum well layers 105a, 105b, 105c, and 105d are Al x In y Ga 1-x-y N or Al x In y Ga 1-x-y When formed from P, light from radiative recombination is emitted in all directions, but the light that satisfies the cavity conditions for the color conversion resonator cavity system 100 is enhanced and has a concentrated emission spectrum and a narrow beam angle.

[0045] Absorption layers 104a, 106a, 104b, 106b, 104c, 106c, 104d, and 106d are made of aluminum indium gallium nitride (Al a In b Ga 1-a-b N) or aluminum indium gallium phosphide (Al a In b Ga 1-a-b Formed from P). Absorption layers 104a, 106a, 104b, 106b, 104c, 106c, 104d, Layer 106d has a lower bandgap than the input light and is formed in a single growth step. In further examples, the absorbing layers 104a, 106a, 104b, 106b, 104c, 106c, 104d, and 106d are formed in the form of stepwise or continuous transition layers, thereby changing the composition of the absorbing layers 104a, 106a, 104b, 106b, 104c, 106c, 104d, and 106d vertically from the associated planar quantum well layer. Advantageously, such absorbing layers provide a material suitable for assisting strain relaxation, thereby improving the quality of the crystalline structure forming the chromatic conversion resonator cavity system 100 while simultaneously absorbing light. In further examples, different compositions and configurations of the absorbing layers are implemented to absorb light from an input LED and enable downconversion from the input light to a conversion wavelength for output.

[0046] The first reflection region 114 and the second reflection region 116 are λ in (N+1) converted / 2n(λ converted The length of the result of multiplying by ) is separated, where N is a positive integer and λ converted This is the second main peak wavelength, n(λ) converted ) is the effective refractive index of the material separating the first reflection region and the second partial reflection region, thereby defining the length of the color conversion resonator cavity. The input light absorbed within the color conversion resonator cavity system 100 has a wavelength (λ). converted ) is converted to light, λ converted The light resonates within the cavity system 100. The resonant light is then output through a further partial reflection region 116.

[0047] The first partial reflection region 114 and the second partial reflection region 116 are configured such that a cavity formed between them is used to convert the input light that has passed through the first partial reflection region 114 into light having a converted main peak wavelength, and the resonant light of the converted main peak wavelength passes through the second partial reflection region 116.

[0048] The first partial reflection region 114 and the second partial reflection region 116 are distributed Bragg reflectors (DBRs). The first partial reflection region 114 has a relatively high reflectivity for the wavelength of the converted light generated within the color conversion resonator cavity system 100 and a relatively high transmittance for the wavelength of the input light. In one example, the first partial reflection region 114 has a relatively low reflectivity, for example, less than 20% of the main peak wavelength of the input light from a light-emitting device bonded to the first partial reflection region 114, and a relatively high reflectivity, for example, more than 80% of the converted light generated by the absorption and re-emission of the input light within the color conversion resonator cavity system 100. In further examples, different reflectivity values ​​are used for the first partial reflection region 114. In one example, the first partial reflection region 114 has a reflectivity of less than 10% of the input light and a reflectivity of more than 90% of the converted light. In a further example, the first partial reflection region 114 has a reflectance of less than 5% of the input light and a reflectance of more than 95% of the converted light.

[0049] The partially reflective regions 114 and 116 are formed from alternating epitaxial crystalline layers with different refractive indices. The refractive indices and thicknesses of the layers are selected to produce a reflectivity response as a function of the wavelength of incident light in the partially reflective layer regions 114 and 116. This method of DBR growth enables the seamless formation of a high-crystal-quality color conversion resonator cavity system 100.

[0050] In one example, the DBR forming the first partial reflection region 114 has a low Herpin refractive index DBR.

[0051] The second partial reflection region 116 is formed in the same manner as the first partial reflection region 114.

[0052] The first and second partial reflection regions 114 and 116 are DBRs, but in further examples alternative or additional regions are used. In further examples the second partial reflection region 116 is two different This includes a vertical stack of DBRs. In further examples, the second partial reflection region 116 is omitted. In further examples, the first partial reflection region 114 and / or the second partial reflection region 116 include a stack of two different DBRs. In further examples, the second partial reflection region 116 includes a dual-band DBR having relatively high reflectivity at both the input and converted wavelengths of light. In further examples, the second partial reflection region 116 includes a DBR having relatively high reflectivity at the converted wavelength of light.

[0053] The partial reflective layers 114 and 116 are DBRs formed from nitride-based epitaxial layers, but in further examples, the partial reflective layers 114 and 116 are formed using different methods, in addition to, or alternatively, while maintaining functionality that allows for the reflection of some wavelengths of light and the transmission of different wavelengths of light. For example, the first partial reflective region 114 and / or the second partial reflective region 116 are formed from a dielectric laminate. In further examples, the first partial reflective region 114 and / or the second partial reflective region 116 are formed from alternating layers of GaN and porous GaN. Since the porosity of epitaxial crystalline layers is related to their refractive index, the porosity of the epitaxial crystalline GaN layer forming the partial reflective layer 104 is controlled to yield a desired reflectivity response as a function of wavelength. Advantageously, the DBR thus formed can be provided using GaN alone.

[0054] To provide light with improved output characteristics, the color conversion resonator cavity system 100 described with reference to Figure 1 is coupled to an input light-emitting device. This configuration is described in more detail with reference to Figure 2, which shows a resonant standing wave 204 within the color conversion resonator cavity system 100 coupled to the light-emitting device 202. Figure 2 shows the color conversion resonator cavity system 100 coupled to the light-emitting device 202 to provide the system 200, thereby guiding the light emitted from the light-emitting device 202 through the light-emitting surface of the light-emitting device 202 facing a first partial reflection region 114 of the color conversion resonator cavity system 100, and as a result the input light generated by the light-emitting device 202 is received within the color conversion resonator cavity system for downconversion to longer wavelength output light output through a further partial reflection region 116 and through the opposite surface of the color conversion resonator cavity system.

[0055] The light-emitting device 202 is a light-emitting diode (LED). In Figure 2, the light-emitting diode 202 is shown as an exemplary system that emits light in different directions, as indicated by the arrows. The light-emitting device 202 is formed using separate individual light-emitting structures in some examples, but in one example, the light-emitting device 202 is an LED device formed from an epitaxial semiconductor crystal layer. Light in such an LED device is generated by carrier injection in one or more quantum well structures. Light is emitted by one or more quantum well structures and extracted through a main light-emitting surface. The main light-emitting surface that emits light in different directions is coupled with a color conversion resonator cavity system 100 to provide improved light output.

[0056] The light-emitting device 202 is bonded to the color conversion resonator cavity system 100. In one example, the light-emitting device 202 is bonded to the color conversion resonator cavity system 100 using a dielectric bond. The surface of the light-emitting device 202 that will be bonded to the color conversion resonator cavity system 100 is terminated with a high-density oxide film. The surface of the color conversion resonator cavity system 100 that will be bonded to the input light-emitting device 202 is also terminated with a high-density oxide film to facilitate wafer-level oxide bonding. Thus, the main light-emitting surface of the light-emitting device 202 is positioned in close proximity to, or in contact with, the first partial reflection region 114 of the color conversion resonator cavity system 100, so that the light emitted from the light-emitting device 202 serves as input light for the color conversion resonator cavity system 100.

[0057] In a further example, the light-emitting device 202 uses polymer bonding, such as polyimide bonding. The light-emitting device 202 is bonded to the color-converting resonator cavity system 100. In further examples, additional or alternative bonding mechanisms are used to attach the light-emitting device 202 to the color-converting resonator cavity system 100. Advantageously, the light-emitting device 202 is bonded to the color-converting resonator cavity system 100 in such a way that interface losses of light emitted from the light-emitting device 202 at the interface with the color-converting resonator cavity system 100 are minimized to form a single device.

[0058] The refractive index of the material used to bond the light-emitting device 202 to the color conversion resonator cavity system is 1 to 2.5.

[0059] The color conversion resonator cavity system 100 is shown in Figure 2 to be bonded to the input light-emitting device 202, but in one example, the color conversion resonator cavity system 100 may be grown with or without the first partial reflection region 114 included in the growth step. For example, the structure in Figure 1 is grown on the substrate without the partial reflection regions 114 and 116, which are deposited later. The structure including the epitaxial layer is etched to expose the entire resonator cavity or a portion of the resonator cavity. The exposed surface is covered with a multi- or single-crystal high-bandgap material such as Al(Ga)N. In one example, the growth substrate and any buffer layers implemented in the growth process to facilitate the structure in Figure 1 are removed by a selective etch process. The first partial reflection region 114 is deposited on the surface opposite the growth substrate surface before bonding the color conversion resonator cavity system 100 to the input light-emitting device 202. The growth substrate and buffer layer are removed, and a second partial reflective region 116 is deposited on top of the structure, providing the light-emitting surface of the color-converting LED structure.

[0060] Figure 2 shows a single light-emitting device 202, but in further examples, an addressable array of light-emitting devices 202 is bonded to an associated color-converting cavity system 100 to provide an array of light-emitting devices, such as a high-resolution array of light-emitting devices. The density of the addressable array is related to the intended use of the array, and the light-emitting surface of the color-converting cavity system 100 bonded to the light-emitting device 202 provides pixels associated with the light-emitting device. The light-emitting device 202 is fabricated using wafer or chip-level processes.

[0061] Figure 2 shows an exemplary standing wavelength of the converted light as a resonant standing wave 204. The wave antinodes of the resonant standing wave 204 of the converted light are shown to coincide with the quantum well layers 105a, 105b, 105c, and 105d, thereby improving at least one of the intensity, spectral width, and directivity of the converted output light having a second principal peak wavelength. The resonant standing wave 204 of the converted light is formed under resonant cavity conditions between a first partial reflection region 114 and a second partial reflection region 116. The first type of barrier layers 108, 110 are thin layers and are configured to be provided within the length of the cavity, as defined by the distance between the parallel planes formed by the partial reflection regions 114, 116. Further examples involve substitution or addition of layers within the structure while improving the characteristics of the output light.

[0062] Figure 3A shows a comparison of angular light distributions from LED-based light-emitting pixels that do not have a color conversion resonator cavity bonded to the light-emitting device in Figure 2, and those that do have a color conversion resonator cavity bonded to the light-emitting device in Figure 2.

[0063] Figure 3A shows Figure 300 of the angular distribution of light emission 306 from a typical LED. Figure 300 is a two-dimensional diagram, and those skilled in the art will understand that the distribution shown in Figure 300 is applicable to three-dimensional light output. Emission 306 is Lambertian. Such emission 306 is typical emission from a standard LED 302 when the color conversion resonator cavity system 100 described with reference to Figures 1 and 2 is not present. However, when an LED such as a light-emitting device 202 is coupled with the color conversion resonator cavity system 100, the angular distribution of the emission changes. When input light from an LED having such emission 306 is absorbed in the MQW and pump absorption layer of the color conversion resonator cavity system 100, electron-hole pairs are generated in the MQW and pump absorption layer. The electrons and holes generated in the pump absorption layer move to the MQW. Therefore, the emission light wavelength is determined by the MQW transition wavelength. When the QW material is AlxInyGa1-x-yN, this transition wavelength has a spectral range (FWHM: full width at half maximum) of about 30 nm for green and about 50 nm for red. Generally, AlxInyGa1-x-yN or Al x In y Ga 1-x-y While the P MQW emits light in all directions, the color-converting cavity resonator improves the emission to satisfy the cavity condition. As a result, a narrow beam angle and concentrated emission spectrum are obtained, as shown by the distribution of the color-converted resonant emission 304 in Figure 3A.

[0064] Figure 3B shows a comparison of the emission spectra 300' from LEDs without a color conversion resonator cavity bonded to the light-emitting device in Figure 2, and from LEDs with a color conversion resonator cavity bonded to the light-emitting device in Figure 2. A graph of emission intensity on the vertical axis 310 versus wavelength on the horizontal axis 308 is shown.

[0065] Figure 3B shows how the emission spectra compare between the converted emission 312 from an LED with color conversion but without a resonator cavity joined to the LED, and the emission 314 from an LED with a color conversion resonator cavity joined to the LED. As a result, the intensity of the emission 314 with the color conversion resonator cavity is greater than that of the emission 312 without a resonator cavity, and the emission 314 with the color conversion resonator cavity has a narrower spectral width than the emission without a resonator cavity. Consequently, the color conversion resonator cavity system results in stronger, higher-purity color emission.

[0066] The improved angular distribution, intensity, and color purity shown in Figures 3A and 3B offer significant advantages, particularly for augmented reality applications where displays are formed very close to the user using high-resolution arrays of LEDs. Furthermore, advantageously, using epitaxially grown layers to form the color conversion resonator cavity system means that the size constraints imposed by quantum dot-based color conversion systems can be overcome, potentially providing smaller light-emitting surfaces for micro-LED-based light-emitting pixels and resulting in arrays of light-emitting pixels with reduced pixel pitch.

[0067] Figure 4 shows, in one example, how a light-emitting pixel 400 based on a light-emitting device 202 is formed together with a lens 402. The implementation of the lens 402 enables a wider emission angle in addition to higher intensity and color purity, resulting in improved light emission for applications such as high-resolution displays, for example, high-resolution LED pixel televisions.

[0068] The color conversion resonator cavity system 100, combined with an input light-emitting device such as an LED device, is implemented as described above. In further examples, the concept of the present invention is implemented using structures formed from different compositions using different step sequences.

[0069] Although the light-emitting device 202 is shown as a discrete input LED, in further examples, the light-emitting device 202 is an LED device formed in the form of an array of LED devices. Such an LED device is provided by conventional means and formed in such a way that its combination with a color conversion resonator cavity is possible. The process is described with reference to an LED light source, but in further examples, alternative or additional light sources are implemented.

[0070] In one example, where the input light source forms part of an array, such as a high-resolution micro-LED array, pixels are formed by a combination of individual LEDs and their associated color conversion resonator cavities. Pixels within a pixel array interact with each other to prevent carrier diffusion between neighboring pixels. It is insulated. Furthermore, in one example, a surface treatment is performed to prevent carrier diffusion into surface defects.

[0071] Methods for forming a color conversion resonator cavity system have been described above with reference to Figures 1 to 4 for those skilled in the art, but those skilled in the art will understand that in further examples additional or alternative steps are used, and in even further examples some steps are omitted. In further examples, one or more LED structures are provided that are combined with one or more color conversion resonator cavities, and the order of the processing steps is changed, while resulting in improved luminescence characteristics as described herein at least.

Claims

1. A near-eye display comprising an array of pixels having a pixel pitch of 10 μm or less, The array includes at least one color conversion resonator system, The aforementioned color conversion resonator system is A partial reflection region configured to transmit light of a first main peak wavelength and reflect light of a second main peak wavelength, A further partial reflection region configured to partially reflect light having the second principal peak wavelength, wherein the further partial reflection region and the further partial reflection region are formed from alternating layers of GaN and porous GaN, An input pump microLED directly connected to the aforementioned color conversion resonator system, A color conversion resonator cavity containing at least one quantum well, The color conversion resonator cavity is equipped with, The input light having the first main peak wavelength is received through the partial reflection region, A near-eye display comprising: a quantum well that converts at least a portion of the received input light to provide light of the second principal peak wavelength, thereby causing the light of the second principal peak wavelength to resonate in the chromatic conversion cavity, and providing light having the second principal peak wavelength of the resonance to be output through the further partial reflection region, wherein the quantum well is positioned to coincide with a standing wavelength wave antinode of the chromatic conversion cavity for the light of the second principal peak wavelength, thereby improving at least one of the intensity, spectral width, and directivity of the output light having the second principal peak wavelength.

2. The aforementioned partial reflection region and the further partial reflection region are (N+1) λ ｃｏｎｖｅｒｔｅｄ / 2n(λ ｃｏｎｖｅｒｔｅｄ The distances are separated by the multiplication of ), where N is an integer and λ ｃｏｎｖｅｒｔｅｄ is the second main peak wavelength, and n(λ) ｃｏｎｖｅｒｔｅｄ The near-eye display according to claim 1, wherein ) is the effective refractive index of a material separating the partial reflection region and the further partial reflection region, thereby defining the length of the color conversion resonator cavity.

3. The aforementioned color conversion resonator cavity absorbs the input light having the first main peak wavelength, and thereafter The near-eye display according to claim 1 or 2, further comprising at least one absorbing layer configured to enable the transfer of energy from input light having the first principal peak wavelength into the at least one quantum well.

4. The near-eye display according to any one of claims 1 to 3, comprising at least one diffusion barrier configured to reduce the diffusion of carriers from the color conversion resonator cavity.

5. The chromatic conversion resonator cavity includes multiple quantum wells, and the multiple quantum wells form a portion of the multiple quantum well structure that is arranged to coincide with the standing wavelength wave antinodes of the chromatic conversion resonator cavity for light of the second principal peak wavelength, and / or the separation of the at least one quantum well and the further quantum wells is λ to N ｃｏｎｖｅｒｔｅｄ / 2n(λ ｃｏｎｖｅｒｔｅｄ This is the result of multiplying by ), where N is an integer and λ ｃｏｎｖｅｒｔｅｄ is the second main peak wavelength, and n(λ) ｃｏｎｖｅｒｔｅｄ The near-eye display according to any one of claims 1 to 4, wherein ) is the effective refractive index of the material between the at least one quantum well and the further quantum well at the second principal peak wavelength.

6. The near-eye display according to any one of claims 1 to 5, wherein the input pump microLED is bonded to the partial reflection region.

7. The near-eye display according to any one of claims 1 to 6, wherein the color conversion resonator system is bonded to the input pump microLED using a polymer bond.

8. The near-eye display according to any one of claims 1 to 7, wherein at least one of the partial reflection region and the further partial reflection region includes a distributed Bragg reflector, and the distributed Bragg reflector is at least one of a dual-band distributed Bragg reflector, a conventional distributed Bragg reflector, and a vertical stack of two distributed Bragg reflectors.

9. The near-eye display according to any one of claims 1 to 8, wherein the input light has a wavelength of 340 nm to 560 nm.

10. The near-eye display according to any one of claims 1 to 9, wherein the partial reflection region has a reflectance of less than 20% of the light of the first main peak wavelength and more than 80% of the light of the second main peak wavelength, or the partial reflection region has a reflectance of less than 10% of the light of the first main peak wavelength and more than 90% of the light of the second main peak wavelength, or the partial reflection region has a reflectance of less than 5% of the light of the first main peak wavelength and more than 95% of the light of the second main peak wavelength.

11. The near-eye display according to claim 1, wherein the first pixel is configured to emit light of a different wavelength than the second pixel.

12. A method for forming a near-eye display including an array of pixels having a pixel pitch of 10 μm or less, The array includes at least one color conversion resonator system, The aforementioned color conversion resonator system A partial reflection region configured to transmit light of a first main peak wavelength and reflect light of a second main peak wavelength, A further partial reflection region configured to partially reflect light having the second principal peak wavelength, wherein the further partial reflection region and the further partial reflection region are formed from alternating layers of GaN and porous GaN, An input pump microLED directly connected to the aforementioned color conversion resonator system, A color conversion resonator cavity containing at least one quantum well, The color conversion resonator cavity is equipped with, The input light having the first main peak wavelength is received through the partial reflection region, A method comprising: providing, by at least one quantum well, a conversion of at least a portion of the received input light to provide light of the second principal peak wavelength, thereby causing the light of the second principal peak wavelength to resonate in the chromatic conversion cavity, and providing light having the second principal peak wavelength of the resonance to be output through the further partial reflection region, wherein the at least one quantum well is positioned to coincide with a standing wavelength wave antinode of the chromatic conversion cavity for the light of the second principal peak wavelength, thereby improving at least one of the intensity, spectral width, and directivity of the output light having the second principal peak wavelength.

13. The partial reflection region and the further partial reflection region are separated by a distance that is a multiple of (N + 1) multiplied by λ ｃｏｎｖｅｒｔｅｄ / 2n(λ ｃｏｎｖｅｒｔｅｄ ), where N is a positive integer, λ ｃｏｎｖｅｒｔｅｄ is the second main peak wavelength, and n(λ ｃｏｎｖｅｒｔｅｄ ) is the effective refractive index of the material separating the partial reflection region and the further partial reflection region, thereby defining the length of the color conversion resonator cavity, the method according to claim 12.

14. The method according to claim 12 or 13, wherein the color conversion resonator cavity includes at least one absorbing layer configured to absorb input light having the first principal peak wavelength, thereby enabling the transfer of energy from the input light of the first principal peak wavelength into the at least one quantum well.

15. The method according to any one of claims 12 to 14, comprising at least one diffusion barrier configured to reduce the diffusion of carriers from the color conversion resonator cavity.

16. The chromatic conversion resonator cavity includes multiple quantum wells, and the multiple quantum wells form a portion of the multiple quantum well structure that is arranged to coincide with the standing wavelength wave antinodes of the chromatic conversion resonator cavity for light of the second principal peak wavelength, and / or the separation of the at least one quantum well and the further quantum wells is λ to N ｃｏｎｖｅｒｔｅｄ / 2n(λ ｃｏｎｖｅｒｔｅｄ This is the result of multiplying by ), where N is an integer and λ ｃｏｎｖｅｒｔｅｄ is the second main peak wavelength, and n(λ) ｃｏｎｖｅｒｔｅｄ The method according to any one of claims 12 to 15, wherein n is the effective refractive index of the material between the at least one quantum well and the further quantum well at the second principal peak wavelength.

17. The method according to any one of claims 12 to 16, wherein the color conversion resonator system is directly bonded to the input pump microLED using a polymer bond.

18. The method according to any one of claims 12 to 17, wherein at least one of the partial reflection region and the further partial reflection region includes a distributed Bragg reflector, and the distributed Bragg reflector is at least one of a dual-band distributed Bragg reflector, a conventional distributed Bragg reflector, and a vertical stack of two distributed Bragg reflectors.

19. The method according to any one of claims 12 to 18, wherein the input light has a wavelength of 340 nm to 560 nm.

20. The partial reflection region has a reflectance of less than 20% of the light of the first principal peak wavelength and more than 80% of the light of the second principal peak wavelength, or the partial reflection region has a reflectance of less than 10% of the light of the first principal peak wavelength and more than 90% of the light of the second principal peak wavelength. The method according to any one of claims 12 to 19, wherein the partial reflection region has a reflectance of less than 5% of the light of the first principal peak wavelength and a reflectance of more than 95% of the light of the second principal peak wavelength.

21. The following steps, The process involves growing the aforementioned color conversion resonator cavity on a substrate, wherein the substrate includes a buffer structure. Depositing or growing the aforementioned partial reflection region and / or the further partial reflection on the substrate, The surface of the LED structure and the surface of the color conversion resonator cavity are terminated with a high-density oxide film. Depositing bonding material, The color conversion resonator system is joined to the LED structure using a dielectric junction, Removing the substrate and / or buffer structure by etching, The aforementioned color conversion resonator cavity is insulated, and one or more pixels are formed therein. The method according to any one of claims 12 to 20, comprising one or more of the above.

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