Light-emitting device with internal non-specular light redirection and position-dependent reflection, transmission or redirection

Abstract

The semiconductor diode structure has one or more light-emitting active layers and a redirection layer on the back surface, including one or more of an array of nanoantennas, a partial photonic band gap structure, a photonic crystal, or an array of meta-atoms or meta-molecules, and exhibits non-mirror internal reflection redirection of output light incident thereon within the diode structure. One or both of the front surface and the back surface exhibit position-dependent redirection, reflection, or transmission of the output light, including one or both of (i) position-dependent internal reflection redirection of the output light incident on the back surface, or (ii) position-dependent internal reflection reduction or position-dependent transmission reduction of the output light incident on the front surface layer or coating. The position-dependence of the brightness of the output light emerging from the diode can be different from the position-dependence of the emission from the active layer. With uniform emission throughout the active layer, the output light can exhibit position-dependent brightness.

Description

[Technical Field]

[0001] [Priority Claim] This application claims priority to (i) U.S. Provisional Application No. 63 / 197,648, entitled "Light-Emitting Device with Internal Non-Specular Light Redirection and Position-Dependent Reflection, Transmission, or Redirection," filed on June 7, 2021, in the name of Lopez et al., and (ii) U.S. Patent Application No. 17 / 825,143, entitled "Light-Emitting Device with Internal Non-Specular Light Redirection and Position-Dependent Reflection, Transmission, or Redirection," filed on May 26, 2022, in the name of Lopez et al., both of which are incorporated by reference as if set forth in their entireties herein.

[0002] [Technical field] The field of the invention relates to light emitting devices. Disclosed herein are devices that include internal non-specular light reduction and position-dependent reflection, transmission or redirection to produce position-dependent brightness. Summary of the Invention

[0003] A semiconductor light emitting device according to the present invention comprises: a semiconductor diode having a front surface and a back surface, one or more light emitting active layers, and a redirection layer on the back surface. The one or more light emitting active layers are arranged to emit output light at a nominal vacuum wavelength λ and propagate within the diode structure. The back surface redirection layer comprises one or more of: (i) a nanoantenna array, (ii) a partial photonic bandgap structure, (iii) a photonic crystal, or (iv) a meta-atom or meta-molecule. At least a portion of the back surface redirection layer is structurally arranged to exhibit non-specular internal reflection redirection of output light incident on the back surface within the diode structure for the nominal output vacuum wavelength λ. One or both of the front and back or front and back surfaces include one or more structural arrangements that exhibit position-dependent redirection, reflection, or transmission of output light, including one or both of: (i) at least a portion of the back redirection layer exhibits position-dependent internal reflective redirection of output light incident on the back surface within the diode structure; or (ii) the front surface has a layer or coating thereon, and at least a portion of the front surface layer or front surface coating exhibits position-dependent internal reflective redirection or position-dependent transmissive redirection of output light incident on the front surface from within the diode structure.

[0004] The position dependence of one or both of the rear redirection layer and the front surface layer or coating can be arranged so that output light exiting the device through the front surface exhibits a position-dependent luminance that varies with position across the front surface. In some embodiments, the position dependence of the luminance of output light exiting the device through the front surface can be different from the position dependence of the emission of output light emitted from the active layer. In some of these embodiments, a substantially uniform emission of output light across the active layer can exhibit a position-dependent luminance that varies with position across the front surface.

[0005] Objects and advantages of the light emitting device may become apparent with reference to the exemplary embodiments illustrated in the drawings and disclosed in the following description or appended claims.

[0006] This Summary is provided to introduce a selection of concepts in a simplified form that are further described below in the Detailed Description. This Summary is not intended to identify key features or essential features of the claimed subject matter, nor is it intended to be used as an aid in determining the scope of the claimed subject matter. [Brief explanation of the drawings]

[0007] [Figure 1] FIG. 1 is a schematic cross-sectional view of three embodiments of the light-emitting device of the present invention. [Figure 2] FIG. 2 is a schematic cross-sectional view of three embodiments of the light-emitting device of the present invention. [Figure 3] FIG. 3 is a schematic cross-sectional view of three embodiments of the light-emitting device of the present invention.

[0008] [Figure 4] FIG. 4 shows schematic cross-sectional views of three further embodiments of light-emitting devices according to the present invention. [Figure 5] FIG. 5 shows schematic cross-sectional views of three further embodiments of light-emitting devices according to the present invention. [Figure 6] FIG. 6 shows schematic cross-sectional views of three further embodiments of light-emitting devices according to the present invention.

[0009] [Figure 7] FIG. 7 is a schematic cross-sectional view of another embodiment of the light-emitting device of the present invention.

[0010] [Figure 8] FIG. 8 is a diagram illustrating a plan view of some exemplary arrangements of redirection layers in light-emitting devices of the present invention. [Figure 9]FIG. 9 is a diagram illustrating a plan view of some exemplary arrangements of redirection layers in light-emitting devices of the present invention. [Figure 10] FIG. 10 is a diagram illustrating a plan view of some exemplary arrangements of redirection layers in light-emitting devices of the present invention.

[0011] [Figure 11A] FIG. 11A is a schematic cross-sectional view of an example of a conventional light-emitting device. [Figure 11B] FIG. 11B is a schematic cross-sectional view of an example of a conventional light-emitting device.

[0012] [Figure 12A] FIG. 12A is a schematic cross-sectional view showing an example of a light-emitting device. [Figure 12B] FIG. 12B is a schematic diagram illustrating an example of non-specular redirection of output light.

[0013] [Figure 13A] FIG. 13A is a schematic cross-sectional view showing an example of a light-emitting device. [Figure 13B] FIG. 13B is a schematic diagram illustrating an example of non-specular reflective redirection and non-refractive transmissive redirection of output light.

[0014] [Figure 14] FIG. 14 is a schematic diagram of three differently scaled images of an exemplary array of four light-emitting devices and an example diagram of the corresponding intensity distributions of the images, the images being formed in the Fourier plane.

[0015] [Figure 15A] FIG. 15A shows the uniform position-dependent luminance for a single light-emitting device. [Figure 15B] FIG. 15B shows the tilted position dependent luminance for a single light emitting device. [Figure 15C]FIG. 15C shows the position-dependent brightness of the 1D peak for a single light-emitting device. [Figure 15D] FIG. 1D shows the position-dependent brightness of the 2D peak for a single light-emitting device. [Figure 15E] FIG. 15E shows the concentrated position-dependent luminance for a single light-emitting device.

[0016] [Figure 16A] Figure 16A shows an exemplary image intensity distribution in the Fourier plane of an array of light-emitting devices having an output intensity distribution shown in Figure 16B (e.g., similar to Figure 15A) when imaged as in Figure 14. [Figure 16B] FIG. 16B shows an output intensity distribution (eg, similar to FIG. 15A).

[0017] [Figure 17A] Figure 17A shows an exemplary image intensity distribution in the Fourier plane of an array of light-emitting devices having an output intensity distribution shown in Figure 17B (e.g., similar to Figure 15B) when imaged as in Figure 14. [Figure 17B] FIG. 17B shows an output intensity distribution (eg, similar to FIG. 15B).

[0018] [Figure 18A] FIG. 18A is a schematic diagram illustrating some examples of nanoantennas. [Figure 18B] FIG. 18B is a schematic diagram illustrating some examples of nanoantennas. [Figure 18C] FIG. 18C is a schematic diagram illustrating some examples of nanoantennas. [Figure 18D] FIG. 18D is a schematic diagram illustrating some examples of nanoantennas.

[0019] [Figure 19A] FIG. 19A is a schematic diagram illustrating a top view of an embodiment of a structured lens for a light emitting device. [Figure 19B] FIG. 19B is a schematic diagram illustrating a perspective view of an embodiment of a structured lens for a light emitting device. [Figure 19C] FIG. 19C is a schematic diagram illustrating a close-up view of an embodiment of a structured lens for a light-emitting device.

[0020] [Figure 20A] FIG. 20A is a schematic diagram illustrating an example of a phase function provided by an embodiment of a structured lens for a light emitting device. [Figure 20B] FIG. 20B is a schematic diagram illustrating an example of a phase function provided by an embodiment of a structured lens for a light emitting device.

[0021] [Figure 21] FIG. 21 is a schematic diagram illustrating the non-refracting transmissive redirection of light by a portion of the front surface coating or layer so that it propagates at an angle smaller than the angle of refraction.

[0022] [Figure 22A] FIG. 22A is a schematic diagram illustrating simulated angular intensity distributions for an array of light-emitting elements without and with non-refractive transmissive redirection, respectively. [Figure 22B] FIG. 22B is a schematic diagram illustrating simulated angular intensity distributions for an array of light-emitting elements without and with non-refractive transmissive redirection, respectively.

[0023] [Figure 23A] FIG. 23A is a schematic diagram illustrating the top view of an exemplary mini LED or micro LED array, showing a close-up of 3×3 LEDs in the array. [Figure 23B] FIG. 23B is a schematic diagram illustrating a top view of a portion of an exemplary LED display in which each display pixel is a red, green, or blue phosphor-converted LED pixel. [Figure 23C]FIG. 23C is a schematic diagram illustrating the top view of a portion of an exemplary LED display, in which each display pixel includes multiple phosphor-converted LED pixels (red, green, and blue) integrated onto a single die bonded to a control circuit backplane.

[0024] [Figure 24A] FIG. 24A is a schematic diagram illustrating a top view of an exemplary electronic substrate onto which an array of pcLEDs may be mounted. [Figure 24B] FIG. 24B similarly illustrates an exemplary array of pcLEDs mounted on the electronics board of FIG. 6A.

[0025] The illustrated embodiments are shown schematically only, and all features may not be shown in full detail or to scale, and for clarity, certain features or structures may be exaggerated or reduced relative to others, or omitted entirely. The drawings should not be considered to be to scale unless explicitly indicated as such; in particular, the height, depth, or width of various elements are often exaggerated relative to other elements or the thickness of, for example, an underlying substrate or diode structure. The illustrated embodiments are merely examples and should not be construed as limiting the scope of the disclosure or the appended claims. DETAILED DESCRIPTION OF THE INVENTION

[0026] A typical light-emitting diode (LED) includes one or more light-emitting active layers within a semiconductor diode structure that emits light when driven by an electric current. The back surface (and sometimes one or more or all side surfaces) of the semiconductor diode structure typically includes a reflector that reflects light incident within the semiconductor diode structure toward the front surface of the diode structure (the front surface may also be referred to herein as the emission surface). Many semiconductor materials have a relatively large refractive index (often about 3 or greater), resulting in a large portion of the emitted light being trapped within the semiconductor diode structure by total internal reflection. In some conventional light-emitting diodes, the front emission surface of the semiconductor diode structure is formed with or attached to texturing (e.g., corrugations, bumps, or dimples, or other surface features or roughness). The back reflector of such so-called cavity emitters ensures that nearly all light propagating within the semiconductor diode structure ultimately strikes the front surface. The front surface texturing functions to at least partially impair total internal reflection, allowing a portion of the emitted light to escape the semiconductor diode structure through the front surface as device output light, while redirecting another portion, allowing it to propagate within the semiconductor diode structure in a direction different from the direction of specular reflection from the flat emission surface. These redirected portions eventually reach the front surface again and have another opportunity to escape by transmitting through the front surface. This light recycling process continues, with each so-called "photon bounce" within the effective "LED cavity" formed by the back reflector and front surface texturing (i.e., each round trip between the front and back surfaces through the semiconductor diode structure) increasing the overall probability that that photon will escape through the front surface as device output light.

[0027] An example of a conventional LED cavity emitter 10 is shown schematically in Figure 11A and includes a semiconductor diode structure 12, a light-emitting active layer 14 within the semiconductor diode structure 12, texturing 16 on the front surface of the semiconductor diode structure 12, and a reflector 18 on the back surface of the semiconductor diode structure 12. Another example of a conventional LED cavity emitter 20 is shown schematically in Figure 11B and includes a semiconductor diode structure 12, a light-emitting active layer 14 within the semiconductor diode structure 12, texturing 16 on the front surface of the diode structure 12, a dielectric layer 19 on the back surface of the diode structure 12, and a reflector 18 on the back surface of the dielectric layer 19. In both Figures 11A and 11B, the reflector 18 exhibits only specular reflection.

[0028] In practice, however, the probability per bounce of a photon transmitting through the front surface is relatively low, so a relatively large number of round trips is required to achieve a sufficiently high probability of photon extraction (e.g., 10-50 bounces to achieve extraction efficiencies approaching 90%, depending on the specific materials used). This relatively high number of round trips, or photon bounces, requires that the optical losses per round trip through the semiconductor diode structure (e.g., losses due to absorption by the diode structure, active layer, or reflector material, or insufficient reflectivity of the reflector) be sufficiently low. In some cases, the low-loss requirement can increase the cost or complexity of the light-emitting device (e.g., using a silver reflector instead of aluminum, using a multilayer thin-film reflector instead of a metallic reflector, or using high-purity materials for the diode structure, active layer, or reflector) or reduce the extraction efficiency of the device (e.g., when low-loss alternatives are unavailable or cost-prohibitive).

[0029] Therefore, it is desirable to provide a light emitting device of the present invention that exhibits a relatively high photon extraction efficiency (e.g., 80% or more) and a relatively low number of photon bounces (e.g., 30 or less). Some examples of LEDs that exhibit a relatively high photon extraction efficiency or a reduced number of photon bounces are disclosed in U.S. Non-Provisional Application No. 17 / 121,014, entitled "Light-emitting device with internal non-specular light redirection and anti-reflective exit surface," filed December 14, 2020, in the names of Antonio Lopez-Julia, Venkata Ananth Tamma, Aimi Abass, and Philipp Schneider, and is incorporated by reference as if set forth in its entirety herein.

[0030] 12A and 12B, in which a backside redirection layer 108 and a frontside anti-reflective coating 106 are employed on the diode structure 102 (including the active layer 104) to reduce the number of photon bounces, improve photon extraction efficiency, and provide specular redirection. The redirection layer 108 is configured to reduce the critical angle Θ (e.g., Θ ) relative to the front and back surfaces, as defined by the refractive index of the diode structure 102 and the surrounding medium 99 in contact with the front, exit surface. CThe LED 200 is arranged to exhibit non-specular reflective redirection of light propagating outside the escape cone (at an angle of incidence within the diode structure 102 less than 0.05°), redirecting that light (e.g., as in FIG. 12B ) to propagate within the escape cone and escape the diode structure 102 by transmission through the front surface. An anti-reflective layer 106 on the front surface reduces the probability that photons incident on the front surface within the escape cone will reflect back into the diode structure 102 for another round trip. A second embodiment of the LED 200 is shown schematically in FIGS. 13A and 13B and includes a specular reflective layer 112 and a transparent dielectric layer 110 between the redirection layer 108 and the reflective layer 112. In this embodiment, the redirection layer 108 exhibits both non-specular reflective redirection and non-refractive transmissive redirection (i.e., transmissive redirection that does not obey Snell's law, e.g., as in FIG. 13B ). Non-specular reflection redirection or non-refractive transmission redirection can be achieved in some embodiments using one or more of: (i) arrays of nanoantennas, (ii) partial photonic bandgap structures, (iii) photonic crystals, or (iv) arrays of meta-atoms or meta-molecules (each of which is further described below).

[0031] Headlight optics (often reflective) used in vehicle headlights are typically adapted to transform light emitted from one or more lighting devices by superimposing multiple images of the one or more lighting devices in corresponding Fourier planes. FIG. 14 shows an example in which three images 299 (labeled “1,” “2,” and “3”) of a row containing four light-emitting devices are superimposed by appropriate imaging optics in a Fourier plane defined by the headlight optics. For illustrative purposes, the images of the light-emitting devices are shown scaled according to the corresponding magnification of the corresponding optics over an exemplary image intensity distribution 690 in the Fourier plane. In the drawing, regions of the image intensity distribution 690 are shown with decreasing intensity from region 601 to region 604 (in the drawing, the corresponding intensity magnitudes are indicated by the density of black dots). A desired light source for a vehicle headlight should be such that the light imaged by the headlight optics (i.e., the intensity profile formed in the Fourier plane defined by the optics) is concentrated along a single direction and emits only a small intensity in other directions to avoid interfering with oncoming traffic.

[0032] 15A-15E show examples of device output intensity distributions (i.e., position-dependent luminance) that can be used in the arrangement of FIG. 14. The exemplary distribution in FIG. 15A has a substantially uniform luminance across each light-emitting device 100. The exemplary distribution in FIG. 15B is a so-called graded distribution, with a position-dependent luminance that has a maximum near one edge of the device 300 and decreases monotonically toward the opposite edge. The exemplary distribution in FIG. 15C is a so-called 1D peaked distribution, with a position-dependent luminance that has a maximum along a line across the center of the device 300 and decreases monotonically along one dimension toward both opposing edges. The exemplary distribution in FIG. 15D is a so-called 2D peaked distribution, with a position-dependent luminance that has a maximum in the central region of the device 300 and decreases along both dimensions toward all edges. The exemplary distribution of FIG. 15E is a so-called concentrated distribution, in which the position-dependent brightness is substantially negligible over the peripheral regions of device 300 and is substantially uniform over the central region of device 300 (i.e., it is essentially a reduced-size, high-brightness replica of the uniform distribution).

[0033] Figure 16A is an imaged intensity distribution 691 (including contour lines 601 / 602 / 603 / 604) resulting from a row of four light-emitting devices 100 imaged according to the arrangement of Figure 14; each device 199 has a position-dependent brightness 692 as shown in Figure 16B, i.e., a substantially uniform brightness as in Figure 15A. Figure 17A is an imaged intensity distribution 693 (including contour lines 600 / 601 / 602 / 603 / 604) resulting from a row of four light-emitting devices 300 imaged according to the arrangement of Figure 14; each device 300 has a position-dependent brightness 694 as shown in Figure 17B, i.e., a tilted distribution as in Figure 15B. The imaged distribution 693 in Figure 17A is more strongly peaked along the desired direction than the distribution 691 in Figure 16A. Thus, in some cases (e.g., in the case of certain automotive headlight assemblies including reflective optics), it may be desirable to provide a light source 300 that can provide a gradient position-dependent brightness similar to that of Figure 15B. In another example, some automotive high beam headlights have been observed to exhibit desirable beam intensity profiles when using LEDs with 2D peak position-dependent brightness, as shown in Figure 15D. The position-dependent brightness of any of Figures 15B-15E can be advantageously employed in a variety of applications, including automotive and non-automotive applications.

[0034] In some previous light-emitting devices (e.g., as in Figures 15B-15D), position-dependent brightness is achieved by driving an LED with a position-dependent current density. In some embodiments, the spatial density of current-carrying vias is varied across the LED to achieve the desired position-dependent current density. In other embodiments, different currents are supplied through different vias in the LED to achieve the desired position-dependent current density. Some examples include, for example: (i) U.S. Non-Provisional Application No. 16 / 875,237, entitled “Light-emitting device with configurable spatial distribution of emission intensity,” filed on May 15, 2020, in the names of Toni Lopez and Floris Crompvoets; and (ii) Disclosed in U.S. Non-Provisional Application No. 117 / 142,960, entitled "Light-emitting device with internal non-specular light redirection and anti-reflective exit surface," filed June 1, 2021, in the names of Toni Lopez and Floris Crompvoets, both of which are incorporated by reference as if set forth in their entireties herein.

[0035] Driving an LED with a position-dependent current density can result in a corresponding position-dependent brightness. However, during its operation, certain areas of the LED need to be driven at less than the maximum current density to produce less than the maximum local brightness. In effect, the LED is not driven at the maximum current density across its entire area, wasting some of the light-generating capacity of the LED die. If position-dependent brightness could be achieved while driving the entire LED area at the maximum current density, the overall light output of the LED could be increased.

[0036] For purposes of this disclosure and the appended claims, the "angle of incidence" and "angle of incidence" of light incident on a front surface or interface refer to the angle between the propagation direction of the incident light and the vector normal to the front surface or interface. Thus, light propagating at normal incidence to a surface will have an angle of incidence of 0°, while light propagating at near grazing incidence to that surface will have an angle of incidence approaching 90°. For purposes of this disclosure and the appended claims, the "critical angle" of light incident on a surface or interface between media of different refractive index refers to the angle of incidence of light propagating in the higher refractive index medium, above which the light undergoes total internal reflection within the higher refractive index medium. For purposes of this disclosure and the appended claims, "oblique light" or "oblique radiation" refers to light propagating through a substrate or diode structure at an angle Θ relative to its front and back surfaces. C"perpendicular light" or "perpendicular radiation" refers to light propagating at a larger angle of incidence than the substrate or diode structure, Θ relative to the surface thereof. C "Normal" refers to light propagating at an angle of incidence less than 90°, even if not literally perpendicular; "normal" is reserved for light incident at a 90° angle of incidence. For purposes of this disclosure and the appended claims, any positioning of a layer, surface, substrate, diode structure, or other structure "on," "over," or "against" another structure shall include not only positions in direct contact between the two structures, but also positions that include some intervening structure between them. Conversely, any positioning of a layer, surface, substrate, diode structure, or other structure "directly on," "directly over," or "directly against" another such structure shall include only positions in direct contact between the two structures.

[0037] The semiconductor light emitting device 300 of the present invention includes a semiconductor diode structure 302 and a redirection layer 308 on the back surface of the diode structure 302. The semiconductor diode structure 302 has a front surface and a back surface and one or more light emitting active layers 304 (e.g., one or more quantum well layers) within the diode structure 302. The active layer(s) 304 are arranged to emit output light at a nominal vacuum wavelength λ and propagate within the diode structure. "At a nominal vacuum wavelength λ" means that the wavelength spectrum of the device output light includes a wavelength range that includes λ. In many examples, the device output light is within about ±5 nm or about ±10 nm of λ; in other examples, the spectral width of the device output light may be greater. In many exemplary embodiments, the semiconductor diode structure 302 can include reflective coatings on one or more or all of its sides; these lateral reflective coatings can be of any suitable type or arrangement and can act to reflect any output light incident thereon within the semiconductor diode structure 302. The redirection layer 308 includes one or more of: (i) a nanoantenna array, (ii) a partial photonic bandgap structure, (iii) a photonic crystal, or (iv) a meta-atom or meta-molecule (described further below). At least a portion of the backside redirection layer 308 is structurally arranged to exhibit non-specular internal reflection redirection of output light incident on a backside within the diode structure for a nominal output vacuum wavelength λ.

[0038] One or both of the front and back surfaces of the diode structure 302 include one or more structural arrangements that exhibit position-dependent redirection, reflection, or transmission of output light. In the embodiment of FIG. 1 , these structural arrangements include at least a portion of a back surface redirection layer 308 that is structurally arranged to exhibit position-dependent internal reflection redirection of output light incident on the back surface within the diode structure 302. In the illustrated embodiment, region 308a of the redirection layer 308 can, for example, exhibit non-specular redirection of output light incident within the diode structure 302, while region 308b, for example, exhibits non-specular redirection or specular redirection (i.e., specular reflection) of output light incident within the diode structure 302 (at a different angle than region 308a). In other embodiments, two or more differently arranged regions of the redirection layer 308 can be used, or the redirection can exhibit a gradient in its redirection behavior across the LED 300. In the embodiment of FIG. 1 , the front surface of the diode structure 302 can include a front surface coating or layer 306 arranged, for example, as a refractive or non-refractive transmissive redirection layer, and in some embodiments includes an anti-reflective coating across the entire front surface; the redirection behavior of the front surface coating or layer 306 is substantially constant across the front surface of the diode structure 302. The non-specular redirection of the output light by at least a portion of the back surface redirection layer 308 and the anti-reflective properties (if present) of the front surface coating or layer 306 can result in a reduction in the average number of photon bounces within the diode structure 302 (as described above). The position dependence of the reflective redirection by the rear redirection layer 308 can result in a desired position-dependent brightness at the front output surface of the diode structure 302 (including, for example, the position-dependent brightness of any of the examples of Figures 15B-15E).

[0039] In the embodiment of FIG. 2 , the front and back surface structural arrangement includes at least a portion of a front surface coating or front surface layer 306 structurally arranged to exhibit position-dependent internal reflection redirection or position-dependent transmission redirection of output light incident on the front surface from within the diode structure 302. In the illustrated embodiment, region 306 a of the front surface coating or front surface layer 306 can exhibit, for example, specular reflection or non-specular reflection redirection of output light incident on the front surface from within the diode structure 302, and region 306 b can exhibit, for example, refractive or non-refractive transmission of output light incident on the front surface from within the diode structure 302. In other embodiments, two or more differently arranged regions of the front surface coating or front surface layer 306 can be used, or the redirection can exhibit a gradient in its redirection behavior across the LED 300. In the embodiment of FIG. 2 , the back surface redirection layer 308 can be arranged such that its redirection behavior is substantially constant across the back surface of the diode structure 302. The non-specular reflective redirection of output light by the backside redirection layer 308 and at least a portion of the front side layer or coating 306, and the anti-reflective behavior (if present) of other portions of the front side layer or coating 306 (as described above) can result in a reduction in the average number of photon bounces within the diode structure 302. The reflective redirection by the backside redirection layer 308 and the position dependence of the front side layer or coating 306 can result in a desired position-dependent brightness at the front output surface of the diode structure 302 (including, for example, the position-dependent brightness of any of the embodiments of FIGS. 15B-15E).

[0040] In the embodiment of Figure 3, both the back redirection layer 308 and the front layer or coating 306 exhibit position-dependent optical behavior, e.g., as described above. The examples of Figures 4, 5, and 6 are similar to the examples of Figures 1, 2, and 3, respectively, but add a back reflector 312 (e.g., a metal or dielectric multilayer or any suitable type) and a substantially transparent dielectric layer 310 between the reflector 312 and the redirection layer 308. In these latter embodiments, the redirection layer 308, or at least a region thereof, can exhibit transparent redirection of output light propagating within the diode structure 302 (e.g., similar to the arrangement of Figure 13B).

[0041] In the exemplary arrangement of Figures 1-6, as shown in Figure 6, the position-dependent reflective redirection of one or both of the front layer 306 and the back layer 308 is arranged to direct output light in the diode structure 302 to desired regions on the front surface of the diode structure to achieve a desired position-dependent brightness (e.g., as shown in Figures 15B-15E) and to direct a sufficiently large portion of that light to be incident on those regions within the escape cone. In some embodiments, the regions of the front surface coating or front layer 306 where the output light exits the diode structure 302 can be arranged to reduce the probability that the light will reflect back into the diode structure 302; in some embodiments, the regions of the front surface coating or front layer 306 where the output light exits the diode structure 302 can be arranged to non-refractively redirect the output light exiting the diode structure 302 to propagate within a desired angular distribution or with a desired convergence, collimation, or divergence (e.g., as shown in Figures 19A-22B).

[0042] The position dependence of the backside redirection layer 308 and / or the front side layer or coating 306 causes output light exiting the diode structure 302 through the front side to exhibit a position-dependent luminance that varies with position across the front side. In some embodiments, the position dependence of the luminance of output light exiting the diode structure 302 through the front side differs from the position dependence of the emission of output light emitted from the active layer 304. In some of these embodiments, a substantially uniform emission of output light across the active layer 304 causes output light exiting the diode structure 302 through the front side to exhibit a position-dependent luminance that varies with position across the front side.

[0043] 7, peripheral region 306a is arranged for specular reflection (e.g., as a distributed Bragg reflector or DBR or as a metallic coating), central region 306b includes an anti-reflective coating, peripheral region 308a redirects perpendicular light to propagate as oblique light, and central region 308b redirects oblique light to propagate as perpendicular light. Some power emitted from the central region of active layer 304 can exit the device directly through coating 306b, or possibly after a single redirection by redirection layer 308. Most output light emitted by active layer 304 is redirected or reflected multiple times by regions 308a / 306b and 306a before exiting through region 308b. The net result of the arrangement of these regions is to redirect light emitted over the entire area of ​​the active layer 304, causing it to exit the device 300 only through the central region 306b of the front surface. The arrangement can result in a focused distribution of position-dependent brightness (e.g., as shown in FIG. 15E ), where the brightness of the device 300 increases due to the reduction in the area or area of ​​the front surface through which light emitted from the entire area of ​​the active layer 304 exits the device 300. The arrangement of the layer regions 306a / 306b / 308a / 308b can also result in an increase in photon extraction efficiency, or a reduction in the average number of photon bounces before exiting the diode structure 302.

[0044] Several exemplary arrangements of different regions of the rear redirection layer 308 or front layer or coating 306 are illustrated schematically in Figures 8-10. While each shows the arrangement of only one of the layers 306 or 308, each arrangement can be applied to either or both of the layers 306 or 308. In Figure 8, a square or rectangular central region 308b is surrounded by peripheral regions 308a. In some embodiments, such an arrangement of regions can result in position-dependent brightness, such as the 2D peak distribution of Figure 15D or the concentrated (rectangular) distribution of Figure 15E. Figure 9 shows a set of concentric regions 306a, 306b, 306c, and 306d. In some embodiments, the arrangement of such regions can result in, for example, the 2D peak distribution of FIG. 15D or the focused (circular) distribution of FIG. 15E, or, for example, the collimation, convergence, divergence, or angular distribution of the emitted output light can vary, for example, as in one or more of FIGS. 19A-22B (described in more detail below). FIG. 10 shows a set of rectangular regions 308a, 308f arranged across device 300. In some embodiments, the arrangement of such regions can result in, for example, the graded distribution of FIG. 15B or the 1D peak distribution of FIG. 15C. Other numbers or arrangements of regions 306a / 306b / 306c / ... or regions 308a / 308b / 308c / ... can also be used (e.g., checkerboard, hexagonal, etc.). In any arrangement of regions, including those shown in the figures, each region can exhibit optical reflectance, transmittance, or redirection properties that are substantially constant across the region but different from adjacent regions (e.g., reflection vs. transmission, specular reflection vs. non-specular reflection, refraction vs. non-refraction, different angles of reflection or transmission redirection, etc.) Alternatively or in addition, one or more regions can exhibit a gradient in optical reflectance, transmittance, or redirection properties.

[0045] In some embodiments, the front surface of the semiconductor diode structure 302 is positioned against a surrounding medium 99, which may be a vacuum, air, a gaseous medium, or a liquid medium. In some embodiments, the surrounding medium 99 includes at least one or more substantially solid materials: doped or undoped silicon; or one or more doped or undoped polymers. In some embodiments, the surrounding medium 99 can be a wavelength-converting material (i.e., a phosphor, e.g., red phosphor 406R / green phosphor 406G / blue phosphor 406B shown in FIGS. 23B and 23C ) that absorbs at least a portion of the output light at a vacuum wavelength λ and emits down-converted light at one or more vacuum wavelengths longer than λ. In some embodiments, the surrounding medium 99 can be interposed between the wavelength-converting material and the front surface of the diode structure 302. In some embodiments, the nominal output vacuum wavelength λ is greater than about 0.20 m, greater than about 0.4 m, greater than about 0.8 μm, less than about 10 m, less than about 2.5 μm, or less than about 1.0 μm. In some embodiments, the light emitting device 300 comprises a light emitting diode. In some embodiments, the semiconductor diode structure 302 or the active layer 304 comprises one or more doped or undoped III-V, II-VI, or IV semiconductor materials or alloys, or mixtures thereof. The semiconductor diode structure 302 and the active layer 304 can typically be formed together by a process sequence, often in which the active layer(s) 304 are formed on the surface of an initial semiconductor layer or substrate, and then additional semiconductor materials are deposited over the active layer(s); it should be noted that other suitable fabrication sequences can be used. In some embodiments, the light emitting layer 304 comprises one or more doped or undoped III-V, II-VI, or IV semiconductor materials or alloys, or mixtures thereof. In some embodiments, the light emitting layer 304 includes one or more pn junctions, one or more quantum wells, one or more multi-quantum wells, or one or more quantum dots. The light emitting device 300 typically includes one or more electrodes (not shown) for delivering current to the active layer 304 to generate output light.

[0046] ΘC For light of nominal vacuum wavelength λ0 incident on the front surface of the semiconductor diode structure 302 at an angle of incidence less than λ (i.e., normal light, or equivalently, light within the escape cone), any anti-reflective coating on the front surface of the semiconductor diode structure 302 (or a portion thereof) exhibits a reflectivity less than the corresponding Fresnel reflectivity between the semiconductor material and the surrounding medium 99 without the anti-reflective coating. The anti-reflective coating may be of any suitable type or arrangement. In some embodiments, the anti-reflective coating may comprise a single-layer quarter-wave dielectric thin film or a multi-layer dielectric thin film. In some embodiments, the anti-reflective coating may comprise a multi-layer dielectric thin film. In some embodiments, the anti-reflective coating may comprise a moth-eye structure or other similar nanostructured film, or a gradient-index film. In principle, it is most desirable for the reflectivity of the front surface of the diode structure 302, from which the output light exits, to be reduced to zero. Indeed, in some embodiments, the anti-reflective coating can reduce the reflectivity of those regions of the front surface of the semiconductor diode structure 302 to less than about 10%, less than about 5%, less than about 2.0%, less than about 1.0%, or less than about 0.5%. Contrast this with the Fresnel reflectivity (at normal incidence) of the interface between semiconductor and air (about 25%) or semiconductor and silicon (about 11%). In some embodiments, the front surface layer or coating 306 can include regions with different wavelength transmissions arranged, for example, as dichroic filters, edge filters, bandpass filters, or notch filters with different spectral characteristics.

[0047] The redirection layer 308 on the back surface of the diode structure 302 (or the portion thereof that exhibits non-specular redirection) comprises one or more of (i) a nanoantenna array, (ii) a partial photonic bandgap structure, (iii) a photonic crystal, or (iv) a meta-atom or meta-molecule (described further below). In some embodiments, some or all of the redirection layer 308 has a Θ CAt least a portion of the light incident within the diode structure 302 at an angle of incidence greater than Θ (i.e., oblique light) C , . . . (i.e., as normal light), within the diode structure 302. By the reciprocity of Maxwell's equations, such portions of the redirection layer 308 also redirect normal light to propagate as oblique light. The effect of the anti-reflection coating on the front surface of the diode structure 302 is to allow normal light propagating within the diode structure 302 to escape or escape as device output light by transmitting through a desired area of ​​the front surface, instead of being reflected by the front surface and redirected by the redirection layer 308 as oblique light. In principle, that redirected oblique light could be redirected again to propagate as normal light and escape through the front surface, but at the expense of another round trip through the diode structure 302.

[0048] In some embodiments, the redirection layer 308 or reflective portion of the front layer or coating 306 exhibits a redirection efficiency of greater than about 80%, greater than about 85%, greater than about 90%, or greater than about 95% of light incident on the diode structure 302. In some embodiments, the redirection layer 308 or reflective portion of the front layer or coating 306 exhibits an optical loss per pass of incident light that is less than about 20%, less than about 10%, less than about 5%, less than about 2.0%, or less than about 1.0%. The design or optimization of the redirection layer 308 or reflective portion of the front layer or coating 306 can be performed (by calculation, simulation, or iterative design / fabrication / testing of prototype or test devices), typically with the increase in overall extraction efficiency as a first or second order figure of merit. Alternatively or additionally, reduction in cost or manufacturing complexity may be used as a primary or secondary figure of merit in such a design or optimization process.

[0049] 4-6, device 300 further includes a dielectric layer 310 and a reflective layer 312. Dielectric layer 310 is positioned on the back surface of redirection layer 308 (the redirection layer 308 is between dielectric layer 310 and the back surface of diode structure 302), is substantially transparent, and is characterized by a refractive index (at the nominal vacuum wavelength λ) lower than that of diode structure 302. Reflective layer 312 is positioned on the back surface of dielectric layer 310 (the dielectric layer 310 is between reflective layer 312 and the back surface of redirection layer 308). Redirection layer 308 (or at least a portion thereof) is arranged to exhibit both reflective and transmissive redirection of output light within diode structure 302. Diode structure 302, active layer 304, and optional front surface layer or coating 306 may be arranged in any suitable manner using any suitable material composition, including those described above. The reflective layer 312 exhibits a reflectivity of greater than about 90%, greater than about 95%, or greater than about 98% at the nominal vacuum wavelength λ. Typically, a greater reflectivity results in a higher extraction efficiency. The reflective layer 312 can be of any suitable type or arrangement and can include one or more of the following materials: doped or undoped silicon; doped or undoped III-V, II-VI, or IV semiconductors; doped or undoped silicon oxides, nitrides, or oxynitrides; one or more doped or undoped metal oxides, nitrides, or oxynitrides; one or more optical glasses; one or more doped or undoped polymers; or one or more metals or metal alloys. In some embodiments, the reflective layer 312 includes a metallic coating or a dielectric coating (e.g., a multilayer dielectric thin film).The dielectric layer 310 can be from a few hundred nanometers thick to a few micrometers thick and can comprise one or more of the following materials: doped or undoped silicon; doped or undoped III-V, II-VI, or IV semiconductors; doped or undoped silicon oxides, nitrides, or oxynitrides; one or more doped or undoped metal oxides, nitrides, or oxynitrides; one or more optical glasses; or one or more doped or undoped polymers.

[0050] In some embodiments arranged as in FIGS. 4-6 , the back surface of the dielectric layer 310 can include corrugations, dimples, bumps, protrusions, or depressions; these surface features can arise during the growth or deposition of the dielectric layer 310 on the redirection layer 308 if the morphology of the redirection layer 308 is non-planar. This is often the case, for example, when the redirection layer 308 includes an array of nanoantennas, meta-atoms, or meta-molecules. That topology is reflected to some extent (typically somewhat smoothed) on the surface of the dielectric layer 310. The deposition or growth of the reflective layer 312 often results in near-conformal coverage of the surface of the dielectric layer 310. The non-planarity of the dielectric layer 310 can be advantageous in that reflections from its surface tend to mix oblique and perpendicular light propagating within the dielectric layer 310, which can potentially increase the overall extraction efficiency. In some embodiments, such non-planarity of the dielectric layer 310 may be imparted by design, for example, to a greater extent than would result from the presence of the redirection layer 308 during deposition or growth of the dielectric layer 310.

[0051] Regardless of which of the above arrangements is used, in some embodiments, light emitting device 300 exhibits a photon extraction efficiency of greater than about 80%, greater than about 90%, or greater than about 95%. In some embodiments, light emitting device 300 exhibits an average number of redirections per photon emitted by active layer 304 (by redirection surface 308 or by reflective layer 312, if present) of less than 30, less than 20, less than 10, or less than 5, prior to transmission by the front surface.

[0052] In some embodiments, the redirection layer 308 (or at least a portion thereof), or the non-specularly reflective or non-refractive portion of the front layer or coating 306, can include an array of nanoantennas 309. Some embodiments are illustrated schematically in FIGS. 18A-18D , where the nanoantennas 309 are shown extending from the semiconductor diode structure 302 into the medium 98 (e.g., the encapsulant or surrounding medium opposite layer 306 or 308); in other embodiments (not shown), the nanoantennas 309 can extend from the back surface of the diode structure 302 into the dielectric layer 310, from the front or back surface of the diode structure 302 into the surrounding medium 99, or from the front or back surface of the diode structure 302 into the semiconductor material. The nanoantennas 309 can include one or more antenna materials and can be shaped, sized, and spaced apart or spaced relative to a nominal output vacuum wavelength λ, e.g., a critical angle Θ C re-emit at least a portion of the active layer output light upon illumination by the active layer output light at a larger angle of incidence, collectively providing a redirection of the active layer output light; and Θ CThe beams can be arranged along the redirection layer 308 or the redirection portions of the coating or layer 306 to propagate at angles of incidence less than 1 / 2 . Other arrangements of the redirection layer 308 or the redirection portions of the coating or layer 306 can be used to achieve other desired combinations of angles of incidence and redirection angles. Any suitable size, spacing, material (e.g., silicon or TiO), antenna shape (e.g., cylindrical, frustoconical, frustoconical, horizontal dimer, vertical dimer, coaxial dimer, etc., see e.g., Figures 18A-18B), and arrangement (e.g., triangular grid, rectangular grid, hexagonal grid, other grids, or irregular, non-periodic, or random arrangements) can be employed.

[0053] Typically, calculations or computer simulations are required to arrive at at least a preliminary design of the nanoantenna array; a final design can typically be arrived at by iterative optimization of various parameters by fabricating and characterizing light-emitting devices incorporating test arrays in the corresponding redirection layer 308 or redirection portion of the layer or coating 306. It should be noted that arrays that are not necessarily fully optimized can still provide sufficient redirection efficiency to provide light-emitting device 100 with an acceptably high extraction efficiency; such partially optimized arrays fall within the scope of this disclosure or the appended claims. Examples of suitable nanoantenna arrays include, for example: (i) U.S. Patent Publication No. 2020 / 0200955, entitled “High brightness directional direct emitter with photonic filter of angular momentum,” published on June 25, 2020, in the names of Antonio Lopez-Julia and Venkata Ananth Tamma; (ii) U.S. Nonprovisional Patent Application No. 17 / 119,528, entitled “Light-emitting device assembly with light redirection or incidence-angle-dependent transmission through an escape surface,” filed on December 11, 2020, in the names of Antonio Lopez-Julia and Venkata Ananth Tamma; (iii) Li et al., “All-Dielectric Antenna Wavelength Router with Bidirectional Scattering of Visible Light”, Nano Letters, 16 4396 (2016), and (iv)(i) Shibanuma et al., “Experimental Demonstration of Tunable Directional Scattering of Visible Light from All-Dielectric Asymmetric Dimers,” ACS Photonics, 4 489 (2017), each of which is incorporated by reference as if fully set forth herein.

[0054] In some embodiments, the non-specular or non-refractive portion of the redirection layer 308 (or at least a portion thereof) or front surface layer or coating 306 may be oriented such that the non-specular or non-refractive portion is oriented at a critical angle Θ C When the active layer output light is irradiated at an incident angle greater than Θ CThe redirection layer 308 may include one or more materials, morphologies, and partial photonic bandgap structures arranged in intervals relative to the nominal output vacuum wavelength λ to propagate at angles of incidence less than the critical angle Θ. Other arrangements of the redirection layer 308 or redirecting portions of the coating or layer 306 may be used to achieve other desired combinations of angles of incidence and angles of redirection. In some embodiments, the non-specular or non-refractive portions of the redirection layer 308 (or at least a portion thereof) or front surface layer or front surface coating 306 may be arranged such that the non-specular or non-refractive portions of the redirection layer 308 (or at least a portion thereof) or front surface layer or front surface coating 306 are arranged such that the non-specular or non-refractive portions of the redirection layer 308 (or at least a portion thereof) are arranged such that the non-specular or non-refractive portions of the redirection layer 308 (or at least a portion thereof) are arranged such that the non-specular or non-refractive portions of the front surface layer or front surface coating 306 ... C When the active layer output light is irradiated at an incident angle greater than Θ, at least a portion of the active layer output light is redirected to C The redirection layer 308 may include one or more materials, crystalline morphologies, and photonic crystals arranged with a crystal lattice spacing relative to the nominal output vacuum wavelength λ to propagate at angles of incidence less than λ. Other arrangements of the redirection layer 308 or the redirection portions of the coating or layer 306 may be used to achieve other desired combinations of angles of incidence and angles of redirection. In some embodiments, the redirection layer 308 (or at least a portion thereof), or the non-specular or non-refractive portion of the front layer or front coating 306, includes an array of meta-atoms or meta-molecules, which are comprised of one or more metamaterials, sized and arranged along the layer 306 or 308, and spaced relative to the nominal output vacuum wavelength λ, e.g., at a critical angle Θ C and shaped to re-emit at least a portion of the active layer output light when illuminated by the active layer output light at an angle of incidence greater than Θ Cpropagates at angles of incidence less than 1 / 2. Other arrangements of redirection layer 308 or redirecting portions of coating or layer 306 can be used to achieve other desired combinations of angles of incidence and redirection angles. In any of these embodiments, calculations or simulations followed by iterative optimization (or at least partial optimization) can be used in a manner similar to that described above.

[0055] The region of the front surface layer or coating 306 where the output light exits the diode structure 306 may include arrangements for non-refractive transmissive redirection of the exiting output light instead of or in addition to an anti-reflection coating. Such arrangements may cause the output light exiting the diode structure 302 to propagate with a desired angular distribution or with a desired convergence, collimation, or divergence.

[0056] 19A-19C schematically illustrate a number of micro- or nanostructured elements 42 forming a structured lens 40 (sometimes referred to as a "metalens"). The elements 42 can comprise a number of appropriately sized and shaped protrusions, holes, depressions, inclusions, or structures formed on or within a substrate 45, and in some embodiments, can comprise, for example, an array of nanoantennas, a partial photonic bandgap structure, a photonic crystal, or an array of meta-atoms or meta-molecules. These micro- or nanostructured elements 42 can be arranged to collectively impart a lateral position-dependent phase delay to the output light that results in the effective focal length of the structured lens 40. In some embodiments, a quadratic phase function can be used to approximate a simple spherical lens. Exemplary phase functions are shown schematically in FIGS. 20A and 20B. As shown in FIGS. 19A-19C, the nano- or microstructured elements are cylindrical columns 42 of various diameters positioned on the surface of a substrate 45. The columns 42 can extend into the semiconductor material of the diode structure 302 or into the surrounding medium 99. The average fractional area occupied by the columns 42 varies across the substrate 45, such that the columns collectively impart a desired phase function and effective focal length to produce a desired collimation, convergence, or divergence of the output light exiting the diode structure 302. That and other examples are disclosed in U.S. Patent Publication No. 2019 / 0113727, entitled "Nanostructured meta-materials and meta-surfaces to collimate light emissions from LEDs," issued April 18, 2019, in the name of Venkata Ananth Tamma; the entire contents of which are incorporated by reference as if set forth herein.

[0057] In some embodiments, non-refractive transmissive redirection of output light to propagate at angles smaller than its angle of incidence or refraction (e.g., as in FIG. 21 ) can be used to produce a desired angular distribution of output light exiting diode structure 302. FIGS. 22A and 22B schematically illustrate angular distributions of output light without and with such non-refractive redirection, respectively. In some embodiments, the region of front surface coating or layer 306 where the output light exits diode structure 302 comprises one or more of: (i) an array of nanoantennas, (ii) a partial photonic bandgap structure, (iii) a photonic crystal, or (iv) an array of meta-atoms or meta-molecules (materials, morphologies, and optimizations described above), with one or more materials, morphologies, and spacing relative to the nominal output vacuum wavelength λ so as to redirect at least a portion of the device output light upon illumination with the device output light to produce a desired or specified non-refractive transmissive redirection. In any of these embodiments, calculations or simulations followed by iterative optimization (or at least partial optimization) can be used in a similar manner as described above to arrive at or near the desired angular distribution of the output light.

[0058] Any of the arrangements described above for the redirection layer 308 or front layer or coating 306 may include one or more of the following materials: doped or undoped silicon; doped or undoped III-V, II-VI, or IV semiconductors; doped or undoped silicon oxides, nitrides, or oxynitrides; one or more doped or undoped metal oxides, nitrides, or oxynitrides; one or more optical glasses; one or more doped or undoped polymers; or one or more metals or metal alloys.

[0059] A method of fabricating light-emitting device 300 includes: (a) forming one or more light-emitting active layers 304 in a diode structure 302; (b) forming a front coating or front layer 306 on a front surface of diode structure 302; and (c) forming a back surface redirection layer 308 on a back surface of diode structure 302. In some embodiments, the method may further include: (d) forming a dielectric layer 310 on a back surface of redirection layer 308, wherein redirection layer 308 is between dielectric layer 310 and the back surface of diode structure 302; and (e) forming a reflective layer 312 on a back surface of dielectric layer 310, wherein dielectric layer 310 is between reflective layer 312 and the back surface of redirection layer 308. In particular, any suitable one or more manufacturing or material processing techniques may be used to form active layer 304, redirection layer 308, and front surface layer or front surface coating 306 in any suitable arrangement (including all of those described above). Suitable techniques may include, but are not limited to, layer growth, masked or unmasked deposition, masked or unmasked lithography, masked or unmasked wet or dry etching, epitaxy, direct writing, self-assembly, etc. Which one or more techniques are appropriate, desirable, or necessary depends on the nature of the active layer 304, redirection layer 308, or front surface layer or coating 306 (e.g., pn junction, multi-quantum well, nanoantenna array, metamolecule, multilayer dielectric, etc.).

[0060] A method of operating light emitting device 300 includes powering light emitting device 300 such that light emitting device 300 emits device output light from a front surface of diode structure 302 for propagation in surrounding medium 99 opposite the front surface.

[0061] In some embodiments, the light emitting device 300 can include a wavelength-converting structure (e.g., red phosphor 406R, green phosphor 406G, and blue phosphor 406B in FIGS. 23B and 23C ); such a light emitting device may be referred to as a phosphor-converted light emitting device 300, or pcLED. The wavelength-converting structure absorbs at least a portion of the output light exiting the diode structure and emits down-converted light at one or more longer wavelengths. The proportion of the output light that is absorbed, the proportion of the output light that is transmitted by the wavelength-converting structure, and the amount and wavelength(s) of down-converted light(s) produced by the wavelength-converting structure determine the color of the overall light output of the pcLED. In some embodiments, white light of various color temperatures can be produced, or light of a different color than the output light of the diode structure can be produced.

[0062] In some examples, only a single light-emitting device 300 or only a handful of light-emitting devices 300 may be employed. In other embodiments, an array 400 of multiple light-emitting devices 300 can be used (e.g., FIGS. 23A-23C and 24B). Multiple LEDs 300 (or pcLEDs 300) can be assembled on a single substrate or formed together on a single substrate to form an array 400. Arrays 400 having one, multiple, or many individual devices per millimeter (e.g., device pitch or spacing of about 1 millimeter, hundreds of microns, or less than 100 microns, spacing between adjacent devices less than 100 microns, or only tens of microns or less) are typically referred to as mini-LED or micro-LED arrays (or μLED arrays), or, if wavelength-converting structures are included, pc-mini-LED or pc-micro-LED arrays. Such arrays 400 can be employed to form actively illuminated displays, such as those employed in smartphones and smartwatches, computer or video displays, augmented or virtual reality displays or other visualization systems, or signs, or to form adaptive illumination sources, such as those employed in automobile headlights, street lighting, camera flash sources, or flashlights (i.e., torches); often in such devices, optical elements or optical systems spaced from the light-emitting array can be employed and arranged to couple light from the array into a display or into a particular area or region to be illuminated. The array 400 can include relatively few light-emitting devices 300 (e.g., a 3x3, 5x5, or 7x7 array), or can include, for example, about 10 light-emitting devices 300, as schematically illustrated in FIG. 23A. 1 , 10 2 , 10 3 , 10 4, or more LEDs and / or pcLEDs. Individual LEDs 300 (i.e., pixels) may have a width w1 (e.g., side length) in the plane of the array 400, for example, 1 millimeter (mm) or less, 500 microns or less, 100 microns or less, 50 microns or less, etc. The LEDs 100 in the array 400 may be spaced apart from one another by streets or lanes or trenches 430 having a width w2 in the plane of the array of, for example, several hundred microns, 100 microns or less, 50 microns or less, 20 microns or less, 10 microns or less, or 5 microns or less. The pixel pitch or spacing D1 is the sum of w1 and w2. While the illustrated example shows rectangular pixels arranged in a symmetrical matrix, the pixels and arrays may have any suitable shape or arrangement, whether symmetrical or asymmetrical. Multiple separate arrays of LEDs may be combined in any suitable arrangement in any applicable format to form a larger combined array or display. LEDs having a dimension w1 (e.g., side length) in the plane of the array of about 0.10 millimeters microns or less are typically referred to as micro LEDs, and arrays of such micro LEDs may be referred to as micro LED arrays. LEDs having a dimension w1 (e.g., side length) in the plane of the array between about 0.10 millimeters and 1.0 millimeters are typically referred to as mini LEDs, and arrays of such mini LEDs may be referred to as mini LED arrays.

[0063] Individual LEDs (pixels) in an LED array can be individually addressable, addressable as part of a group or subset of pixels in the array, or non-addressable. Light-emitting pixel arrays are therefore useful for any application that requires or benefits from fine-grained intensity, spatial, and temporal control of light distribution. These applications may include, but are not limited to, precise and specific patterning of light emitted from pixel blocks or individual pixels. In some cases, this includes forming images as a display device. Depending on the application, the emitted light can be spectrally distinct, adaptive over time, and / or environmentally responsive. The light-emitting pixel array can provide pre-programmed light distributions with various intensity, spatial, or temporal patterns. The emitted light can be based at least in part on received light sensor data and can be used for optical wireless communication. The associated electronics and optics can be distinct at the pixel, pixel block, or device level.

[0064] 23B and 23C are examples of LED arrays 400 used in display applications, where the LED display includes a large number of display pixels. In some embodiments (e.g., as in FIG. 23B ), each display pixel includes a single semiconductor LED pixel 300 (not visible) and a corresponding phosphor pixel 406R, 406G, or 406B of a single color (red, green, or blue). Each display pixel provides only one of three colors. In some embodiments (e.g., as in FIG. 23C ), each display pixel includes multiple semiconductor LED pixels 300 (not visible) and multiple corresponding phosphor pixels 406 of multiple colors. In the illustrated embodiment, each display pixel includes a 3×3 array of semiconductor pixels 300; three of these LED pixels include red phosphor pixels 406R, three include green phosphor pixels 406G, and three include blue phosphor pixels 406B. Thus, each display pixel can generate any desired color combination. In the illustrated embodiment, the spatial arrangement of the different colored phosphor pixels 406 varies between display pixels; in some embodiments (not shown), each display pixel can have the same arrangement of different colored phosphor pixels 406. Either the arrangement of Figure 23B or 23C can be adapted to include direct-emitting LEDs instead of or in addition to the pcLEDs.

[0065] 24A and 24B, the pcLED array 400 can be mounted on an electronics board 500 that includes a power and control module 502, a sensor module 504, and an LED mounting area 506. The power and control module 502 can receive power and control signals from an external source and signals from the sensor module 504, based on which the power and control module 502 controls the operation of the LEDs. The sensor module 504 can receive signals from any suitable sensor, such as a temperature sensor or a light sensor. Alternatively, the pcLED array 400 can be mounted on a separate board (not shown) from the power and control module and the sensor module.

[0066] In addition to the above, the following exemplary embodiments are within the scope of the present disclosure or claims:

[0067] Example 1 Semiconductor light emitting devices are: (a) a semiconductor diode structure comprising a front surface, a back surface, and one or more light-emitting active layers within the diode structure, the front surface, the back surface, and the one or more light-emitting active layers arranged, configured, or configured to emit output light at a nominal vacuum wavelength λ and propagate within the diode structure; (b) a redirection layer on a back surface of the diode structure, the back surface redirection layer comprising one or more of: (i) an array of nanoantennas; (ii) a partial photonic bandgap structure; (iii) a photonic crystal; or (iv) an array of meta-atoms or meta-molecules, at least a portion of the back surface redirection layer being structurally arranged to exhibit non-specular internal reflection redirection of output light incident on the back surface within the diode structure for a nominal output vacuum wavelength λ; (c) one or both of the front or back surfaces include one or more structural arrangements that exhibit position-dependent redirection, reflection, or transmission of output light, the one or more structural arrangements including one or both of: (i) at least a portion of a back surface redirection layer is structurally arranged to exhibit position-dependent internal reflective redirection of output light incident on the back surface within the diode structure; or (ii) the front surface has a layer or coating thereon, and at least a portion of the front surface layer or front surface coating is structurally arranged to exhibit position-dependent internal reflective redirection or position-dependent transmissive redirection of output light incident on the front surface from within the diode structure.

[0068] Example 2 The device of Example 1, wherein the position dependence of the rear redirection layer and / or the front layer or coating is arranged such that output light exiting the diode structure through the front surface exhibits a position dependent brightness that varies with position across the front surface.

[0069] Example 3 The device of Example 1 or 2, wherein the position dependence of one or both of the back redirection layer and the front layer or coating is arranged such that the position dependence of the brightness of the output light exiting the diode structure through the front surface is different from the position dependence of the emission of output light emitted from the active layer.

[0070] Example 4 The device of any of Examples 1 to 3, wherein the position dependence of the back redirection layer and / or the front layer or coating is arranged such that, with substantially uniform emission of output light across the active layer, output light exiting the diode structure through the front surface exhibits a position-dependent brightness that varies with position across the front surface.

[0071] Example 5 The device of any of Examples 2 to 4, wherein the position-dependent luminance: (i) exhibits a maximum value nearer one edge of the diode structure and decreases monotonically from the maximum value along one lateral dimension across the diode structure, (ii) exhibits a maximum intensity along a line extending across a central region of the diode structure and decreases in both directions along one lateral dimension toward the opposing edge of the semiconductor diode structure, or (iii) exhibits a maximum intensity in the central region of the diode structure and decreases in both directions along both lateral dimensions toward the edges of the semiconductor diode structure.

[0072] Example 6 The device of any of Examples 2 to 4, wherein the position-dependent luminance includes (i) a central region that exhibits a substantially constant non-zero luminance, and (ii) a peripheral region surrounding the central region that exhibits only negligible luminance.

[0073] Example 7 The device of any of Examples 1 to 6, wherein at least a portion of the back surface redirection layer is structurally arranged to exhibit position-dependent specular or non-specular internal reflection redirection of output light incident on the back surface within the diode structure.

[0074] Example 8 The device of Example 7, wherein the back surface redirection layer exhibits non-specular internal reflection redirection over only a first portion of the back surface of the diode structure and exhibits specular internal reflection over a second portion of the back surface of the diode structure that is different from the first portion.

[0075] Example 9 The device of Examples 7 or 8, wherein at least a portion of the backside redirection layer exhibits a position-dependent angle of non-specular internal reflection redirection.

[0076] Example 10 The device of any of Examples 1 to 9, wherein the back surface redirection layer comprises two or more distinct area regions that differ from one another with respect to internal reflection redirection, and over which the internal reflection redirection is substantially constant.

[0077] Example 11 Example 10. The device of Example 10, wherein the two or more distinct area regions of the rear redirection layer include a central region surrounded by one or more nested peripheral regions.

[0078] Example 12 The device of any of Examples 1 to 11, wherein the backside redirection layer comprises at least one area region exhibiting a gradient in internal reflection redirection.

[0079] Example 13 13. The device of any of Examples 1 to 12, wherein at least a portion of the front surface has a critical angle Θ at a nominal vacuum wavelength λ with respect to the surrounding medium. C and at least a portion of the backside redirection layer is in contact with the backside redirection layer in the diode structure. C and redirecting at least a portion of the output light incident at an angle of incidence greater than Θ relative to the front surface. C The diode structure is structurally arranged to propagate towards the front surface of the diode structure at an angle of incidence less than .

[0080] Example 14 The device of any of Examples 1 to 13, wherein at least a portion of the front surface is oriented relative to the surrounding medium at a critical angle Θ at a nominal vacuum wavelength λ. C and at least a portion of the front surface includes an anti-reflective coating that provides a reflection of Θ at a nominal vacuum wavelength λ. CThe diode structure is arranged to exhibit, for light incident on the front surface within the diode structure at an angle of incidence less than 100° C., a reflectivity with the front surface against the ambient medium that is less than the corresponding Fresnel reflectivity of an interface between the diode structure and the ambient medium without the anti-reflection coating.

[0081] Example 15 The device of any of Examples 1 to 14, wherein at least a portion of the front surface includes a front surface redirection layer arranged such that, at the front surface facing the ambient medium, at the nominal vacuum wavelength λ, that portion of the front surface exhibits non-refractive transmissive redirection of output light propagating outside the diode structure at an angle that is smaller than the corresponding angle of incidence of output light incident on the front surface within the diode structure.

[0082] Example 16 The device of Example 15, wherein the front surface layer or coating comprises one or more of: (i) an array of nanoantennas; (ii) a partial photonic bandgap structure; (iii) a photonic crystal; or (iv) an array of meta-atoms or meta-molecules, which are shaped, sized, and arranged to exhibit non-reflective, transmissive redirection for a nominal output vacuum wavelength, λ.

[0083] Example 17 The device of any of Examples 1 to 16, wherein at least a portion of the front surface comprises a front surface layer having micro- or nanostructured elements arranged as a structured lens that results in a reduced angular divergence or narrow angular intensity distribution of output light exiting the diode structure for a nominal output vacuum wavelength λ.

[0084] Example 18 The device of Example 17, wherein the micro- or nanostructured elements of the structured lens include a multitude of appropriately sized and shaped protrusions, holes, recesses, inclusions, or structures that form, are formed on, or are formed in the front layer.

[0085] Example 19 The device of Example 17 or 18, wherein the micro- or nanostructured elements of the structured lens comprise an array of nanoantennas, a partial photonic bandgap structure, a photonic crystal, or an array of meta-atoms or meta-molecules.

[0086] Example 20 The device of any of Examples 1 to 19, wherein the backside redirection layer comprises an array of nanoantennas that (i) comprise one or more antenna materials, (ii) are shaped, sized, and spaced relative to a nominal output vacuum wavelength, λ, and (iii) are arranged along the backside redirection layer so as to collectively re-emit at least a portion of the output light to provide non-specular internal reflection redirection thereof upon illumination by the output light.

[0087] Example 21 The device of any of Examples 1 to 20, wherein the backside redirection layer comprises a partial photonic bandgap structure arranged with one or more materials, morphologies, and spacings to redirect at least a portion of the output light upon illumination by the active layer output light for a nominal output vacuum wavelength λ, and collectively provide non-specular internal reflection redirection thereof.

[0088] Example 22 The device of any of Examples 1 to 21, wherein the back redirection layer comprises partial photonic crystals arranged with one or more materials, crystalline morphologies, and crystal lattice spacings to redirect at least a portion of the output light upon illumination with the output light, collectively providing non-specular internal reflection redirection thereof, for a nominal output vacuum wavelength λ.

[0089] Example 23 The device of any of Examples 1 to 22, wherein the backside redirection layer comprises an array of meta-atoms or meta-molecules that (i) comprise one or more metamaterials, (ii) are shaped, sized, and spaced apart relative to a nominal output vacuum wavelength, λ, and (iii) are arranged along the backside redirection layer such that, upon illumination by the output light, the array of meta-atoms or meta-molecules re-emit at least a portion of the output light, collectively providing non-specular internal reflection redirection thereof.

[0090] Example 24 The device of any of Examples 1 to 23, wherein the back redirection layer comprises diffuse backscatterers arranged to, upon illumination by the output light, backscatter at least a portion of the output light to collectively provide non-specular internal reflection redirection thereof.

[0091] Example 25 The device of any of Examples 1 to 24, wherein the front surface includes a front surface layer or coating thereon, at least a portion of which is structurally arranged to exhibit position-dependent specular or non-specular internal reflection reduction, or position-dependent refractive or non-refractive transmission reduction, of output light incident on the front surface from within the diode structure.

[0092] Example 26 Example 25. The device of Example 25, wherein the front surface coating or front surface layer is structurally arranged such that (i) a first set of one or more area regions on the front surface of the diode structure exhibit, for output light incident into the diode structure, a transmittance at the front surface facing the ambient medium at a nominal vacuum wavelength λO that is greater than the Fresnel transmittance from an interface between the front surface of the diode structure without the front surface coating or front surface layer and the ambient medium, or (ii) a second set of one or more area regions on the front surface of the diode structure, different from the first set of area regions, exhibit, for output light incident into the diode structure, a transmittance at the front surface facing the ambient medium at a nominal vacuum wavelength λO that is less than the Fresnel transmittance.

[0093] Example 27 26. The device of Example 26, wherein the front surface of the diode structure is positioned facing a surrounding medium, the surrounding medium being substantially solid and comprising one or more materials selected from the group consisting of doped or undoped silicon, or one or more doped or undoped polymers.

[0094] Example 28 26. The device of Example 26, wherein the front surface of the diode structure is positioned facing an ambient medium, the ambient medium comprising a vacuum, air, a gaseous medium, or a liquid medium.

[0095] Example 29 The device of any of Examples 26 to 28, wherein the first portion of the front surface layer (i) is positioned over the first set of area regions, and (ii) the first set of area regions are arranged as an anti-reflective coating such that the front surface facing the ambient medium exhibits a transmittance greater than a Fresnel transmittance for output light at a nominal vacuum wavelength λ incident on the front surface within the diode structure.

[0096] Example 30 The device of Example 29, wherein the antireflective coating comprises a single layer quarter-wave dielectric thin film or a multi-layer dielectric thin film.

[0097] Example 31 29. The device of Example 29, wherein the antireflective coating comprises a moth-eye structure or a graded index film.

[0098] Example 32 The device of any of Examples 29 to 31, wherein the reflectivity of the front surface of the diode structure having an antireflective coating is less than about 10%, less than about 5%, less than about 2.0%, less than about 1.0%, or less than about 0.5%.

[0099] Example 33 The device of any of Examples 29 to 32, wherein the antireflective coating comprises one or more of the following materials: doped or undoped silicon; doped or undoped III-V, II-VI, or IV semiconductor; doped or undoped silicon oxide, nitride, or oxynitride; one or more doped or undoped metal oxides, nitrides, or oxynitrides; one or more optical glasses; or one or more doped or undoped polymers.

[0100] Example 34 The device of any of Examples 26 to 33, wherein a first portion of the front surface layer (i) is positioned over a first set of the area regions and (ii) is arranged at the front surface facing the ambient medium to exhibit a non-refractive transmissive reduction of output light at a nominal vacuum wavelength λ incident on the front surface within the diode structure such that the output light propagates outside the diode structure at an exit angle that is smaller than the corresponding refraction angle of the output light incident on the front surface within the diode structure.

[0101] Example 35 The device of any of Examples 26 to 34, wherein the second portion of the front surface layer (i) is positioned over the second set of area regions and (ii) is arranged to exhibit specular internal reflection of light incident on the front surface within the diode structure.

[0102] Example 36 The device of Example 35, wherein the front layer or second portion of the coating comprises a multilayer dielectric reflective coating or a metallic reflective coating.

[0103] Example 37 The device of any of Examples 26 to 36, wherein the second portion of the front surface layer (i) is positioned in a second set of area regions and (ii) is arranged to exhibit non-specular internal reflection redirection for output light at a nominal vacuum wavelength λ incident on the front surface within the diode structure.

[0104] Example 38 The device of Example 37, wherein the second portion of the front surface layer or coating exhibits a position-dependent angle of non-specular internal reflection redirection.

[0105] Example 39 A device according to any of Examples 25 to 38, wherein each area region of the first and second sets differs from at least one other area region of the first and second sets in terms of internal reflection redirection or transmission redirection, and the internal reflection redirection or transmission redirection is substantially constant over the corresponding area region.

[0106] Example 40 39. The device of Example 39, wherein the first and second sets of area regions include a central region surrounded by one or more nested peripheral regions.

[0107] Example 41 The device of any of Examples 25 to 40, wherein the front surface layer or coating comprises at least one area region exhibiting a gradient of internal reflection redirection or transmission redirection.

[0108] Example 42 The device of any of Examples 1 to 41, wherein the front surface layer or coating comprises one or more of: (i) an array of nanoantennas; (ii) a partial photonic bandgap structure; (iii) a photonic crystal; or (iv) an array of meta-atoms or meta-molecules, arranged to exhibit non-specular internal reflection redirection or non-refractive transmission redirection for the nominal output vacuum wavelength, λ.

[0109] Example 43 The device of any of Examples 25 to 42, wherein the front surface layer or coating comprises an array of nanoantennas that (i) comprise one or more antenna materials, (ii) are shaped, sized, and spaced relative to a nominal output vacuum wavelength, λ, and (iii) are arranged along the front surface coating or layer such that, upon illumination by the output light, the array of nanoantennas re-emit at least a portion of the output light, collectively providing a non-specular internal reflection redirection or non-refractive transmission reduction thereof.

[0110] Example 44 The device of any of Examples 25 to 43, wherein the front surface layer or coating comprises a partial photonic bandgap structure, the partial photonic bandgap structure being arranged with one or more materials, morphologies, and spacings to redirect at least a portion of the output light upon illumination by the active layer output light, for a nominal output vacuum wavelength λ, and collectively provide that non-specular internal reflection redirection or non-refractive transmission reduction.

[0111] Example 45 The device of any of Examples 25 to 44, wherein the front surface layer or coating comprises a partial photonic crystal arranged with one or more materials, crystalline morphologies, and crystal lattice spacings to redirect at least a portion of the output light upon illumination with the output light, for a nominal output vacuum wavelength λ, and to provide non-specular internal reflection redirection or non-refractive transmission reduction thereof.

[0112] Example 46 The device of any of Examples 1 to 45, wherein the front surface layer or coating comprises an array of meta-atoms or meta-molecules that (i) comprise one or more metamaterials, (ii) are shaped, sized, and spaced apart relative to a nominal output vacuum wavelength, λ, and (iii) are arranged along the front surface layer or coating so as to re-emit at least a portion of the output light upon illumination with the output light, collectively providing a non-specular internal reflection redirection or non-refractive transmission reduction thereof.

[0113] Example 47 The device of any of Examples 1 to 46, wherein the front surface layer or coating includes at least one region having a wavelength-dependent transmittance that differs from the wavelength-dependent transmittance of at least one other region of the front surface layer or coating.

[0114] Example 48 In the device of any of Examples 1 to 47, one or both of the back redirection layer and the front layer or coating comprises one or more of the following materials: doped or undoped silicon; doped or undoped III-V, II-VI, or IV semiconductor; doped or undoped silicon oxide, nitride, or oxynitride; one or more doped or undoped metal oxides, nitrides, or oxynitrides; one or more optical glasses; one or more doped or undoped polymers; or one or more metals or metal alloys.

[0115] Example 49 The device of any of Examples 1 to 48, wherein one or both of the back redirection layer and the front layer or coating are arranged such that the device exhibits an average total number of internal redirections and internal reflections per photon of output light emitted by the active layer before exiting the diode structure through the front surface of less than 30, less than 20, less than 10, or less than 5.

[0116] Example 50 The device of any of Examples 1 to 49, wherein the light emitting device exhibits a photon extraction efficiency of greater than about 80%, greater than about 90%, or greater than about 95%.

[0117] Example 51 The device of any of Examples 1 to 50, wherein the rear redirection layer exhibits a redirection efficiency of greater than about 80%, greater than about 85%, greater than about 90%, or greater than about 95%.

[0118] Example 52 The device of any of Examples 1 to 51, wherein the rear redirection layer exhibits an optical loss per pass of incident light that is less than about 20%, less than about 10%, less than about 5%, less than about 2.0%, or less than about 1.0%.

[0119] Example 53 The device of any of Examples 1 to 52, further comprising: (i) a dielectric layer on the back surface redirection layer, the back surface redirection layer being between the dielectric layer and the back surface of the diode structure, the dielectric layer being substantially transparent at the nominal vacuum wavelength λ and characterized by a refractive index lower than the refractive index of the diode structure; and (ii) a reflective layer on the dielectric layer, the dielectric layer being between the reflective layer and the back surface redirection layer.

[0120] Example 54 The device of Example 53, wherein the rear redirection layer exhibits a redirection efficiency of greater than about 20%, greater than about 40%, greater than about 60%, or greater than about 80%.

[0121] Example 55 The device of Example 53 or 54, wherein the reflective layer exhibits a reflectivity of greater than about 90%, greater than about 95%, or greater than about 98% at the nominal vacuum wavelength λ.

[0122] Example 56 The device of any of Examples 53 to 55, wherein the reflective layer comprises a metal coating or a dielectric coating.

[0123] Example 57 57. The device of any of Examples 53 to 56, wherein the dielectric layer comprises: The material may comprise one or more of the following: doped or undoped silicon; doped or undoped III-V, II-VI, or IV semiconductors; doped or undoped silicon oxides, nitrides, or oxynitrides; one or more doped or undoped metal oxides, nitrides, or oxynitrides; one or more optical glasses; or one or more doped or undoped polymers.

[0124] Example 58 In the device of any of Examples 53 to 57, the reflective layer comprises one or more of the following materials: doped or undoped silicon; doped or undoped III-V, II-VI, or IV semiconductor; doped or undoped silicon oxide, nitride, or oxynitride; one or more doped or undoped metal oxides, nitrides, or oxynitrides; one or more optical glasses; one or more doped or undoped polymers; or one or more metals or metal alloys.

[0125] Example 59 The device of any of Examples 1 to 58, wherein the nominal output vacuum wavelength λ is greater than about 0.20 m, greater than about 0.4 m, greater than about 0.8 μm, less than about 10 m, less than about 2.5 m, or less than about 1.0 μm.

[0126] Example 60 The device of any of Examples 1 to 59, wherein the semiconductor diode structure comprises a semiconductor light emitting diode.

[0127] Example 61 The device of any of Examples 1 to 60, wherein the diode structure comprises one or more of doped or undoped III-V, II-VI, or IV semiconductor materials or alloys or mixtures thereof.

[0128] Example 62 The device of any of Examples 1 to 61, wherein the light-emitting layer comprises one or more of doped or undoped III-V, II-VI, or IV semiconductor materials or alloys or mixtures thereof.

[0129] Example 63 The device of any of Examples 1 to 62, comprising one or more pn junctions, one or more quantum wells, one or more multi-quantum wells, or one or more quantum dots.

[0130] Example 64 The device of any of Examples 1 to 63, further comprising a wavelength-converting structure facing the front surface and positioned and arranged to absorb at least a portion of the output light propagating away from the front surface and emit downconverted light at one or more wavelengths longer than the nominal vacuum wavelength λ.

[0131] Example 65 A method of manufacturing the device of any of Examples 1 to 64, comprising: (a) forming one or more light-emitting active layers within a diode structure; (b) forming a front surface coating or layer on a front surface of the diode structure; and (c) forming the back surface redirection layer on a back surface of the diode structure.

[0132] Example 66 The method of Example 65 further includes the steps of: (d) forming a dielectric layer on the back surface of the redirection layer, wherein the redirection layer is between the dielectric layer and the back surface of the diode structure; and (e) forming a reflective layer on the back surface of the dielectric layer, wherein the dielectric layer is between the reflective layer and the back surface of the redirection layer.

[0133] Example 67 A method of operating the device of any of Examples 1 to 64, the method including powering the light emitting device such that the light emitting device emits device output light from a front surface of the diode structure and propagates in an ambient medium opposite the front surface.

[0134] Example 68 An array of a plurality of the light emitting devices of any of Examples 1 to 64.

[0135] Example 69 In the array of Example 68, each light emitting device of the array is operable independently of at least one other light emitting device of the array.

[0136] Example 70 68. The array of Example 68, wherein each light emitting device of the array is operable independently of all other light emitting devices of the array.

[0137] Example 71 In any of the devices of embodiments 68 to 70, the non-zero spacing or pitch of the light emitting devices in the array is less than about 1.0 mm, less than about 0.5 mm, less than about 0.3 mm, less than about 0.2 mm, less than about 0.10 mm, less than about 0.08 mm, less than about 0.05 mm, less than about 0.03 mm, or less than about 0.02 mm.

[0138] Example 72 The device of any of Examples 68 to 71, wherein the light emitting devices of the array are separated by non-light emitting pixel boundaries having a non-zero width of less than 0.10 mm, less than 0.05 mm, less than 0.03 mm, less than 0.02 mm, less than 0.010 mm, or less than 0.005 mm.

[0139] Example 73 A display system comprising: (i) the array of any of Examples 68 to 72; (ii) a display; and (iii) an optical element or optical system spaced from the array and arranged to couple light from the array into the display.

[0140] Example 74 A mobile device comprising: (i) a camera; (ii) an array of any of Examples 68 to 72; and (iii) an optical element or optical system spaced from the array and arranged to direct light emitted by the array into the field of view of the camera.

[0141] Example 75 An illumination system comprising: (i) an array of any of Examples 68 to 72; and (iii) an optical element or optical system spaced from the array and arranged to direct light emitted by the array into an area or region to be illuminated.

[0142] It is intended that equivalents of the disclosed exemplary embodiments and methods be within the scope of this disclosure or the appended claims. It is intended that the disclosed exemplary embodiments and methods, and their equivalents, can be modified while remaining within the scope of this disclosure or the appended claims.

[0143] In the foregoing detailed description, various features may be grouped together in some exemplary embodiments for the purpose of streamlining the disclosure. This method of disclosure is not to be interpreted as reflecting an intention that the claimed embodiments require more features than are expressly recited in the corresponding claim. Rather, as the appended claims reflect, inventive subject matter may reside in fewer than all features of a single disclosed exemplary embodiment. Accordingly, the present disclosure shall be construed as implicitly disclosing any embodiment having any suitable subset of one or more features, which may include subsets that may not be explicitly disclosed herein, and which features are shown, described, or claimed in this application. A "suitable" subset of features includes only features that are neither interchangeable nor mutually exclusive with respect to any other features of that subset. Accordingly, the appended claims are hereby incorporated into the detailed description, with each claim standing on its own as a separate disclosed embodiment. Additionally, each of the appended dependent claims shall be construed as if written in multiple dependent form and dependent on all non-conflicting preceding claims, solely for purposes of disclosure by said incorporation of the claims into the detailed description. It is further noted that the cumulative scope of the appended claims may, but does not necessarily, encompass the entirety of the subject matter disclosed in the present application.

[0144] The following interpretation shall apply for purposes of this disclosure and the appended claims: The article "a" shall be interpreted as "one or more" unless "only one," "single," or other similar limitation is expressly stated or implied in the specific context, and similarly, the article "the" shall be interpreted as "one or more" unless "only one," "single one," or other similar limitation is expressly stated or implied in the specific context. The conjunction "or" is to be interpreted inclusively (e.g., "dogs or cats" is to be interpreted as "dogs, cats, or both" (e.g., "dogs or cats" is to be interpreted as "dogs or cats, or both"; e.g., "dogs, cats, or mice" is to be interpreted as "dogs, cats, or mice, or any two or all three species"). Similarly, "one or more dogs or cats" is to be interpreted as including (i) one or more dogs that do not include any cats; (ii) any dogs that do not include any cats; or (iii) any dogs that do not include any cats, unless expressly stated otherwise or the alternatives are understood or disclosed (implicitly or explicitly) to be mutually exclusive or incompatible. Similarly, "one or more of dogs, cats, or rats" is interpreted to include (i) one or more dogs without any cats or rats, (ii) one or more cats without any dogs or rats, (iii) one or more rats without any dogs or cats, (iv) one or more dogs and one or more cats, (v) one or more dogs and one or more rats, (vi) one or more cats and one or more rats, or (vii) shall be interpreted as one or more dogs, one or more cats, and one or more rats. "Two or more of dogs, cats, or rats" shall be interpreted as (i) one or more dogs and one or more cats, with no rats; (ii) one or more dogs and one or more rats, with no cats; (iii) one or more cats and one or more rats, with no dogs; or (iv) one or more dogs, one or more cats, and one or more rats; and "three or more," "four or more," etc. shall be interpreted similarly.For any of the foregoing statements, if any pair or combination of included alternatives is understood or disclosed (implicitly or explicitly) as being incompatible or mutually exclusive, such pair or combination is understood to be excluded from the corresponding statement. For purposes of this disclosure and the appended claims, the words "comprising," "including," "having," and variations thereof, wherever they appear, unless expressly stated otherwise, shall be construed as open-ended terms having the same meaning as if a phrase such as "at least" were added after each instance thereof.

[0145] For purposes of this disclosure or the appended claims, when terms such as "approximately equal," "substantially equal," "greater than about," "less than about," and the like are used in connection with numerical quantities, standard practices regarding measurement precision and significant digits shall apply unless a different interpretation is expressly stated. With respect to null quantities described by phrases such as "substantially prevented," "substantially absent," "substantially eliminated," "equivalent to approximately zero," "negligible," and the like, each such phrase shall indicate that the quantity in question is reduced or diminished to an extent that, for practical purposes in the context of the intended operation or use of the disclosed or claimed device or method, the overall operation or performance of the device or method is no different from what would have occurred if the null quantity had in fact been completely eliminated and equal to or otherwise rendered exactly zero.

[0146] For purposes of this disclosure and the appended claims, any labeling of elements, steps, limitations, or other portions of an embodiment, example, or claim (e.g., first, second, third, etc.; (a), (b), (c), etc.; or (i), (ii), (iii), etc.) is for clarity only and should not be construed as implying any kind of ordering or priority of the portions so labeled. If any such ordering or priority is intended, it will be explicitly set forth in the embodiment, example, or claim, or in some cases it is implicit or inherent based on the particular content of the embodiment, example, or claim. In the appended claims, when the provisions of 35 U.S.C. § 112(f) are desired to be invoked in an apparatus claim, the word "means" will appear in that apparatus claim. When these provisions are desired to be invoked in a method claim, the word "step for" will appear in that method claim. Conversely, if the words "means for" or "step for" do not appear in a claim, the provisions of 35 USC §112(f) are not intended to be invoked with respect to that claim.

[0147] If any one or more disclosures are incorporated herein by reference and such incorporated disclosures conflict in part or in whole with or differ in scope from this disclosure, then to the extent of the conflict, broader disclosure, or broader term definition, this disclosure will control. If the contents of the incorporated disclosures, in part or in whole, conflict with each other, the later-dated disclosure will control to the extent of the conflict.

[0148] The Abstract is optionally provided as an aid to those searching for particular subject matter within the patent document. However, the Abstract is not intended to imply that any element, feature, or limitation described therein is necessarily covered by any particular claim. The scope of subject matter covered by each claim shall be determined by the language of that claim alone.

Claims

1. 1. A semiconductor light emitting device comprising: A semiconductor diode structure having a front surface, a back surface, and one or more light-emitting active layers, which emit light at a nominal vacuum wavelength λ ０ a semiconductor diode structure, the semiconductor diode structure being arranged to emit output light at and propagate within the diode structure; a redirection layer on the backside of the diode structure, the backside redirection layer comprising one or more of: (i) a nanoantenna array; (ii) a partial photonic bandgap structure; (iii) a photonic crystal; or (iv) a meta-atom or meta-molecule, wherein at least a portion of the backside redirection layer is oriented at the nominal vacuum wavelength λ ０ a redirection layer structurally arranged to exhibit non-specular internal reflection redirection of output light incident on the back surface within the diode structure to a front surface layer or coating on the front surface of the diode structure, at least a portion of the front surface layer or coating being structurally arranged to exhibit position-dependent internal reflection redirection or position-dependent transmission redirection of output light incident on the front surface from within the diode structure; Equipped with The front surface layer or the front surface coating is (i) a first set of one or more area regions on the front surface of the diode structure is oriented at a wavelength equal to or less than the nominal vacuum wavelength λ ０ or exhibiting a transmittance at the front surface facing the surrounding medium for output light incident into the diode structure at (ii) a second set of one or more area regions on the front surface of the diode structure are oriented at a wavelength equal to or less than the nominal vacuum wavelength λ ０ a diode structure having a front surface facing a surrounding medium, the front surface being structurally arranged to exhibit, for output light incident into the diode structure, a transmittance at the front surface facing a surrounding medium that is less than a Fresnel transmittance from an interface between the front surface of the diode structure and a surrounding medium without the front surface layer or coating.

2. the position dependence of the front surface layer or front surface coating is arranged such that output light exiting the diode structure through the front surface exhibits a position dependent luminance that varies with position across the front surface. The device of claim 1.

3. The position dependent luminance is: (i) exhibiting a maximum value nearer to one edge of the diode structure and decreasing monotonically from the maximum value along one lateral dimension across the diode structure; (ii) exhibiting a maximum intensity along a line extending across a central region of the diode structure and decreasing in both directions along one lateral dimension toward the opposing edge of the diode structure; (iii) exhibiting a maximum intensity in a central region of the diode structure and decreasing in both directions along both lateral dimensions toward the edges of the diode structure; or (iv) comprising: (1) a central region exhibiting a substantially constant non-zero luminance; and (2) a peripheral region surrounding the central region exhibiting only negligible luminance. The device of claim 2.

4. the position dependence of the front surface layer or front surface coating is arranged such that, with a substantially uniform emission of output light across the light-emitting active layer, output light exiting the diode structure through the front surface exhibits a position-dependent brightness that varies with position across the front surface. The device of claim 1.

5. at least a portion of the back surface redirection layer is structurally arranged to exhibit position-dependent specular or non-specular internal reflection redirection of output light incident on the back surface within the diode structure; The device of claim 1.

6. (i) the back surface redirection layer exhibits non-specular internal reflection redirection over only a first portion of the back surface of the diode structure and specular internal reflection over only a second portion of the back surface of the diode structure that is different from the first portion; or (ii) at least a portion of the back surface redirection layer exhibits a position-dependent angle of non-specular internal reflection redirection; The device of claim 5.

7. The backside redirection layer includes one or more of (i) the nanoantenna array, (ii) the partial photonic bandgap structure, (iii) the photonic crystal, or (iv) the array of meta-atoms or meta-molecules, which are oriented at the nominal vacuum wavelength λ ０ shaped, sized and arranged to collectively provide said non-specular internal reflection redirection of output light to The device of claim 5.

8. At least a portion of the front surface layer or coating comprises one or more of: (i) nanoantenna arrays, (ii) partial photonic bandgap structures, (iii) photonic crystals, or (iv) arrays of meta-atoms or meta-molecules, which are oriented at or above the nominal vacuum wavelength λ. ０ with the front surface facing the surrounding medium, and the nominal vacuum wavelength λ ０ wherein the portion of the front surface is shaped, sized, and arranged such that it exhibits non-specular reduction of output light and propagates outside the diode structure at an angle that is less than a corresponding angle of incidence of output light incident on the front surface within the diode structure. The device of claim 1.

9. At least a portion of the front surface layer or the front surface coating has a wavelength that is less than the nominal vacuum wavelength λ ０ a front layer having micro- or nanostructured elements arranged as a structured lens to provide a reduced angular divergence or a narrow angular intensity distribution of output light exiting the diode structure, The device of claim 1.

10. (i) the micro- or nanostructured elements of the structured lens comprise a multitude of appropriately sized and shaped protrusions, holes, recesses, inclusions, or structures forming, formed on, or formed in the front layer; or (ii) the micro- or nanostructured elements of the structured lens comprise nanoantenna arrays, partial photonic bandgap structures, photonic crystals, or arrays of meta-atoms or meta-molecules; The device of claim 9.

11. at least a portion of the back surface redirection layer includes diffuse backscatterers arranged to, upon illumination by output light, backscatter at least a portion of the output light to collectively provide non-specular internal reflection redirection thereof; The device of claim 1.

12. (i) a first portion of the front surface layer or coating is positioned on a first set of area regions, with the front surface facing the surrounding medium, and the nominal vacuum wavelength λ incident on the front surface within the diode structure; ０ and arranged to provide a non-refracting transmissive reduction of output light at a front surface of the diode structure such that the output light propagates outside the diode structure at an exit angle that is smaller than a corresponding refraction angle of the output light incident on the front surface within the diode structure; (ii) a second portion of the front surface layer or coating is positioned over a second set of area regions and either (1) exhibits specular internal reflection incident on the front surface within the diode structure, or (2) exhibits a reflection at the nominal vacuum wavelength λ incident on the front surface within the diode structure. ０ and arranged to provide non-specular internal reflection redirection for output light at The device of claim 1.

13. the second portion of the front surface layer or coating exhibits a position-dependent angle of non-specular internal reflection redirection; 13. The device of claim 12.

14. At least a portion of the front surface layer or coating comprises one or more of: (i) nanoantenna arrays, (ii) partial photonic bandgap structures, (iii) photonic crystals, or (iv) arrays of meta-atoms or meta-molecules, which are oriented at or above the nominal vacuum wavelength λ. ０ and arranged to exhibit non-specular internal reflection redirection or non-refractive transmission redirection with respect to The device of claim 1.

15. the front surface layer or the front surface coating comprises at least one region having a wavelength-dependent transmittance that differs from the wavelength-dependent transmittance of at least one other region of the front surface layer or the front surface coating; The device of claim 1.

16. the light emitting device exhibits a photon extraction efficiency of greater than about 80%, greater than about 90%, or greater than about 95%; The device of claim 1.

17. (i) a dielectric layer on the backside redirection layer, the backside redirection layer being between the dielectric layer and the backside of the diode structure, the dielectric layer being substantially transparent at the nominal vacuum wavelength λ and characterized by a refractive index lower than the refractive index of the diode structure; (ii) a reflective layer on the dielectric layer, the dielectric layer being between the reflective layer and the back redirection layer; The device of claim 1.

18. 18. An array of a plurality of devices according to any one of claims 1 to 17, each light emitting device of the array is operable independently of at least one other light emitting device of the array; a non-zero spacing or pitch of the light emitting devices in the array is less than 1.0 mm; the light emitting devices of the array are separated by non-emissive pixel boundaries having a non-zero width of less than 0.10 mm; array.

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