Micro-LED emitting Lambert radiation pattern

Abstract

An LED light source for producing a pattern of more Lambertian radiation, the LED light source having a micro LED die wherein the sidewalls of the die are reflective and inclined at an angle greater than 20 degrees, and wherein the top surface of the LED die is roughened. Scattering particles may also be placed on the top emission surface of the micro-LED. An optical element having a roughened surface may be placed over the micro LED die. The micro LED die may also be placed in a cup structure having reflective sidewalls.

Description

Technical Field

[0001] This invention relates in general to micro-LED light sources. Background Technology

[0002] Semiconductor light-emitting diodes (“LEDs”) are among the most efficient light sources available today. The emission spectrum of an LED typically presents a single narrow peak at a wavelength determined by the device’s structure and the composition of the semiconductor materials that make it up. Traditional LEDs have a large planar emission region in which most of the light is emitted through the top surface of the LED. However, microLEDs are five-sided light emitters, with a significant amount of light emitted from the sides of the LED.

[0003] In some applications, such as direct-view displays (which prefer a Lambert-like radiation pattern), lateral light emission from microLEDs is undesirable. A Lambert radiation pattern occurs when the radiation from a light source is independent of the viewing angle. Summary of the Invention

[0004] This application discloses a microLED light source with a more Lambertian radiation pattern, which is more suitable for direct-view displays than currently available microLEDs. In one embodiment, such a light source includes a microLED thin-film flip-chip (TFFC) die. In one embodiment, the light source includes a microLED with a sapphire layer less than 30 micrometers thick. In one embodiment, the microLED die has dimensions less than 20 micrometers: for example, less than 20 micrometers in length, less than 20 micrometers in width, and less than 20 micrometers in thickness. The microLED die has n-contacts and p-contacts on the same side of the microLED die. In one embodiment, the microLED die has multiple semiconductor layers, including an n-doped layer, a p-doped layer, an active region, and a current spreading layer. In another embodiment, the microLED die has multiple semiconductor layers, including two or more n-doped layers, two or more p-doped layers, two or more active regions, one or more tunnel junctions, and a current spreading layer. Each of these layers has a sloping sidewall. The sloping sidewall forms an angle greater than 20 degrees with respect to the perpendicular from the bottom surface of the die. In one embodiment, the sidewall forms an angle of approximately 45 degrees with respect to the perpendicular from the bottom surface of the die. In one embodiment, the angle of the sidewall of the current spreading layer is different from the angle of the sidewall of other layers.

[0005] The sidewalls of the semiconductor layer are coated with a reflective optical side coating. This reflective optical side coating is applied to the sidewalls of the semiconductor layer, forming a conformal coating. The reflective side coating eliminates or significantly reduces light emitted from the sides of the microLED, resulting in a more Lambertian radiation pattern. The reflective optical coating can also be applied to the bottom semiconductor surface of the microLED die.

[0006] In one embodiment, the reflective optical side coating comprises a dielectric layer and a metal layer. The dielectric layer may be a material with a low refractive index, such as silica or silicon dioxide (SiO2), magnesium fluoride (MgF2), or silicon nitride. The metal layer may comprise silver or gold. The interface between the dielectric layer and the metal layer has a critical angle that allows for total internal reflection at the interface.

[0007] In one embodiment, the reflective optical side coating includes a distributed Bragg reflector (DBR) consisting of alternating sequences of two different optical materials with different refractive indices. When the reflective side coating includes a DBR, an additional metal layer may or may not be used. If the reflective optical coating includes a metal layer, an additional dielectric layer coated with the metal layer may be included.

[0008] In one embodiment, the reflective optical side coating may include scattering particles dispersed in a matrix material. For example, the optical side coating may be titanium oxide (TiOx) particles dispersed in a silicone matrix. The percentage of scattering particles in the optical coating is high enough to scatter all or substantially all of the light emitted from the side of the microLED back into the semiconductor layer of the microLED.

[0009] In one embodiment, the top surface of the microLED die is roughened to randomize the light emitted from the top surface, resulting in a more Lambertian radiation pattern. In another embodiment, the top surface of the current spreading layer is roughened.

[0010] In one embodiment, all sidewalls of the n-doped semiconductor layer and the p-doped semiconductor layer are covered with a reflective optical side coating. In another embodiment, one sidewall of the current spreading layer is not covered with a reflective optical side coating. For example, in a rectangularly shaped microLED, three sidewalls of the current spreading layer may be covered with a reflective optical side coating, and one sidewall may not be covered with a reflective optical side coating. In an alternative embodiment, all sidewalls of the current spreading layer are covered with a reflective optical side coating.

[0011] In one embodiment, the light source comprises scattering particles placed on the top surface of the microLED die (e.g., on the top surface of the current spreading layer). Multiple thin film layers are used to bond the scattering particles in place. The scattering particles may be TiOx particles. The scattering particles on the top surface of the microLED may be several layers thick. The thin film layers may be transparent and may be deposited onto the scattering particles by chemical vapor deposition (CVD) or atomic layer deposition (ALD) to bond the particles in place. The scattering particles randomly scatter the light emitted by the microLED die, resulting in a more Lambertian radiation pattern.

[0012] In one embodiment, an optical element is placed above the top surface of a microLED. The optical element is held above the microLED by a hollow base. The inner wall of the base, the top surface of the microLED, and the bottom surface of the optical element define an internal cavity that can be filled with air. The optical element may be made of glass, silicone, or a transparent material. The top and bottom surfaces of the optical element may be roughened. In one embodiment, the top and bottom surfaces of the optical element may be coated with an anti-reflective coating. In one embodiment, the inner wall of the base may be coated with a reflective material, such as silver or gold. In one embodiment, the inner wall of the base may include a distributed Bragg reflector. In one embodiment, the top or bottom surface, or both surfaces, are curved to form a lens.

[0013] In one embodiment, the light source comprises microLEDs mounted on the bottom surface of a cup structure and located inside the cup structure. The cup is filled with a filler material, which may be silicone resin. The filler material may cover the sides of the microLEDs but not their top surfaces. In one embodiment, the inner surface of the cup's sidewalls is covered with a reflective metal. In one embodiment, the cup's sidewalls comprise distributed Bragg reflectors. In one embodiment, the inner surface of the cup's sidewalls is roughened to randomize the direction of light reflected off the inner surface of the cup's sidewalls. In one embodiment, the filler material may comprise a small percentage of scattering particles, such as TiOx particles. In one embodiment, the filler material may comprise a high percentage of scattering particles.

[0014] These and other embodiments, features and advantages of the invention will become more apparent to those skilled in the art when taken in conjunction with the accompanying drawings, which have been briefly described above, and with reference to the following more detailed description of the invention. Attached Figure Description

[0015] Figure 1 A schematic cross-sectional view of a microLED chip is shown.

[0016] Figure 2 A cross-sectional view of a microLED die with scattering particles is shown schematically.

[0017] Figure 3 A cross-sectional view of a microLED die with a transparent cover is schematically shown.

[0018] Figure 4 A schematic cross-sectional view of the microLED die in the cup structure is shown.

[0019] Figure 5 A cross-sectional view of a semiconductor structure with multiple active regions is schematically shown.

[0020] Figure 6 A cross-sectional view of a semiconductor structure with multiple active regions is schematically shown.

[0021] Figure 7 A cross-sectional view of a semiconductor structure with multiple active regions is schematically shown.

[0022] Figure 8 A cross-sectional view of a semiconductor structure with multiple active regions is schematically shown.

[0023] Figure 9 A schematic cross-sectional view of the microLED die in the cup structure is shown.

[0024] Figure 10 The angular far-field radiation of microLEDs on micro-scale patterned sapphire substrates (microPSS) and nano-scale patterned sapphire substrates (nanoPSS) is shown. Detailed Implementation

[0025] The following detailed description should be read with reference to the accompanying drawings, in which the same reference numerals indicate similar elements throughout the various figures. The drawings are not drawn to scale, depict selective embodiments, and are not intended to limit the scope of the invention. The detailed description illustrates the principles of the invention by way of example, not limitation.

[0026] Figure 1 A schematic cross-sectional view of an example microLED die 100 is shown. For example, the size of the microLED is less than 20 micrometers. For example, the thickness or height h of the die (see...) Figure 1 The length 142 and width 141 (not shown) of the microLED can be less than 5 micrometers. The die 100 is a thin-film flip-chip (TFFC) microLED die in which the sapphire growth substrate has been removed, and p-contacts 142 and n-contacts 141 are located at the bottom of the die. In some embodiments, the die 100 can be a flip-chip die with a thin sapphire layer on top of the die; for example, the die can be like a TFFC die except that the sapphire substrate is not completely removed. This thin sapphire layer is less than 30 micrometers thick. The die 100 includes an n-doped semiconductor layer 112, a p-doped semiconductor layer 114, and a multiple quantum well (MQW) active region 113 located between the n-doped and p-doped layers. The die 100 also includes a semiconductor layer 111 serving as a current spreading layer. The semiconductor layer 111 may be n-doped.

[0027] In some embodiments, a microLED die includes multiple active regions separated by tunnel junctions. Tunnel junctions allow current to flow through very thin depletion regions, such as bidirectional tunneling of electrons and holes. This is achieved through appropriate heavy doping to create tunnel junctions. For example, a microLED die may have two MQW active regions separated by one or more tunnel junctions, such as... Figure 5 and Figure 6As shown in the diagram. Other configurations are possible, such as the microLED die having three MQW active regions separated by one or more tunnel junctions, such as... Figure 7 and Figure 8 As shown. Figures 5 to 8 As shown, a die having more than one MQW active region separated by one or more tunnel junctions may include more than one n-doped semiconductor layer and more than one p-doped semiconductor layer.

[0028] For ease of understanding, Figures 5 to 8 The semiconductor layer stack is shown as independent of other parts of the light-emitting device. Figures 5 to 8 The semiconductor layer stack shown can be replaced Figures 1 to 4 Any of the semiconductor stacks shown (e.g., a stack consisting of any one of layers 111, 112, 113, 114, 115). For example, Figure 6 The stack shown can be replaced Figure 1 Layers 112, 113, 114, and 115 shown make... Figure 6 The topmost semiconductor layer 112 and Figure 1 The semiconductor layer 111 in the middle is in direct contact, and Figure 6 The bottom semiconductor layer 112 and Figure 1 The dielectric layer 112 in the middle is in direct contact.

[0029] Figure 5 The system includes two MQW active regions 113, each defined and directly contacted by an n-doped semiconductor layer 112 and a p-doped semiconductor layer 114, which are stacked on top of each other with a tunnel junction 116 between them. The tunnel junction can directly contact the p-doped semiconductor layer 114 and the n-doped semiconductor layer 112. At the bottom of the stack is a transparent conductive oxide (TCO) layer 115. Figure 6 It shows the relationship with Figure 5 A similar stack, except that there is a second tunnel junction 116 and an n-doped semiconductor layer 112 instead of a bottom TCO layer 115. Figure 7 A stack is depicted having three MQW active regions 113 and three pairs of n-doped semiconductor layers 112 and p-doped semiconductor layers 114, with two tunnel junctions 116 between them, and a bottom TCO layer 116. Figure 8 It shows the relationship with Figure 7A similar stack exists, except that a third tunnel junction 116 and an n-doped semiconductor layer 112 are present instead of a bottom TCO layer 115. As in some of the embodiments described above, if each end of the stack terminates with an n-doped semiconductor layer 112, the necessity of a TCO can be effectively eliminated (unlike p-type semiconductors, n-type semiconductors can be grown as good electrically extended layers). Stacked tunnel junctions with multiple active regions can achieve higher power densities, as described in the following equation: Optical Output = Nj * Vf * If * EQE * EE, where Nj: number of active regions, Vf: forward voltage of an active region, EQE: external quantum efficiency of the device, and EE: electrical efficiency of an active region. The equation assumes that all active regions are identical, but they may not need to be identical, in which case the equation can be adjusted.

[0030] MicroLED dies with multiple MQW active regions separated by one or more tunnel junctions exhibit increased light emission. The greater light emission from a multi-active-region die results in greater lateral light emission from the die, which can be disadvantageous for some applications, as mentioned above, but can be improved by the techniques discussed below.

[0031] To achieve a more Lambertian-like radiation pattern, the sidewalls of die 100 are sloped, and a reflective coating is added to the sidewalls. Specifically, the four sidewalls of the semiconductor layer of the die are sloped. For example, in Figure 1 In the middle, semiconductor layers 111, 112, 113 and 114 are tilted. Figure 1 Only two sidewalls of each semiconductor layer are shown. The other two sidewalls, not shown, are... Figure 1 The cross-section shown is both inside and outside the plane. For dies with multiple active regions and tunnel junctions, the semiconductor layers associated with these active regions and tunnel junctions are similarly tilted. For example... Figure 1 As shown, the sidewalls of the semiconductor layer are inclined at an angle θ away from the vertical line 150, where line 150 is perpendicular to the bottom surface of the semiconductor layer. Furthermore, all four sidewalls of semiconductor layers 111, 112, and 114 are inclined in a similar manner. In some embodiments, the angle θ of the current spreading layer 111 may differ from the angles of other parts of the die.

[0032] The inclined sidewalls of semiconductor layers 111, 112, and 114, as well as the bottom surface of semiconductor layer 114, are coated with an optical side coating 120. Figure 1 In one example, the optical side coating comprises a dielectric layer 121 composed of a low-refractive-index material such as silicon dioxide, and a metallic layer 122 made of silver or gold. Figure 1In this example, an additional dielectric layer 130 is required to cover the metal layer 122 to prevent, for example, electrical short circuits between the n-contact and the p-contact. The optical side coating 120 reflects light emitted from the side of the die. Due to the angle θ of the sidewall inclination, the light reflected by the optical side coating 120 is redirected toward the top surface 110 of the microLED die. To achieve a Lambertian-like radiation pattern, the inventors have found that the angle θ must be greater than 20 degrees. In the most preferred embodiment, the angle θ is approximately 45 degrees. The top surface 110 is roughened to randomize light emission and achieve a more Lambertian radiation pattern.

[0033] Alternatively or additionally, the top surface 110 can be patterned on a nanoscale to transmit light with a narrow angular distribution centered coaxially. This is in Figure 9 As shown in the diagram. Typical nanoscale features can include periodic shapes that form regular patterns and possess any of the following properties: a hexagonal lattice (based on sapphire crystal structure), a pitch (P) of approximately 200 nm to approximately 500 nm, a height (H) of approximately 200 nm to approximately 500 nm, and a spacing (S) of approximately 20% (i.e., pitch). Other shapes are possible as long as the size remains within a few hundred nanometers. Figure 9 As shown in the illustration, the shape 902 used in the patterning of the top surface 110 can be substantially frustoconical. For steep trench angles (approximately 5 degrees or less), an optimal pitch for the nanoPSS features is approximately 350 nm to approximately 400 nm, which produces the maximum light extraction efficiency (ExE) within this angle range, with a reasonably high simulated forward emission. A trade-off may also exist between forward emission and ExE. For sloping trench angles, a smaller pitch / size may be preferred. The optimal pitch for ExE (regardless of trench angle) can be less than approximately 400 nm. The dependence of size on trench angle means that the optimal pitch can decrease as the trench angle increases. These nanoscale features can be obtained, for example, by nanolithography or by growing epis on a nanoscale patterned sapphire substrate (nanoPSS). After laser lift-off (LLO), the exposed nanoscale features on the GaN surface are able to effectively guide angular emission forward. For 45° conical emission with trench sidewall angles less than approximately 8°, LEDs with nanoPSS characteristics outperform LEDs with planar epitaxy. For trench angles of approximately 5° (relative to the normal angle of the emission surface), a 6% improvement in total flux and a 25% flux gain can be achieved within a coaxial 45° cone.

[0034] Figure 10 The following are examples. Figure 9The angular far-field radiation of the microLED exhibits both microPSS and nanoPSS characteristics. As shown, the LED with nanoPSS provides a narrower and stronger emission compared to the LED with microPSS (PSS2).

[0035] In some embodiments, the angles θ of semiconductor layers 111, 112, and 114 are substantially the same. In other embodiments, the angles θ of semiconductor layers 112 and 114 are substantially the same, but different from the angle θ of semiconductor layer 111. Because the semiconductor layers are at different levels within the LED die, the angles θ can be optimized to different angles to more effectively reflect or scatter light onto the top surface 110.

[0036] exist Figure 1 In the example, only three sidewalls of semiconductor layer 111 are covered with optical side coating material. One sidewall of semiconductor layer 111 is left uncovered to allow n-contact 141 to contact semiconductor layer 111. Leaving one sidewall uncovered simplifies the fabrication process of the microLED. However, all four sidewalls of semiconductor layer 111 can be covered with optical side coating material (not shown). In this case, n-contact 141 can be electrically connected to semiconductor layer 111 by using a via or by an optically transparent electrical contact on the top surface 110 in a vertical die structure. p-contact 142 is electrically connected to semiconductor layer 114 by a metal via 143 passing through layer 130 and optical side coating 120. The metal via 143 is electrically connected to transparent conductive oxide (TCO) layer 115, which in turn contacts semiconductor layer 114.

[0037] In another embodiment, the optical side coating 120 may include a distributed Bragg reflector (not shown). For example, the DBR may include an alternating sequence of two different optical materials: one layer may be a thin film of a high-refractive-index material, and the other layer may be a thin film of a low-refractive-index material. For example, the DBR may consist of alternating layers of titanium dioxide and silicon dioxide. Light emitted from the sides of semiconductor layers 111, 112, and 114 will be reflected by the DBR. Due to the sloping sidewalls of the LED die, the light reflected off the DBR will be directed toward the top surface 110. If only the DBR is used, a separate dielectric layer 130 may not be necessary. In some embodiments, the optical side coating includes the DBR and a metal layer, wherein the interface between the DBR and the metal layer forms an additional interface over which light reflection can occur. If a metal layer is used, a separate dielectric layer 130 may be required.

[0038] In another embodiment, the optical side coating 120 may be a silicone coating containing a high concentration of light-scattering particles, such as titanium oxide (TiOx) particles. Light emitted from the sides of semiconductor layers 111, 112, and 114 will be scattered back into the semiconductor layers by the high concentration of TiOx particles. For example, the optical side coating 120 may include TiOx particles comprising between 40% and 60% of its volume. Due to the angled sidewalls of the LED die, the scattered light will be directed toward the top surface 110. If a silicone side coating is used, a separate dielectric layer 130 is not required.

[0039] Figure 2 A schematic cross-sectional view of an example LED die with scattering particles 210 on the top surface 110 of the die is shown. Figure 2 The scattering particles 210 shown are not to scale, and LED light sources typically have more scattering particles than illustrated. Furthermore, there may be more than one layer of scattering particles 210 (not shown). The scattering particles 210 may be TiOx particles. The scattering particles 210 may be held in place by a thin film layer 220, which may be deposited using chemical vapor deposition (CVD) or atomic layer deposition (ALD). The thin film layer 220 may be transparent. Figure 2 The thin film layer 220 in the figure is not drawn to scale. Scattering particles 210 scatter the light emitted from the top surface 110 and randomize the light emitted from the top surface 110, which produces a more Lambertian radiation pattern.

[0040] Figure 3 A schematic cross-sectional view of an example LED die with optical element 320 is shown. Optical element 320 can be made of glass, silicone, or any transparent material with a refractive index higher than that of air. The top surface 321 and bottom surface 322 of the optical element can be roughened or have an anti-reflective coating. The roughened surfaces of the optical element randomize light emission, thereby contributing to a more Lambertian radiation pattern. The anti-reflective coating reduces specular reflection and thus gives the light source a more Lambertian radiation pattern. Optical element 320 can, for example, have a curved top surface, a curved bottom surface, or both a curved top surface and a curved bottom surface (not shown). The curved top or bottom surface of the optical element can form a lens and can alter the emission radiation pattern of the LED die to a more Lambertian radiation pattern.

[0041] The optical element 320 is supported by a hollow base 305 mounted on the surface of material 301. Material 301 can be an optical side coating material or any other material supporting the base 305. Figure 3As shown, the inner wall 310 of the base is located around the top surface 110 of the LED die. The inner wall 310, the top surface 110 of the LED die, and the bottom surface 322 of the optical element define a cavity 330 (thus making the base hollow). The cavity 330 may be filled with air. Figure 3 Only the cross-sectional view of two sidewalls 310 is shown, but for rectangular or square LED chips, there are two other sidewalls not shown, which are located at... Figure 3 The sidewalls 310 can be coated with a reflective coating, such as gold, silver, or a distributed Bragg reflector. The choice of reflective coating depends on the wavelength of the light emitted from the LED die. By forming the cavity 330, the base creates three distinct surfaces (321, 322, 110) where radiative emission can be randomized and specular reflection can be reduced, i.e., by using an anti-reflective coating. Thus, the optical element 320 with the hollow base 305 increases the emission radiation pattern of the LED die to a more Lambertian radiation pattern.

[0042] Figure 4 A schematic cross-sectional view of an example microLED die 400 mounted on the bottom surface 402 of a cup structure 401 is shown. The die 400 does not have an optical side coating. The cup structure 401 is filled with filler 430. Figure 4 As shown, filler 430 covers the sides of LED die 400 but not the top surface 410 of LED die. In one example, filler 430 is a transparent silicone filler, and the sidewalls 420 of the cup are covered with a reflective coating. The reflective coating can be a reflective metal (such as silver or gold) or a distributed Bragg reflector. The sidewalls 420 are angled away from the interior of the cup, such that light emitted from the sides of the LED die (ray 451) is reflected off the sidewalls 420 and towards the top of the cup and out of the cup (ray 452). Rays 451 and 452 are example rays; there are rays not present in the cup. Figure 4 Many other reflected light rays are shown. In some embodiments, a reflective coating, such as a high-% TiOx coating (a coating with TiOx particles having a volume of between 40% and 60%), may also be applied to the inner surface of the bottom surface 402 of the cup structure. In this embodiment, light can be scattered away from the bottom surface of the cup toward the top of the cup.

[0043] In one example, the sidewall 420 of the cup can be roughened to randomize the reflection angles exiting the sidewall. Randomized reflection angles contribute to a more Lambertian radiation pattern. In another example, the filler 430 may include a small percentage of scattering particles, such as TiOx particles. In this example, the concentration of scattering particles is between 2% and 20% by weight. In this example, light emitted from the side of the LED die will be randomly scattered by the scattering particles (not shown). Light not scattered towards the top of the cup can be reflected off the sidewall 420 and then scattered towards the top of the cup after reflection. The bottom surface 402 of the cup can also be coated with a reflective material so that light can be reflected off the bottom surface of the cup. The random nature of the scattering contributes to a more Lambertian radiation pattern.

[0044] In another example, the percentage of scattering particles in filler 430 is high enough to prevent light from escaping from the sides of LED die 400. For example, filler 430 could be a silicone resin containing 40% to 60% TiOx particles by volume. The high percentage of scattering particles in the filler acts as an optical side coating and helps with... Figure 1 The example is a more Lambert-like radiating pattern.

[0045] This disclosure is illustrative and not restrictive. Further modifications based on this disclosure will be apparent to those skilled in the art and are intended to fall within the scope of the appended claims.

Claims

1. An LED light source, comprising: A microLED thin-film flip-chip die or a microLED die having a sapphire layer less than 30 micrometers thick, the die comprising: Top surface, Bottom surface A semiconductor layer, the semiconductor layer comprising an n-doped layer, a p-doped layer and an active region; each semiconductor layer having sidewalls inclined at an angle greater than 20 degrees from the vertical line away from the bottom surface; A reflective side coating that covers the sidewalls of the semiconductor layer; n contact; and p-contact, the n-contact and the p-contact are on the same side of the die.

2. The LED light source according to claim 1, wherein the reflective side coating comprises a dielectric layer and a metal layer.

3. The LED light source according to claim 1, wherein the semiconductor layer comprises two or more n-doped layers, two or more p-doped layers, two or more active regions, and one or more tunnel junctions.

4. The LED light source according to claim 2, comprising a second dielectric layer between the n-contact and the metal layer of the side coating.

5. The LED light source according to claim 1, wherein the reflective side coating comprises a distributed Bragg reflector.

6. The LED light source according to claim 1, wherein the reflective side coating comprises scattering particles.

7. The LED light source according to claim 1, wherein the angle between the sidewall of the semiconductor layer and the perpendicular line of the bottom surface is approximately 45 degrees.

8. The LED light source according to claim 1, wherein the semiconductor layer includes a semiconductor current spreading layer adjacent to the top surface of the die, the current spreading layer including a first sidewall and a second sidewall, wherein the reflective side coating covers the first sidewall of the current spreading layer but does not cover the second sidewall of the current spreading layer.

9. The LED light source according to claim 1, wherein the top surface of the die is roughened.

10. The LED light source according to claim 1, comprising scattering particles in contact with the top surface of the die.

11. The LED light source according to claim 10, comprising an atomic layer deposition (ALD) layer on the top surface of the scattering particles and the die.

12. The LED light source according to claim 1, wherein the semiconductor layer comprises two or more n-doped layers, two or more p-doped layers, two or more active regions, one or more tunnel junctions, and a transparent conductive oxide (TCO) layer.

13. The LED light source of claim 1, comprising a transparent cover above the top surface of the die; an air-filled cavity between the transparent cover and the top surface of the die; and a base configured to hold the transparent cover above the top surface of the die.

14. The LED light source of claim 1, wherein the top surface of the die includes a pattern having nanoscale features configured to narrow and concentrate the light emitted by the active region onto the same axis.

15. The LED light source of claim 13, wherein the base is coated with a coating to reflect light emitted by the microLED die.

16. An LED light source, comprising: Micro LED chips, including: n-doped semiconductor layer; p-doped semiconductor layer; and Active region, A cup structure, including a bottom and reflective, sloping sidewalls, wherein the microLED die is located within the bottom of the cup structure and attached to the bottom of the cup structure; and Silicone resin filler, the silicone resin filler being located inside the cup structure.

17. The LED light source according to claim 16, wherein the silicone resin filler comprises scattering particles.

18. The LED light source according to claim 16, wherein the microLED die comprises two or more n-doped semiconductor layers, two or more p-doped semiconductor layers, two or more active regions; and one or more tunnel junctions.

19. An LED light source, comprising: Micro LED chips, including: n-doped semiconductor layer; p-doped semiconductor layer; and Active region, A cup structure, including a bottom and sidewalls, wherein the microLED die is located within the bottom of the cup structure and attached to the bottom of the cup structure; and A silicone resin filler is provided inside the cup structure, wherein the volume of scattering particles in the silicone resin filler is between 40% and 60%.

20. The LED light source of claim 19, wherein the microLED die comprises two or more n-doped semiconductor layers, two or more p-doped semiconductor layers, two or more active regions; and one or more tunnel junctions.

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