Micro LED with nano-patterned surface

Abstract

A lighting device is provided to incorporate light extraction features in a micro light emitting diode (micro LED). The micro LED includes a semiconductor stack including n-type and p-type semiconductors and an active region therebetween. The micro-LED has an emission surface from which light generated by the active region exits the micro-LED. The emission surface has nano-scale patterned sapphire substrate (nano PSS) features therein. The nanoPSS features have periodic frustoconical shapes, each periodic frustoconical shape having a pitch of about 200 nm to about 500 nm, a height of about 200 nm to about 500 nm, and an interval of about 20%. A metal sidewall extends from the emission surface to form a trench in which the micro LED is disposed. The metal sidewall extends at a trench angle of less than about 9 DEG relative to a normal to the emission surface and electrically contacts the n-type semiconductor.

Description

[0001] Priority claim This application claims the benefit of priority to U.S. Provisional Patent Application Serial No. 63 / 432,935, filed December 15, 2022, which is incorporated herein by reference in its entirety. Technical Field

[0002] The present disclosure relates to micro light emitting diodes (micro LEDs). In particular, embodiments are directed to light extraction in micro LEDs. Background Art

[0003] Efforts are currently underway to improve micro-LEDs. In particular, there is a desire to improve light extraction efficiency and increase angular emission. BRIEF DESCRIPTION OF THE DRAWINGS

[0004] Figure 1 A lighting device according to some examples is shown.

[0005] Figure 2A A monolithic LED pixel array according to some examples is shown.

[0006] Figure 2B Shown according to some examples Figure 2A A single pixel in a monolithic LED pixel array.

[0007] Figure 2C Shown according to some examples Figure 2A Replaces individual pixels in a monolithic LED pixel array.

[0008] Figure 3A Shown according to some examples Figure 2A A single pixel in a monolithic LED pixel array.

[0009] Figure 3B Shown according to some examples Figure 3A Angular far-field radiation of a monolithic LED pixel array on micrometer-scale patterned sapphire substrate (micro-PSS) and nano-PSS.

[0010] Figure 4 Far-field angular emission responses according to some examples are shown.

[0011] Figure 5 The simulated extraction efficiencies (ExE) of various nanoPSS designs according to some examples are shown.

[0012] Figure 6 Shown are simulated forward emission gains for various nano-PSS designs according to some examples.

[0013] Figure 7 An example of an electronic device in accordance with some embodiments is shown.

[0014] Figure 8 An example lighting system is shown in accordance with some embodiments.

[0015] Figure 9 A block diagram illustrating an example of a system according to some embodiments is shown.

[0016] Figure 10 An example hardware arrangement for implementing the above-disclosed subject matter is shown, according to some embodiments.

[0017] Figure 11 An example method of fabricating an LED device according to some embodiments is shown. DETAILED DESCRIPTION

[0018] A lighting device and method for manufacturing the lighting device are provided to incorporate light extraction features in a micro-light-emitting diode (micro-LED). The emitting surface of the micro-LED has nanoscale patterned sapphire substrate (nano-PSS) features. These features are in the surface of a semiconductor layer and / or in a transparent film on the semiconductor layer.

[0019] Figure 1 A lighting device 100 is shown according to some examples. Lighting device 100 may be, for example, a smartphone or a standalone camera that includes an adaptive LED light source. Lighting device 100 may include both a light source 110 and a camera 120. Regardless of whether scene 104 is illuminated by light source 110, camera 120 may capture an image of scene 104 during an exposure duration of camera 120. A processor 130 may be used to control various functions of light source 110 and camera 120, including whether a shutter in opening 108 of a housing of lighting device 100 is open.

[0020] The opening 108 may be Figure 1 Similarly, the shutter may be a single shutter covering both the light source 110 and the camera 120, or may include multiple separate shutters that cover only one of the light source 110 or the camera 120 and that can be individually controlled by the processor 130.

[0021] The lighting device 100 may include one or more LED arrays 112. Each of the one or more LED arrays 112 may include a plurality of LEDs 114 that can generate light during at least a portion of an exposure duration of the camera 120. Each of the one or more LED arrays 112 may include segmented LEDs 114, where the LEDs 114 are divided into a grid of light-emitting regions (LEDs 114) and non-light-emitting regions (between LEDs 114). In some embodiments, the effect of the non-light-emitting regions on an image captured using the one or more LED arrays 112 can be compensated for by moving the one or more LED arrays 112 and / or at least one lens 116 during the exposure duration of the scene 104 using one or more actuators to slightly move the LEDs 114 to illuminate areas of the scene 104 that would be affected by the non-light-emitting regions.

[0022] Each LED 114 can be formed using one or more inorganic semiconductor materials (e.g., binary compounds such as gallium arsenide (GaAs) or gallium nitride (GaN), ternary compounds such as aluminum gallium arsenide (AlGaAs), or quaternary compounds such as indium gallium arsenide phosphide (InGaAsP)), or other suitable materials. LEDs 114 are typically Group III-V materials (defined by the columns of the periodic table) or Group II-VI materials. Each LED 114 can emit light in the visible spectrum (approximately 400 nm to approximately 780 nm) or in the infrared spectrum (above approximately 780 nm). In some embodiments, one or more additional layers (such as a phosphor layer) can be provided over each of the one or more LED arrays 112 to convert the light from the LEDs 114 into white light (or light of another color). LEDs 114 emitting light in the infrared spectrum in a particular LED array 112 can, for example, be interspersed with LEDs 114 emitting light in the visible spectrum, or each type of LED (visible light emitter / infrared emitter) can be provided in different portions of a particular LED array 112. Alternatively, each LED array 112 may emit light only in the visible spectrum or the infrared spectrum; separate LED array(s) may be used to emit light in the infrared spectrum, and each of the separate LED arrays 112 , LEDs 114 , and / or LED segments may be controlled by the processor 130 .

[0023] Each of the one or more LED arrays 112 can be, for example, a micro-LED array, which includes thousands to millions of micro-LEDs 114 that can emit light and can be controlled individually or in groups of pixels (e.g., 5×5 pixel groups). Micro-LEDs are small (e.g., side length <0.01 mm) and can use inorganic semiconductor materials (such as those indicated above) to provide monochromatic or polychromatic light, typically red, green, or blue.

[0024] Light source 110 may include at least one lens 116 and / or other optical elements (such as a reflector) that may direct light emitted by one or more LED arrays 112 toward scene 104 as illumination 102 .

[0025] Camera 120 can sense at least one or more wavelengths of light emitted by one or more LED arrays 112. Similar to light source 110, camera 120 can include optics (e.g., at least one camera lens 122) capable of collecting light 106 reflected from scene 104 and / or reflected from illumination 102 emitted by scene 104. Camera lens 122 can direct reflected light 106 onto a multi-pixel sensor 124 (also referred to as a light sensor) to form an image of scene 104 on multi-pixel sensor 124.

[0026] The processor 130 may receive a data signal representing an image of the scene 104. The processor 130 may additionally control and drive the LEDs 114 in the one or more LED arrays 112 via one or more drivers 132. For example, the processor 130 may optionally control one or more LEDs 114 in the one or more LED arrays 112 independently of one or more LEDs 114 in the one or more LED arrays 112 to illuminate the scene in a specified manner.

[0027] Furthermore, one or more detectors 126 may be incorporated into camera 120. In other embodiments, one or more detectors 126 may be incorporated into one or more different areas, such as light source 110 or elsewhere near camera 120, rather than being incorporated into camera 120. One or more detectors 126 may include multiple different sensors to sense visible light and / or infrared light (e.g., from scene 104) and, in addition to receiving reflected light from LED 114, further sense ambient light and / or changes / flickering in ambient light. The multi-pixel sensor 124 of camera 120 may have a higher resolution than the sensors of one or more detectors 126 to obtain an image of the scene with a desired resolution. Similar to LED array 112, the sensors of one or more detectors 126 may have one or more segments (capable of sensing the same wavelength / wavelength range or different wavelengths / wavelength ranges). In some embodiments, if multiple detectors are used, one or more detectors may detect visible light wavelengths and one or more detectors may detect infrared wavelengths. Like one or more LED arrays 112, one or more detectors 126 may be individually controllable by processor 130.

[0028] In some embodiments, one or more sensors of one or more detectors 126 may be disposed in light source 110 instead of or in addition to being disposed in camera 120. In some embodiments, light source 110 and camera 120 may be integrated into a single module, while in other embodiments, light source 110 and camera 120 may be separate modules disposed on a PCB. In other embodiments, light source 110 and camera 120 may be attached to different PCBs—for example, because camera 120 may be thicker than light source 110, which may cause design issues if light source 110 and camera 120 were attached to the same PCB. In the latter embodiment, there may be multiple openings in the housing, at least one of which may be eliminated by using an integrated variant of light source 110 and camera 120.

[0029] LEDs 114 can be driven using either a direct current (DC) driver or pulse-width modulation (PWM). If segmented LED arrays 112 are driven at different current densities, DC drive may result in color shading, while PWM drive may produce artifacts due to ambient lighting conditions. If a flicker sensor is present, it can sense changes in artificial lighting at the wall current frequency or electronic ballast frequency (e.g., 50 Hz or 60 Hz, or integer multiples thereof) in addition to the phase of the flicker. The camera sensor is then tuned to an integration time that is an integer multiple of the time period (1 / f) or is triggered at the phase where the lighting changes most slowly (either minimum or maximum intensity, with maximum intensity being preferred for signal-to-noise ratio considerations). PWM can be used to drive LEDs 114, with the phase shift varying between LEDs 114 to reduce potential current surge issues. As shown, one or more drivers 132 can be used to drive the LEDs 114 in one or more LED arrays 112, as well as other components such as actuators.

[0030] The lighting device 100 may also include an input device 134, for example a user-activated input device such as a button that is pressed to take a picture. The light source 110 and the camera 120 may be provided in a single housing.

[0031] As mentioned above, Figure 1 The light source 110 can be an adaptive flash that contains individually addressable LED segments to allow selective illumination of the scene 104. For array sizes larger than a 3×3 matrix, the LED segments can be combined with an integrated driver to allow individually addressable functionality and achieve the small form factor desired for mobile devices without creating issues in the layout of the semiconductor layers used to create the integrated device.

[0032] As mentioned above, Figure 1 The lighting device 100 shown in FIG. 1 , micro-LEDs can be used to form different types of displays, LED matrices, and light engines, including adaptive headlights for automotive vehicles, augmented reality, virtual reality, and mixed reality (AR / VR / MR) headsets, smart glasses, and displays for mobile phones, smartwatches, monitors, and TVs. As described above, the individual LED pixels in these architectures can have an area ranging from a few square millimeters to a few square microns, depending on the size of the matrix or display and the pixel-per-inch requirements. A common approach is to create a monolithic array of LED pixels on an epitaxial wafer and then transfer and mix the LED array to a backplane to allow individual control of the pixels, as described in more detail below.

[0033] Micro-LEDs can be formed by combining n-type and p-type semiconductors (e.g., the aforementioned III-V semiconductors) on a substrate, such as silicon, sapphire aluminum oxide (Al2O3), or silicon carbide (SiC). During micro-LED fabrication, various layers are deposited and processed on the substrate. Prior to depositing the layers, the substrate surface may be pre-treated to anneal, etch, polish, or perform other surface treatments.

[0034] Generally speaking, the various LED layers can be fabricated using epitaxial semiconductor deposition (e.g., by physical or chemical vapor deposition) to deposit one or more semiconductor layers on a substrate, metal deposition (e.g., by sputtering), oxide growth or deposition, and other operations such as etching, stripping, and cleaning. In some aspects, the growth / deposition substrate can be removed from the LED structure after fabrication and after the contacts are connected to the backplane. This connection can be via metal bonding, such as via wires or ball bonds. The backplane can be a printed circuit board or a wafer containing an integrated circuit (IC), such as a CMOS IC wafer.

[0035] Semiconductor deposition operations can be used to create LEDs with active regions where electron-hole recombination occurs and light from the LED is generated. The active region can be, for example, one or more quantum wells. Metal contacts can be used to provide current from an IC (such as a driver) on a backplane on which the LED is mounted to the n-type and p-type semiconductors. Methods for depositing materials, layers, and thin films can include, for example, sputtering deposition, atomic layer deposition (ALD), chemical vapor deposition (CVD), physical vapor deposition (PVD), plasma-enhanced atomic layer deposition (PEALD), plasma-enhanced chemical vapor deposition (PECVD), and combinations thereof.

[0036] Multiple LEDs can be arranged on a backplane to form a monolithic array. Figure 2A A monolithic LED pixel array according to some examples is shown. Figure 2B Shown according to some examples Figure 2A A single pixel in a monolithic LED pixel array. Figure 2AA monolithic LED pixel array 200 is shown, comprising pixels 210, each pixel 210 having sidewalls and a semiconductor stack 202 (shown as a mesa structure). Dielectric material 204 surrounds the sidewalls of each pixel 210, and n-contact material 208 is located between adjacent pixels on dielectric material 204. A common cathode 208a electrically contacts the n-type layer of semiconductor stack 202 and n-contact material 208. An anode 208b contacts each p-type layer of semiconductor stack 202 and a corresponding contact 208c of backplate 206. Common cathode 208a contacts contact 208c of backplate 206. The upper edge of each semiconductor stack 202 can be offset from the upper edge of n-contact material 208 and common cathode 208a.

[0037] Another dielectric material 204a may be opposite the n-type layer of the semiconductor stack 202 and portions of the dielectric material 204. The n-contact material 208 may serve as a reflective sidewall adjacent to the semiconductor stack 202. A current spreading layer 208d may contact the n-type layer of the semiconductor stack 202.

[0038] like Figure 2B As shown in more detail in FIG. 1 , in some aspects, the semiconductor stack 202 of the LED can be formed from GaN. Specifically, the semiconductor stack 202 can have a height H and a lateral distance D, and can include an active region 202c sandwiched between an n-type semiconductor 202a and a p-type semiconductor 202b. In some embodiments, a metal side contact 216 can be coupled to the n-type semiconductor 202a to drive it, while a metal contact (p-metal 214) is coupled to the p-type semiconductor 202b. The metal side contact 216 can be isolated from the p-type semiconductor 202b and the active region 202c by an oxide layer 216. The oxide layer 216 can be formed, for example, of silicon oxide. The wafer bonding metal 212 can be configured to provide contact to the p-metal 214 and the metal side contact 216. The p-metal 214 and the metal side contact 216 can be formed from aluminum or other material(s) that are substantially reflective (e.g., having a reflectivity greater than approximately 99% at normal incidence) of light emitted by the active region 202c. The p-metal 214 and the metal side contact 216 can be formed of the same metal or different metals. In these architectures, as described above, after the LED array is integrated with the backplane 206 (which contains, among other things, the driver and controller), the original substrate (e.g., sapphire, silicon) can be removed from the side of the pixel 210 opposite the backplane 206 (e.g., by lift-off). This provides several advantages, such as enhanced light extraction and beam profile. Although the p-metal 214 is Figure 2B The p-metal 214 is shown as being the same width as the various layers of the semiconductor stack 202 , but in other aspects, the p-metal 214 can be larger than the various layers of the semiconductor stack 202 (which can allow contact between the p-metal 214 and the p-type semiconductor 202 b ).

[0039] Figure 2C Shown according to some examples Figure 2A Replaces individual pixels in a monolithic LED pixel array. Figure 2C The materials of each layer can be Figure 2B The materials of each layer are the same. Figure 2C As shown in FIG, pixel 220 may include a semiconductor 222 having an active region 222c sandwiched between an n-type semiconductor 222a and a p-type semiconductor 222b. A metal side contact 224 may be coupled to the n-type semiconductor 222a to drive the n-type semiconductor 222a, while a metal contact (p-metal 234) is coupled to the p-type semiconductor 222b. The metal side contact 224 may be isolated from the p-type semiconductor 222b and the active region 222c by an oxide layer 226. The wafer bonding metal 232 may be configured to provide contact with the p-metal 234. Figure 2B The pixels 210 in the image are different. Figure 2C The pixels 220 in the embodiment may have a relative orientation to the growth direction (which is Figure 2C The z-direction is shown in FIG. 2 and is perpendicular to the angled sidewalls of the emitting surface 222d of the n-type semiconductor 222a. Further details regarding the formation of the various layers can be found in US Patent Application 17 / 193,017, which is incorporated herein by reference in its entirety.

[0040] One method for removing the sapphire substrate on which the GaN-based pixels 210 are fabricated is through a laser lift-off (LLO) process, in which a laser beam (a UV laser in the case of a sapphire substrate) is used to separate the substrate from the epitaxial layers that form the LED. In large emitters, the substrate can be patterned with micrometer-scale features (i.e., features on the order of microns). In this case, the exposed GaN surface of the LED (pixel 210) can be textured, for example, after LLO, which facilitates light extraction from the pixel 210. However, in microLEDs, this is not possible because the patterned sapphire substrate (PSS) feature size is too large relative to the pixel size (which is less than one micron). A discussion of PSS formation can be found in U.S. Patent 11,264,530, which is incorporated herein by reference in its entirety.

[0041] Scaling down the size of micron-scale features to nanoscale features achieves both manufacturing and performance advantages in terms of light emission. Such nanopatterning can be particularly advantageous for small pixel sizes with limited constraints to shape the pixel sidewalls to facilitate light extraction, since small pixel emitters with planar extraction surfaces can suffer from low extraction efficiency and wide-angle radiation profiles. Simulations show that nanopatterned structures on the emission surface produced by PSS can provide greater than about 25% flux gain for a system with a collection cone angle of about 45° compared to an unpatterned emission surface. An unpatterned emission surface can result in poor ExE and unfavorable wide-angle radiation emission, especially for small pixel sizes with relatively steep trench sidewall angles, as in Figure 2C 220. Note that, as indicated, the trench extends at least along the height of semiconductor 222 and maintains (within manufacturing constraints) a relatively constant angle.

[0042] Therefore, using a nanoscale patterned sapphire substrate (nano-PSS) emitting surface can result in on-axis centered light with a narrow angular distribution. After LLO, exposed nanoscale features on the GaN surface can effectively steer the angular emission in the forward direction. Figure 3A Shown according to some examples Figure 2A As shown, the n-type semiconductor 302 of a single pixel 300 may have a nano-PSS emitting surface 302a with a regular pattern. Figure 3A As shown in the inset of FIG, nano-PSS shape 302b can be substantially truncated conical. Typical nanoscale features can include periodic shapes with the following characteristics: a hexagonal lattice (based on the sapphire lattice 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% of the pitch. Of course, other shapes are possible as long as the dimensions are kept within a few hundred nanometers.

[0043] Figure 3B Shown according to some examples Figure 3A Figure 2 shows the angular far-field radiation of the monolithic LED pixel array with micron-PSS and nano-PSS. As shown, the LED with nano-PSS provides a narrower and more intense emission compared to the LED with micron-PSS (PSS2).

[0044] Figure 4 The far-field angular emission response according to some examples is shown. In particular, Figure 4The simulated far-field angular emission response for a 5 μm pixel size is shown. As can be seen, LEDs with nano-PSS can outperform LEDs with planar epitaxy for 45° cone emission with trench sidewall angles less than approximately 8°. For trench angles of approximately 5° (relative to the normal to the emitting surface), a 6% improvement in total flux and a 25% flux gain can be achieved within the on-axis 45° cone. The dimensions of the nano-PSS structures are approximately 350 nm pitch and height.

[0045] Figure 5 Simulated EXEs of various nano-PSS designs according to some examples are shown. Figure 6 Shown are simulated forward emission gains for various nano-PSS designs according to some examples. Figure 5 and Figure 6 The table shows an example where the height of each nanoPSS feature is equal to the spacing between nanoPSS features, each nanoPSS structure has a substantially frusto-conical shape, and the spacing is 20%. As is clear, for steep trench angles (approximately 5° or less), an optimal spacing of the nanoPSS features is approximately 350 nm to approximately 400 nm, which yields the maximum simulated ExE within this angle range, with moderately high simulated forward emission. A trade-off between forward emission and ExE may also exist. Figure 5 and Figure 6 It also shows that for tilted trench angles, a smaller pitch / size may be preferred. The optimal pitch for ExE (regardless of the trench angle) may be less than about 400 nm. The dependence of size on trench angle may mean that the optimal pitch may decrease as the trench angle increases.

[0046] Figure 7 An example of an electronic device according to some embodiments is shown. Electronic device 700 may be a mobile device such as a laptop computer (PC), tablet PC, or smartphone, or a dedicated electronic device such as a camera. Various components may be provided on the aforementioned PCB. As described herein, examples may include logic or a number of components, modules, or mechanisms, or may operate across a number of components, modules, or mechanisms. Modules and components are tangible entities (e.g., hardware) capable of performing specified operations and may be configured or arranged in a certain manner. In one example, circuits may be arranged as modules in a specified manner (e.g., internally or relative to external entities such as other circuits). In one example, all or part of one or more computer systems (e.g., standalone, client, or server computer systems) or one or more hardware processors may be configured as modules to perform specified operations using firmware or software (e.g., instructions, application components, or applications). In one example, the software may reside on a machine-readable medium. In one example, when executed by the module's underlying hardware, the software causes the hardware to perform the specified operations.

[0047] Therefore, the term "module" (and "component") should be understood to encompass a tangible entity, i.e., a physically constructed, specially configured (e.g., hardwired), or temporarily (e.g., temporarily) configured (e.g., programmed) entity that operates in a specified manner or performs some or all of any of the operations described herein. Considering examples where modules are temporarily configured, each module need not be instantiated at any one time. For example, where a module comprises a general-purpose hardware processor configured using software, the general-purpose hardware processor can be configured as corresponding different modules at different times. The software can accordingly configure the hardware processor, for example, to configure a particular module at one time and to configure different modules at different times.

[0048] Mobile device 700 may include a hardware processor (or equivalent processing circuitry) 702 (e.g., a central processing unit (CPU), a GPU, a hardware processor core, or any combination thereof), main memory 704, and static memory 706, some or all of which may communicate with each other via an interconnect (e.g., a bus) 708. Main memory 704 may include any or all of removable and non-removable storage, volatile memory, or non-volatile memory. Mobile device 700 may also include a display 710 (such as a video display), an alphanumeric input device 712 (e.g., a keyboard), and a user interface (UI) navigation device 714 (e.g., a mouse). In one example, display 710, input device 712, and UI navigation device 714 may be touchscreen displays. Mobile device 700 may additionally include a storage device (e.g., a drive unit) 716, a signal generating device 718 (e.g., a speaker), a network interface device 720, one or more cameras 728, and one or more sensors 730 (such as a global positioning system (GPS) sensor, a compass, an accelerometer, or other sensors such as those described herein). The mobile device 700 may also include an output controller, such as a serial connection (e.g., Universal Serial Bus (USB)), a parallel connection, or other wired or wireless connection (e.g., infrared (IR), near field communication (NFC), etc.) to communicate with or control one or more peripheral devices (e.g., a printer, a card reader, etc.).

[0049] The storage device 716 may include a non-transitory machine-readable medium 722 (hereinafter referred to as a machine-readable medium) on which one or more sets of data structures or instructions 724 (e.g., software) are stored. These sets of data structures or instructions 724 embody or are used by any one or more of the techniques or functionality described herein. The non-transitory machine-readable medium 722 is a tangible medium. The inclusion of a non-transitory machine-readable medium in the storage device 716 should not be interpreted as meaning that the device or machine-readable medium itself cannot be physically moved. During execution of its instructions 724 by the mobile device 700, the instructions 724 may also reside, completely or at least partially, within the main memory 704, within the static memory 706, and / or within the hardware processor 702. Although the machine-readable medium 722 is illustrated as a single medium, the term "machine-readable medium" may include a single medium or multiple media (e.g., a centralized or distributed database, and / or associated caches and servers) configured to store one or more instructions 724.

[0050] The term "machine-readable medium" may include any medium capable of storing, encoding, or carrying instructions for execution by the mobile device 700 and causing the mobile device 700 to perform any one or more of the techniques disclosed herein; or any medium capable of storing, encoding, or carrying data structures used by or associated with such instructions. Non-limiting examples of machine-readable media may include solid-state memory, as well as optical and magnetic media. Specific examples of machine-readable media may include: non-volatile memory, such as semiconductor memory devices (e.g., electrically programmable read-only memory (EPROM), electrically erasable programmable read-only memory (EEPROM)) and flash memory devices; magnetic disks, such as internal hard disks and removable disks; magneto-optical disks; random access memory (RAM); and CD-ROM and DVD-ROM disks.

[0051] The instructions 724 may also be transmitted or received over a communication network using a transmission medium 726 via the network interface device 720 using any of a number of wireless local area network (WLAN) transmission protocols (e.g., frame relay, Internet Protocol (IP), transmission control protocol (TCP), user datagram protocol (UDP), hypertext transfer protocol (HTTP), etc.). Example communication networks may include a local area network (LAN), a wide area network (WAN), a packet data network (e.g., the Internet), a mobile phone network (e.g., a cellular network), a plain old telephone (POTS) network, and a wireless data network. Communications over the network may include one or more different protocols, such as the Institute of Electrical and Electronics Engineers (IEEE) 802.11 family of standards known as Wi-Fi, the IEEE 802.16 family of standards known as WiMax, the IEEE 802.15.4 family of standards, the Long Term Evolution (LTE) family of standards, the Universal Mobile Telecommunications System (UMTS) family of standards, peer-to-peer (P2P) networks, next generation (NG) / fifth generation (5G) standards, and the like. In one example, the network interface device 720 may include one or more physical jacks (eg, Ethernet jacks, coaxial jacks, or telephone jacks) or one or more antennas to connect to the transmission medium 726 .

[0052] Note that the term "circuit," as used herein, refers to, is part of, or includes a hardware component, such as an electronic circuit, a logic circuit, a processor (shared, dedicated, or grouped) and / or memory (shared, dedicated, or grouped), an application-specific integrated circuit (ASIC), a field-programmable device (FPD) (e.g., a field-programmable gate array (FPGA), a programmable logic device (PLD), a complex PLD (CPLD), a high-capacity PLD (HCPLD), a structured ASIC, or a programmable SoC), a digital signal processor (DSP), or the like, that is configured to provide the described functionality. In some embodiments, the circuit may execute one or more software or firmware programs to provide at least some of the described functionality. The term "circuit" may also refer to a combination of one or more hardware elements (or a combination of circuits used in an electrical or electronic system) and program code for performing the functions of the program code. In these embodiments, the combination of hardware elements and program code may be referred to as a specific type of circuit.

[0053] As used herein, the term "processor circuit" or "processor" therefore refers to, is part of, or includes a circuit that is capable of sequentially and automatically performing a series of arithmetic or logical operations or recording, storing, and / or transmitting digital data. The term "processor circuit" or "processor" may refer to one or more application processors, one or more baseband processors, a physical central processing unit (CPU), a single-core or multi-core processor, and / or any other device capable of executing or otherwise operating computer-executable instructions (such as program code, software modules, and / or functional processes).

[0054] Figure 8 800. As described above, some of the elements shown in lighting system 800 may not be present, while other additional elements may be provided in lighting system 800. Lighting system 800 may be based on Figure 1 The lighting system 800 may provide illumination based on the captured image described in , or may independently generate illumination based on stored information. For example, the lighting system 800 may include a controller 802 that controls the display of an image using a pixel array 810 comprising a plurality of individual pixels 812 .

[0055] In some embodiments, some or all of the components described as controller 802 may be provided on a backplane (such as, for example, a composite metal oxide semiconductor (CMOS) backplane). Controller 802 may be coupled to or include one or more processors 804. Controller 802 may receive image data and queries from one or more processors 804 (if external to controller 802). In this case, controller 802 may further provide feedback to one or more processors 804. One or more processors 804 may receive image data via a digital interface and may process the image data to control PWM generator 806a, for example, to control the PWM duty cycle and / or on-time, so that lighting system 800 produces an image indicated by the image data.

[0056] The controller 802 may further include a frame buffer 808. The frame buffer 808 may store one or more images before the one or more processors 804 and store instructions for implementation by the one or more processors 804.

[0057] The PWM generator 806a can be controlled by one or more processors 804 and can generate a PWM signal according to instructions. The PWM generator 806a can be connected to the driver 806b to drive the pixel array 810 so that the pixels 812 provide a desired light intensity.

[0058] Each pixel 812 can include one or more micro-LEDs 814. The micro-LEDs 814 can be of different colors and can be controlled individually or in groups. As shown, for each pixel 812 or micro-LED 814, the pixel 812 can include a PWM switch and a current source. The pixel 812 can be driven by a driver 806b. The PWM signal from the PWM generator 806a can cause the PWM switch to open and close according to the value of the PWM signal. The signal corresponding to the light intensity can cause the current source to generate a current, thereby causing the pixel 812 to produce the corresponding light intensity.

[0059] The lighting system 800 can further include a power supply 820. In some embodiments, the power supply 820 can generate power for the controller 802.

[0060] Figure 9 A block diagram illustrates an example of a system according to some embodiments. System 900 can use micro-LEDs to provide augmented reality (AR) / virtual reality (VR) functionality. System 900 can include a wearable housing 912, such as a headset or goggles. Housing 912 can mechanically support and house the components described in detail below. In some examples, one or more of the components described in detail below can be included in one or more additional housings that can be separate from wearable housing 912 and can be coupled to wearable housing 912 wirelessly and / or via a wired connection. For example, a separate housing can reduce the weight of wearable goggles, such as by including batteries, radios, and other components. Housing 912 can include one or more batteries 914 that can power any or all of the components described in detail below. Housing 912 can also include circuitry that can be electrically coupled to an external power source (such as a wall outlet) to charge batteries 914. Housing 912 can also include one or more radios 916 for wireless communication with a server or network via a suitable protocol (such as WiFi).

[0061] The system 900 may include one or more sensors 918, such as optical sensors, audio sensors, tactile sensors, thermal sensors, gyroscope sensors, time-of-flight sensors, triangulation-based sensors, and the like. In some examples, one or more of these sensors may sense the location, position, and / or orientation of the user. In some examples, one or more sensors 918 may generate a sensor signal in response to the sensed location, position, and / or orientation. The sensor signal may include sensor data corresponding to the sensed location, position, and / or orientation. For example, the sensor data may include a depth map of the surrounding environment. In some examples, such as for an AR system, one or more sensors 918 may capture real-time video images of the surrounding environment near the user.

[0062] System 900 may include one or more video generation processors 920. The one or more video generation processors 920 may receive scene data representing a three-dimensional scene, such as a set of position coordinates of objects in the scene or a depth map of the scene. This data may be received from a server and / or a storage medium. The one or more video generation processors 920 may receive one or more sensor signals from one or more sensors 918. In response to the scene data representing the surrounding environment and at least one sensor signal representing the location and / or orientation of the user relative to the surrounding environment, the one or more video generation processors 920 may generate at least one video signal corresponding to a view of the scene. In some examples, the one or more video generation processors 920 may generate two video signals, one for each eye of the user, the two video signals representing views of the scene from the perspective of the user's left eye and right eye, respectively. In some examples, the one or more video generation processors 920 may generate more than two video signals and combine these video signals to provide one video signal for both eyes, two video signals for both eyes, or other combinations.

[0063] System 900 may include one or more light sources 922 that can provide light for a display of system 900. For example, suitable light sources 922 may include the micro-LEDs described above. One or more light sources 922 may include light-emitting elements having different colors or wavelengths. For example, the light sources may include a red light-emitting diode that can emit red light, a green light-emitting diode that can emit green light, and a blue light-emitting diode that can emit blue light. The red, green, and blue light may be combined in a specific ratio to produce any suitable color that is visually perceptible in the visible portion of the electromagnetic spectrum.

[0064] The system 900 may include one or more modulators 924. The modulator 924 may be implemented in one of at least two configurations. In a first configuration, the modulator 924 may include a circuit that can directly modulate the light source 922. For example, the light source 922 may include an array of light-emitting diodes, and the modulator 924 may directly modulate the electrical power, voltage, and / or current directed to each light-emitting diode in the array to form modulated light. The modulation may be performed in an analog manner and / or digitally. In some examples, the light source 922 may include an array of red light-emitting diodes, an array of green light-emitting diodes, and an array of blue light-emitting diodes, and the modulator 924 may directly modulate the red light-emitting diodes, the green light-emitting diodes, and the blue light-emitting diodes to form modulated light to produce a particular image.

[0065] In a second configuration, the modulator 924 may include a modulation panel, such as a liquid crystal panel. The light source 922 may generate uniform or nearly uniform illumination to illuminate the modulation panel. The modulation panel may include pixels. Each pixel may selectively attenuate a corresponding portion of the modulation panel area in response to an electrical modulation signal to form modulated light. In some examples, the modulator 924 may include multiple modulation panels capable of modulating light of different colors. For example, the modulator 924 may include a red modulation panel capable of attenuating red light from a red light source (such as a red light-emitting diode), a green modulation panel capable of attenuating green light from a green light source (such as a green light-emitting diode), and a blue modulation panel capable of attenuating blue light from a blue light source (such as a blue light-emitting diode).

[0066] In some examples of the second configuration, the modulator 924 can receive uniform white light, or nearly uniform white light, from a white light source, such as a white light emitting diode. The modulation panel can include a wavelength selective filter on each pixel of the modulation panel. The panel pixels can be arranged in groups, such as three or four groups, where each group can form a pixel of a color image. For example, each group can include a panel pixel with a red filter, a panel pixel with a green filter, and a panel pixel with a blue filter. Other suitable configurations can also be used.

[0067] The system 900 can include one or more modulation processors 926 that can receive a video signal (such as from one or more video generation processors 920) and, in response, can generate an electrical modulation signal. For configurations in which the modulator 924 directly modulates the light source 922, the electrical modulation signal can drive the light source 922. For configurations in which the modulator 924 includes a modulation panel, the electrical modulation signal can drive the modulation panel.

[0068] System 900 may include one or more beam combiners 928 (also known as beam splitters) that can combine light beams of different colors to form a single polychromatic light beam. For configurations in which light source 922 may include multiple light emitting diodes of different colors, system 900 may include one or more wavelength-sensitive (e.g., dichroic) beam combiners 928 that can combine the different colors of light to form a single polychromatic light beam.

[0069] System 900 can direct modulated light toward an observer's eyes in one of at least two configurations. In a first configuration, system 900 can function as a projector and can include suitable projection optics 930 that can project the modulated light onto one or more screens 932. Screens 932 can be positioned at a suitable distance from the user's eyes. System 900 can optionally include one or more lenses 934 that can position a virtual image of screen 932 at a suitable distance from the eyes, such as a close-focus distance of 500 mm, 750 mm, or another suitable distance. In some examples, visualization system 900 can include a single screen 932 so that the modulated light can be directed toward both eyes of the user. In some examples, system 900 can include two screens 932 so that the modulated light from each screen 932 can be directed toward a respective eye of the user. In some examples, system 900 can include more than two screens 932. In a second configuration, system 900 can direct the modulated light directly into one or both eyes of the observer. For example, projection optics 930 may form an image on the retina of one eye of a user, or on the retina of each of both eyes of a user.

[0070] For some configurations of the AR system, system 900 may include a display that is at least partially transparent so that the user can view the user's surroundings through the display. For such configurations, the AR system can generate modulated light corresponding to an enhancement of the surrounding environment rather than the surrounding environment itself. For example, in the example of a retailer displaying chairs, the AR system can direct modulated light corresponding to the chairs rather than the rest of the room toward the screen or toward the user's eyes.

[0071] Figure 10 An example hardware arrangement for implementing the disclosed subject matter described above is shown, according to some embodiments. Specifically, hardware arrangement 1000 may include an integrated LED 1008. Integrated LED 1008 may include an LED die 1002 containing an array of micro-LEDs (one or more) and a backplane, such as a CMOS backplane 1004. LED die 1002 may be coupled to CMOS backplane 1004 via one or more interconnects 1010, wherein interconnects 1010 may provide signal transmission between LED die 1002 and CMOS backplane 1004. Interconnects 1010 may include one or more solder bump joints, one or more copper pillar bump joints, other types of interconnects known in the art, or some combination thereof.

[0072] LED die 1002 may include circuitry for implementing a micro-LED array. In particular, LED die 1002 may include multiple micro-LEDs. LED die 1002 may include a shared active layer and a shared substrate for the micro-LED array, and thus the micro-LED array may be a monolithic micro-LED array. Each micro-LED in the micro-LED array may include a separate, segmented active layer and / or substrate. In some embodiments, LED die 1002 may further include a switch and a current source to drive the micro-LED array. In other embodiments, the PWM switch and current source may be included in CMOS backplane 1004.

[0073] CMOS backplane 1004 may include circuitry for implementing a control module and / or an LED power supply. CMOS backplane 1004 may utilize interconnects 1010 to provide a PWM signal and an intensity signal to the micro-LED array, causing the micro-LED array to generate light in accordance with the PWM signal and intensity. Because the number and density of connections required to drive a micro-LED array are relatively large compared to a standard LED array, different embodiments may be used to electrically connect CMOS backplane 1004 and LED die 1002. Alternatively, the bonding pad pitch of CMOS backplane 1004 may be the same as the bonding pad pitch of the micro-LED array, or the bonding pad pitch of CMOS backplane 1004 may be greater than the bonding pad pitch of the micro-LED array.

[0074] Hardware arrangement 1000 may further include a PCB 1006. PCB 1006 may include circuitry for implementing the various functions described herein. PCB 1006 may be coupled to CMOS backplane 1004. For example, PCB 1006 may be coupled to CMOS backplane 1004 via one or more wire bonds 1012. PCB 1006 and CMOS backplane 1004 may exchange image data, power, and / or feedback, among other signals, via the coupling.

[0075] As shown, the microLEDs and the circuitry supporting the microLED array can be packaged and include a substrate or printed circuit board for powering the microLEDs and controlling the light produced by the microLEDs. The PCB 1006 supporting the microLED array can include electrical vias, a heat sink, a ground plane, electrical traces, and a flip chip or other mounting system. The substrate or PCB can be formed from any suitable material (e.g., ceramic, silicon, aluminum, etc.). If the substrate material is conductive, an insulating layer can be formed over the substrate material, and a metal electrode pattern can be formed over the insulating layer to contact the microLED array. The substrate can act as a mechanical support, providing an electrical interface between the electrodes on the microLED array and the power supply, and also provide a heat sink function.

[0076] As described above, microLED arrays can support a variety of applications. These applications can include providing general illumination (for example, within a room or vehicle) or standalone applications that provide specialized images. In addition to devices such as lamps, projectors, and mobile devices, this system can also be used to provide applications based on augmented reality (AR) and virtual reality (VR). Visualization systems (such as VR and AR systems) are becoming increasingly common in a wide range of fields, including entertainment, education, medicine, and business. Various types of devices can be used to provide AR / VR to users, including headsets, glasses, and projectors. Such AR / VR systems may include components similar to those described above: a microLED array, a display or screen (which may include a touchscreen element), a microLED array controller, sensors, and a controller. The AR / VR components may be arranged in a single structure, or one or more of the components shown may be mounted separately and connected via wired or wireless communication. The controller can be provided with power and user data. User data input may include audio commands, haptic feedback, eye or pupil positioning, or information provided by a connected keyboard, mouse, or game controller. Sensors may include cameras, depth sensors, audio sensors, accelerometers, two-axis or three-axis gyroscopes, and other types of motion and / or environmental / wearer sensors that provide user input data. Other sensors may include, but are not limited to, air pressure, strain sensors, temperature sensors, or any other suitable sensor for local or remote environmental monitoring. In some embodiments, control inputs may include detected touches or taps, gesture inputs, or controls based on the position of the headset or display. As another example, an estimated position of the AR / VR system relative to an initial position may be determined based on one or more measurement signals from one or more gyroscopes or position sensors that measure translational or rotational movement.

[0077] In some embodiments, a controller can control individual microLEDs or one or more microLED pixels (microLED groups) to display content (AR / VR and / or non-AR / VR) to the user, while simultaneously controlling other microLEDs and sensors used in eye tracking to adjust the displayed content. The content-displaying microLEDs can be designed to emit light in the visible wavelength band (approximately 400 nm to 780 nm), while the microLEDs used for tracking can be designed to emit light in the IR band (approximately 780 nm to 2200 nm). In some embodiments, the tracking microLEDs and content microLEDs can be activated simultaneously. In some embodiments, the tracking microLEDs can be controlled to emit tracking light during periods when the content microLEDs are deactivated and therefore not displaying content to the user. The AR / VR system can incorporate optics (such as those described above) and / or an AR / VR display, for example, to couple light emitted by the microLED array to the AR / VR display.

[0078] In some embodiments, the AR / VR controller can use data from the sensor to time-integrate the measurement signal received from the accelerometer to estimate a velocity vector, and time-integrate the velocity vector to determine the estimated position of a reference point for the AR / VR system. In other embodiments, the reference point used to describe the position of the AR / VR system can be based on a depth sensor, a camera positioning view, or a light field flow. Based on changes in the position, orientation, or movement of the AR / VR system, the system controller can send an image or instruction to the light array controller. Changes or modifications to the image or instruction can also be made through user data input or automatic data input.

[0079] Generally speaking, in a VR system, a display can present a view of a scene (such as a three-dimensional scene) to a user. The user can move within the scene, such as by repositioning the user's head or by walking. The VR system can detect the user's movement and change the view of the scene to account for the movement. For example, when the user rotates the user's head, the system can present a view of the scene that changes in view direction to match the user's gaze. In this way, the VR system can simulate the user's presence in the three-dimensional scene. In addition, the VR system can receive tactile sensory input, such as from a wearable position sensor, and can optionally provide tactile feedback to the user.

[0080] On the other hand, in an AR system, the display can incorporate elements from the user's surroundings into the view of the scene. For example, an AR system can add text subtitles and / or visual elements to the view of the user's surroundings. For example, a retailer can use an AR system to show a user what a piece of furniture would look like in a room in the user's home by combining a visualization of the furniture on top of a captured image of the user's surroundings. As the user walks around the user's room, the visualization interprets the user's movements and changes the visualization of the furniture in a manner consistent with the movement. For example, an AR system can place a virtual chair in a room. The user can stand in front of the virtual chair's location in the room to view the front of the chair. The user can move to an area behind the virtual chair's location in the room to view the back of the chair. In this way, the AR system can add elements to the dynamic view of the user's surroundings.

[0081] Figure 11 An example method of manufacturing an LED device according to some embodiments is shown. Not all operations may be performed in method 1100, and / or additional operations may be present.

[0082] At operation 1102, a semiconductor stack forming a micro-LED can be deposited on a sapphire or other substrate having a nano-PSS structure. For example, for a GaN-based multilayer semiconductor stack, hydride vapor phase epitaxy (HVPE) can be used. For other compound semiconductors, methods such as metal-organic vapor phase epitaxy (MOCVD) or molecular beam epitaxy (MBE) can be used to fabricate the semiconductor stack. The semiconductor stack can include, for example, a quantum well active region that emits light. The emitting surface of the semiconductor stack in contact with the substrate can have nano-PSS features.

[0083] After fabricating the semiconductor stack, sidewalls may be formed in operation 1104. To form the sidewalls, each layer in the semiconductor stack may be sequentially etched using a photolithography process to form a via, and metal may be deposited in the via before stripping the photoresist. The sidewalls may be formed from aluminum or another material that is substantially reflective (e.g., having a reflectivity greater than approximately 99% at normal incidence) to light emitted by the semiconductor stack. The sidewalls may direct the light toward the emitting surface of the semiconductor stack.

[0084] The overall structure can be attached to a PCB or other wafer at operation 1106. For example, flip-chip or ball bonding can be used to electrically connect the micro-LEDs to the circuit.

[0085] At operation 1108 , the substrate may be peeled from the semiconductor stack, exposing the emitting surface containing the nano-PSS features.

[0086] The semiconductor stack (and therefore the trench height) can be, for example, approximately 4 μm to approximately 6 μm thick. This allows the n-type semiconductor in contact with the substrate having the nano-PSS structure to have sufficient structural integrity to form a regular periodic semiconductor lattice structure for the active region. In other embodiments, to reduce the aspect ratio of the micro-LED, the epitaxial n-type semiconductor can be etched into thinner layers (e.g., approximately 1 μm to approximately 2 μm) after substrate lift-off. Therefore, in this embodiment, the substrate may or may not have a nano-PSS structure.

[0087] Regardless of whether the substrate has a nano-PSS structure, however, the epitaxial n-type semiconductor can be etched to form either a substantially planar surface or a nano-PSS structure (which includes the nano-PSS features described herein). In the former case, the nano-PSS structure can be formed by depositing a dielectric layer (e.g., titanium oxide (TiO2)) and processing the dielectric layer through etching and other photolithography techniques. In the latter case, the nano-PSS structure can be formed by nanopatterning the surface of the thin-film epitaxial n-type semiconductor (nanoimprinting) using various etching techniques. In either case, a metal-semiconductor n-contact can be formed on the sidewalls of the trench.

[0088] Another embodiment may use a film that is substantially transparent to the light from the micro-LEDs. The transparent film may be a transparent conductive oxide (TCO) such as indium tin oxide (ITO). In such an embodiment, the nano-PSS structure may be patterned on the surface of a capping TCO layer that is deposited on top of a thin film epitaxial n-type semiconductor extending above the trench metal region, forming a top n-contact. The patterned features may be formed by etching a thin dielectric layer (e.g., TiO2 as described above), which may be patterned by etching and other photolithographic techniques. In this case, the trench sidewalls may be completely coated with a dielectric (e.g., in the Figure 2C In the embodiment shown in FIG. 2 , the oxide layer 226 may extend all the way through the trench sidewalls), which may be optically more efficient than using lateral sidewall contacts at the trench.

[0089] More details regarding patterning of thin film epitaxial semiconductors, oxide layers, or transparent films can be found in US Patent 10,090,437, which is incorporated herein by reference in its entirety.

[0090] Example Example 1 is a micro light emitting diode (microLED) structure comprising: a microLED comprising a semiconductor stack, the semiconductor stack including an n-type semiconductor, a p-type semiconductor, and an active region sandwiched between the n-type semiconductor and the p-type semiconductor, the microLED having an emitting surface from which light generated by the active region exits the microLED, the emitting surface having nanoscale patterned sapphire substrate (nano-PSS) features therein; and a metal sidewall extending from the emitting surface of the n-type semiconductor to the p-type semiconductor and configured to be electrically coupled to the n-type semiconductor, the metal sidewall forming a trench in which the microLED is disposed, the metal sidewall being substantially reflective to the light generated by the active region.

[0091] In Example 2, the subject matter of Example 1 includes, wherein the nano-PSS features include periodic shapes, each periodic shape having a hexagonal lattice and being smaller than about 1 μm.

[0092] In Example 3, the subject matter of Example 2 includes, wherein the periodic shape has a pitch of about 200 nm to about 500 nm, a height of about 200 nm to about 500 nm, and a spacing of about 20%.

[0093] In Example 4, the subject matter of Example 3 includes, wherein the pitch and the height are substantially the same.

[0094] In Example 5, the subject matter of Examples 2-4 includes, wherein each periodic shape is frustoconical.

[0095] In Example 6, the subject matter of Examples 1-5 includes, wherein: the metal sidewalls extend at a groove angle relative to a normal to the emitting surface, and the groove angle is less than about 9°, and the nano-PSS features include a periodic shape having a pitch of about 350 nm to about 400 nm, a height of about 350 nm to about 400 nm, and a spacing of about 20%.

[0096] In Example 7, the subject matter of Examples 1-6 includes, wherein the trench height of the trench is about 4 μm to about 6 μm.

[0097] In Example 8, the subject matter of Examples 1-7 includes, wherein the n-type semiconductor is an etched n-type semiconductor, and the trench height of the semiconductor stack is about 1 μm to about 2 μm.

[0098] In Example 9, the subject matter of Examples 1-8 includes, wherein the surface of the n-type semiconductor includes nano-PSS features.

[0099] In Example 10, the subject matter of Examples 1-9 includes, wherein the micro-LED further comprises a substantially transparent film disposed on the n-type semiconductor, the n-type semiconductor being substantially planar, the substantially transparent film having nano-PSS features.

[0100] Example 11 is a lighting device comprising: a micro light emitting diode (microLED) structure comprising a microLED comprising a semiconductor stack, the semiconductor stack comprising an n-type semiconductor, a p-type semiconductor, and an active region sandwiched between the n-type semiconductor and the p-type semiconductor, the microLED having an emitting surface from which light generated by the active region exits the microLED, the emitting surface having nanoscale patterned sapphire substrate (nano-PSS) features therein; and a backplate to which the microLED structure is attached, the backplate comprising control circuitry for controlling light emission from the microLED.

[0101] In Example 12, the subject matter of Example 11 includes wherein the nano-PSS features comprise periodic frusto-conical shapes less than about 1 μm, and each frusto-conical shape has a hexagonal lattice.

[0102] In Example 13, the subject matter of Example 12 includes, wherein the periodic shape has a pitch of about 200 nm to about 500 nm, a height of about 200 nm to about 500 nm, and a spacing of about 20%.

[0103] In Example 14, the subject matter of Example 13 includes, wherein the pitch and the height are substantially the same.

[0104] In Example 15, the subject matter of Examples 11-14 includes, wherein: the micro-LED structure further includes: a metal sidewall extending from the emitting surface of the n-type semiconductor to the p-type semiconductor and configured to be in electrical contact with the n-type semiconductor, and an insulating layer disposed between the metal sidewall and both the p-type semiconductor and the active region, the metal sidewall forming a trench in which the micro-LED is disposed, the metal sidewall being substantially reflective to light generated by the active region, and the metal sidewall extending at a trench angle relative to a normal to the emitting surface.

[0105] In Example 16, the subject matter of Example 15 includes, wherein: the trench angle is less than about 9°, the nano-PSS features are formed in an n-type semiconductor and include periodic truncated conical shapes having a pitch of about 350 nm to about 400 nm, a height of about 350 nm to about 400 nm, and a spacing of about 20%, and the trench height of the trench is about 4 μm to about 6 μm.

[0106] In Example 17, the subject matter of Examples 11-16 includes, wherein the surface of the n-type semiconductor includes nano-PSS features.

[0107] In Example 18, the subject matter of Examples 11-17 includes, wherein: the micro-LED further comprises a substantially transparent film disposed on the n-type semiconductor, the n-type semiconductor being substantially planar, and the substantially transparent film having nano-PSS features.

[0108] Example 19 is a method for manufacturing a lighting device, the method comprising: epitaxially growing a semiconductor stack on a substrate, the semiconductor stack comprising an n-type semiconductor, a p-type semiconductor, and an active region sandwiched between the n-type semiconductor and the p-type semiconductor; and manufacturing a micro light emitting diode (microLED) comprising the semiconductor stack, such that the microLED has an emitting surface from which light generated by the active region is emitted from the microLED, the emitting surface having a nanoscale patterned sapphire substrate (nano-PSS) feature therein.

[0109] In Example 20, the subject matter of Example 19 includes wherein the nano-PSS features comprise periodic frusto-conical shapes less than about 1 μm, and each frusto-conical shape has a hexagonal lattice.

[0110] In Example 21, the subject matter of Example 20 includes, wherein the periodic shape has a pitch of about 200 nm to about 500 nm, a height of about 200 nm to about 500 nm, and a spacing of about 20%.

[0111] In Example 22, the subject matter of Example 21 includes, wherein the pitch and the height are substantially the same.

[0112] In Example 23, the subject matter of Examples 19-22 includes, wherein fabricating the micro-LED further comprises: depositing an insulating layer over the p-type semiconductor and the active region to form a partial insulating structure, and depositing metal sidewalls over the partial insulating structure and the n-type semiconductor to make electrical contact with the n-type semiconductor, the metal sidewalls forming a trench in which the micro-LED is disposed, the metal sidewalls being substantially reflective to light generated by the active region, the metal sidewalls extending at a trench angle relative to a normal to the emitting surface.

[0113] In Example 24, the subject matter of Example 23 includes, wherein: the trench angle is less than about 9°, the nano-PSS features are formed in an n-type semiconductor and include periodic truncated conical shapes having a pitch of about 350 nm to about 400 nm, a height of about 350 nm to about 400 nm, and a spacing of about 20%, and the trench height of the trench is about 4 μm to about 6 μm.

[0114] In Example 25, the subject matter of Examples 19-24 includes, wherein fabricating the micro-LED further comprises: peeling the substrate from the semiconductor stack to expose a top surface of the n-type semiconductor; etching the top surface of the n-type semiconductor to form a planar top surface and reducing the height of the n-type semiconductor to less than about 2 μm; depositing a substantially transparent film on the planar top surface of the n-type semiconductor; and patterning the substantially transparent film to have nano-PSS features.

[0115] In Example 26, the subject matter of Examples 19-25 includes attaching the micro-LEDs to a backplane that includes control circuitry that controls light emission from the micro-LEDs.

[0116] Example 27 is at least one machine-readable medium comprising instructions that, when executed by a processing circuit, cause the processing circuit to perform operations to implement any of Examples 1-26.

[0117] Example 28 is an apparatus comprising means for implementing any of Examples 1-26.

[0118] Example 29 is a system implementing any of Examples 1-26.

[0119] Example 30 is a method of implementing any of Examples 1-26.

[0120] Although only certain features of the systems and methods have been illustrated and described herein, many modifications and variations will occur to those skilled in the art. Therefore, it should be understood that the appended claims are intended to cover all such modifications and variations. The method operations may be performed substantially simultaneously or in a different order.

[0121] Although the embodiments have been described with reference to specific example embodiments, it will be apparent that various modifications and changes may be made to these embodiments without departing from the broader scope of the present disclosure. Therefore, the description and drawings should be considered in an illustrative sense, and not in a restrictive sense. The drawings forming part of this specification show, by way of illustration and not limitation, specific embodiments in which the present subject matter may be practiced. The illustrated embodiments are described in sufficient detail to enable those skilled in the art to practice the teachings disclosed herein. Other embodiments may be utilized and derived therefrom, such that structural and logical substitutions and changes may be made without departing from the scope of the present disclosure. Therefore, this detailed description should not be interpreted in a restrictive sense, and the scope of the various embodiments is limited only by the appended claims and the full scope of equivalents to which such claims are entitled.

[0122] In this document, the subject matter may be referred to individually and / or collectively as the term "embodiment" for convenience only, and if more than one inventive concept is actually disclosed, there is no intention to actively limit the scope of this application to any single inventive concept. Therefore, although specific embodiments have been shown and described herein, it should be understood that any arrangement intended to achieve the same purpose can replace the specific embodiments shown. This disclosure is intended to cover any and all modifications or variations of the various embodiments. Upon reading the above description, combinations of the above embodiments and other embodiments not specifically described herein will be clear to those skilled in the art.

[0123] In this document, the terms "a" or "an," as commonly used in patent documents, include one or more than one, independent of any other instance or usage of "at least one" or "one or more." In this document, the term "or" is used to refer to a non-exclusive or, such that "A or B" includes "A but not B," "B but not A," and "A and B," unless otherwise indicated. In this document, the terms "including" and "wherein" are used as the plain English equivalents of the respective terms "comprising" and "wherein." In addition, in the claims below, the terms "including" and "comprising" are open-ended, that is, systems, UEs, articles, compositions, formulas, or processes that include elements other than those listed after such terms in the claim are still considered to fall within the scope of the claim. In addition, in the claims below, the terms "first," "second," and "third," etc. are used merely as labels and are not intended to impose numerical requirements on their objects. As indicated herein, although the term "a" is used herein, one or more associated elements may be used in different embodiments. For example, the term "processor" that is configured to perform a specific operation includes both a single processor that is configured to perform all operations and multiple processors that are individually configured to perform some or all operations (which may overlap), such that a combination of the processors performs all operations. In addition, the term "comprising" may be interpreted as meaning "including at least" the following element.

[0124] The Abstract of this disclosure is submitted with the understanding that it will not be used to interpret or limit the scope or meaning of the claims. Furthermore, in the foregoing Detailed Description, it can be seen that various features are grouped together in a single embodiment for the purpose of streamlining the disclosure. This method of disclosure should not be interpreted as reflecting an intention that the claimed embodiments require more features than are expressly recited in each claim. Rather, as reflected in the following claims, the inventive subject matter has less than all the features of a single disclosed embodiment. Accordingly, the following claims are hereby incorporated into the Detailed Description, with each claim standing on its own as a separate embodiment.

Claims

1. A micro light-emitting diode (micro-LED) structure, comprising: A micro-LED comprising a semiconductor stack, the semiconductor stack including an n-type semiconductor, a p-type semiconductor, and an active region sandwiched between the n-type semiconductor and the p-type semiconductor, the micro-LED having an emitting surface from which light generated by the active region exits the micro-LED, the emitting surface having nanoscale patterned sapphire substrate (nano-PSS) features therein; and A metal sidewall extends from an emitting surface of the n-type semiconductor to the p-type semiconductor and is configured to be electrically coupled to the n-type semiconductor, the metal sidewall forming a trench, the micro LED being disposed in the trench, the metal sidewall being substantially reflective to light generated by the active region.

2. The micro-LED structure of claim 1 , wherein the nano-PSS features comprise periodic shapes, each periodic shape having a hexagonal lattice and being smaller than about 1 μm.

3. The micro LED structure of claim 2, wherein the periodic shape has a pitch of about 200 nm to about 500 nm, a height of about 200 nm to about 500 nm, and a spacing of about 20%. The micro LED structure according to claim 3 , wherein the pitch and the height are substantially the same. The micro-LED structure of claim 2 , wherein each periodic shape is frusto-conical.

6. The micro-LED structure according to claim 1, wherein: The metal sidewalls extend at a trench angle relative to a normal to the emitting surface, and The groove angle is less than about 9°, and the nano-PSS features include a periodic shape having a pitch of about 350 nm to about 400 nm, a height of about 350 nm to about 400 nm, and a spacing of about 20%.

7. The micro LED structure according to claim 1, wherein a groove height of the groove is about 4 μm to about 6 μm.

8. The micro LED structure of claim 1, wherein the n-type semiconductor is an etched n-type semiconductor, the semiconductor stack having a trench height of about 1 μm to about 2 μm. 9 . The micro-LED structure of claim 1 , wherein a surface of the n-type semiconductor comprises the nano-PSS features.

10. The micro-LED structure of claim 1, wherein the micro-LED further comprises a substantially transparent film disposed on the n-type semiconductor, a surface of the n-type semiconductor opposite the substantially transparent film being substantially planar, the substantially transparent film having the nano-PSS features.

11. A lighting device comprising: A micro light emitting diode (microLED) structure comprising a microLED comprising a semiconductor stack, the semiconductor stack including an n-type semiconductor, a p-type semiconductor, and an active region sandwiched between the n-type semiconductor and the p-type semiconductor, the microLED having an emitting surface from which light generated by the active region exits the microLED, the emitting surface having nanoscale patterned sapphire substrate (nano-PSS) features therein; and A backplate to which the micro-LED structure is attached, the backplate containing control circuitry that controls light emission from the micro-LEDs.

12. The illumination device of claim 11, wherein the nano-PSS features comprise periodic frusto-conical shapes less than about 1 μm, and each periodic frusto-conical shape has a hexagonal lattice.

13. The lighting device of claim 12, wherein the periodic frusto-conical shapes have a pitch of about 200 nm to about 500 nm, a height of about 200 nm to about 500 nm, and a separation of about 20%. The lighting device of claim 13 , wherein the spacing and the height are substantially the same.

15. The lighting device according to claim 11, wherein: The micro LED structure further includes: a metal sidewall extending from an emitting surface of the n-type semiconductor to the p-type semiconductor and configured to electrically contact the n-type semiconductor, and an insulating layer disposed between the metal sidewall and both the p-type semiconductor and the active region; The metal sidewall forms a groove, and the micro LED is arranged in the groove; The metal sidewalls are substantially reflective to light generated by the active region; and The metal sidewalls extend at a trench angle relative to a normal to the emitting surface.

16. The lighting device according to claim 15, wherein: The groove angle is less than about 9°, The nano-PSS features are formed in the n-type semiconductor and include periodic truncated cone shapes having a pitch of about 350 nm to about 400 nm, a height of about 350 nm to about 400 nm, and a spacing of about 20%, and The trench has a trench height of about 4 μm to about 6 μm.

17. The lighting device of claim 11, wherein the micro LED structure further comprises a substantially transparent film disposed on the n-type semiconductor, a surface of the n-type semiconductor opposite the substantially transparent film being substantially planar, the substantially transparent film having the nano-PSS features.

18. The lighting device according to claim 11, wherein: The micro-LED further includes a substantially transparent film disposed on the n-type semiconductor, The n-type semiconductor is substantially planar, and The substantially transparent film has nano-PSS characteristics.

19. A method of manufacturing a lighting device, the method comprising: epitaxially growing a semiconductor stack on a substrate, the semiconductor stack comprising an n-type semiconductor, a p-type semiconductor, and an active region sandwiched between the n-type semiconductor and the p-type semiconductor; and A micro light emitting diode (microLED) comprising the semiconductor stack is fabricated such that the microLED has an emitting surface from which light generated by the active region exits the microLED, the emitting surface having nanoscale patterned sapphire substrate (nano-PSS) features therein.

20. The method of claim 19, wherein fabricating the micro-LED further comprises: peeling the substrate from the semiconductor stack to expose a top surface of the n-type semiconductor; etching a top surface of the n-type semiconductor to form a planar top surface and reducing a height of the n-type semiconductor to less than about 2 μm; depositing a substantially transparent film on a planar top surface of the n-type semiconductor; and The substantially transparent film is patterned to have nano-PSS features.

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