TW200847482A - Pyramidal photonic crystal light emitting device - Google Patents

Abstract

A light-emitting device (LED) is described which comprises a light generating layer disposed between first and second layers of semiconductor material, each having a different type of doping. An upper surface of the first layer has either a tiling arrangement of pyramidal or frustro-pyramidal protrusions of semiconductor material surrounded by a material of different refractive index, or it has a tiling arrangement of inverted pyramidal or inverted frustro-pyramidal indentations in the semiconductor material filled by a material of different refractive index. Each comprises a photonic band structure. The protrusions or indentations and their tiling arrangement are configured for efficient extraction of light from the device via the upper surface of the first layer and in a beam with an emission profile that is substantially more directional than from a Lambertian source. An enhanced device employs a reflector beneath the second layer to utilise the microcavity effect. Methods for fabricating the device are also described, which employs anisotropic wet etching to produce the pyramidal protrusions or the inverted pyramidal indentations.

Description

200847482 IX. DESCRIPTION OF THE INVENTION: FIELD OF THE INVENTION The present invention relates to a light-emitting diode 5 having improved light exiting and directivity, and in particular to a device employing a photonic crystal structure. BACKGROUND OF THE INVENTION The light of light-emitting diodes (LEDs) is based on a forward-biased p_n junction and is sufficiently close to high brightness to make it suitable as a new solid-state illumination application and replacement projection. Light source. The economic benefits of high-efficiency LEDs, along with their high reliability, long life and environmental benefits, enable them to enter these markets. In particular, in solid-state lighting applications, LEDs are required to exceed the efficiency currently achieved with alternative fluorescent lighting technologies. The backlight unit (BLU) of a liquid crystal display (LCD) panel is a key component in the performance of an LCD panel. Most LCD panels now use a small cathode fluorescent lamp (ccfl) source. However, these sources are not ideal due to some problems, including poor color gamut, environmental recycling and manufacturing controversy, thickness and profile, high voltage conditions, poor thermal management, weight and high power consumption. In order to reduce these problems, LCD manufacturers are implementing LED backlighting unit 20. These proposals can be helpful in many areas, including color gamut, lower power consumption, thin profile, low voltage requirements, good thermal management, and low weight. Today's LED backlighting systems distribute LEDs on the back side of the LEDs, which are typically low cost designs for small displays as described in US7052152. However, for larger LCD panels, for example, large 200847482

At 32 inches, the number of LEDs required to evenly distribute light across the back of the LCD panel makes this approach no longer cost effective. The 124 LEDs application is presented in US7052152 as a 32" LCD panel display. For some applications, Lue's more isotropic or a led lang 5 bert light distribution is needed and one technique used to achieve this property is to combine the roughening of light through the surface. A certain degree of roughness may be inherent to the production process of the led. However, by utilizing, for example, etching techniques, a controlled degree of surface roughness can be achieved to improve the irregularity and uniformity of the light emitted by the LED. 10 US 2006/0181899 and US 2006/0181903 disclose an optical light guide or waveguide arranged to evenly distribute light over the surface of a complete LCD panel. Light is coupled into the light guide by using a side-mounted LED source. When compared to direct LED backlighting, side suspension is advantageous because the number of LEDs required per unit area of the backlight LCD is significantly reduced. There are already μ-leaf 15 LCD panels that can take advantage of the low-light source recommendations. However, maximizing the light diffused on the LCD panel requires optimal integration of the LED light into the light guide. Another area of application for high-brightness LEDs is the light engines of front-projection and rear-projection projectors. Low efficiency and short life have been obstacles to the conventional high-intensity 20-light projector light engine, which has been delayed by the consumer market. The etendue value of the source in the present application needs to be less than or matched to the microdisplay etendue value. This interoperability is important to improve the overall system efficiency of a complete light projection engine. In addition, the high total output of the light and the low power consumption are also very important, especially in the case of the large rear projection screen (for the material) and the front projection 200847482:,, v" In order to minimize thermal control problems, low power consumption is required. The single-color & LED fields from the _ group with small etendue values are transmitted by the township to produce the desired color in the projection system. This eliminates the need for color ring and cost. The etendue value of five can be β π ΠΤ value is calculated according to the following equation·· ^ Αχ η2 Xsin(a) (1) where E is the etendue of the light source, the surface area of the branching device, and “is the half angle of the light source. Therefore, it can be understood that for projection applications, the degree of collimation of the illumination source is a key factor and reducing the half angle of the light source can significantly change the overall efficiency of the good light engine. The overall efficiency of the led can be quantified by three main factors. That is, internal quantum efficiency, injection efficiency, and graining efficiency. One of the main limiting factors for reducing the light-out efficiency of LEDs is the total internal reflection of photons and their trapping in the high refractive index material forming the LED. These trapped waveguides 15 are modally propagated in the structure of the LED until they are scattered or reabsorbed. The thickness of the LED structure determines the number of modes that can be supported. Both US5779924 and US5955749 are described using the definition in led. The photonic crystal structure in the semiconductor layer affects the light transmission through the superficial structure. The formed photonic band structure allows the trapping mode to be extracted and thus increases the efficiency of the light and ultimately increases the LED. The overall external efficiency. The use of photonic crystal structures in an LED is more advantageous than other light> and the technology is that they scale with the effective surface area of the LED, thus providing an improvement _ large area south-acceptance LED structure light &gt The ideal method for LED size scaling is very important for solid-state lighting applications that require absolute illuminating output. However, these photonic crystals are not as good as the more conventional surface roughening LEDs. And US 2 〇〇 5 / 〇 285132 describe a method of fabricating a light-emitting diode 5 having a photonic crystal structure using a material based on a sulphide (GaN). In both cases, the processing includes the final effect on the LED crystal. There are many complicated and expensive steps in the production and cost. In particular, us683i3〇2 4 Tian Yiyi includes the following steps: · An n-GaN layer is grown on the lattice of a matched single crystal wafer. a QW region and a p-GaN layer, followed by eutectic bonding on the top surface to an underlying package or encapsulation carrier, wafer flip-chip sealing, growth wafer stripping (using a strip such as laser stripping) Technology), surface polishing to provide an optically smooth surface (using a private sequence such as chemical mechanical polishing) to define a photonic crystal on the surface (by a method such as nanoimprint, lithography, or laser photography) And finally, one of the photonic crystals is properly dried (eg RIE or ICP) or wet etched to the GaN material. 15 One of the complex processing steps involved is the polishing of the wafer, due to the quality of the control across the entire wafer surface. Difficulties, this step will have an adverse effect on throughput. Small scratches on the full surface may affect the current spreading on the LED wafer and eventually cause a path that shorts the entire led, or No adverse effects. In addition, the thickness of the GaN superficial structure is important for the effective design of the light exiting pattern of the light sub-crystal. The high refractive index acts as a multi-mode waveguide, and the thickness determines the number of modes present in the LED heterostructure. Poor control of the absolute thickness of the LED structure due to the use of a polishing process ultimately affects the overall output of the LED wafer from one process batch to another. The fabrication process of 200847482 is to define the feature spacing of the first-order photonic crystals of the J-scale between Qnm and 5〇〇ηΐχ, and the straightness of the holes from 200nm to 400nm. Such graphics are currently using nanoimprint or laser photography to define the illusion that this small feature on LED wafers is not yet a mature technology and can only achieve low throughput. In addition, the lack of this technology requires a relatively low cost. The latter's lithography technology is missing due to complex alignment and stability and low throughput. There is therefore a need for a new type of surface patterned LED that behaves better than conventional surface roughening or photonic crystal LED devices and can be fabricated in a simple and cost effective manner. SUMMARY OF THE INVENTION In accordance with a first aspect of the present invention, a light emitting device (LED) includes: a first layer comprising a first semiconductor material having a first type of doping; 15 a second layer comprising a first a second type doped second semiconductor material; and a light generating layer disposed between the first layer and the second layer, wherein the first layer has an upper surface retreating from the light generating layer and a lower surface adjacent to the light generating layer And wherein the light generated in the light generating layer is present by the 20 LED structure via the upper surface of the first layer, the first layer further comprising a pyramidal or truncated cone shaped upper surface protrusion of the first semiconductor material Arranged, the protrusion is surrounded by a material different from the refractive index of the first semiconductor material, wherein the tiling arrangement of the protrusion is formed with the surrounding material-photonic band structure, and wherein the arrangement of the protrusion and its tiling arrangement is such that The light formed by the 200847482 led structure through the upper surface is substantially more directional than the light from a Lambertian source. According to a second aspect of the present invention, a light emitting device (LED) includes a first layer comprising a first semiconductor material having a first type of doping; and a second layer comprising a second type doped a second semiconductor material; and,

a light generating layer disposed between the first layer and the second layer, wherein the first layer has a surface away from the upper surface of the light generating layer and a surface of the lower surface adjacent to the light generating layer, and wherein the light generating layer is in the light generating layer The generated light is formed by the ED structure through the upper surface of the first layer, the first layer further comprising an extension from the upper surface toward the light generating layer in the first semiconductor material, and a refractive index and the first semiconductor material a chamfered or inverted truncated indented 1 watt configuration of different materials, wherein the tiling of the dent is disposed and surrounded by a photonic band structure, and wherein the dent and its tiling are adapted to pass through the upper surface The light emerging from the structure of the LED is more directional than the one obtained from a Lambertian source. - the cosine of the angle between the luminous flux per unit solid angle of the Lambert source in either direction and the surface normal to which it is emitted

proportion. This results in a uniform illumination of the spherical distribution. An LED includes a structure in accordance with the present invention that combines greater directional illumination and improved efficiency in the efficiency of the beam produced by the device. This can be achieved by a pyramidal or truncated cone shaped surface projection, or a chamfered or inverted truncated dent in a new tiling configuration. 10 200847482 There are two preferred photonic silicon configurations, namely short-range and long-range ordered photonic crystals, short-range disordered but long-range ordered quasi-photonic crystals, short-range interval ordered but long-spatial disordered and non-small-form tile patterns. In the case of amorphous, the adjacent pyramidal regions are fixed and the rotational symmetry is randomized. 5 A high-order pyramidal or chamfered cone photonic crystal proposed in the present invention

Or quasi-crystal mode can be used to increase the amount of light when compared to the more conventional first-order photonic crystal mode. The careful design of the photonic crystal also allows for the customization of the far-field light produced by the device. In particular, the pyramidal shape of the pyramid with an angled side wall or the chamfered cone shape of the indentation, and their definitively defined 10 watt configuration, can extract a more collimated beam from the LED than from a Lambertian source. This is true even in a mode with a large lattice constant (>1μη1). Preferably, the 'tapered-shaped projection or the chamfered-cone shaped dimple has a size greater than 1·〇μηη. However, their size may be greater than i 5 哗 or 2 〇 or even greater than 2·5 μιη. The relatively large pyramid or chamfer cone size releases the tolerance of the fabrication and is also intended to be in the pyramidal or chamfered cone

Surface polishing is not required prior to formation because their dimensions are sufficiently larger than the residual surface roughness. In addition, 'better is the spacing of the tiling configuration is greater than 15) Lmi or 2·5μηι even greater than 3.0. 20 For many applications, the projections or indentations are preferably configured such that a significant proportion (> 35%) of the light has a 3 〇 on a pair of vertical axes. The central cone of the half-angle is pulled out. Preferably, greater than 37%, 38% or even 40% is scooped out of the central cone. This enables light to be efficiently and uniformly coupled into the elongated light guide which is typically used with the light source in projection applications. 11 200847482 Or 'The pyramid or chamfer cone and the tile pattern can be configured such that light is predominantly out of the side illumination pattern at a greater angle than this. For example, the light can be split out around the vertical axis as a ring of sight or a donut-like distribution. In this case, the center of the distribution can be 5 - greater than or equal to 3 与 from the vertical axis. , 4 (). , 5 (). Or (9). The angle, or equal to the surface, is less than or equal to 60. 50. 40. Or 30. Angle. The first semiconductor material having the first type of doping may be doped or p

Type doping, in which case the second semiconductor material having the second type of doping will be p-type doped or n-type doped. The first layer may include a layer of etch stop material buried in the first semiconductor material at a predetermined depth, in which case the protrusion formed by the first semiconductor material may extend from one surface of the etch stop material and be inverted. The dent will extend all the way to the etch stop material layer.

In a particularly preferred embodiment, the first semiconductor material comprises 11-type 杂 15 GaN or InGaN and the second semiconductor material comprises 1) doped GaN or InGaN. Preferably, the light generating layer comprises a multiple quantum well structure of GaN-InGaN. In terms of the diameter of the pyramid, the higher order photonic crystal size is typically in the range of Ι.Ομιη to 3·0μηι, but it depends on a range of factors including wavelength, far field pattern, LED thickness and overall Multiple quantum well structures within the GaN heterostructure 20. Suitable residual stop materials include AlGaN and InGaN. To further enhance light exit, the LED preferably further includes an optical reflector to reflect light transmitted from the surface of the first layer that would otherwise not be ejected. The optical reflector is disposed adjacent to a layer of 12 200847482 of the second semiconductor material such that the layer is located between the light generating layer and the reflection 1 §. Preferably, the optical reflector comprises a single layer of metallic material or it may comprise a multilayer dielectric structure. Alternatively, the optical reflector may comprise a distributed Brass reflector (DBR) or an omnidirectional reflector 5 (ODR). Preferably, the separation distance between the light-generating layer and the optical reflector is such that a microcavity that increases the amount of generated light propagating toward the light-extracting surface above the first layer is formed. This microcavity effect provides even greater light extraction efficiency over the optical reflection of the optical reflector in terms of light extraction efficiency. An optimum separation 10 is between 0.5 and 0.7 times the wavelength of the light generating layer. When a microcavity is present, the best pyramidal or chamfered indentation and its tiling arrangement are combined to provide optimal coordination with the microcavity effect to further increase the efficiency of light from the LED. In accordance with a third aspect of the present invention, the light engine 15 of an optical projector unit includes a plurality of illumination devices in accordance with the first or second level. The above-mentioned leds are particularly suitable for use in solid state lighting sources, including front and rear projectors. In accordance with a fourth aspect of the present invention, a method of fabricating a light emitting device (LED) according to a first level includes the steps of providing a light emitting device heterostructure comprising: a first one having a 20th type doping a first layer of a semiconductor material, comprising a second layer having a first type of semiconductor, and a light generating layer disposed between the first and second layers, wherein the first layer has a Moving away from the upper surface of the light generating layer and a lower surface close to the light generating layer, and wherein the light generated in the light generating layer passes through the upper surface of the first layer is visualized by the LED structure, 200847482 forming an etching light on the first layer a cover, the light cover comprises a light military block, the island block is located at a position corresponding to a predetermined tile arrangement, wherein the step of the photomask comprises a plurality of steps of: depositing a layer of photoresist on the first layer 5; forming a photoresist pattern by exposure according to a predetermined tiling configuration; and removing the unexposed photoresist to form an island block corresponding to the predetermined tiling with the photoresist; placed in the first layer Borrowing along a predetermined crystal plane I an isotropic wet engraved first half

(d) material to - 骇 depth at the location under the island of fresh material to form 10 pyramidal or truncated cone shaped portions of the first semiconductor material; and, removing the island block of the reticle material to leave a predetermined pyramid or truncated cone A type of tab tiling arrangement that combines with a surrounding material of a different index of refraction to form a photonic strip structure. w 15 20 The fifth layer 1 according to the present invention as a method according to the second level light-emitting device (LED) comprises the steps of: providing a light-emitting device heterostructure, the material f structure comprising a first-type doped a first layer of the first semiconductor material, a second portion of the second semiconductor material having the second type doping, and a light generating layer between the first and second layers, wherein the first layer has a separation The upper surface of the light generating layer is adjacent to the light generated in the light generating layer, and the first surface is formed by the led surface:

The reticle includes a position corresponding to the step in which the reticle is formed to form an etched reticle on the first layer, and the reticle material 14 is disposed in a predetermined tiling arrangement. The method includes: forming a watt by 1 watt by exposure a photoresist pattern; and, removing the unexposed orbital agent to leave a missing photoresist island block at a position corresponding to the predetermined tile configuration; by pre-twisting the crystal plane to be isotropic wet (four) the first semiconductor = predetermined Depth to form a pyramid or truncated cone indentation below the island block where the reticle material is missing in the first layer of the first semiconductor;

Removing a remaining reticle material leaving a predetermined tiling arrangement of chamfered or inverted truncated dents in the first semiconductor material, the dent comprising a surrounding material having a different refractive index of the first semiconductor material and - It forms a photonic band structure. The optical device heterostructure itself may be fabricated by any suitable conventional procedure 'including flip chip packaging procedures.

The resist layer may itself be a photomask layer, in which case the island of the reticle material is an island of photoresist. Any suitable procedure for forming a photoresist pattern by exposure can be utilized, including ultraviolet lithography. The unexposed photoresist is removed using a suitable developer and the remaining unexposed photoresist islands are removed by lift-off. A variety of different etchants are available for isotropic wet etching, including KOH, NaOH or H3P〇4 solutions. 20 Alternatively, a harder reticle material can be used which is etch resistant to isotropic wet etching. Therefore, further procedural steps are required. In the method of the fourth aspect, the step of forming an etch mask preferably further comprises the steps of: 15 200847482 material depositing a hard mask on the first layer before removing the photoresist layer before the step of depositing the photoresist layer After the step, the hard mask material is removed to leave a hard mask material island P under the island of light and the agent and the remaining island block from which the photoresist is removed leaving an etch mask that etches light corresponding to the predetermined tile configuration Location of hard reticle material island blocks. In the method of the fifth aspect, the step of forming a mask is further included in the following steps: Into the 10 material, a layer of hard mask is deposited on the first layer before the step of depositing the photoresist layer.

Removing the hard mask material after the step of removing the photoresist to leave an island block missing the hard mask material under the island of photoresist; and, sheet = residual photoresist to leave a reticle, _ light The cover constitutes a missing hard reticle material island block corresponding to a predetermined one watt configuration. 15

Suitable hard reticle materials include ton or post 4 deposited by PECVD or metal deposited by sputtering or rutting. The eagle-shaped pyramid has been formed, and the hard reticle material is removed by a suitable wet or dry (four) procedure. Similarly, the inverted dent has been formed, and the remaining hard reticle material surrounding the island block is removed by the appropriate wet or dry (10) procedure to remove the 层面 20 纟 fourth layer. The depth will determine whether the truncated cone or pyramidal protrusion is formed and its size. However, if the time is priced according to the speed of the money and the time of the last name, the precise control of the depth of the isotropic name may be difficult. Therefore, the etch stop layer can be used to ensure that the utterance is terminated at a particular depth. Similarly, if in the method of the fifth level, 16 200847482 isotropic deep etching will determine the size of the indentation. — If the etch rate is based on the etch rate and the etch time, an isotropic precision control etched the deep shovel may have _. In addition, it is necessary to form a stop layer in order to form a mark 0 5 . Preferably, the first layer of the heterostructure of the light-emitting device comprises a layer buried in the N#

- The predetermined depth of the semiconductor material towel is used to stop the material. The isotropic burn of the first half of the conductor material will then continue until the arrival of the stop material layer, thus providing a higher uniformity and reproducibility of the fabrication process. In the fifth aspect method, a flattened or truncated cone type dimple is allowed to be formed. 1 〇 ·目 & 'The invention also provides - a simplified photonic crystal structure of the LED structure i 113⁄4 _ low-cost photolithography technology or similar program enables the large-scale feature photonic crystal definition to be transferred to _ coffee and not A complicated polishing procedure is required. BRIEF DESCRIPTION OF THE DRAWINGS 15 Examples of the invention will now be described in detail with reference to the drawings, in which:

The figure shows the cross section of the device proposed by the invention; the 2A chart does not have a pyramid arranged in a regular square lattice; the 2BH table has a pyramid of 12th symmetric quasicrystals arranged; The function of the image separation distance represents the normalized illumination intensity of a (10) 20 LED; the 4A to 4D diagrams are not fabricated. The manufacturing method based on the high speed flip chip package; 4E to 41_ shows the production of the milk Additional manufacturing steps for the pyramidal photonic crystal construction in the upper layer of the device shown in the figure; 17 200847482 The following figure shows that for a pyramidal photonic crystal-LED, the light is not improved compared to the device without a graphic structure. . Cone; Figure 5B is not for the pyramid-type photonic crystal-LED, compared to the device with no pattern structure, the total light output is improved. 5 The slave map indicates 30° for the non-pyramid photonic crystal illuminator. The percentage of the light in the cone; the 6A chart is not a far field pattern of the photonic crystal-LED structure according to a preferred embodiment of the present invention; the 6B drawing is not based on the photon according to another preferred embodiment of the present invention. a far field pattern of a crystal 10 body-LED structure; FIG. 7A shows an electron micrograph of an isolated pyramid formed without using the inventive method; FIG. 7B shows a method formed using the fabrication method of the present invention Electron microscopic image of the photonic quasi-crystal configuration of a pyramid; 15 Figure 8A is a conventional photonic crystal-LED with a microcavity pyramidal photonic crystal-LED compared to a non-graphic LED Increasing the pattern of the filling portion of the photonic crystal; FIG. 8B is a graph of the pyramidal photonic crystal_LED compared to the light-emitting of the non-graphical LED with and without the microcavity ;as well as, The pattern of the core thickness of the LED heterostructure is improved by the light output of the LED® pyramidal photonic crystal-LED compared to a non-graphical structure. Figure 10 is a cross-sectional view of one of the chamfered cone-shaped devices; the 11A-liD diagram illustrates a method for fabricating a high-speed flip-chip seal of a light-emitting device 18 200847482; 11E to 111 are illustrated at the 111th An additional manufacturing step of fabricating a chamfered or truncated cone-shaped photonic crystal structure in the upper layer of the apparatus shown in FIG. 5; FIG. 12A illustrates a pyramidal photonic crystal-LED compared to a non-graphical structure device 30. The light in the cone increases. Figure 12B illustrates the increase in total pupil output of a pyramidal photonic crystal-LED compared to a device without a graphic structure;

Figure 12C shows a different pyramidal photonic crystal illuminator at 3 〇. The percentage of light in a circle of 10 cones; Figure 13 is a diagram showing the far-field pattern characteristic of a photonic crystal-LED structure according to a preferred embodiment of the present invention; and Figure 14 is a diagram showing the shape of the method of the present invention. An electron micrograph of a pyramid of a wire isolated chamfer cone; 15 帛 15A is a conventional photonic crystal - led and - with a microcavity pyramid

The photonic crystal-LED has a pattern of filling the photonic crystal compared to the light-emitting of a non-patterned LED; FIG. 15B is a chamfered cone photonic crystal _led compared to one with and without a microcavity The light of the graphic structure LED does not increase the pattern of the filling portion of the photonic crystal. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT The present invention is directed to providing improved light exit and custom far field emission of a light emitting device. These devices can be used with a wide range of luminescent semiconductor materials, including but not limited to, InGaN, InGaP, InGaAs, InP or ZnO. SUMMARY OF THE INVENTION A focus will be placed on directional light extraction techniques implemented in green InGaN light emitting devices. However, the design can be optimized and implemented in other emission wavelengths (such as blue or ultraviolet) that utilize such a material, as well as in the use of other material systems, such as InGaP, which is suitable for emitting red and yellow wavelengths. A novel high order pyramidal photonic crystal (PC) or quasi-crystal pattern proposed in a preferred embodiment of the present invention provides increased light extraction compared to a first order photonic crystal structure. The photonic crystal design also takes into account the customization of the far-field light distribution by the device 10. The pyramidal shape of the photonic crystal sub-region and its well-defined tiling arrangement allow the device to illuminate with a beam of light that is more collimated than the light exiting from a Lambertian source. A simplified procedure for making the device will also be described. In terms of the pyramid diameter, the higher order photonic crystal size is larger than 丨·0哗 on the dimension side 15 and may be larger than 1·5μπι or 2·0μιη, and the size can be as large as 3·0μηι· ' 5μιη and 4·0μηι But it is not limited to this. This depends on the far field pattern, the thickness of the LED, and the location of the quantum well in the GaN heterostructure. 1 is a cross-sectional view of a light-emitting device of the present invention comprising an angle 20 pyramidal, quasi-crystalline, amorphous or other complex periodically protruding from an n-type doped GaN or InGaN layer. Ordered or heavily covered tile configuration. The pyramidal tile configuration is designed to provide a dispersion band that allows trapped light to enter the Bloch mode of the photonic crystal. Once the light enters the Bloch mode, the photonic crystal provides a way to get the light into free space. The device shown in Fig. 1 comprises a luminescent heterostructure, the heterostructure package 20 200847482 comprising an n-GaN or InGaN top layer 1 〇 2 and a lower p_ type GaN or InGaN layer 104, - multiple quantum wells (MQW) Structure 103 exists between these layers. There is a reflective layer 1〇5 beneath the p-type layer 104, which may be in the form of a metal reflector such as silver, or in the form of a DBR or omnidirectional reflector (ODR).

5 The light emitting structure is supported by a carrier substrate or carrier 106. In a preferred embodiment, the carrier substrate comprises a conductive material having a high thermal conductivity such as a metal or metal alloy or a stone or stone. In another preferred embodiment, there is a stop stop layer 107, which may be formed of, but not limited to, a material such as AlGaN, InGaN, etc., which allows for precise control of the pyramid depth. This layer is buried between the n-type layers 101 and 102. There are three preferred photonic tile configurations in the present invention, and the configurations have the following properties: short-range and long-range order, that is, photonic crystal; short-range translation disorder but long-range ordering, that is, photon quasicrystal; and short-range interval Sequence and long-range disorder, that is, amorphous tiling configuration. In the case of an amorphous configuration, the separation distance between the 15 adjacent pyramidal and chamfered conical regions is fixed but rotationally symmetrically randomized.

The types of these graphic definitions may also include a repeating unit having the above-described tiling configuration. In addition, they can include areas with defects, i.e., corners and chamfers are removed or the shape or size of the pyramid is corrected. The sub-region may also consist of a pyramid having a sharp apex region that is not etched, causing a flat (truncated) pyramid. The graphical definition can be characterized by a number of parameters, including the lattice spacing defined as the distance separating the two adjacent pyramids or the center of the chamfer, and the angle 0 formed between the crystallographic exposure surface of the pyramid and the GaN lattice. An etch stop layer 107 is used to control the etch depth at a level as described in the present invention. This allows proper control of the diameter of the base of the pyramid. For a particular etch depth d, the base diameter φ of the pyramid is: Φ = 2^d/tan(0) (2) 5 A major primary aspect of the invention is the use of large features that are crystallographically aligned to provide maximum Graphic reproduction accuracy as well as relaxed positional accuracy.

Hexagonal pyramids or chamfer cones (formed in tantalum GaN) can be arranged in a regular pattern 'quasi-crystalline mode, amorphous mode or other 10 suitable arrangements. In one of the examples shown in Fig. 2A, the hexagonal pyramids are arranged in a regular square lattice to form a photonic crystal. Figure 2B shows a row of pyramids or chamfers of a 12-symmetric square-triangular quasi-crystal tiling to form a photonic quasicrystal.

An enhanced version of the invention applies a light placed beneath the illumination area to reflect light propagating upwardly downward. Furthermore, the separation distance between the illuminating region and the reflector is designed to raise the upwardly emitted light based on the so-called microcavity effect. The pyramidal or chamfered cone photonic crystals are then optimized in combination with the microcavity effect to further enhance light exit. As described in Appl. PhysLett. 82, 14, 2221, on April 7, 2003, Equation 20 below describes the relative power intensity at the top surface of an LED as a function of the separation distance between the Qw region and the reflector: E2 = y^〇2+ wr2+2w〇wrcos(n+0+0f) (3) Φ' 2 2 Tt(2dcos(e))an (4) The correlation in the equation is as follows: 22 200847482 W(f= Emitted light vibration; the reflected light vibration; the phase shift of the mirror reflection; Φ due to the difference in path length between the emitted light and the reflected light, the phase shifts with the microcavity and the interval between The distance and (4) the incident angle and wavelength of the material change; and the emission angle relative to the normal. To illustrate the microcavity effect, Figure 3 shows the light intensity obtained by a GaN LED with a mirror as a quantum well and A plot of the distance between the mirrors. This intensity is often 10-stated by the intensity of a GaN LED without a mirror to illustrate its enhancement. For simplicity, the mirror is assumed to have a reflectivity of 100%. It is apparent that approximately three to five times more light is ejected than a flat mirrorless GaN light-emitting device. The only contribution, which is equivalent to about 175 times more light due to the microcavity effect, is that the placement of a subwell at the correct distance from the mirror is the key to achieving maximum light extraction efficiency in an LED. The microcavity effect also introduces a bias in the far field radiation shape of the LED when compared to a Lambertian source. In the context of the present invention, increasing the lobe radiation can be optimized along with the surface photonic crystal structure, It enables greater light extraction and square diversion from LEDs than those required by the two applications. The microcavity effect reduces the homogeneity of emission within the heterostructure, thereby allowing internal incidence to the photonic crystal. The light is more collimated. Due to the high aspect ratio characteristics and the large dielectric contrast provided by the photonic band structure, the waveguide mode of the LED can effectively overlap with the dispersion band of the photonic band structure to have a strong face between the valleys. An isotropic wave inside a thick core 23 200847482 Under the shooting situation, many waveguide modes are established. The dispersion band of the photonic crystal cannot be designed to overlap with all trap modes. However, by utilizing The number of modes waveguide cavity may reduce the collimated light beam construction. Photonic band structure may subsequently be pumped out to serve effectively caught in catching LED 5 in more closely spaced and smaller number of modes to optimize the design.

A still further aspect of the present invention is a simplified lead manufacturing method for a photonic band structure having the above-described pyramidal structure. A possible manufacturing procedure is not shown in Figures 4A through 41. Initially, an n-type doped GaN or InGaN layer 401 is grown on a lattice-matched substrate 410 by metal organic chemical vapor phase vapor deposition (MOCVD) or other similar 10 techniques (such as ΜβΕ), usually used. It is sapphire, GaN and SiC. In a preferred embodiment of the invention, an etch stop layer 409 formed of a material such as InGaN or AlGaN is buried in the n-GaN layer. The η-GaN or InGaN layer continues to grow to a layer 408 over the etch stop layer 403. Multiple GaN_InGaN quantum wells 402 are then grown 15 by a type GaN layer 403. The completed LED heterostructure produced in this stage is shown in Figure 4A.

The mirror 404 is deposited on the p-GaN layer 403 as shown in Fig. 4B. The reflector may be metallic, including a suitable metal such as silver or gold deposited by evaporation or evaporation. Alternatively, the reflector can be a dielectric multilayer in the form of a distributed inverse feedback reflector (DBR) or an omnidirectional reflector (ODR). Such a construction can be deposited by sputtering using techniques such as PECVD. As shown in Fig. 4C, the heterostructure of Fig. 4B is then bonded to a substrate 405. Substrate 405 is preferably a metal alloy that provides good thermal and electrical conductivity, but may be comprised of other materials such as Sic or Si. Additional layers may be deposited on the 24 200847482 mirror 404 prior to the bonding operation to aid in the bonding process. In the final conventional fabrication step, the sapphire substrate 41 is then removed by laser lift-off or other similar technique to provide a heterostructure as shown in Figure 4. Although typically the etch stop layer is not present, this structure can form a final, conventional device. The laser lift-off procedure roughens the surface of the .GaN layer 401 (typically on the order of 5 〇 nm to 3 〇〇 nm). In a more conventional device, the surface can be further roughened to improve light exit. In one aspect of the invention, the size of the photonic band structure pyramid is larger than the surface roughness, so that no polishing surface is required prior to defining the pattern. 10 Figures 4E through 4I illustrate an incremental process step for fabricating a device as shown in Figure 41 in accordance with the present invention. Figure 4E depicts the deposition of the masking layer. In particular, a method step is shown in which the hard mask layer 4〇6 is deposited for subsequent transfer of the desired pattern to the η-GaN layer 401. The hard mask layer is composed of PECVD-deposited Si〇2 15 or S!3N4 or it may be a metal deposited by hetero or vapor. A photoresist 407 is then deposited on the hard mask 4〇6. However, in some cases, the hard mask layer may be omitted and the photoresist layer 4〇7 is deposited directly onto the ~(10) layer 401. Due to the large size of the pyramidal features, the photoresist 407 can be exposed using standard ultraviolet 20-line lithography techniques to have a pattern of the desired tile configuration. The lateral shape of the exposed area may correspond to the cross-sectional shape of the desired pyramid, or may be a relatively simple shape such as a square. The exposed photoresist is then developed leaving a separate island of material corresponding to the desired location of the pyramid apex, as shown in Figure 4F. If the hard mask 4〇6 is present, use the ruler, icp or a similar 25 200847482 program to make money. This step transfers the pattern definition from the photoresist 407 to the hard mask 406' as shown in Fig. 4G. The remaining photoresist 407 is then stripped. Next, the 'n-GaN layer 401 is wet etched by the crystal by an isotropic wet etching as shown in Fig. 4H. A preferred method of wet etching GaN is to use a bath of KOH at a temperature ranging from room temperature to 1 °C in the range of 1 M to 8 M. The etching time range is about 45 minutes. Optional wet etchant contains NaOH or H3P〇4 〇

The crystal plane of the hexagonal pyramid formed by the residual process is the { 10-M } plane of the GaN crystal. They form an angle 58 4 with the bottom of the pyramid. . The presence of the etch stop layer 409 allows the correct control of the height and thus allows the base diameter of the pyramid to be properly controlled. Finally, if a hard mask 406 is used, it can be removed using a suitable wet or dry etch procedure leaving the final structure shown in Figure 41.

Fig. 7A is a scanning 15 electron micrograph of a pyramid produced by this method. In this case, the pyramids are isolated and formed using a preferred fabrication embodiment, and the small crystal interface { 10-1-1} is shown at 701. Figure 7B is a broom electron micrograph of a photonic quasi-crystal tiling of such a pyramid, which has been etched into the top surface of the n-GaN using a preferred fabrication technique. The pyramids 7 are arranged in a square-triangle tiling and the knots shown in Fig. 7B show the tiling squares and triangles of the bottom layer, while the circles emphasize the apex of the quasi-crystal pattern. In a preferred embodiment, the composite n-GaN upper region including layers 401, 409, and 408 is disposed over the light emitting structure. Thus, light is emitted from layer 402 and undergoes multiple internal reflections before being finally released via the 401 region. 26 200847482 A thick n-GaN growth region must reduce the defect density in order to form a high quality quantum well (QW) layer and thus improve the internal quantum efficiency of the LED. In order to manufacture the upper upper region (layers 401 '409 and 408) as a protective layer of the QW region 402 of the zygomatic arch, it is prevented from being damaged by 5 to the mussel during the wet etching of the pyramid and the surface of the QW region Minimal compounding. The rest of the area will also adversely affect the total illuminating output of the LED by reducing the maximum effective illuminating area.

In addition, with regard to the improvement of the light extraction, the required pyramidal diameter is up to a scale of 1.75 μm, and the distance between the centers is 2·5 μm. The size limits the minimum thickness of the layer 4〇1 10, so the pyramid is preferably located on the thick n-GaN layer. At the same time, in order to improve the pupil output, the total number of trapping modes in the heterostructure is reduced by etching to reduce the total thickness of the LED waveguide region. This allows the photonic band structure to overlap with a larger percentage of trapping modes to provide improved light exit as shown in FIG. In addition, n-GaN is highly conductive and this property minimizes the need for 15 separate current spreading layers to deposit on the top surface of the photonic structure.

Less, the deposition of the independent current spreading layer has an adverse effect on the light exit from the device. The results of the numerical simulations are shown in Figures 5A, 5B and 5C, illustrating the performance of a typical pyramidal photonic band structure device. The Z-axis shows the overall light output improvement factor compared to a reflector that is not a 20-shaped LED. The results are plotted as a function of the fill portion (in %) along the X-axis 501 and along the γ-axis 5〇2 as a function of the distance (in nm) between the photonic band structures. The fill portion is defined as diameter/pitch*1〇〇. Figure 5A illustrates a pyramidal photonic crystal in a central portion 30 compared to a non-patterned LED having a bottom reflector. The light in the cone is not out. 27 200847482 High. The results show a maximum increase of 5.45 for an optimized microcavity design with a pitch of 2500 nm and a fill portion of 75% and a QW region below a position of d = 〇·6/ λ n~13lnm. These parameters correspond to a device having a cone diameter of about 1·9 μηη spaced apart by a distance of 2.5 μπι. 5 Simulate the simulation using a 2D finite difference time domain method. It is important to note that these simulations do not incorporate numerical deviations from 2D to 3D simulations in space and thus allow experimental results to be expected to provide greater pupil output values. The fifth diagram is enhanced by the lattice constant and the fill portion function representation compared to the light exit of a non-patterned LED having a bottom reflector. As shown in Figure 5, Figure 10, the focus of the results is that the optimal operating range occurs at a pitch of 2500 nm and a fill portion of 75% with an optimized microcavity design under QWs. Finally, Figure 5C shows that the light of the device having the pyramidal photonic crystal structure is at 30. The percentage in the cone. As seen in the figure, up to 45% of the light 15 emitted by the device can be directed to have a 3 垂直 perpendicular to the surface of the device. The center of the half angle is in the cone. This corresponds to an 84% more light in a directional cone than the -Lambert illuminator. The increase in directionality is due to the ordered arrangement of the pyramids and the good oblique side walls of the pyramids. Compared with the straight (four), _, and air rods, the inclined side wall can be 30. Approximately 3% more light is provided within the cone. 2〇 Figures 6A and 6B show the transverse wear of the light distribution in a plane. The result is plotted as a function of the far field angle 601 along the X axis and indicates that the light intensity is normalized by a non-patterned LED having a reflector at the bottom. The far field pattern is the vertical line on the surface of the reference LED. 6A_ shows the far-field pattern of the LED with the lattice constant of the lion (10) and the pyramidal diameter of 1120 nm, the total light and the extraction of the LED 28 200847482 is higher than the luminescence with a reflector and optimized microcavity 2.67 times the device. The increase in the 30° cone is 4.57 times and contains 40.5% of the total pupil output in the 30° cone. Figure 6 shows the far field pattern of an LED with a lattice constant of 2500 nm and a pyramidal diameter of 5 1870 nm. The total light output of the LED is increased by 3.61 times that of a light-emitting device having a reflector and an optimized microcavity. 30. The increase in the cone was 5.45 times and contained 35.8% of the total light in the 30° cone.

This corresponds to 46% more light in a directional cone than a Lambertian illuminator. 10 Below Table 1 is the same green GaN LED designed to include an etched empty

A simple Lambert emitter of a gas-pole one-step photonic crystal LED, and a pyramidal photonic crystal LED designed to include an etched pyramid, is represented by a percentage of total emitted light at a narrow 30. A comparison of the light emitted within the cone angle. In the case of a photonic crystal device, the size is optimized to extract a maximum of 15 parts of light in a 3-inch cone. The first-order photonic crystal size is composed of a lattice air rod having a pitch of 350 nm, a diameter of about 210 nm, and an etching depth of about 12 Å, and the pyramidal photonic crystal size is as described above. Table 1 Device Types Lambert LED Photonic Crystal LED Pyramid Photonic Crystal LED Percentage of light in a 30° cone 24.9 34.9 45.0 As can be seen, the increase in directivity can be achieved with a more optimized structure. Figures 8A and 8B illustrate the increase in light achieved when a photonic band structure is maximized by a microcavity illumination device. In this example, a conventional photonic crystal having a pitch of 5 and having a simple reflector is compared to a chamfered cone photonic crystal having the same pitch but also having a microcavity reflector. The overall light is extracted in Figures 8 and 88 and 802 is plotted as a function of photonic crystal filling portion 801. 5 In Fig. 8A, solid line 803 indicates that a total of the non-patterned LEDs with a reflector is added to the output to the output. The dashed line 8〇4 represents an increase in the total pupil output of a photonic crystal having both a microcavity and a reflector and a non-patterned LED having a reflector. Fig. 8B highlights the effect of the vertical light addition and the effect obtained by the microcavity effect. The dashed line 8〇5 shows the increased photonic crystal light-off effect compared to the solid line 803 when combined with the microcavity, normalized to a non-patterned LED having 10 reflectors and a microcavity, The result of a non-patterned LED with only a simple reflector normalized to the same device. Therefore, the increase in the difference caused by the combined effect is clearly visible. Figure 9 illustrates the effect of reducing the thickness of a photo-emitting heterostructure region for both a pyramidal and a chamfered cone. The light is out of 9〇2 and the bare flat LED with a reflector is compared to the thickness of the led heterostructure core 901, which varies in nanometers. It can be clearly seen that when the thickness of the heterostructure is reduced, the amount of light is increased. In the case of this example, the photonic crystal structure size and composition were fixed for all heterostructure thicknesses and no microcavity effect was applied. The mouth is advantageous for the light to exit and the pyramid structure is left to the heterostructure, since the effective thickness of the LED is reduced. In another preferred embodiment of the invention, a novel high-order chamfer cone photonic crystal (PC) or quasi-crystal pattern is proposed which provides increased light output with the first-order photonic crystal pattern. The photonic crystal design also takes into account the customization of the far-field light distribution issued by 30 200847482. The chamfered cone shape of the photonic crystal sub-region and its well-defined tiling configuration allow light to be extracted from the device by a beam that is more collimated than from a Lambertian source. A simplified procedure for making the device will also be described. 5 According to the chamfer cone diameter, the higher order photonic crystal size is larger than Ι.Ομχη and may be greater than 1·5μπι or 2·0μηι, and may be large but not limited to 3·0μηι, 3·5μπι and 4·0μηι. This is a function of the far field pattern, the thickness of the LED, and the position of the quantum well in the light generating region of the GaN heterostructure.

Figure 10 illustrates a cross-section of the proposed illumination device comprising pyramids engraved in an n-type doped GaN or InGaN layer with a periodicity of 10, quasi-crystal, amorphous or other composite ordered or heavily covered tiles. 1〇〇1. The chamfered cone tiling configuration is designed to provide a dispersion band for the trapped light to couple into the Bloch mode of the photonic crystal. Once the light is coupled into the Bloch mode, the photonic crystal provides a means of coupling the light into the free space. 15 The device shown in Figure 1 comprises a luminescent heterostructure, the heterostructure

An η-GaN or InGaN top layer 1002 and a lower p-type GaN or InGaN layer 1004 are included, and a multiple quantum well (MQW) structure 1003 is interposed between the two layers. Below the p-type layer 104 there is a reflective layer 1 〇〇 5 which may be a metal reflector in the form of a DBR, such as silver, or an omnidirectional 20 reflector (〇DR). The light emitting structure can be supported by a carrier substrate or pallet 1006. In a preferred embodiment, the carrier substrate comprises a conductive material having a high thermal conductivity such as a metal or a metal alloy or tantalum or tantalum carbide. The photonic crystal may be a defective region, that is, a chamfer cone 31 200847482 The area where the shape or size of the chamfered cone is removed or corrected. The sub-areas may also be composed of sharp apex regions that are not engraved, resulting in a flat top (frusto) chamfer.

The graphical definition can be characterized by a number of parameters, including the lattice spacing defined as the distance between the two adjacent pyramids or the center of the chamfer cone and the angle between the crystallographically exposed faces of the pyramidal and the horizontal crystallization of the GaN lattice. . An etch stop layer 1007 is used to control the etch depth at a level of the present invention. This allows for proper control of the diameter of the base of the pyramid. For a specific surname depth d, the base diameter φ of the pyramid is: 10 O=2xd/tan(0)(5)

A further aspect of the invention is a simplified method of fabricating an LED having the chamfer cone type photonic band structure described above. Two variations of a possible manufacturing method are shown in Figures 11A through 11J. A starting n-type doped GaN or InGaN layer 1101 is grown on a lattice-matched substrate mo by metal organic chemical vapor deposition (MOCVD) or other similar technique 15 (such as MBE). The substrates generally used are sapphire, GaN and SiC. In a particular embodiment of the invention, a etch stop layer 409 formed of a material such as InGaN or AlGaN is buried in the η-GaN layer. The n-GaN or InGaN layer continues to grow as layer 1108 above the etch stop layer. A plurality of GaN-InGaN quantum wells 11〇2 are grown and followed by a P-type GaN layer 1103. The complete LED heterostructure stack produced in this stage is shown in Figure 11A. As shown in Fig. 11B, a mirror 1104 is then deposited on top of the p-GaN layer 1103. The reflector can be metallic, including a suitable layer of metal, such as silver or gold deposited by sputtering or evaporation. Alternatively, the reflector may be comprised of a 32 200847482 dielectric multilayer stack in the form of a distributed feedback (DBR) or omnidirectional reflector (ODR). Such a construction can be deposited in a splashing manner using deposition techniques such as PECVD. As shown in Fig. 11C, the heterostructure of Fig. 11B is then bonded to a 5 base 1105. The substrate 11〇5 is preferably a metal alloy which may have good thermal and electrical conductivity, but may also be composed of other materials such as siC or Si. Additional layers may be deposited on the mirror 1104 prior to the bonding operation to aid in the bonding operation.

In the final conventional fabrication step, the sapphire substrate 1110 is then removed using a 10 laser lift or other similar technique to provide a heterostructure as shown in Figure 11D. While there may typically be no etch stop layers, this configuration may still result in a well-formed conventional device. The laser lift-off procedure roughens the surface 1101 of the n-GaN layer. (typically 5 〇 nm to 300 nm grade). In a more conventional device, this surface may be further coarsened 15 to improve light extraction. At one level of the invention, the size of the photonic strip structure pyramid is relatively large in surface roughness, so that no polished surface is required prior to defining the pattern. Fig. 11E to 111 or 11J show the steps of increasing the procedure required for making the final apparatus in accordance with the present invention' as shown in Figs. 11 and 11J. With respect to the embodiment of the procedure of the last -12 step shown in Fig. 111, the last stop layer η 〇 9 is not present in the aforementioned steps 11 Α to 11 ,, but exists in the implementation of the apparatus as shown in Fig. In the example. Figure 11E shows the deposition of the masking layer. In particular, a method step is shown in the figure whereby a hard mask layer 1106 is deposited for subsequent transfer of the pattern required by 33 200847482 to the n-GaN layer 1101. This may consist of a Si 2 or SUN* deposited by PECVD, or it may be a metal deposited by sputtering or evaporation. A layer of photoresist 1107 is then deposited on the hard mask 1106. However, in some cases the hard mask layer may be omitted and the photoresist 1107 deposited directly onto the 5 n-GaN layer 1101.

Due to the large size of the chamfered cone features, the photoresist 1107 can define the desired tiling pattern using standard UV lithography. The lateral shape of the exposed area may correspond to the cross section of the desired chamfer, or may be a simpler shape such as a square. The exposed photoresist is then developed to leave a separate island of material corresponding to the desired apex position of the chamfer cone, as shown in Figure 11F. If the hard mask 1106 is present, it is dry etched using a ruler, ICP or a similar procedure. This step transfers the graphic definition from the photoresist 11〇7 to the hard mask 1〇6 as shown in Fig. 11G. The remaining photoresist 4〇7 is then stripped.

Next, the n-GaN layer 1101 is wet etched using an isotropic wet etch crystal, 15 as shown in FIG. A preferred method of wet etching G aN is to use a bath temperature ranging from room temperature to 1% to 1 Torr to a concentration range of 11 solutions. The range between the etchings k is about 45 minutes. An optional wet residual agent contains or HsPO4. The crystal plane of the hexagonal chamfer cone formed by the etching process is the { 10-M } plane of the corpus callosum. They form an angle of 20 58·4 with the bottom of the pyramid. . Finally, if a hard mask 4〇6 is used, it can be removed by a suitable wet or dry process to leave the final structure shown in the UI diagram. The absolute size of the chamfered cone will be largely determined by the size of the hard mask area. The perimeter of the hard mask will provide a last-stop barrier and allow the top surface of the GaN® (c-plane) to be down-cut to form a chamfer. The chamfer cones of 34 200847482 are nominally straight (four) and are equal in distance to any (four) f-direction on the side hard material _ circumference. Secondly, the diameter of the (iv) cone is also determined by the selectivity_rate of the plane of the different crystals and hence by the total paste time. In an alternative embodiment, the surname stop layer, 11〇9, is buried 5 in the n-type doping material between the layer blue and the swollen. The remaining stop reed includes: such as the rule, InGaN material, but other materials can also be used ^ The presence of the stop layer 1109 allows the formation of a truncated chamfer cone (reverse cone) and also a diagonal pyramid structure Correct control while the last name determines the chamfer

The absolute diameter of the body. The insertion of the second paste is shown in the enlarged top view of the truncated chamfer cone 10 structure. + Figure 所示 shows a broom electron micrograph of the chamfer cone made for this program. In this case, the pyramids are isolated and formed using the preferred fabrication embodiment, and the {1 (Μ.1} small crystal interface of the crystal is shown at 7〇1. In the preferred embodiment, layers 1101, 11〇 are included. The composite 15 upper region 1 of 9 and 11〇8 is placed above the illuminating structure. Therefore, light exits from the layer 11〇2 and undergoes multiple internal reflections before being finally discharged through the 1101 region.

A thick n-GaN growth region must reduce the defect density to form a quality quantum well (QW) layer and thus improve the internal quantum efficiency of the LED. For the benefit of manufacture, the upper regions (layers 11〇1, 11〇9 and 11〇8) act as a protective layer for the fragile 20 weak QW region n〇2, preventing it from being damaged during wet etching of the chamfer cone and The surface recombination of the QW region is minimized. The engraving of the QW region also adversely affects the total illumination output of the LED by reducing the maximum effective illumination area. In addition, with regard to the improvement of the optical pick-up, the required chamfer cone 35 200847482 is a grade of 1.75 μm, and the direct control is located at the center of a distance of 2.5 gm. This size limits the minimum thickness of layer 1101, so the pyramid is preferably located on a thick n-GaN layer. At the same time, in order to improve the pupil output, the number of trap modes in the heterostructure is reduced by etching to reduce the total thickness of the LED waveguide region. This 5 overlaps the photonic band structure with a larger percentage of trapping modes to provide the exit pupil as shown in FIG. In addition, n_GaN & is highly conductive and this twin is made to minimize the independent current spreading layer deposited on the top surface of the photonic strip structure. The independent current spreading layer of the deposit adversely affects the light output of the device. The results of the numerical simulation are shown in Figures 12A, 12B and 12C, illustrating the performance of a typical chamfer cone photonic band structure. The 2-axis display shows an increase in total light output compared to a non-patterned LED with a reflector. The results are plotted along the axis 12〇2 as a function of the distance between the photonic band structures (Wnm). The fill portion is defined as diameter/pitch* 1〇〇. 15 Figure 12A shows a chamfered cone photonic crystal in a central 30 compared to a non-graphic LED having a bottom reflection. The light in the cone is raised. The results show a maximum increase of 4.90 for an optimized microcavity design for a pitch of 1500 nm and a filled portion of 100%, and below the QW region at a position of d - 0 · 6 / λ η ~ 131 nm. These parameters correspond to a device having a chamfer diameter of about 1.5 μm separated by a distance of between 1.5 μm and 20 μm. The simulation was carried out using a 2D finite-difference time domain method as in the case of the pyramidal cone. Thus, in this case, the results of this experiment are also expected to provide even larger pupil values. The UB diagram has a lattice constant and a fill portion function as compared to a 36 200847482 light having a bottom reflector without a patterned reflector. As shown in the i2A figure, the focus of the results is that the optimal operating range appears at a distance of !5_Well filling is divided into %, and under QWs there is "optimized microcavity design." 5 After taking the figure, the figure shows that the light with the chamfered cone-shaped photonic crystal structure is at 30. The percentage in the cone. As seen in the figure, 39% of the light emitted by the device can be directed to have a 3 垂直 perpendicular to the surface of the device. In the center cone of the half angle. This is equivalent to 57% more light than the __ special illuminator m in an oriented cone. The increase in directivity is due to the ordered 10 arrangement of the chamfer cones and the well defined oblique side walls of the chamfer cone. The oblique side wall can be 3 较 compared with the normal straight side wall, the surname, and the air rod. Approximately 15% more light is provided inside the cone. Figure 13 is a cross section of the light distribution of a chamfered pyramid structure on a plane. The result is plotted as a function of the far field angle 1301 along the X-axis and indicates that the light intensity 15 1302 is normalized by a non-patterned LED with a reflector at the bottom. far

The field pattern is the vertical line of the surface of the reference LED. Figure 13 shows the far field pattern of an LED having a lattice constant of 1500 nm and a pyramidal diameter of 1500 nm. The total light output of the LED is increased to 2.98 times that of a light-emitting device having a reflector and an optimized microcavity. The increase in the 30° cone is 4.85 times and 30. 20 of the cone contains 38.6% of the total light emitted. Table 2 below shows the same green GaN LED as a simple Lambertian emitter containing an etched air rod one-order photonic crystal LED, and a pyramidal photonic crystal LED containing an etched chamfer cone, expressed as a percentage of total emitted light. In a narrow 30. A comparison of the light emitted within the cone angle. For the 37 200847482 photonic crystal device, the size is optimized at 30. The largest percentage of light is extracted from the cone. The first-order photonic crystal size is composed of a lattice air rod having a pitch of 35 〇 nm and a diameter of about 21 〇 nm and an etching depth of about 12 〇 11111. The chamfered cone photonic crystal size is as described above. Device Type Lambert LED Photonic Crystal LED Pyramid Photonic Crystal LED Light in a 30° Cone 24.9 34.9 38.6

As can be seen, the increase in directionality can be obtained using a more optimized structure.

The figures 15A and 15B illustrate that the light that can be achieved when a photonic band structure is placed in a microcavity light-emitting device is increased. In this example, a conventional photonic crystal having a pitch of 5 〇〇 nm and having a simple reflector is compared with a chamfered cone photonic crystal having the same pitch but also having a microcavity reflector. The overall light rain 1502 is plotted as a function of the photonic crystal fill portion 1501 in Figures 15A and 15B. In Fig. 15A, solid line 1503 indicates that a total light output from a non-figure LED having a reflector is added to the output. Dotted line 1504 represents a total optical output enhancement of a photonic crystal having both a microcavity and a reflector compared to a non-patterned LED having a reflector. Figure 15B highlights the increased light extraction effect due to the microcavity effect. Dotted line 1505 shows that when combined with a microcavity, normalized to a non-patterned LED having a reflector and a microcavity, the photon effect of the photonic crystal is increased with the solid line 1503, showing that there is only one simple reflection from one. The result of the non-patterned LEDs normalized to the same device. Therefore, the increase in the difference caused by the combined effect is clearly visible. 38 200847482 It will be appreciated by those skilled in the art that the present invention enables high efficiency and directivity illumination devices to be implemented, thereby making it a useful alternative source of light for possible sources. The present invention is elaborately designed with pyramidal projections and chamfered cone etching and its tiling arrangement, which is designed to produce a pair of 5 effective optical coupling optimized photonic band structures while controlling the light emitted by the device. The spread and the nature of the far field. The utility of the device can be improved by providing a simple graphical definition and etching procedure to make the device, and the device can be readily utilized to enhance existing techniques for making more conventional devices.

BRIEF DESCRIPTION OF THE DRAWINGS [10] Figure 1 shows a cross section of the device proposed by the invention; Figure 2A shows a pyramid arranged in a regular square lattice; and Figure 2B shows a pyramid arranged in a 12-symmetric quasicrystal. Figure 3 shows the normalized illumination intensity of a GaN LED as a function of the distance between the mirrors of the quantum wells; 15 Figures 4A to 4D illustrate the fabrication of a light-emitting device based on a high-speed flip chip package;

4E to 41 are diagrams showing an additional manufacturing step of fabricating the pyramidal photonic crystal structure in the upper layer of the device shown in FIG. 4D; FIG. 5A is a view showing a pyramidal photonic crystal-LED and a 20-free graphic structure. The device is increased by a 30° cone compared to the pupil; Figure 5B shows that for a pyramidal photonic crystal-LED, the total pupil output is improved compared to a device without a graphic structure; Figure 5C shows the different pyramidal photons for different angles. Percentage of light in a 30° cone for a crystal illuminating device; 39 200847482 Figure 6A shows a far field pattern for a photonic crystal-LED configuration in accordance with a preferred embodiment of the present invention; Figure 6B shows A far field pattern of a photonic crystal-LED structure according to another preferred embodiment of the present invention; 5 Figure 7A shows an electron micrograph of an isolated pyramid formed using the fabrication method of the invention; An electron micrograph of a photonic quasi-crystal configuration of a pyramid formed by the fabrication method of the present invention; FIG. 8A is a conventional photonic crystal LED compared with a photonic crystal-led with a microcavity The light-emitting of the non-graphical structure LED increases the pattern of the filling portion of the photonic crystal. The image of the photonic crystal-filled portion of the LED is improved compared to the light-emitting of the non-graphical LED with and without the microcavity. One of the graphics; and, the first solid angle pyramidal photonic crystal-LED, compared to the optical output of a non-graphical LED, improves the pattern of the core and thickness of the heterogeneous structure. Figure 10 is a cross-sectional view of a chamfer-cone type device; Figures UA to 11D illustrate a manufacturing method based on a high-speed flip chip package process for fabricating a light-emitting device; Figure E to Figure 111 shows the image shown in Figure iij An additional manufacturing step of making a chamfered or truncated cone-shaped photonic crystal structure in the upper layer of the device; ° Figure 12A shows a pyramidal photonic crystal-LED compared to a non-graphical device at -30. The light in the cone did not increase. 40 200847482 Figure 12B shows that the pyramidal photonic crystal _ fused with _ no graphic structure compared to the total optical output of the device; Figure 12C shows different pyramidal photonic crystal illuminating devices at 3 〇. Percentage of light in the cone; 5 Figure 13 illustrates a far field pattern characteristic of a photonic crystal-LED configuration in accordance with a preferred embodiment of the present invention; and Figure 14 illustrates a method of fabrication using the fabrication method of the present invention. An electron micrograph of the pyramid of the isolated chamfer cone; Figure 15A shows a conventional photonic crystal-led light with a microcavity pyramid type 10 photonic crystal-LED compared to a non-patterned LED汲 提高 提高 提高 提高 ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; Graphics. 15 [Description of main component symbols] 101...Corner cone 403···ρ-type layer 102···Top layer 4〇4...Mirror 103···Multiple quantum well structure 405.··Base 104···ρ-type Layer 406...hard mask layer 105···reflective layer 407...photoresist layer 106...carrier 408...layer 107·.recess stop layer 409...remaining stop layer 401···!!, doping layer 410 ...Sapphire Matrix 402.··Multiple Quantum Wells 1001···Corners 200847482 1004.. P-type Layer 1005.. Reflective Layer 1006.. Pallet 1101...n-type Doping Layer 1102.. GaN-InGaN Quantum well 1103.. p-type layer 1104.. mirror 1105.. substrate 1106.. hard mask layer 1107.. photoresist 1109.. etch stop layer 1110.. substrate

t 42

Claims (1)

200847482 X. Patent application scope: 1. A light-emitting device (LED) comprises: a first layer comprising a first semiconductor material having a first type doping; 5 a second layer comprising a second type doped a semiconductor material; and a light generating layer disposed between the first layer and the second layer, Wherein the first layer has an upper surface away from the light generating layer and a lower surface adjacent to the light generating layer, and wherein 10 light generated in the light generating layer is formed by the LED structure via the upper surface of the first layer, the first The layer further comprises a pyramidal or truncated conical upper surface protrusion tile arrangement of the first semiconductor material, the protrusion being surrounded by a material different from the refractive index of the first semiconductor material, wherein the tiling of the protrusion Configuring a photonic strip structure with the surrounding material, and wherein the projections and their tiling arrangement are arranged such that light formed by the LED structure through the upper surface is substantially more directional than light from a Lambertian source source . 2. A light emitting device (LED) comprising: a first layer comprising a first semiconductor material having a first type of doping; and a second layer comprising a second semiconductor material having a second type of doping And a light generating layer disposed between the first layer and the second layer, wherein the first layer has a surface away from the upper surface of the light generating layer and a lower surface adjacent to the light generating layer, and wherein the light generating layer is in the light generating layer The generated light passes through the upper surface of the first layer 43 200847482 by the LED structure, the first layer further comprising a first semiconductor material extending from the upper surface toward the light generating layer, and a refractive index and the first semiconductor a chamfered or inverted truncated dent tiling arrangement of materials having different materials, wherein the tiling arrangement of the dent and the first semiconductor material surrounding the rib comprises a photonic band structure, and wherein the dent and the cover thereof The arrangement of the tile arrangement is such that light emerging from the structure of the LED through the upper surface is more directional than that obtained from a Lambertian source. 3. The LED of claim 1 or 2, wherein the tiling arrangement comprises a photonic crystal, a photonic quasicrystal or an amorphous tiling pattern. 10 4. The LED of claim 3, wherein the tiling arrangement comprises a photonic crystal, a photonic quasicrystal, or an amorphous tiling pattern. 5. The LED of any of the preceding claims, wherein the tiling arrangement comprises a defect. 6. The LED of any one of claims 1-5, wherein the protrusion 15 or the indentation has a size greater than Ι.Ομπι. 7. The LED of any one of clauses 1-5, wherein the protrusion or indent has a size greater than 1·5 μm. 8. The LED of any of claims 1-5, wherein the protrusion or indent has a size greater than 2. Ομπι. The LED of any one of claims 1-5, wherein the protrusion or indent has a size greater than 2.5 μm. 10. The LED of any of claims 1-9, wherein the tile arrangement has a pitch greater than 1.5 μm. 11. The LED of any one of claims 1-9, wherein the tiling 44 200847482 is configured with a spacing greater than 2.0 μπΐ. 12. The LED of any of claims 1-9, wherein the tile arrangement has a pitch greater than 2.5 μm. 13. The LED of any one of claims 1-9, wherein the tiling 5 is disposed at a pitch greater than 3·0μηι. 14. The LED of any of the preceding claims, further comprising a light reflector arranged adjacent to the second layer of the second semiconductor material such that the second layer is between the light generating layer and the reflector. 15. The LED of claim 14, wherein a spacing distance between the light generating layer and the optical reflector comprises a microcavity that increases the amount of light that propagates toward the surface above the first layer. 16. The LED of claim 15 wherein the projections or indentations and their tile configurations are configured to optimally cooperate with the microcavity effect to further increase the efficiency of light extraction from the LED. The LED of any one of claims 1 to 16, wherein the light that appears through the upper surface from the L E D structure exceeds 35 % by a half angle at a half of a pair of surface normals. Inside the cone. 18. The LED of any of claims 1-16, wherein more than 37% of the light emerging from the LED structure through the upper surface is within a cone of 30° to a half of the surface normal 20 . 19. The LED of any of claims 1-16, wherein more than 38% of the light emerging from the LED structure through the upper surface is within a cone of 30° at a half of a pair of surface normals. 20. The LED of any one of claims 1 to 16, wherein more than 45 200847482 40% of the light generated by the LED structure passing through the upper surface is 30 at a half angle of a pair of surface normals. Inside the cone. 21. The invention as claimed in any one of the preceding claims, wherein the light distribution from the LED structure through the upper surface of the 5 10 15 20 is concentrated on a relative surface of less than or equal to 6 〇. Within the angle. 22. The LED of any of claims 1 to 16, wherein the light distribution manifested by the LED, the structure through the upper surface is concentrated on - the upper surface is less than or equal to 50. Within the angle. 23. The ED of any of the above-mentioned patents, wherein the light distribution exhibited by the structure of the LED through the upper surface is concentrated on a relative upper surface of less than or equal to 4 〇. Within the angle. 24. The LED of any of clauses, wherein the light distribution manifested by the LED structure through the upper surface is concentrated on an upper surface that is less than or equal to 30. Within the angle. 25. (4) The LED of any of the patent applications, wherein the first layer is self-contained-embedded in the first semiconductor material, and the first semiconductor material is used in the first semiconductor material. The protrusion X formed thereon is formed by a stopper-surface extension, or such that the first semi-conductor = the indentation in the material only extends to a surface of the side stop material layer. 26. The coffee of any of the patent claims, wherein the first material comprises iM doped, GaN. The method of including the protruding portion of the p-doping range item 1 includes the steps of the method for producing a light-emitting device (led) having a layer as claimed in the patent application. 46 200847482 5 10 providing a light emitting device heterostructure comprising a first layer comprising a first type doped first semiconductor material and a second layer comprising a second type doped second semiconductor And a light generating layer disposed between the first and second layers, wherein the first layer has an upper surface away from the light generating layer and a lower surface adjacent to the light generating layer, and wherein in the light generating layer The generated light is transmitted through the LED structure through the upper surface of the first layer, and an etch mask is formed on the first layer, the reticle includes an island block of the reticle material, and the island block is located at a position corresponding to a predetermined tiling arrangement. The step of forming the photomask includes the steps of: depositing a layer of photoresist on the first layer; forming a photoresist pattern by exposure according to the pre-twisted tile arrangement; 15 spear, to the unexposed photoresist and leave the island block of photoresist in the corresponding position; the tile is placed in the first layer along the (10) flat (four) directional semiconductor material to - in the fresh material a pyramidal or truncated cone shaped protrusion of a semiconductor material; 20 The island block of the enamel material is left to leave a predetermined pyramid. The sacred 4 watt configuration is combined with a different refractive index material to form a photonic band structure. j 28. The method of applying the stipulations of the stipulations, wherein the step of forming further comprises the steps of: 47 200847482 depositing a hard reticle material on the first layer before the step of depositing the photoresist layer; Removing the hard mask material after the step of removing the photoresist to leave a hard mask material under the island of photoresist; removing the photoresist_remaining island block to leave a mask, the touch mask including An island block of hard reticle material at a location where the tiling is predetermined. 29. A light-emitting device (LE_ method) for producing a first layer having a dimple as claimed in claim 2, the method comprising the steps of: providing a light-emitting device heterostructure, the heterostructure comprising an inclusion a first layer of a first doped first semiconductor material, a second layer comprising a second semiconductor material having a second type of doping, and a light generating layer disposed between the first and second layers, wherein the first The layer has a top surface away from the light generating layer and a lower surface adjacent to the light generating layer and wherein light generated in the light generating layer emerges from the LED structure through the upper surface of the first layer, on the first layer Forming an etch mask, the reticle including a missing reticle material corresponding to a predetermined tiling configuration, wherein the step of forming the reticle comprises: forming a photoresist pattern by exposure according to the pre-tile configuration; and, removing An unexposed photoresist leaving a missing photoresist island at a location corresponding to a predetermined tile configuration; by first isotropically wet etching the first semiconductor 48 200847482 body material along a predetermined crystal plane to - a predetermined depth to form a pyramid or a cone-shaped indentation at a position below the island block of the first 1st material; the removal of the remaining mask material in the _ chamfer cone or the inverted cone type dent The tiling arrangement includes - the surrounding - the semiconductor material has a different refractive index = and = constitutes a photonic band structure. 30. The method of claim 29, wherein an etch history is formed... The step further comprises the following steps Step · v v reticle 10 before the step of depositing the photoresist layer on the #th hard reticle material; deposit a layer 15 20 on the layer after the step of removing the photoresist remove the hard reticle material in the absence of light A missing hard reticle material is left underneath the resist island block; and the remaining smear_left reticle is removed, and the side reticle leaves the island block constituting the missing hard reticle at a position where the predetermined tiling is disposed. The method of any one of clause 27, wherein the first layer of the luminescent material f heterostructure comprises a layer of etch stop material embedded in the pre-freezing degree of the first semiconductor material. The method of item 31, wherein the predetermined depth is in accordance with the illuminating garment One needs thickness. 33. ΓΙΓ ΓΙΓ 第 第 第 第 第 第 第 第 第 第 第 第 第 第 第 第 第 第 第 第 第 第 第 第 第 第 ' ' ' ' ' ' ' ' ' ' ' ' ' ' ' ' ' ' ' ' The method of any of the items jj, wherein the optical device heterostructure is manufactured using a high speed flip chip packaging process. 50