JP4449113B2 - 2D display device - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
  The present invention relates to a self-luminous element.UseThe present invention relates to a two-dimensional display device.
[0002]
[Prior art]
Conventionally, a flat display in which light emitting diodes (hereinafter referred to as “LEDs”) are arranged, a backlight of a liquid crystal display, a light source for projection, and the like have been tried. However, the luminous efficiency of the LEDs is not sufficient, and a large area is made uniform. The problem is that it is difficult to emit light. Further, even in an electroluminescent (hereinafter referred to as “EL”) display, luminous efficiency is not sufficient.
[0003]
[Problems to be solved by the invention]
Luminous efficiency can be expressed as internal quantum efficiency x external extraction efficiency. The external extraction efficiency is mainly determined by the difference in refractive index between the components constituting the LED and EL. Therefore, a structure for extracting light from the sapphire substrate side with a GaN-LED as shown in FIG. 24 will be specifically described. The refractive indexes of the layer (GaN) 2 in contact with the light emitting layer and the sapphire substrate 6 are 2.46 and 1.76, respectively. The emission angle distribution of the light emitting layer 1 is isotropic. That is, the solid angle is 4π. Light rays exceeding the critical angle determined by the refractive index difference at the interface with the sapphire substrate 6 are confined in the layer (GaN) 2 in contact with the light emitting layer. Here, the critical angle is 46 °, and the solid angle in this range is 2π × 0.3. Even when 100% of light is reflected by the surface of the p-electrode 3 on the back surface, only 30% of light enters the sapphire substrate 6.
[0004]
Similarly, light rays exceeding the critical angle of 58 ° are reflected from the sapphire substrate 6 to the back surface side as shown in FIG. 24 even at the interface incident on the ball lens 8 (refractive index 1.5) as shown in FIG. Eventually, only 20% of the light is emitted to the front.
[0005]
The same applies to a structure in which the sapphire substrate side is the back surface and a reflective film is formed on the back surface. That is, the structure of a general GaN-LED is a structure in which the sapphire substrate 6 is below as shown in FIG. 26A. The angular distribution of the light emitted from the light emitting layer is 4π, but the light emitted to the sapphire substrate 6 side exceeds the critical angle determined by the refractive index difference with the sapphire substrate 6. It is totally reflected at the interface and travels toward the transparent electrode 25 side. When ITO is used as the transparent electrode 25, the refractive index is generally larger than that of the sapphire substrate 6 (1.8 to 1.9), and the light beam totally reflected at the interface with the sapphire substrate 6 is totally reflected at the interface of ITO, and externally. Does not come out. The light beam that has passed through the sapphire substrate 6 is reflected by the reflector on the back surface and travels toward the transparent electrode 25 side.
[0006]
Of the light rays that have passed through the transparent electrode 25, light rays that exceed the critical angle determined by the ratio between the refractive index of the transparent electrode 25 and the refractive index of the ball lens 8 shown in FIG. 26B are totally reflected. Eventually, the ratio of light rays that can enter the ball lens 8 depends on the critical angle determined by the ratio between the refractive index of GaN and the refractive index of the ball lens 8. If light rays leaking from the side face are ignored, the total reflection is about 20%.
The same applies to materials other than GaN.
[0007]
Furthermore, the external extraction efficiency becomes a problem for EL devices (organic and inorganic). Many materials constituting the organic EL have a refractive index of about 1.5, but the external extraction efficiency is about 25% at most.
[0008]
Another problem is that when the light emitting area is increased in order to increase the total luminous flux, the effective light emitting area cannot be increased due to the concentration of current near the electrodes. FIG. 27 shows a light emission intensity distribution example when the input current is changed by the LED. That is, as shown in FIG. 27B, the change in the emission intensity on the aa line passing through the n-electrode 7 is as shown in FIG. 27A. As the distance from the n-electrode 7 increases, the emission intensity decreases. This tendency is remarkable when the input current is increased, and it is found that it is difficult to obtain a uniform emission intensity distribution.
[0009]
  The present invention has been made in view of such problems, and a self-luminous element capable of improving luminous efficiency.UseTo provide a two-dimensional display deviceTo do.
[0010]
[Means for Solving the Problems]
  The two-dimensional display device of the present invention isA light emitting layer;Transparent electrode layerAnd a layer in contact with the light emitting layer, and the light emitting layer formed on the opposite side of the layer in contact with the light emitting layer.Reflective functionIncluding electrodesAboveOf the layer in contact with the light emitting layer,the aboveLight is emitted from the surface opposite to the light emitting layerOne or moreSelf-luminous elementDimensional display device with one pixelInThe self-luminous element is (i) the refractive index of the light emitting layer is about 1.5, which is smaller than the refractive index of the transparent electrode layer, and the refractive index of the layer in contact with the light emitting layer is the refractive index of the light emitting layer. Equal to or greater than the refractive index of the light emitting layer, (b) aboveThe layer in contact with the light emitting layer has a shape in which the side surface is open in the direction of emitting light, and the cross-sectional shape of the side surface becomes a part of a parabolic shape.Thus, when the size L1 on the emission side of the layer in contact with the light emitting layer is 100, the parabolic focal length is 8.2, the size L2 of the light emitting layer is 37, and the thickness d of the layer in contact with the light emitting layer is d = 66, (c)At least a part of the side surface isthe aboveIt has a shape that totally reflects light from the light emitting layer.
[0014]
  Self-luminous element of the present inventionUseAccording to the two-dimensional display device, the side surface of the layer in contact with the light emitting layer has a shape that is open in the direction of emitting light, and at least one part of the side surface has a shape that totally reflects light from the light emitting layer. To improve the external extraction efficiencyit can.
[0015]
DETAILED DESCRIPTION OF THE INVENTION
Embodiments of the present invention will be described below.
First, embodiments of the invention relating to self-luminous elements such as LEDs and EL will be described with reference to FIGS.
[0016]
In the self-luminous element, the light beam confined inside under the total reflection condition is guided in a direction orthogonal to the substrate while being repeatedly reflected at the interface. For example, in the case of a GaN-LED structure in which the back surface is an electrode and the sapphire substrate is located on the front surface, the light is guided while being totally reflected at the sapphire substrate and the GaN interface and being reflected by the opposing electrode surface. At this time, reflection on the metal surface always involves absorption, and absorption also occurs in the light emitting layer when crossing the light emitting layer, so that the amount of light attenuates as the number of reflections increases. A part of the light is emitted from the end face to the outside, but is in a direction perpendicular to the substrate and cannot be an effective light beam.
The present invention is a structure that effectively uses the ineffective light emission in the side surface direction, and specifically has a structure in which the side surface is inclined from the normal direction of the substrate.
[0017]
This inclination angle is set so that the interface satisfies the total reflection condition for light rays parallel to the substrate. This critical angle is defined as θ1. By satisfying this condition, the side total reflection condition can be satisfied for almost all light emission. Assuming that the metal electrode is positioned on the back surface, light rays having an angle lower than the angle parallel to the substrate are reflected by the back electrode to satisfy the total reflection condition of the side surface. However, there are cases where light rays that reach the side surface directly without being reflected by the back electrode are not satisfied. Therefore, it is desirable that the position of the light emitting layer is as close to the back electrode as possible.
[0018]
Next, the total reflection condition at the interface with the substrate is considered. A line connecting the boundary point of the interface between the side surface and the substrate facing each other by the light beam emitted from the end of the light emitting layer partitioned by the inclined side surface to the substrate side is the maximum incident angle to the substrate. Let this critical angle be θ2. This angle is set so as not to exceed the critical angle.
[0019]
By satisfying the above two conditions, almost all light rays are emitted to the substrate side. A shape that satisfies these two conditions will be specifically described with reference to FIG. As shown in FIG. 1, the shape satisfying these two conditions has a side surface that is a part of a parabolic shape.
In the self-luminous element shown in FIG. 1, light generated from the light emitting layer 1 is emitted from the sapphire substrate 6 through the layer (GaN) 2 in contact with the light emitting layer.
[0020]
In FIG. 1, a light emitting layer 1 is a layer that emits light by applying a voltage between a p-electrode 3 and an n-electrode (not shown). The layer (GaN) 2 in contact with the light emitting layer is made of GaN and is in contact with the light emitting layer 1. The critical angle θ1 determined by the refractive index of GaN and the refractive index of air is 24 °, and the critical angle θ2 determined by the refractive index of GaN and the refractive index of the sapphire substrate 6 is 46 °. The parabolic shape satisfying these two conditions is, for example, when the output side size L1 is 100, the parabolic focal length is 6.2, the light emitting layer size L2 is 55.6, and the GaN thickness d. Becomes 70.
[0021]
A sapphire substrate 6 is bonded to the light emission side of the layer (GaN) 2 in contact with the light emitting layer.
The p-electrode 3 is formed on the opposite side of the light-emitting layer 1 from the layer (GaN) 2 in contact with the light-emitting layer. The p-electrode 3 is in contact with the light emitting layer 1 through the p-side GaN 19. The p electrode 3 is made of metal and has a reflection function.
[0022]
In FIG. 1, the structure composed of the layer (GaN) 2 in contact with the light emitting layer, the light emitting layer 1, and the p-side GaN 19 is shown in detail as shown in FIG. That is, the layer (GaN) 2 and the light emitting layer 1 in contact with the light emitting layer in FIG. 1 correspond to the n-side GaN 17 and the light emitting layer (GaInN) 20 in FIG. In FIG. 1, only the p-side GaN 19 is provided between the light-emitting layer 1 and the p-electrode 3, but actually there are two layers of AlGaN 18 and p-side GaN 19 as shown in FIG. 2. Here, since the light emitting layer (GaInN) 20 and the AlGaN 18 are sufficiently thin with respect to the wavelength of light, the space between the p electrode 3 and the sapphire substrate 6 can be represented by the refractive index of GaN. Further, as shown in FIG. 1, the AlGaN 18 of FIG. 2 can be omitted.
[0023]
As described above, the layer (GaN) 2 in contact with the light emitting layer preferably has a parabolic shape as shown in FIG. 3A in order to improve the external extraction efficiency. However, the layer (GaN) 2 in contact with the light emitting layer is not limited to the above-mentioned paraboloid shape. 3B and C, a quadrangular pyramid as shown in FIG. 4A, and a split shape as shown in FIGS. 4B and 4C are hexagonal and square, and each cross-sectional shape is a variation. Parabolic shapes and the like can be mentioned. In short, the layer (GaN) 2 in contact with the light emitting layer has a side surface that is open in the direction of emitting light, that is, the side surface is inclined so that the back surface is convex with respect to the emission surface. If at least a part of the side surface has a shape that totally reflects light from the light emitting layer, the external extraction efficiency can be improved.
[0024]
Next, an embodiment of the invention relating to the lighting device will be described with reference to FIGS.
The practical dimensions of the self-luminous element described above are determined by how much the layer (GaN) 2 in contact with the light emitting layer is thickened. When the layer (GaN) 2 in contact with the light emitting layer is set to 7 μm, for example, the chip size is 10 μm, and it is necessary to arrange a plurality of light sources in order to obtain an absolute light amount. Various arrangements of the self-luminous elements can be considered as shown in FIGS. A one-dimensional structure having a parabolic or trapezoidal cross-sectional shape as shown in FIG. 7 is also conceivable.
[0025]
8 and 9 show examples of structures realized as the lighting device. The p-electrode 3 of each self-luminous element shown in FIG. 9 is electrically connected to the p-electrode bonding pad 11 of the submount substrate 13 shown in FIG. The n-electrode 7 is formed on the side surface in order to make the light emitting region as small as possible. 9A is an ineffective light emitting region, and is electrically connected to the n-electrode bonding pad 12 of the submount substrate 13 by solder or the like. The number of divisions is determined by the required amount of light, driving conditions, the thickness of the layer (GaN) 2 in contact with the light emitting layer due to process restrictions, and the like.
[0026]
As shown in FIG. 9, the divided elements are driven in parallel. On the n side, each divided element is wired in series with an electrode formed on the side surface. In order to inject current uniformly into each divided element, it is necessary to reduce the n-side wiring resistance or increase the resistance in series with each element. When the series resistance of each element is increased, the drive voltage increases and the efficiency of the series resistance decreases. In this sense, it is desirable to reduce the n-side wiring resistance. This structure can form a relatively thick wiring electrode by using the side surface. As a result, the wiring resistance can be reduced, and driving can be performed without variation among the divided elements.
[0027]
Further, as shown in FIG. 10, the wiring method may employ a structure in which the entire light emitting region is divided into a plurality of parts and each is connected in series. That is, as shown in FIG. 10B, the rear surface of a part of the divided projections (GaN) 16 and the side surfaces of the projections (GaN) 16 adjacent thereto are electrically connected. When the same material as the example described in FIG. 9 is used, it can be driven uniformly even if the electrode film thickness is relatively thin. However, the series division number times drive voltage rises.
[0028]
As for n-side electrode formation, the sapphire substrate can be removed after crystal growth, and the transparent electrode can be formed in a planar manner. In this case, since the resistance may be high only with the transparent electrode, it is also possible to form a bus electrode composed of the mesh electrode 24 as shown in FIG. 11 or the stripe electrode 27 as shown in FIG.
[0029]
With this structure, it is possible to emit nearly 100% light to the sapphire substrate side, but in order to efficiently extract it into the air, the sapphire substrate is processed into a ball lens shape or a ball lens made of a material having a refractive index close to that of the substrate. It is desirable to form. Here, the ball lens is a spherical lens centering on the interface position between the layer (GaN) 2 in contact with the light emitting layer and the sapphire substrate 6 as shown in FIG. The material for bonding the sapphire substrate 6 and the ball lens 8 is preferably a material having a refractive index close to both. This is because the reflection at the interface between the sapphire substrate 6 and the ball lens 8 is reduced and the external extraction efficiency is increased.
[0030]
In general, many materials used for optical lenses and adhesive materials for bonding a substrate and a lens are smaller than the refractive index of sapphire. When the refractive index of the ball lens is 1.5, it is possible to improve the overall external extraction efficiency by reviewing the shape of the layer (GaN) 2 in contact with the light emitting layer. In determining the total reflection condition between the substrate and GaN described above, the substrate is designed with a refractive index of 1.5. At that time, the critical angle is 38 °. When L1 is 100, the focal length of the paraboloid is 5.4, the light emitting layer size L2 is 49, and the depth d is 88.
[0031]
Taking it one step further, by setting the substrate refractive index to air, the extraction efficiency into the air can be made close to 100% without the ball lens. At this time, if the critical angle is 24 ° and L1 is 100, the focal length of the paraboloid is 4.1, the light emitting layer size L2 is 37, and the depth d is 133.
[0032]
As described above, by increasing d with respect to L1, a lens function can be added, and the entire lighting device can be simplified. On the other hand, since the size of the light emitting layer is reduced, it is necessary to increase the chip size in order to obtain the same amount of light. Therefore, the ratio between L1 and d is determined within the constraints of the yield of the LED manufacturing process, the number of substrates that can be obtained by the relationship between the substrate size and the chip size, the overall design of the lighting device, and the like.
[0033]
Next, an embodiment of the invention relating to a method for manufacturing a self-luminous element will be described with reference to FIGS.
An example of the process here is a method using reactive ion etching. That is, normal planar crystal growth is performed on a sapphire substrate, and then SiO 2₂The GaN layer is divided into inclined side structures by reactive ion etching using the above as a mask. A sectional view of the final self-luminous element is as shown in FIG.
[0034]
Next, a method for manufacturing a self-luminous element using reactive ion etching will be described with reference to FIGS.
First, as shown in FIG. 15, in the LED structure growth step of Step 1, normal planar crystal growth is performed on the sapphire substrate 6, and the light emitting layer (GaInN) 20 and the n-side GaN 17 (light emission) are formed on the sapphire substrate 6. A layer in contact with the layer) or the like.
[0035]
Step 2 SiO₂In the layer formation process, a silicon oxide film (SiO2) having a thickness of about 200 μm is formed on the wafer on which the LED structure is grown.₂) 29 is formed by a method such as vacuum deposition, sputtering, or plasma CVD.
[0036]
In the step of forming a photoresist pattern in step 3, the pattern of the photoresist 30 is formed so that the portion from which silicon oxide is removed becomes an opening.
[0037]
In the etching step of step 4, an opening is formed in the silicon oxide film. This may be wet etching or dry etching. In the case of wet etching, only silicon oxide is removed using Buffered-HF or HF.
[0038]
In step 5 of removing the photoresist, the resist used for the silicon oxide etching mask is removed. If wet etching is used in step 4, the resist is removed with a suitable organic solvent. Further, when dry etching is used in step 4, the resist is altered and cannot be removed with a normal organic solvent. Therefore, the resist is ashed with oxygen plasma and completely removed with a resist stripping solution.
[0039]
As shown in FIG. 16, in the reactive ion etching step of step 6, a concave portion is formed in the layer in contact with the light emitting layer from the opening by reactive ion etching. That is, the n-clad layer is exposed by reactive ion etching using the silicon oxide film having the pattern transferred as an etching mask. Etching conditions include, for example, Cl (chlorine) gas at a flow rate of 12 sccm, Ar (argon) at a flow rate of 2 sccm, a gas pressure of 0.12 Pa, and an RF power of 100 W. At this time, the etching rate of the silicon oxide film is smaller than the etching rate of the GaN-based material constituting the LED, but the silicon oxide film is similarly etched, and the side surface of the pattern of the silicon oxide film slightly recedes. Due to this property, as the etching progresses, the pattern width of the silicon oxide becomes narrower, and the GaN-based material is etched in a taper shape (a plateau shape) as shown in 6 of FIG. That is, the recess becomes narrower toward the bottom. The thinner the silicon oxide film, the greater the receding by etching, and the taper angle can be increased.
[0040]
In the step of forming a photoresist pattern in step 7, a resist pattern is formed so that the bottom surface (the n-side GaN 17 exposed by etching) of the LED structure remaining in a plateau shape is opened.
[0041]
In the n-electrode formation step of step 8, the n-electrode is formed using vacuum deposition or the like. For example, Ti / Al / Pt / Au (Ti is the first layer) = 10/100/100/300 nm can be adopted as the material and film thickness.
[0042]
In step 9 of removing the photoresist and alloying, the lift-off method is used to leave only the electrode formed in the resist opening and remove the other portions. Thereafter, heat treatment is performed at 800 ° C. for 10 minutes in a nitrogen atmosphere. As a result, the n-side GaN 17 is also heated, so that the hydrogen contained in this layer is removed, and the resistance of the p-side GaN 19 is reduced.
[0043]
As shown in FIG. 17, in the step of forming a photoresist pattern in Step 10, the photoresist 30 is patterned so that the plateau-like upper surface left by etching becomes an opening for forming the p-side electrode. To do.
[0044]
In the etching step of Step 11, the silicon oxide film under the photoresist pattern is removed using the photoresist pattern as an etching mask. As the etching method, the same method as described in Step 4 can be used.
[0045]
In the step of forming the p electrode in step 12, the p-side electrode is formed by vacuum deposition or the like. For example, Ni / Pt / Au (Ni is first) = 10/100/300 nm can be adopted as the material and film thickness.
[0046]
In step 13 of removing the photoresist, an organic solvent such as acetone is used to remove other than the electrode 3 formed on the p side. As the method for removing the photoresist, the same method as described in Step 9 can be used.
[0047]
Next, an embodiment of the invention relating to a two-dimensional display device will be described with reference to FIGS.
The self-luminous element of the present invention can be applied not only as a light source but also to a two-dimensional display device having one or two or more self-luminous elements as one pixel, that is, a matrix display. That is, each self-light-emitting element or a plurality of self-light-emitting elements forms one pixel and functions as an XY matrix display as a whole.
[0048]
18 and 19 are examples in which a TFT switch is connected to the p-side electrode of each self-luminous element. Thereby, a matrix display element using LEDs is realized. That is, for active matrix driving, an active element corresponding to one pixel is connected to the back side of each self-light-emitting element or a plurality of self-light-emitting elements.
[0049]
The operation of the circuit will be described with reference to FIG. 18. First, a data signal corresponding to line sequential scanning is supplied to the signal line 31. Next, a scanning pulse is input to the scanning line 38, and the switching TFT 36 is opened. While the switching TFT 36 is open, the potential of the difference between the potential of the capacitor line 38 and the signal line 31 is charged in the storage capacitor 37. Next, the storage capacitor 37 holds data until the switching TFT 36 is closed and a scanning pulse in the next frame period is input. A current corresponding to the voltage held in the storage capacitor 37 is supplied from the power supply line 32 to the LED 34 and is lit until the next frame.
[0050]
In the example of the matrix display shown in FIG. 19, a common electrode 33 is formed around each convex portion (GaN) 16 (including side surfaces). Here, the gate 40 is connected to the storage capacitor and operates the driving TFT with a predetermined current value. The drain 41 connects the LED of the convex portion (GaN) 16 and the driving TFT drain. The source 42 connects the drive TFT source side and the power supply line.
[0051]
FIG. 20 shows an application example to an XY simple matrix display. As shown in FIG. 20, for simple matrix driving, the back surface of each convex portion (GaN) 16 or the plurality of convex portions (GaN) 16 is connected to a row or column electrode. In addition, column or row electrodes are formed in a direction orthogonal to the row or column electrodes. At least a part of the n-electrode 7 formed on the front side of the convex portion (GaN) 16 needs to be transparent.
[0052]
Although the above description has been made on GaN, the luminous efficiency of the LED element can be improved by using the same shape for other materials. For example, in the case of a quaternary mixed crystal of AlGaNInP, the refractive index is estimated to be about 3.4. Estimating the optimum shape incident on a ball lens of 1.5 gives a parabolic focal length of 3.62, a light emitting layer size L2 of 47, and a depth d of 135 with a critical angle of 26 °, L1 of 100. In GaN, the sapphire substrate is transparent, but GaAs is used as the substrate for this quaternary mixed crystal. Since GaAs is opaque, it must be removed after crystal growth. Except for this point, the process is the same as that of GaN described above.
[0053]
Next, other embodiments of the illumination device and the two-dimensional display device will be described with reference to FIGS.
The present invention is not limited to LEDs. External extraction efficiency can also be improved for EL (organic, inorganic) devices.
[0054]
For example, as shown in FIG. 21, a structure in which an electrode (reflective layer) 46, a light emitting layer 45, a transparent electrode 44, and a convex portion 43 are sequentially laminated on a substrate 47 can be considered. Here, the convex portion 43 is in contact with the light emitting layer 45 through the transparent electrode 44. When the refractive index of the light emitting layer 45 is about 1.5, the refractive index is smaller than the material of the transparent electrode 44. The total reflection in the light emitting layer occurs when the refractive index of the material in contact is smaller than the refractive index of the material of the light emitting layer, and this problem does not occur here.
[0055]
In addition, when the convex part 43 as shown in FIG. 21 is comprised in the part which is not directly related to the light emitting layer 45, a refractive index becomes a problem for selection of the material of the convex part 43. FIG. In this case, if it is made of a material smaller than the refractive index of the light emitting layer 45, an angle exceeding the total reflection condition exists at the interface between the transparent electrode 44 and the convex portion 43. Therefore, the refractive index of the material of the convex portion 43 needs to be the same as or larger than the refractive index of the material of the light emitting layer 45.
[0056]
The interface critical angle with air is 41.8 °. When there is no convex 43 on the transparent electrode 44, the external extraction efficiency is at most 25%. However, the light emitting area and the convex 43 have a one-to-one correspondence, and the light emitting layer is sufficiently thinner than the convex 43. If it is, the extraction efficiency close to 100% can be obtained. Assuming that L1 is 100, the ideal convex portion 43 has a paraboloid focal length of 8.2, a light emitting layer size L2 of 37, and a depth d of 66.
[0057]
FIG. 22 shows a structure in which the convex portion 43 is smaller than one pixel of the light emitting layer 45 and a plurality of convex portions 43 correspond to one pixel. This structure is advantageous in that it is not necessary to align the light emitting portion and the convex portion 43.
[0058]
As shown in FIG. 23, the effect of the convex portion 43 differs depending on the light emission angle and position. The light beam emitted under the convex portion 43 is totally reflected by the inner surface of the convex portion 43 and is emitted to the outside. Light emission other than under the convex portion 43 may be a light beam totally reflected at the interface or a light beam having a critical angle or less. Light rays having a critical angle or less are emitted to a material having a small refractive index (which may be air) and are almost all incident on the convex portion 43. Next, the light is totally reflected on the inner surface of the convex portion 43 and then emitted to the outside. A light beam having an angle larger than the critical angle repeats total reflection between the back surface and the material having a small refractive index, and eventually enters the convex portion 43 and is extracted outside. In this structure, since light leakage may occur in adjacent pixels, it is desirable that there is a reflective layer 48 between the adjacent pixels.
[0059]
From the above, according to the embodiment of the present invention, the side surface of the layer in contact with the light emitting layer has a shape that is open in the direction of emitting light, and at least one part of the side surface completely transmits the light from the light emitting layer. A step of forming a recess in the layer in contact with the light emitting layer by reactive ion etching from the opening, or the recess becomes narrower toward the bottom, or the lighting device is Since a plurality of light emitting elements are arranged, or in the two-dimensional display device, one or two or more self-light emitting elements are used as one pixel, so that external extraction efficiency can be improved, and unevenness in emission intensity is uneven. Can be suppressed. Therefore, the light emission efficiency can be improved and a large area can be emitted uniformly.
[0060]
As a result, a bright light source and illumination device (direct-view large-screen XY display device, LCD backlight, projector light source, and various illumination devices) with low power consumption can be realized. Further, a two-dimensional display device driven by an XY matrix (passive and active) is possible.
[0061]
The present invention is not limited to the above-described embodiment, and various other configurations can be adopted without departing from the gist of the present invention.
[0062]
【The invention's effect】
The present invention has the following effects.
The side surface of the layer in contact with the light emitting layer has a shape that is open in the light emitting direction, and at least one part of the side surface has a shape that totally reflects the light from the light emitting layer, or from the opening, the reactivity Forming a recess in a layer in contact with the light emitting layer by ion etching, and the recess becomes narrower toward the bottom, or the two-dimensional display device has one or more self-luminous elements as one pixel. Therefore, the light emission efficiency can be improved.
In addition, since the lighting device has a plurality of self-luminous elements arranged, the light emission efficiency can be improved and a large area can be emitted uniformly.
[Brief description of the drawings]
FIG. 1 is a diagram showing an embodiment of the invention relating to a self-luminous element.
FIG. 2 is a diagram illustrating an example of a device structure of a GaN-LED.
FIG. 3 is a diagram showing an example of a convex portion relating to a self-luminous element (No. 1).
FIG. 4 is a diagram showing an example of a convex portion relating to a self-luminous element (part 2).
FIG. 5 is a diagram showing an example of an arrangement of convex portions related to a self-light-emitting element (part 1);
FIG. 6 is a diagram illustrating an example of an array of convex portions related to a self-light-emitting element (part 2);
FIG. 7 is a diagram showing an example of an array of convex portions related to a self-light emitting element (part 3);
FIG. 8 is a diagram showing a submount substrate used in the invention relating to the illumination device.
FIG. 9 is a diagram showing an embodiment of the invention relating to a lighting device.
FIG. 10 is a diagram showing another embodiment of the invention relating to the lighting device.
FIG. 11 is a diagram showing another embodiment of the invention relating to the lighting device.
FIG. 12 shows another embodiment of the lighting device.
FIG. 13 is a view showing an example in which a ball lens is bonded to an array of self-luminous elements.
FIG. 14 is a cross-sectional view showing an example of a self-luminous element according to the present invention.
FIG. 15 is a diagram showing an example of a manufacturing process of the self-luminous element (No. 1).
FIG. 16 is a diagram showing an example of a manufacturing process of the self-luminous element (No. 2).
FIG. 17 is a diagram showing an example of a manufacturing process of the self-luminous element (No. 3).
FIG. 18 is a diagram showing an embodiment of the invention relating to a two-dimensional display device.
FIG. 19 is a diagram showing an embodiment of the invention relating to a two-dimensional display device.
FIG. 20 is a diagram showing an embodiment of the invention relating to a two-dimensional display device.
FIG. 21 is a diagram showing another embodiment of the illumination device or a two-dimensional display device.
FIG. 22 is a diagram showing another embodiment of the illumination device or a two-dimensional display device.
FIG. 23 is a diagram showing another embodiment of an illumination device or a two-dimensional display device.
FIG. 24 is a diagram showing an example of a conventional self-luminous element.
FIG. 25 is a view showing an example in which a conventional self-luminous element is bonded to a ball lens.
FIG. 26 is a diagram showing another example of a conventional self-luminous element.
FIG. 27 is a diagram showing a light emission intensity distribution when a supplied current is changed in a conventional self-light-emitting element.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 ... Light emitting layer, 2 ... Layer in contact with light emitting layer (GaN), 3 ... p electrode, 4 ... Self-light emitting element, 5 ... side, 6 ... sapphire substrate, 7 ... n electrode, 8 ... Ball lens, 9 ... p-side input terminal, 10 ... n-side input terminal, 11 ... p-electrode bonding pad, 12 ... n-electrode bonding pad, 13 ... submount substrate, 14 ... n-electrode lead-out part 15 ... LED substrate, 16 ... convex (GaN), 17 ... n-side GaN, 18 ... AlGaN, 19 ... p-side GaN, 20 ... light emitting layer (GaInN), 21 ... p-electrode extraction , 22 ... Insulating layer, 23 ... Contact electrode, 24 ... Mesh electrode, 25 ... Transparent electrode, 26 ... Wire bonding, 27 ... Stripe electrode, 28 ... GaN buffer, 29 ... SiO₂, 30 ... Photoresist, 31 ... Signal line, 32 ... Power line, 33 ... Common electrode, 34 ... LED, 35 ... Drive TFT, 36 ... Switching TFT, 37 ... Storage capacitor, 38 ... ... Capacitance line, 39 ... Scanning line, 40 ... Gate, 41 ... Drain, 42 ... Source, 43 ... Projection, 44 ... Transparent electrode, 45 ... Light emitting layer, 46 ... Electrode (reflection film) ), 47 ... Substrate, 48 ... Reflective layer, 49 ... Electrode, 50 ... Terminal (Reflector)

Claims (1)

A light emitting layer, via the transparent electrode layer, and the layer in contact with the light-emitting layer, the light emitting layer, an electrode having a reflection function is formed on the opposite side of the layer in contact with the light emitting layer seen including, in the light-emitting layer the contact layer, the two-dimensional display device according to one or more of one pixel self-luminous element that emits light from the surface opposite to the light emitting layer,
The self-luminous element is
(A) The refractive index of the light emitting layer is about 1.5, which is smaller than the refractive index of the transparent electrode layer, and the refractive index of the layer in contact with the light emitting layer is the same as the refractive index of the light emitting layer or the light emission. Greater than the refractive index of the layer,
(B) a layer in contact with the light emitting layer has a shape open in the direction in which the side surface for emitting light, Ri Do sectional shape of the side surface and part of a parabola shape, emission of the layer in contact with the light emitting layer When the side size L1 = 100, the parabolic focal length = 8.2, the light emitting layer size L2 = 37, and the layer thickness d = 66 in contact with the light emitting layer,
(C) at least a portion of the side, the two-dimensional display device characterized by having a shape that totally reflects the light from the light emitting layer.

Images