JP2001085738A - Self-emitting element and manufacturing method of the same and illuminating device and two-dimensional display device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a self-emitting element for improving the light-emitting efficiency. SOLUTION: In this self-emitting element 4, a layer (GaN) 2 brought into contact with a light emitting layer, a light-emitting layer 1, a p side GaN 19, and a p electrode 3 are formed on a sapphire substrate 6. Lights, generated from the light-emitting layer 1, are emitted through the layer (GaN) 2 brought into contact with the light emitting layer to the direction of the sapphire substrate 6. In this case, the p electrode 3 is made of metal and provided with a reflecting function. Also, the side face of the layer (GaN) 2 brought into contact with the light emitting layer is shaped, so as to open in the direction in which lights are emitted. Moreover, at least one part of the side face of the layer (GaN) 2, brought into contact with the light emitting layer, is shaped so that lights from the light emitting layer 1 can be totally reflected.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a self-luminous element, a method of manufacturing the same, a lighting device, and a two-dimensional display device.

[0002]

2. Description of the Related Art Conventionally, a light emitting diode (hereinafter referred to as "LE
D ". ), Flat panel displays, backlights for liquid crystal displays, light sources for projection, etc. have been tried, but the luminous efficiency of LEDs is not sufficient,
It is difficult to uniformly emit light over a large area. Further, the luminous efficiency is not sufficient even in an electroluminescent (hereinafter, referred to as “EL”) display.

[0003]

The luminous efficiency can be expressed by internal quantum efficiency × external take-out efficiency. The external take-out efficiency is mainly determined by the difference in the refractive index of the components making up the LED and EL. Therefore, a structure for extracting light from the sapphire substrate side by using a GaN-LED as shown in FIG. 24 will be specifically described. The refractive index of the layer (GaN) 2 in contact with the light emitting layer and the refractive index of the sapphire substrate 6 are 2.46 and 1.76, respectively. The light emitting angle distribution of the light emitting layer 1 is isotropic. That is,
It is 4π in solid angle. Light rays exceeding the critical angle determined by the difference in the refractive index 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% is reflected on the surface of the p electrode 3 on the back surface, only 30% of the light enters the sapphire substrate 6.

Similarly, even at the interface from the sapphire substrate 6 to the ball lens 8 (refractive index 1.5) as shown in FIG. 25, a light beam exceeding the critical angle of 58 °, as shown in FIG. reflect. 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 a back surface and a reflection film is formed on the back surface. That is, the structure of a general GaN-LED is as shown in FIG. 26A.
This is a structure in which a sapphire substrate 6 is provided below. Although the angular distribution of the light emitted from the light emitting layer is 4π, the light out of the light emitted to the sapphire substrate 6 that exceeds the critical angle determined by the refractive index difference from the sapphire substrate 6 is out of the sapphire substrate 6. The light is totally reflected at the interface and goes to 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 totally reflected at the interface with the sapphire substrate 6 is also totally reflected at the interface of ITO, and Does not come out. The light beam that has passed through the sapphire substrate 6 is reflected by the reflection plate on the back surface, and travels toward the transparent electrode 25 side.

Among the light beams that have passed through the transparent electrode 25, those that exceed a critical angle determined by the ratio of the refractive index of the transparent electrode 25 to the refractive index of the ball lens 8 shown in FIG. 26B are totally reflected. As a result, the ratio of light rays that can enter the ball lens 8 depends on the critical angle determined by the ratio of the refractive index of GaN to the refractive index of the ball lens 8. If light rays leaking from the side surface by repeating total reflection are ignored, it is about 20%. Note that the above
The same applies to materials other than GaN.

[0007] Furthermore, the efficiency of external extraction is also 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 at most about 25%.

Another problem is that when the light emitting area is increased to increase the total luminous flux, the effective light emitting area cannot be increased due to current concentration near the electrodes. FIG. 27 shows an example of the emission intensity distribution when the input current is changed in the LED. That is, as shown in FIG. 27B, the change in the light emission intensity on the line aa passing through the n-electrode 7 is shown in FIG.
7A. The emission intensity decreases as the distance from the n-electrode 7 increases. This tendency is remarkable as the applied current increases, and it is found that it is difficult to obtain a uniform emission intensity distribution.

SUMMARY OF THE INVENTION The present invention has been made in view of such problems, and has as its object to provide a self-luminous element capable of improving luminous efficiency, a method of manufacturing the same, and a two-dimensional display device. Further, another object of the present invention is to provide a lighting device that can improve luminous efficiency and emit light uniformly over a large area.

[0010]

The self-luminous element according to the present invention comprises:
A light-emitting layer, directly or via another layer, a layer in contact with the light-emitting layer, and an electrode formed on the light-emitting layer on the side opposite to the layer in contact with the light-emitting layer, wherein the electrode has a reflective function; A self-luminous element that emits light from a surface of the layer that is in contact with the light-emitting layer and that is opposite to the light-emitting layer, characterized in that: (A) The layer in contact with the light emitting layer has a shape whose side surface is open in the direction in which light is emitted.
(B) At least a portion of the side surface has a shape that totally reflects light from the light emitting layer.

Further, the method for manufacturing a self-luminous element according to the present invention comprises:
Forming a light emitting layer and a layer in contact with the light emitting layer on the substrate; further forming a silicon oxide film; forming an opening in the silicon oxide film; Forming a recess in a layer in contact with the light emitting layer by etching, wherein the recess becomes narrower toward the bottom.

Further, the lighting device of the present invention includes a plurality of the self-luminous elements having the above-described configuration.

Further, in the two-dimensional display device of the present invention, one or two or more of the above-mentioned self-luminous elements are formed as one pixel.

A self-luminous element of the present invention and a method of manufacturing the same;
According to the lighting device, and 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 a direction in which light is emitted,
Forming at least a part of the side surface in a shape in which light from the light emitting layer is totally reflected, or from an opening, by reactive ion etching to form a concave portion in a layer in contact with the light emitting layer, Since the width becomes narrower toward the bottom, or because the lighting device arranges a plurality of self-luminous elements, or because the two-dimensional display device uses one or more self-luminous elements as one pixel, the external extraction efficiency is increased. Can be improved, and the occurrence of uneven emission intensity can be suppressed.

[0015]

Embodiments of the present invention will be described below. First, a self-luminous element such as an LED or EL
An embodiment according to the present invention will be described with reference to FIGS.

In the self-luminous element, the light beam confined inside under the condition of total reflection is guided in a direction perpendicular to the substrate while repeating reflection at the interface. For example, in the case of a GaN-LED structure having an electrode on the back surface and a sapphire substrate on the front surface, light is guided while totally reflecting at the interface between the sapphire substrate and GaN and reflecting metal at the opposing electrode surface. At this time, since the reflection on the metal surface always involves absorption, and absorption occurs in the light emitting layer when the light crosses the light emitting layer, 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 in a direction orthogonal to the substrate, it cannot be an effective light beam. The present invention is a structure that makes effective use of the invalid light emission in the side direction, and specifically, is characterized in that the side surface is inclined from the normal direction of the substrate.

The angle of inclination is set so that the interface is in a condition of total reflection for a ray parallel to the substrate. This critical angle is defined as θ1. By satisfying this condition, it is possible to satisfy the condition of total reflection on the side surface for almost all light emission. Assuming that the metal electrode is located on the back surface, a light beam having an angle lower than an angle parallel to the substrate is reflected by the back electrode to satisfy the condition of total reflection on the side surface. However, a light beam that reaches the side surface directly without being reflected by the back electrode may not be satisfied. Therefore, it is desirable that the position of the light emitting layer is as close to the back electrode as possible.

Next, the condition of total reflection at the interface with the substrate will be considered. The line connecting the boundary point of the interface between the opposing side surface and the substrate with the light emitted from the end of the light emitting layer partitioned by the inclined side surface toward the substrate side is the maximum incident angle on the substrate. This critical angle is defined as θ2. The angle is set so as not to exceed the critical angle.

By satisfying the above two conditions, almost all light beams are emitted to the substrate side. A shape satisfying these two conditions will be specifically described with reference to FIG.
As shown in FIG. 1, the side surface of the shape satisfying these two conditions is a part of the paraboloid 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.

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. Critical angle θ determined by the refractive index of GaN and the refractive index of air
1 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 °. A parabolic shape that satisfies these two conditions is, for example, a size L1 on the emission side of 10
When it is set to 0, the focal length of the paraboloid is 6.2, the size L2 of the light emitting layer is 55.6, and the thickness d of GaN is 70.

A sapphire substrate 6 is joined to the light emitting side of the layer (GaN) 2 in contact with the light emitting layer. p electrode 3
Represents a layer (GaN) 2 in contact with the light emitting layer with respect to the light emitting layer 1
Is formed on the opposite side. The p-electrode 3 is connected to the p-side G
It is in contact with the light emitting layer 1 via aN19. The p electrode 3 is made of metal and has a reflection function.

Incidentally, a detailed structure of the layer (GaN) 2 in contact with the light emitting layer, the light emitting layer 1 and the p-side GaN 19 in FIG. 1 is as shown in FIG. That is, the layer (Ga) in contact with the light emitting layer in FIG.
N) 2 and the light emitting layer 1 are respectively n-side GaN 1 of FIG.
7 and the light emitting layer (GaInN) 20. Also,
In FIG. 1, p-side Ga is provided between the light emitting layer 1 and the p-electrode 3.
Although only N19 is used, actually, as shown in FIG.
There are two layers, AlGaN 18 and p-side GaN 19. Here, the light emitting layer (GaInN) 20 and AlGa
Since N18 is sufficiently thin with respect to the wavelength of light, the distance between the p-electrode 3 and the sapphire substrate 6 can be represented by the refractive index of GaN. Also, as shown in FIG.
N18 can be omitted.

As described above, the layer (Ga) in contact with the light emitting layer
The N) 2 desirably has a parabolic shape as shown in FIG. However, the layer (GaN) 2 in contact with the light emitting layer is not limited to the above-mentioned parabolic shape. As modifications thereof, cones and hexagons as shown in FIGS. 3B and C, quadrangular pyramids as shown in FIG. 4A, and division shapes as shown in FIGS. Parabolic shapes and the like can be mentioned. In short, the layer (GaN) 2 which is in contact with the light emitting layer has a shape whose side surface is open in the light emitting direction, that is, the side surface is inclined so that the back surface is convex with respect to the light emitting surface. If at least a part of the side surface has a shape that totally reflects the light from the light emitting layer, the external extraction efficiency can be improved.

Next, an embodiment of the invention relating to a lighting device will be described with reference to FIGS. The practical dimensions of the self-luminous element described above are based on the layer (G
aN) 2 is determined by the thickness. When the layer (GaN) 2 in contact with the light emitting layer is set to, for example, 7 μm, the chip size becomes 10 μm, and a plurality of illumination devices need to be arranged in order to obtain an absolute light quantity. Various arrangements of the self-light emitting elements are conceivable as shown in FIGS. A one-dimensional structure having a parabolic or trapezoidal cross section as shown in FIG. 7 is also conceivable.

FIG. 8 shows an example of a structure realized as a lighting device.
And 9. P electrode 3 of each self-luminous element shown in FIG.
Is electrically connected to the p-electrode bonding pad 11 of the submount substrate 13 shown in FIG. 8 by soldering or the like. The n-electrode 7 is formed on the side surface in order to make the light emitting area as small as possible. 9A is an ineffective light emitting area, and is electrically connected to the n-electrode bonding pad 12 of the submount substrate 13 by soldering 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.

As shown in FIG. 9, the divided elements are driven in parallel. On the n side, each of the divided elements is wired in series with electrodes formed on the side surfaces. In order to uniformly inject current into each of the divided elements, 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, there is a problem that 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. In this structure, a relatively thick wiring electrode can be formed by using the side surface. Thereby, the wiring resistance can be reduced, and the driving can be performed without variation among the divided elements.

As a wiring method, as shown in FIG. 10, a structure in which the entire light emitting region is divided into a plurality of regions and each is connected in series can be adopted. That is, as shown in FIG. 10B, the structure has a structure in which the rear surface of a part of the divided convex portion (GaN) 16 and the side surface of the convex portion (GaN) 16 adjacent thereto are electrically connected. When the same material as in the example described with reference to FIG. 9 is used, uniform driving can be performed even when the electrode film thickness is relatively small. However, the driving voltage is increased by the number of times divided in series.

Regarding the formation of the n-side electrode, the sapphire substrate may be removed after crystal growth, and a transparent electrode may be formed in a planar manner. In this case, since the resistance may be high only with the transparent electrode, the mesh electrode 24 as shown in FIG. 11 or the stripe electrode 27 as shown in FIG.
A bus electrode made of

With this structure, 100% is applied to the sapphire substrate side.
Although it is possible to emit a light beam close to the substrate, it is desirable to process the sapphire substrate into a ball lens shape or to form a ball lens using a material having a refractive index close to that of the substrate in order to extract the light efficiently into the air. Here, the ball lens is a layer (GaN) in contact with the light emitting layer as shown in FIG.
A lens having a spherical shape centered on the interface position between the substrate 2 and the sapphire substrate 6. Further, the material for bonding the sapphire substrate 6 and the ball lens 8 is desirably a material having a refractive index close to those of the two. The reason for this is to reduce the reflection at the interface between the sapphire substrate 6 and the ball lens 8 and increase the external extraction efficiency.

Generally, the material used for the optical lens and the bonding material for bonding the substrate and the lens are often smaller than the refractive index of sapphire. The refractive index of the ball lens is 1.5
In this case, the overall external extraction efficiency can be improved by reviewing the shape of the layer (GaN) 2 in contact with the light emitting layer. In determining the conditions for total reflection between the substrate and GaN, the substrate is designed with a refractive index of 1.5. At that time, the critical angle becomes 38 °. When L1 is 100, the focal length of the paraboloid is 5.4, the size L2 of the light emitting layer is 49, and the depth d is 88.

If the refractive index of the substrate is set to air, the extraction efficiency into the air can be made close to 100% in the absence of a ball lens. At this time, assuming that 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.

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 becomes smaller, it is necessary to increase the chip size to obtain the same light amount. Therefore, the ratio between L1 and d is determined in consideration of the yield of the LED production process, the number of chips determined by the relationship between the substrate size and the chip size, the overall design of the lighting device, and the like.

Next, an embodiment of the invention relating to a method for manufacturing a self-luminous element will be described with reference to FIGS. The process example here is a method using reactive ion etching. That is, normal planar crystal growth is performed on a sapphire substrate, and then the GaN layer is divided into inclined side structures by reactive ion etching using SiO ₂ or the like as a mask. A cross-sectional view of the final self-luminous element is as shown in FIG.

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 are formed on the sapphire substrate 6.
(A layer in contact with the light emitting layer) and the like.

In the step of forming the SiO ₂ layer in step 2, a silicon oxide film (SiO ₂ ) 29 having a thickness of about 200 μm is formed on the wafer on which the LED structure has been grown by a method such as vacuum deposition, sputtering, or plasma CVD. .

In the step of forming a photoresist pattern in step 3, a pattern of the photoresist 30 is formed so that a portion from which silicon oxide is removed becomes an opening.

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.

In the step of removing the photoresist in step 5, the resist used as the silicon oxide etching mask is removed. When wet etching is used in step 4, the resist is removed with an appropriate organic solvent. When dry etching is used in step 4, the resist is deteriorated and cannot be removed with an ordinary organic solvent. Therefore,
The resist is ashed (ashed) by oxygen plasma and completely removed by a resist stripper.

As shown in FIG. 16, in the reactive ion etching step of step 6, a recess is formed in the layer in contact with the light emitting layer from the opening by reactive ion etching. That is, the n-cladding layer is exposed by reactive ion etching using the pattern-transferred silicon oxide film as an etching mask. The etching conditions are, for example, Cl (chlorine) gas at a flow rate of 12 sccm, Ar (argon) at a flow rate of 2 sccm, gas pressure of 0.12 Pa, R
The operation is performed at an F 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 is slightly receded. Due to this property, the pattern width of the silicon oxide becomes narrower as the etching proceeds, and the GaN-based material is etched in a tapered shape (plateau shape) as shown in 6 of FIG. That is, the concave portion becomes narrower toward the bottom. As the silicon oxide film is thinner, the recession due to the etching increases, and the taper angle can be increased.

In the step of forming a photoresist pattern in step 7, a resist pattern is formed such that the bottom surface of the LED structure remaining on the plateau (the n-side GaN 17 exposed by etching) is opened.

In the step 8 for forming an n-electrode, an n-electrode is formed by vacuum evaporation or the like. The material and film thickness are
For example, Ti / Al / Pt / Au (Ti is the first layer) = 1
0/100/100/300 nm can be adopted.

In the step of removing the photoresist and alloying in step 9, the lift-off method is used to leave only the electrode formed in the resist opening and remove the other portions. Thereafter, a 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 hydrogen contained in this layer is removed, and the p-side Ga
The resistance of N19 is also reduced.

As shown in FIG. 17, in the step of forming a photoresist pattern in step 10, in order to form a p-side electrode, the photoresist is so formed that the plateau-shaped upper surface left by etching becomes an opening. 30 is patterned.

In the etching step of step 11,
Using the photoresist pattern as an etching mask, the underlying silicon oxide film is removed. As the etching method, the same method as described in Step 4 can be used.

In the step 12 of forming the p-electrode,
The p-side electrode is formed by vacuum evaporation or the like. The material and the film thickness are, for example, Ni / Pt / Au (Ni is first) = 10/100 /
300 nm can be adopted.

In the step of removing the photoresist in step 13, the portions other than the electrode 3 formed on the p-side are removed using an organic solvent such as acetone. As the method for removing the photoresist, the same method as described in Step 9 can be used.

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 to a simple light source but also to a two-dimensional display device having one or more self-luminous elements as one pixel, that is, a matrix display. That is, each self-luminous element or a plurality of self-luminous elements form one pixel, and function as an XY matrix display as a whole.

FIGS. 18 and 19 show examples in which a TFT switch is connected to the p-side electrode of each light emitting 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-luminous element or a plurality of self-luminous elements.

The operation of the circuit will be described with reference to FIG.
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,
The switching TFT 36 is opened. Switching TFT3
While the switch 6 is open, the storage capacitor 37 is charged with the potential difference between the potential of the capacitance line 38 and the potential of the signal line 31. Next, the storage capacitor 37 holds data until the switching TFT 36 is closed and a scanning pulse in the next frame cycle 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 the LED lights up until the next frame.

In the example of the matrix display shown in FIG. 19, a common electrode 33 is formed around each of the convex portions (GaN) 16 (including side surfaces). Here, the gate 40 is connected to the storage capacitor, and the drive TF
T is operated at a predetermined current value. The drain 41 is composed of the LED of the convex portion (GaN) 16 and the driving TFT.
It connects the drain. Source 42 is driven T
The FT source is connected to the power supply line.

FIG. 20 shows an example of application 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 a plurality of convex portions (GaN) 16 is connected to a row or column electrode. Further, a column or row electrode is formed in a direction orthogonal to the above-mentioned row or column electrode. N-electrode 7 formed on the front side of convex portion (GaN) 16
Must be at least partially transparent.

Although the above description has been made with reference to GaN, the luminous efficiency of the LED element can be improved by using other materials in the same shape. For example, Al
In the case of a quaternary mixed crystal of GaNInP, the refractive index is estimated to be about 3.4. Estimating the optimal shape for incidence on the 1.5 ball lens results in a parabolic focal length of 3.62, a luminous layer size L2 of 47, and a depth d of 135, with a critical angle of 26 °, L1 being 100. In GaN, the sapphire substrate is transparent, but GaAs is used as the substrate for the quaternary mixed crystal. GaAs is opaque and must be removed after crystal growth. Except for this point, the process is the same as that for GaN described above.

Next, another embodiment of the present invention relating to a lighting device and a two-dimensional display device will be described with reference to FIGS. The present invention goes beyond LEDs. For an EL (organic, inorganic) device, the external take-out efficiency can be improved.

For example, as shown in FIG. 21, an electrode (reflection layer) 46, a light emitting layer 45, a transparent electrode 44,
And a structure in which the projections 43 are sequentially laminated.
Here, the convex portion 43 is provided with the light emitting layer 4 via the transparent electrode 44.
5 is touched. 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 with the light emitting layer is smaller than the refractive index of the material of the light emitting layer, and the problem does not occur here.

In the case where the protrusion 43 shown in FIG. 21 is formed of a portion not directly in contact with the light emitting layer 45, the selection of the material of the protrusion 43 has a problem with the refractive index. In this case, if the light emitting layer 45 is made of a material having a refractive index smaller than that 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 equal to or larger than the refractive index of the material of the light emitting layer 45.

The critical angle at the interface with air is 41.8 °. When there is no protrusion 43 on the transparent electrode 44, the external extraction efficiency is at most 25%, but the light emitting area and the protrusion 43
Have a one-to-one correspondence, and if the light emitting layer is sufficiently thinner than the convex portion 43, an extraction efficiency close to 100% can be obtained.
Assuming that L1 is 100, the parabolic focal length is 8.2, the light emitting layer size L2 is 37, and the depth d is 100.
Becomes 66.

FIG. 22 shows a projection 4 compared to one pixel of the light emitting layer 45.
3 is small and a plurality of protrusions 43 correspond to one pixel. This structure has an advantage that alignment between the light emitting portion and the convex portion 43 is unnecessary.

As shown in FIG. 23, the effect of the projection 43 differs depending on the light emission angle and position. The light beam emitted under the convex portion 43 is
3, the light is totally reflected by the inner surface and emitted to the outside. The light emission other than below the convex portion 43 may be a ray totally reflected at the interface and a ray smaller than the critical angle. Light rays having a critical angle or less are emitted to a material having a small refractive index (in some cases, air), and almost all enter the convex 43 portion. Next, the light is totally reflected by the inner surface of the convex portion 43 and is substantially emitted to the outside. Light rays having an angle larger than the critical angle repeat total internal reflection between the back surface and the material having a small refractive index.
And is extracted outside. In this structure, light leakage may occur in adjacent pixels, and therefore, it is desirable that the reflective layer 48 be provided between the adjacent pixels.

As described above, according to the embodiment of the present invention, the side surface of the layer that is in contact with the light emitting layer has a shape that is open in the light emitting direction, and at least a part of the side surface is in contact with the light emitting layer. Forming a concave portion in the layer in contact with the light emitting layer by reactive ion etching from the opening or from the opening, or the concave portion becomes narrower toward the bottom, or lighting Since the device arranges a plurality of self-luminous elements, or the two-dimensional display device uses one or more self-luminous elements as one pixel, it is possible to improve the external extraction efficiency and to improve the light emission intensity. The occurrence of unevenness can be suppressed. Therefore, luminous efficiency can be improved, and a large area can be uniformly illuminated.

Accordingly, a bright light source with low power consumption,
A lighting device (a direct-view large-screen XY display device, an LCD backlight, a projector light source, various lighting devices) becomes possible. Further, a two-dimensional display device driven by an XY matrix (passive or active) is possible.

It should be noted that the present invention is not limited to the above-described embodiment, but can adopt various other configurations without departing from the gist of the present invention.

[0062]

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 direction in which light is emitted, and at least a part of the side surface has a shape that totally reflects light from the light-emitting layer. Forming a concave portion in a layer in contact with the light-emitting layer by ion etching, wherein the concave portion becomes narrower toward the bottom, or the two-dimensional display device includes one or more self-luminous elements as one pixel. Therefore, the luminous efficiency can be improved. In addition, since the lighting device has a plurality of self-luminous elements arranged, the luminous efficiency can be improved and a large area can emit light 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 an element structure of a GaN-LED.

FIG. 3 is a diagram illustrating an example of a protrusion relating to a self-luminous element (part 1).

FIG. 4 is a diagram illustrating an example of a protrusion related to a self-luminous element (part 2).

FIG. 5 is a diagram illustrating an example of an arrangement of protrusions according to a self-luminous element (part 1).

FIG. 6 is a diagram illustrating an example of an arrangement of protrusions according to a self-luminous element (part 2).

FIG. 7 is a diagram illustrating an example of an arrangement of protrusions according to a self-luminous element (part 3).

FIG. 8 is a diagram showing a submount substrate used in the invention relating to the lighting 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 present invention relating to a lighting device.

FIG. 11 is a diagram showing another embodiment of the invention relating to a lighting device.

FIG. 12 is a diagram showing another embodiment of the invention relating to a lighting device.

FIG. 13 is a diagram showing an example in which a ball lens is bonded to an array of self-luminous elements.

FIG. 14 is a sectional view showing an example of a self-luminous element according to the present invention.

FIG. 15 is a diagram illustrating an example of a manufacturing process of the self-luminous element (part 1).

FIG. 16 is a diagram illustrating an example of a manufacturing process of the self-luminous element (part 2).

FIG. 17 is a view illustrating an example of a manufacturing step of the self-luminous element (part 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 invention relating to a lighting device or a two-dimensional display device.

FIG. 22 is a diagram showing another embodiment of the invention relating to a lighting device or a two-dimensional display device.

FIG. 23 is a diagram showing another embodiment of the invention relating to a lighting device or a two-dimensional display device.

FIG. 24 is a diagram illustrating 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 in a conventional self-luminous element when the applied current is changed.

[Explanation of symbols]

1} light-emitting layer, 2} layer in contact with light-emitting layer (GaN), 3
{P electrode, 4} self-luminous element, 5} side surface, 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 mm n electrode bonding pad, 13 mm
Submount substrate, 14 ‥‥ n electrode take-out part, 15 ‥
{LED substrate, 16} convex part (GaN), 17 n-side GaN, 18 AlGaN, 19 p-side GaN, 2
0 ° light-emitting layer (GaInN), 21 ° p-electrode extraction portion, 22 ° insulating layer, 23 ° contact electrode, 24 °
{Mesh electrode, 25} Transparent electrode, 26} Wire bonding, 27% Stripe electrode, 28% Ga
N buffer, 29 SiO ₂ , 30 photoresist, 31 signal line, 32 power line, 33 common electrode, 34 LED, 35 drive TFT, 36
{Switching TFT, 37} Storage capacitance, 38}
Capacitance line, 39 ° scanning line, 40 ° gate, 41 ° drain, 42 ° source, 43 ° convex, 44 ° transparent electrode, 45 ° light emitting layer, 46 ° electrode (reflective film) , 47
{Substrate, 48} reflective layer, 49 electrode, 50 terminal (reflective plate)

Continued on the front page F term (reference) 3K007 AB03 AB17 AB18 BA06 CB01 CC01 DA01 DB03 EC00 FA01 5F041 AA03 CA34 CA40 CA46 CA74 CB11 CB22 CB25 EE23

Claims (4)

[Claims] 1. A light emitting layer, directly or through another layer,
A layer in contact with the light-emitting layer, and an electrode formed on the side of the light-emitting layer opposite to the layer in contact with the light-emitting layer, wherein the electrode is
A self-luminous element which has a reflecting function and emits light from a surface of a layer which is in contact with the light-emitting layer and which is opposite to the light-emitting layer. (A) The layer in contact with the light emitting layer has a shape whose side surface is open in the direction in which light is emitted. (B) At least a portion of the side surface has a shape that totally reflects light from the light emitting layer. A step of forming a light-emitting layer and a layer in contact with the light-emitting layer on a substrate; a step of forming a silicon oxide film; a step of forming an opening in the silicon oxide film; From, by reactive ion etching,
Forming a concave portion in a layer in contact with the light emitting layer,
The method for manufacturing a self-luminous element, wherein the concave portion becomes narrower toward the bottom. 3. A lighting device, comprising a plurality of the self-luminous elements according to claim 1 arranged. 4. A two-dimensional display device, wherein one or two or more of the self-luminous elements according to claim 1 constitute one pixel.