JPH0818097A - Light emitting diode - Google Patents

Abstract

PURPOSE:To improve the external emitting efficiency and the current using efficiency by preventing the absorption of a light generated from a light emitting region to an opaque layer or an opaque board and contributing to the external emission of the light directed obliquely from the emitting region. CONSTITUTION:Clad layers 15, 17 (transparent layers), and totally reflecting layers 14, 18 having smaller refractive indexes than those of the layers 15, 17 are formed among a board 10, a buffer layer 11 and a contact layer 21 (opaque layer). A light generated from the layer 16 includes, in addition to light rays (a) directly reaching the side, light rays (b), (c) directed to upward and downward and to an element side face upon reflecting on the layers 14, 18 to be emitted externally from the sides of the layers 15, 17, thereby enhancing the external emitting efficiency. Since this LED has much light output quantity from the element side, its productivity can be enhanced by horizontally mounting it on a printed board.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a light emitting diode used for display, communication, signal transmission and the like.

[0002]

2. Description of the Related Art Conventionally, in the above-mentioned light emitting diode (hereinafter referred to as LED), it is necessary to effectively take out the light generated in the internal light emitting region, that is, to improve the external emission efficiency.
This is very important for obtaining high output and high efficiency light emission.

However, when a substrate that absorbs the emission wavelength is used, downward light is absorbed by the substrate and cannot be used as outgoing light, which causes a decrease in external outgoing efficiency. Therefore, measures have been considered to prevent the light absorption by the substrate by providing a multilayer reflective layer between the substrate and the light emitting section.

FIG. 12 shows a cross-sectional view of an LED as an example of a conventional LED, in which a multilayer reflective layer is arranged on a substrate opaque to the emission wavelength and light is emitted from the upper surface. This LE
D is produced as follows.

As shown in FIG. 12, first, n-type GaAs
N-type AlInP / AlGaIn is formed on the entire surface of the substrate 510.
P multilayer reflective layer (layer thickness of AlInP layer = 0.041 μm,
AlGaInP layer thickness = 0.040 μm, number of pairs 2
0) 511, n-type AlGaInP cladding layer 512, undoped AlGaInP light emitting layer 513, p-type AlGaI.
An nP clad layer 514 and a p-type GaAs contact layer 515 are sequentially laminated. After that, the surface electrode 5 is formed on the device surface.
16 is formed by vapor deposition, and this surface electrode 516 and p-type G
The aAs contact layer 515 is etched leaving only the central portion of the element. Further, a back surface electrode 517 is provided on the back surface of the element by vapor deposition.

[0006]

In the above-mentioned conventional LED, the multilayer reflective film 511 has a property of having a high reflectance only for light in a specific incident direction (in this case, vertically incident light). . Therefore, only the light ray p directed downward from the light emitting area is reflected by the multilayer reflective layer 511 and emitted from above, but the light ray q directed obliquely downward from the light emitting area is absorbed by the multilayer reflective layer 511 and emitted to the outside. There was a problem that it did not contribute to.

Further, in the above-mentioned LED, since the multilayer reflection layer 511 mainly reflects the light p directed downward, the light is exclusively extracted from the upper surface of the chip, and the amount of light emitted from the side surface of the chip is extremely small. Therefore, it is inconvenient to apply the following simple mounting method.

That is, as a simple mounting method for directly mounting an LED on a printed circuit board without wire bonding, for example, Japanese Patent Laid-Open No. 57-49284 discloses the following method.

As shown in FIG. 13A, first, a p-type semiconductor layer 711 is stacked on an n-type semiconductor substrate 710 to form a p-type semiconductor layer 711.
An electrode 713 is formed on the upper surface of the LED chip that generates light in the vicinity of the n-junction surface 712, and an electrode 714 is formed on the lower surface thereof, and solder is applied on each electrode. On the other hand, this L
As a printed circuit board section for mounting the ED chip, as shown in FIG. 13B, electrode wirings 716 and 717 are printed on an insulating substrate 715, a solder resist film 718 is formed on the electrode wirings 716, and adhesive bonding is further performed. A material coated with the agent 719 is prepared. By fixing the LED chip on the printed circuit board portion, heating the solder to once melt and then solidify the electrode wiring 716, 717 and the electrode 7 of the LED.
Solder 719 for electrically connecting 13 and 714, respectively
And In this way, the LED chip is laterally placed and fixed, so that light is emitted from the side surface of the chip.

The above mounting method is premised on an LED capable of extracting a large amount of light from the side surface of the chip. Generally, a semiconductor laser has a waveguide structure in which the upper and lower sides of an active layer are covered with cladding layers, and light is guided through the active layer. The waveguiding phenomenon in this case is considered to be caused by total reflection at the interface between the active layer and the cladding layer, and the totally reflected light is
Almost confined in the active layer. Since the active layer strongly absorbs light, when the current injection amount is small, the ratio of light extracted to the outside is very small, and only the light in the vicinity of the laser emission end face leaks to the outside. When the current injection amount exceeds the laser oscillation threshold value, the totally reflected light is amplified and laser oscillation occurs, and the laser light is emitted from the emission end face. However, in the LED that does not oscillate, the ratio of light emitted from the side surface is small. Even in the above-mentioned conventional LED in which a multilayer reflective film is formed on an opaque substrate that absorbs light, it is not practical to apply the above-mentioned simple mounting method because the amount of light emitted from the side surface of the chip is extremely small as described above. It was

The present invention solves the above-mentioned conventional problems by preventing the light generated from the light emitting region from being absorbed by the opaque layer or the opaque substrate, and externally emitting the light traveling obliquely from the light emitting region. It is an object of the present invention to provide an LED capable of improving the external emission efficiency and the current utilization efficiency by contributing to the above. Another object of the present invention is to provide an LED that can mainly extract light from the side surface of the chip and can be easily mounted to improve productivity.

[0012]

The light emitting diode of the present invention comprises a light emitting region, a light transmitting layer transparent to light generated in the light emitting region, and an opaque opaque layer to light generated in the light emitting region. A light layer or an opaque substrate is arranged in this order, and a total reflection layer having a smaller refractive index than the light transmitting layer is provided between the light transmitting layer and the non-light transmitting layer or the opaque substrate in contact with the light transmitting layer. ,
At least a part of the light generated in the light emitting region and reflected by the total reflection layer is emitted to the outside from the side surface of the light transmitting layer and the light emitting region, whereby the above object is achieved.

Further, the light emitting diode of the present invention has, on one wide surface of the light emitting region, a first transparent layer which is transparent to the light generated in the light emitting region, and the light generated in the light emitting region. An opaque first non-translucent layer or an opaque substrate is arranged in this order from the light emitting region side, and on the side of the light emitting region opposite to the first light transmissive layer, for the light generated in the light emitting region. A transparent second transparent layer and a second non-transparent layer which is opaque to the light generated in the light emitting region are arranged in this order from the light emitting region side, and the first transparent layer and the first transparent layer are arranged in this order. A first total reflection layer having a refractive index smaller than that of the first light-transmitting layer is provided between the first light-transmitting layer and the opaque substrate and is in contact with the first light-transmitting layer. A second total reflection layer having a refractive index smaller than that of the second light-transmitting layer is provided between the light-transmitting layer and the second light-impermeable layer so as to be in contact with the second light-transmitting layer. At least said generated in the optical domain 1
At least a part of the light reflected by the total reflection layer or the second total reflection layer of the above is emitted to the outside from the side surfaces of the first light transmission layer, the second light transmission layer and the light emitting region, whereby The above object is achieved.

The product of the film thickness and the refractive index of the total reflection layer is preferably 1.41 times or more the central emission wavelength of the light emitting diode.

The transparent layer is AlGaAs or AlGa.
When the total reflection layer is made of InP, the total reflection layer has a lower refractive index than that of the translucent layer such as AlAs, AlGaAs, AlInP or A.
It is preferably composed of 1GaInP.

When the translucent layer is made of GaAsP, the total reflection layer has GaP and GaA whose refractive index is lower than that of the translucent layer.
It is preferably composed of sP or AlGaAs.

When the translucent layer is made of ZnSe, ZnSSe or ZnMgSSe, the total reflection layer has a lower refractive index than ZnCdS, ZnCdSSe or Z.
It is preferably composed of nMgSSe.

The transparent layer is GaN or AlGaInN.
When it is made of, the total reflection layer is preferably made of AlGaInN having a refractive index lower than that of the translucent layer.

A protective film is preferably formed on the side surface of the light transmitting layer.

A first electrode and a second electrode are formed on the surface of the substrate, and the surfaces of the first conductivity type electrode and the second conductivity type electrode of the light emitting diode are formed in the vicinity of the first electrode and the second electrode. The light emitting diode is arranged such that the base and the opposite side surface of the first electrode and the second electrode are substantially orthogonal to each other, and the first electrode, the first conductivity type electrode, and the second electrode.
It is desirable that the electrode and the second conductivity type electrode are electrically connected to each other.

In the present invention, a medium that can obtain a reflectance of 50% or more is defined as a total reflection layer.

[0022]

In the present invention, the light-emitting region (junction interface between the p-type layer and the n-type layer, the light-emitting layer provided between the p-type layer and the n-type layer, etc.) and the light generated in the light-emitting region are used. On the other hand, a transparent transparent layer (clad layer, etc.) and an opaque layer (buffer layer, cap layer, electrode, etc.) opaque to the light generated in the light emitting region or an opaque substrate are arranged in this order. .
A total reflection layer having a smaller refractive index than the transparent layer is provided between the transparent layer and the non-transparent layer or the opaque substrate, and the total non-transparent light of the light generated in the light emitting region is provided. Light traveling toward the layer or the opaque substrate is reflected by the total reflection layer and does not reach the opaque layer or the opaque substrate. Therefore, even if a semiconductor layer or substrate that absorbs light is used, the light is not absorbed, and the efficiency of extracting the emitted light to the outside can be improved. In addition, since there is a light-transmitting layer that is transparent to the emission wavelength and does not absorb or emit light between the light-emitting region and the total reflection layer, at least a part of the light reflected by the total reflection layer is in the light-transmission layer. It is released from the side.
Therefore, even in the case of an LED that does not oscillate, it is possible to extract light from the side surface, and an LED suitable for horizontal mounting can be obtained.

In addition, a first light-transmitting layer that is transparent to the light generated in the light-emitting region and a first light-transmitting layer that is opaque to the light generated in the light-emitting region are provided on one wide surface of the light-emitting region. Alternatively, an opaque substrate is arranged in this order from the light emitting region side, and on the side of the light emitting region opposite to the first light transmitting layer, a second light transmitting layer transparent to light generated in the light emitting region, and When the second opaque layer that is opaque to the light generated in the light emitting region is arranged in this order from the light emitting region side, that is, the light opaque layer or the opaque substrate exists on both upper and lower sides of the light emitting region. In that case, the respective light-transmitting layers are provided between the first light-transmitting layer and the first light-transmitting layer or the opaque substrate and between the second light-transmitting layer and the second light-transmitting layer. With a smaller refractive index than each translucent layer
And a second total reflection layer. in this case,
Since the light is reflected by both the first total reflection layer and the second total reflection layer, not only the light that goes to the lower part of the light emitting layer but also the light that is absorbed near the electrode and goes to the upper part of the light emitting layer is on the side surface. It is possible to guide, and it is possible to guide to the side face more efficiently.

In order to obtain a sufficient reflectance, it is necessary to increase the film thickness of the total reflection layer, and the product of the film thickness and the refractive index (optical path length) is 1.41 times or more the central emission wavelength of the light emitting diode. Is desirable. This value can be applied approximately regardless of the wavelength.

It is desirable that the material of the total reflection layer not only has a smaller refractive index than the incident side (translucent layer) but also has a lattice matching material. When the light-transmitting layer is made of AlGaAs, the total reflection layer has a refractive index lower than that of the light-transmitting layer, such as AlAs and AlGaAs (however, A
l mixed crystal ratio is larger than that of the translucent layer), AlInP or AlGa
It is preferably composed of InP. The transparent layer is AlGaInP
When the total reflection layer is composed of Al, the refractive index of which is lower than that of the translucent layer.
As, AlGaAs, AlInP or AlGaInP
(However, the Al mixed crystal ratio is larger than that of the translucent layer). When the translucent layer is made of GaAsP, the total reflection layer is preferably made of GaP, GaAsP (where the P mixed crystal ratio is larger than that of the translucent layer) or AlGaAs having a lower refractive index than the translucent layer. When the translucent layer is made of ZnSe or ZnSSe, the total reflection layer is made of ZnCdS, Z having a lower refractive index than the translucent layer.
It is preferably composed of nCdSSe or ZnMgSSe. When the translucent layer is made of ZnMgSSe, the total reflection layer is preferably made of ZnCdS, ZnCdSSe or ZnMgSSe having a lower refractive index than the translucent layer (however, the Mg mixed crystal ratio or the S mixed crystal ratio is larger than that of the translucent layer). GaN transparent layer
When the total reflection layer is composed of Al, the refractive index of which is lower than that of the translucent layer.
It is preferably made of GaInN. The transparent layer is AlGaI
When it is made of nN, it is desirable that the total reflection layer is made of AlGaInN having a lower refractive index than the translucent layer (however, the Al mixed crystal ratio is larger than the translucent layer or the In mixed crystal ratio is smaller than the translucent layer).

By forming a protective film on the side surface of the light-transmitting layer, it is possible to prevent electric leakage on the side surface and prevent deterioration of the semiconductor crystal forming the LED.

A printed circuit board is manufactured by forming a first electrode and a second electrode on the surface of a substrate, and a surface electrode and a back surface electrode of a light emitting diode are formed in the vicinity of the first electrode and the second electrode. The light emitting diode is arranged (horizontally placed) such that the base body and the opposite side surface of the first electrode and the second electrode are substantially orthogonal to each other, and the first electrode, the surface electrode, and the second electrode
When the electrode and the back electrode are electrically connected to each other, the LED chip can be directly mounted on the printed circuit board without performing wire bonding, so that the process is simple and the electrical connection is highly reliable. Since the LED of the present invention can increase the amount of light extracted from the side surface, such lateral mounting is possible.

[0028]

Embodiments of the present invention will be described below.

Example 1 FIG. 1 is a sectional view of an AlGaInP LED according to Example 1 of the present invention. The thickness of each layer is the thickness in the direction perpendicular to the substrate surface, and GaInP is Ga _0.5 In _0.5 P, AlIn.
P is Al _0.5 In _0.5 P and AlGaInP is (Al _y Ga
_1-y ) _0.5 In _0.5 P.

In FIG. 1, an n-type Ga having a thickness of 0.5 μm is formed on an n-type GaAs substrate 10 having a (100) surface.
As buffer layer 11, n-type Al _0.5 G with a thickness of 0.2 μm
a _0.5 As intermediate band gap layer 12, n having a thickness of 1 μm
-Type AlAs total reflection layer 14, n-type AlGa having a thickness of 25 μm
InP (y = 0.7) clad layer 15, undoped AlGaInP (y = 0.5) light emitting layer 16 having a thickness of 1 μm, p-type AlGaInP (y = 0.7) clad layer 17 having a thickness of 25 μm, p-type having a thickness of 1 μm An AlAs total reflection layer 18, a p-type Al _0.5 Ga _0.5 As intermediate bandgap layer 20 having a thickness of 0.2 μm, and a p-type GaAs contact layer 21 having a thickness of 1 μm are formed. Further, the contact layer 21
A front electrode (p-side electrode in this case) 25 made of AuZn is formed on the upper surface, and a back electrode (n-side electrode in this case) 26 made of AuGe is formed on the surface opposite to the semiconductor layer growth surface of the substrate 10. Has been done. In this LED, the cladding layers 15 and 18 are transparent to the light generated in the light emitting layer 16, and the substrate 10, the buffer layer 11, and the contact layer 21 are opaque to the light generated in the light emitting layer 16.
Further, the refractive index of the total reflection layers 14 and 18 is determined by the cladding layer 1
It is smaller than the refractive index of 5,17. From the above, AlGaIn
A P-type LED is constructed.

This LED can be manufactured as follows.

First, n-type Ga whose surface is a (100) plane
MOCVD (Metal Organic Chemical Vapor Deposition) on As substrate 10
N-type GaAs buffer layer 11, n-type Al _0.5 G
a _0.5 As intermediate band gap layer 12, n-type AlAs total reflection layer 14, n-type AlGaInP (y = 0.7) cladding layer 15, undoped AlGaInP (y = 0.5) light-emitting layer 16, p-type AlGaInP (y = 0.7) Cladding layer 17, p-type AlAs total reflection layer 18, p-type Al _0.5 Ga
_0.5 As intermediate bandgap layer 20, p-type GaA
The s contact layer 21 is sequentially laminated and formed.

Next, after forming the front surface electrode 25 and the back surface electrode 26 and applying solder (not shown) on each electrode,
It is diced at intervals of 140 μm and divided into chips. In this way, the LED chip 30 as shown in FIG. 2 is obtained.

The plurality of LED chips 30 are connected to vertical wirings C1, C2, C3 and horizontal wirings R1, R as shown in FIG.
2, the surface electrodes 25 and 26 of the chip 30 are arranged so as to be substantially perpendicular to the surfaces of the vertical wiring and the horizontal wiring on the printed circuit board 31 in which R3 and the like are wired in a matrix, and the surface electrode 25 is the horizontal wiring. Then, the back surface electrode 26 is mounted horizontally so as to be connected to the vertical wiring. After that, a protective resin is applied so as to cover the entire printed circuit board.

The operating principle of this LED will be described below with reference to FIG. In FIG. 3, the medium 1 is a translucent layer having a refractive index of 3.527, the medium 2 is a total reflection layer having a refractive index of 3.189 lower than that of the medium 1, and the medium 3 is a refractive index of 4.066−. It is an opaque layer of 0.276i. The side surface 4 of the LED is an interface with a medium (resin) 5 having a refractive index of 1.5. Further, A is the incident angle of light from the medium 1 to the medium 2, C is the incident angle of the light emitted from the side face 4 to the side face, and d is the layer thickness of the medium 2.

FIG. 4 shows the calculation results of the change in the reflectance R when the layer thickness d of the medium 2 is changed for the incident angles A in FIG. 3 of 50 ° and 66 °. However,
The wavelength λ of light was 0.564 μm. As shown in FIG. 4, when the incident angle A is 50 ° which is less than the total reflection critical angle Ac = 64.7 °, the reflectance R periodically increases and decreases as the value of the layer thickness d of the medium 2 increases. repeat. When the incident angle A is 66 ° which exceeds the total reflection critical angle Ac, the total reflection condition A> A
Since c is satisfied, the reflectance R is 100% when the layer thickness d of the medium 2 is sufficiently larger than the wavelength λ, but the reflectance R is small when the layer thickness d of the medium 2 is thin.

When the reflectance R exceeds 50%, that is, the medium 2 is a total reflection layer, the layer thickness d of the medium 2 is 0.
It is about 25 μm, and the reflectance becomes close to 100% when the layer thickness d of the medium 2 is about 1 μm or more. This is because even if the incident angle A satisfies the condition of total reflection A> Ac, the medium 2 has an exudation of light called an evanescent wave. Therefore, in order to obtain a sufficient reflectance, the medium is more than the exudation distance. This is because the layer thickness d of 2 must be sufficiently large. The lower limit layer thickness for obtaining a reflectance of 50% or more in which the medium 2 becomes a total reflection layer is 0.25 μm, but this varies depending on the wavelength. If this is converted into the optical path length (refractive index × layer thickness), 1.41 times the wavelength (3.189 × 0.25 μm / 0.564 μ)
m), and this value can be applied regardless of the wavelength.

Here, the lower limit layer thickness of the total reflection layer is much larger than the layer thickness of the low refractive index layer in the conventionally used multilayer reflection layer. The thickness of the low refractive index layer in the multilayer reflective layer is λ / 4n
(N is a refractive index, and the optical path length is 0.25 times the wavelength. On the other hand, the optical path length of the total reflection layer is 1.41 times the wavelength, and the ratio of both is at least 5.6 times or more. Therefore, the multilayer reflection layer is Bragg reflection and the total reflection layer is total reflection, and the operating principles are completely different, and the two are different.

When light is emitted from the element side surface 4 on which such a total reflection layer (medium 2) is formed, the condition of the incident angle C that the light emitted from the element side surface 4 should satisfy is 0 ° <C <
It is Cmax. The total reflection critical angle Cmax of the light emitted from the medium 1 to the medium 5 is arcsin (1.5 / 3.52).
7) = 25.16. When the element side surface 4 is perpendicular to the total reflection layer (medium 2), A = 90 ° −C. Therefore, in order for the total reflection layer (medium 2) to reflect the light emitted from the element side surface 4 with high reflectance, Amin =
90 ° -Cmax = 64.84 °, 64.84 °
It is sufficient to have a high reflectance for light with <A <90 °. Amin = 64.84 is a total reflection layer (medium 2)
Is substantially equal to the total reflection critical angle Ac = 64.7, and the light emitted from the element side surface 4 can be reflected with high reflectance.

Therefore, if the total reflection layer (medium 2) has a sufficiently large layer thickness d, the light emitted from the element side surface 4 can be almost completely reflected, and in the case of an LED emitting the light from the element side surface 4. It is not necessary to use a multi-layered reflective layer which has been used conventionally. However, the total reflection critical angle Ac is the medium 1
Since the critical angle Cmax of total reflection depends on the difference in refractive index between the medium 1 and the medium 5, the total reflection critical angle Cmax depends on the difference in refractive index between the medium 1 and the medium 5. Good. The multilayer reflective layer to be combined can have a high reflectance with respect to obliquely incident light in order to compensate for the reflectance with respect to the light emitted to the element side surface 4, and can also be used for light with nearly vertical incidence to be emitted to the upper surface. It is also possible to use one having a high reflectance.

Although the refractive index of each material is often not known exactly, the refractive index of a material having a large band gap is generally low. Particularly in III-V semiconductors, II
In the group I element, the material having a larger ratio of Ga than In and Al than Ga is lower in refractive index, and in the group V element, the material having a higher ratio of P than As and N than P is lower in refractive index. Also in the II-VI group semiconductor, Zn and Zn are contained in the group II element rather than Cd.
A material having a higher Mg ratio has a lower refractive index, and a material having a higher Se ratio than Te and a higher S ratio than Se in the Group VI elements has a lower refractive index. Similarly, Group IV semiconductors (SiC, SiGe)
Etc.) also has a low refractive index of a material having a larger ratio of Si than Ge and C than Si.

As described above, the total reflection layer made of a material having a refractive index lower than that of the light-transmitting layer such as the cladding layer is used as the non-light-transmitting layer (substrate,
When it is formed so as to be in contact with the transparent layer between the buffer layer and the contact layer) and the transparent layer, it is suitable for an LED that emits light from the side surface of the device.

FIG. 5A shows a schematic diagram when light is emitted from the upper surface, and FIG. 5B shows a schematic diagram when light is emitted from the side surface. When the light is emitted from the upper surface, as shown in FIG. 5A, of the light emitted from the point P, the component emitted from the upper surface is restricted due to the total reflection on the upper surface, and is circular. Area 6 only. Therefore, the ratio of the solid angle of the light that can be emitted from the upper surface to the total solid angle is 5.1.
%. On the other hand, when light is emitted from the side,
As shown in (b), the light emitted from the point Q on the central axis of the cylinder is emitted from the belt-shaped region 7 on the side surface of the cylinder.
Therefore, the ratio of the solid angle of the light that can be emitted from the side surface of the element to the total solid angle is 44.1%, which is overwhelmingly larger than the solid angle of the light that can be emitted from the upper surface.

Here, in order to emit the light from the side surface without using the total reflection layer, it is necessary to transmit the light so that the light beam emitted at the center reaches the side surface without being absorbed by the opaque substrate or the light opaque layer. It is necessary to make the characteristic region sufficiently thick or to reflect the light obliquely incident on the substrate. However, by providing an opaque substrate or an opaque layer and a total reflection layer between the translucent region,
It is possible to guide the light generated at the center to the side surface without increasing the thickness of the translucent region to an extreme extent, and it is possible to improve the external emission efficiency. Further, by providing the total reflection layer not only on the lower portion of the light emitting layer but also on the upper portion, the light that is directed to the upper portion and absorbed in the vicinity of the electrode can be guided to the side surface.

In the LED of this embodiment, the total reflection layer 1
Since the light emitting layers 4 and 18 are formed, it is possible to prevent light from being absorbed from the light emitting layer 16 downward to the buffer layer 11 and the substrate 10, and from the light emitting layer 16 upward to the contact layer 21. It is also possible to prevent absorption in the vicinity of the electrodes. In addition to the light ray a directly reaching the side surface, the light rays emitted from the light emitting layer 16 are also light rays b and c directed to the upper and lower portions and reflected by the total reflection layers 14 and 18 and guided to the element side surface. Since the light is emitted to the outside from the side surfaces of the layers 15 and 17, it is possible to enhance the efficiency of external emission and achieve high current utilization efficiency.

Since the light emitting surface of the LED in this embodiment is the side surface of the element and the emitting surface is not formed on the upper surface, the chip size can be reduced to 140 μm square.
Therefore, the number of elements per wafer can be four times or more as compared with the conventional element having an element size of 300 μm square, and the productivity can be significantly improved.

The LED of this embodiment emits light with a center wavelength of 560 nm, and can obtain a luminous intensity of about 1.7 times that of a conventional top emission LED. This is because, as described above, the proportion of light that can be emitted to the upper surface is greater than the proportion of light that can be emitted to the upper surface.

Since a large amount of light can be taken out from the side surface of the chip in this manner, the chip can be mounted horizontally on a printed circuit board, and highly reliable electrical connection can be performed by a simple production process. it can. In addition, since it can be mounted at a high density by being placed horizontally, a large number of LEDs can be arranged in a narrow area. Therefore, planar or linear LED
It can be suitably used for light sources, LED displays, interconnections using LEDs, etc., and can be widely applied for display, communication, and signal transmission.

The following modifications can be made in this embodiment.

Any of the above-mentioned total reflection layers 14 and 18 can be used as long as it is made of a material having a refractive index lower than that of the clad layers 15 and 17 which are light transmitting layers. AlAs, Al whose refractive index is lower than the layer
GaAs (however, the Al mixed crystal ratio is larger than that of the translucent layer), AlIn
Those made of P or AlGaInP are preferable. Further, the layer thickness of the total reflection layers 14 and 18 may be 0.25 μm or more, but depending on the emission wavelength, the refractive index and the layer thickness are adjusted so that the optical path length of the total reflection layer is 1.41 times the wavelength. It is desirable to do. Further, when an AlGaAs layer is formed as the light transmitting layer, the refractive index A is lower than that of the light transmitting layer.
lAs, AlGaAs, AlInP or AlGaIn
A P layer can be used, but in that case AlGaIn
As the P layer, one having an Al mixed crystal ratio larger than that of the translucent layer can be used.

Although the LED chip is electrically connected to the electrode wiring by using solder in this embodiment, it is connected to the electrode wiring by using a conductive material other than solder, such as Ag paste or conductive resin. It may be electrically connected. In addition to mounting on the printed circuit board 31 in FIG. 2, resin may be sealed after die bonding and wire bonding to an ordinary cup-shaped stem.

Furthermore, in this embodiment, the electrodes 25 and 26 of the LED chip are formed on the entire front and back surfaces.
A part of the electrode may be removed so that light can be emitted from a part of the upper surface or the lower surface. In that case, if the total reflection layer formed under the electrode to be removed is also removed at the same time and the clad layer or the current spreading layer, which is a clad layer in a broad sense, directly contacts the outside (resin, air, vacuum, etc.), the interface Since the difference in the refractive index becomes large, the function of the total reflection layer becomes large, which is preferable.

Further, although AuZn is used as the surface electrode 25 in this embodiment, it may be used with other p-side ohmic electrodes. Further, although AuGe is used as the back electrode 26 in this embodiment, other n-side ohmic electrodes may be used.

Further, in this embodiment, the intermediate band gap layers 12 and 20 have the effect of reducing the voltage applied to the element, but they may not necessarily be formed, and in addition to AlGaAs, the band between GaAs and AlAs. Other materials having a gap (such as AlGaInP) may be used. Further, it may be a graded layer whose composition is gradually changed or a superlattice layer.

Furthermore, although the conductivity type of the substrate 10 is n-type in the present embodiment, it is not limited to n-type but may be p-type.
In this case, it is necessary to make the conductivity types of the layers all opposite.
Further, in the present embodiment, the plane orientation of the substrate 10 is set to (100), but it is not limited to (100) and may be any plane orientation.

Further, in this embodiment, each of the semiconductor layers 11 to 11 is
21 is formed by MOCVD method, but may be formed by growth method such as MBE (molecular beam epitaxy) method, gas source MBE method, MOMBE (organic metal MBE) method, CBE (chemical beam epitaxy) method.

(Embodiment 2) FIG. 6 is a top view of an AlGaInP LED of Embodiment 2 of the present invention, and FIG. 7 is a sectional view thereof.

In FIGS. 6 and 7, the surface is (10
The upper part of the n-type GaAs substrate 50, which is the (0) plane, is partially removed to have a truncated cone shape, and a thickness of 0.5 μm is formed thereon.
N-type GaAs buffer layer 51, 0.2 μm thick n-type GaInP intermediate bandgap layer 52, 1 μm thick n
-Type AlInP total reflection layer 53, n-type AlG having a thickness of 25 μm
aInP (y = 0.7) clad layer 55, undoped AlGaInP (y = 0.5) light emitting layer 56 having a thickness of 1 μm,
A p-type AlGaInP (y = 0.7) clad layer 57 having a thickness of 25 μm and a p-type AlInP total reflection layer 5 having a thickness of 1 μm
9, a p-type GaInP intermediate bandgap layer 60 having a thickness of 0.2 μm, and a p-type GaAs contact layer 61 having a thickness of 1 μm are sequentially formed, and the side surface 69 is slightly inclined 10
A mesa shape 68 of 0 μmφ is formed. This mesa shape 6
A protective film 67 made of SiO ₂ is formed on the side surface 69 of No. 8. A surface electrode (p-side electrode in this case) 65 is formed on the contact layer 61, and the substrate 50
A back surface electrode (n-side electrode in this case) 66 is formed on the surface opposite to the semiconductor layer growth surface. From the above, AlG
An aInP LED is constructed.

In this LED, the cladding layers 55, 5
7 is transparent to the light generated in the light emitting layer 56, and the substrate 50, the buffer layer 51, and the contact layer 61 are the light emitting layer 56.
It is opaque to the light generated by. In addition, the total reflection layer 5
The refractive index of 3,59 is smaller than the refractive index of the cladding layers 55,57.

This LED can be manufactured as follows.

First, n-type Ga whose surface is the (100) plane
N-type GaAs is formed on the As substrate 50 by MOCVD.
Buffer layer 51, n-type GaInP intermediate bandgap layer 52, n-type AlInP total reflection layer 53, n-type AlGaIn
P (y = 0.7) clad layer 55, undoped AlGa
InP (y = 0.5) light emitting layer 56, p-type AlGaInP
(Y = 0.7) A clad layer 57, a p-type AlInP total reflection layer 59, a p-type GaInP intermediate bandgap layer 60, and a p-type GaAs contact layer 61 are sequentially laminated.

Next, the front surface electrode 65 and the back surface electrode 66 are vapor-deposited on the entire surface of the substrate 50 side and the contact layer 61 side to form a resist pattern of 100 μmφ on the front surface electrode 65. Subsequently, each layer is etched by wet etching to form a groove having a depth of 50 μm. By this etching, the side surface of each layer becomes a slightly inclined side surface 69.
A mesa shape 68 of 0 μmφ is formed.

After that, the SiO ₂ protective film 67 is formed on the side surface 69. At that time, since the protective film 67 also adheres to the surface electrode 65, after covering the side surface 69 with a resist,
The protective film on the surface electrode 65 is removed by etching.

Next, the wafer is diced at intervals of 140 μm and divided into chips.

After that, as shown in FIG. 8, Ag paste is applied to the stem 80 and the back electrode 6 of the LED chip 81 is applied.
Stick 6 on the stem 80 with the bottom down. A wire 83 is connected between the surface electrode 65 and the lead wire 82, and the entire stem is sealed with a resin 84.

In the LED of this embodiment, the total reflection layer 5
Since 3, 59 are formed, it is possible to prevent light from being absorbed from the light emitting layer 56 toward the lower portion by the buffer layer 51 and the substrate 50, and from the light emitting layer 56 toward the upper portion. It is also possible to prevent absorption in the vicinity of the electrodes. In addition to the light rays directly reaching the side surfaces, the light rays emitted from the light emitting layer 56 also travel toward the upper and lower portions and are reflected by the total reflection layers 53 and 59 to be guided to the side surfaces.
Is also emitted to the outside from the side surfaces of the clad layers 55 and 57, which are translucent layers. These rays are reflected by the side wall of the stem 80 as shown by the dotted line in FIG.

According to the LED of this embodiment, since the mesa shape 68 is provided, it has the following advantages.

First, the conical shape increases the external emission efficiency as compared with the quadrangular prism. Secondly, the side surface 68 is not damaged by dicing, which is advantageous in terms of reliability. Thirdly, the protective film 67 can be formed on the side surface 69.

By thus forming the protective film 67, it is possible to prevent electrical leakage at the side surface 69 and prevent deterioration of the semiconductor crystal forming the LED. By setting the layer thickness of the protective film 67 × refractive index to 1/4 of the emission wavelength, it can serve as an antireflection film, and the light emission efficiency can be further increased.

Further, since the side surface 69 of this LED chip is provided with the protective film 67, it is suitable for the horizontal mounting as shown in the first embodiment.

In this embodiment, the mesa shape 68 has a conical shape, but it may have a shape other than a cone, such as an octagonal pyramid, a hexagonal pyramid, a quadrangular pyramid, or a triangular pyramid. Further, in the present embodiment, the side surface 69 is slightly inclined with respect to the surface of the substrate 50, but it may be perpendicular to the substrate 50. Furthermore, mesa shape 6
In this embodiment, the etching for forming 8 is performed after forming the front surface electrode 65 and the back surface electrode 66, but may be performed before forming the electrodes. In addition, this etching is RI
It may be performed by a BE (reactive ion beam etching) method or the like.

Further, as the protective film 67, alumina, silicon nitride, or other dielectric layers other than SiO ₂ can be used, and examples of the method for forming these include a vacuum vapor deposition method and a sputtering method. Further, as the protective film 67, Al
GaAs, AlGaInP, or other semiconductor film may be used. However, when a semiconductor film is formed as the protective film 67, it is desirable to perform it before forming the front surface electrode 65 and the back surface electrode 66. Further, a resin may be used as the protective film 67.

In addition, the same changes as those shown in the first embodiment can be made.

(Embodiment 3) FIG. 9 is a sectional view of a GaAsP-based LED of Embodiment 2 of this embodiment. In addition, G
aAsP is an abbreviation for GaAs _1-x P _x .

In FIG. 9, an n-type GaA substrate having a thickness of 25 μm is formed on an n-type GaP substrate 70 whose surface is a (111) B plane.
sP (gradually changing x from 0.6 to 0.5) Graded buffer layer 71, n-type GaAs with a thickness of 50 μm
P (x = 0.65) layer 72, n-type GaAsP: N (x =
0.65) layer 73, p-type GaAsP: N (x = 0.6
5) Layer 74, and p-type GaP total reflection layer 7 having a thickness of 5 μm
5 are sequentially formed. Further, a front surface electrode (p-side electrode in this case) 76 is formed on the total reflection layer 75, and a back surface electrode (n-side electrode in this case) 77 is formed on the surface of the substrate 70 opposite to the semiconductor layer growth surface. Has been done. The GaAsP LED is constructed as described above.

In this LED, the light emission is n-type GaAs.
P: N (x = 0.65) layer 73 and p-type GaAsP:
It occurs near the pn junction formed at the interface of the N (x = 0.65) layer 74. The translucent layer is transparent to the light generated in the light emitting region, and the electrodes 76 and 77 are opaque to the light generated in the light emitting region. Further, the refractive index of the total reflection layer 75 is smaller than the refractive index of the translucent layer.

This LED can be manufactured as follows.

First, n-type G whose surface is the (111) B plane
An n-type GaAsP graded buffer layer 71, an n-type GaAsP layer 72, an n-type GaAsP: N layer 73, and an undoped GaP total reflection layer 75 are sequentially formed on the aP substrate 70 by the LPE method.

Next, this wafer and Zn are put in a quartz tube and heated to 700 ° C. to diffuse Zn from the surface. As a result, the upper portion of the n-type GaAsP: N layer 73 and the undoped G
The aP total reflection layer 75 and p-type GaA are converted to p-type
It becomes the sP: N layer 74 and the p-type GaP total reflection layer 75. By this step, the back surface of the n-type GaP substrate 80 is also converted to p-type, but this portion is removed by polishing.

Subsequently, the front surface electrode 76 and the back surface electrode 77.
Is vapor-deposited on the entire surface, and is diced at intervals of 250 μm to divide into chips.

Thereafter, similarly to the first embodiment, it is horizontally mounted on the printed board.

In the LED of this embodiment, the total reflection layer 7
Since 5 is formed, it is possible to prevent light from being absorbed by the surface electrode 76 from the light emitting region toward the upper side. The light emitted from the light emitting region is not only the light ray directly reaching the side surface, but also the light traveling upward is reflected by the total reflection layer 75 and guided to the side surface, and as a light ray k, the light transmitting layer (GaAsP: N layer 7).
Since the light is emitted from the side surface of (3, 74), a high external emission efficiency can be obtained.

Further, the GaP substrate 70 has the composition of the total reflection layer 7
5 is the same as that of FIG.
0, resulting in a similar effect to the total reflection layer 75. However, the total reflection layer in the present invention is a thin film for total reflection intentionally inserted in front of the absorption region when viewed from the light emitting region, and therefore differs from the idea of the present invention.

In this embodiment, GaP and GaAsP are used.
GaAsP graded buffer layer 7 whose composition is gradually changed on the GaP substrate 70 because the lattice coefficient of
1 is provided to grow the GaAsP layer and prevent crystal defects due to lattice mismatch from reaching the light emitting region. on the other hand,
In the GaP total reflection layer 75 formed on the GaAsP layer, the light emitting region is already formed. Therefore, even if the graded buffer layer is omitted, the light emitting region is less likely to have lattice defects. Therefore, although the graded buffer layer is not formed below the total reflection layer in this embodiment, it may be formed.

Further, in this embodiment, Ga is formed on the GaP substrate.
Although the AsP layer is grown, it may be grown on a GaAs substrate. In general, GaP substrates are used for yellow, orange, and red GaAsP LEDs, and red and infrared GaA are used.
A GaAs substrate is used for the sP LED.

Any material can be used for the total reflection layer 75 as long as it is made of a material having a refractive index lower than that of the light transmitting layer. However, in consideration of lattice matching, Ga having a lower refractive index than the light transmitting layer is used.
P, GaAsP (however, the P mixed crystal ratio is larger than that of the transparent layer) or AlGaAs is preferable. Further, the total reflection layer 75 is preferably adjusted in refractive index and layer thickness so that the optical path length is 1.41 times the wavelength or more.

In addition, the same changes as those shown in the first and second embodiments can be made.

(Embodiment 4) FIG. 10 is a sectional view of a ZnCdSe-based LED according to Embodiment 4 of the present invention. In addition,
ZnCdSe is Zn _1-x Cd _x Se, ZnCdS is Zn
_1-x Cd _x S, ZnMgSSe is Zn _1-x Mg _x S _y Se _1-y
Stands for.

In FIG. 10, an n-type GaAs substrate 100
On top, an n-type GaAs buffer layer 10 having a thickness of 0.5 μm is formed.
1. n-type Al _0.5 Ga _0.5 As first intermediate band gap layer 102 having a thickness of 0.2 μm, n-type AlA having a thickness of 0.2 μm
s Second intermediate bandgap layer 103, 1 μm thick n-type ZnCdS total reflection layer 104, 20 μm thick n-type ZnS
Se clad layer 105, 0.01 μm thick undoped ZnCdS (X = 0.2) strained quantum well emission layer 106,
20 μm thick p-type ZnSSe cladding layer 107, 1 μm thick p-type ZnCdS total reflection layer 108, 0.2 μm thick
An n-type AlAs second intermediate bandgap layer 109 having a thickness of 0.2 m, an n-type Al _0.5 Ga _0.5 As first intermediate bandgap layer 110 having a thickness of 0.2 μm, and a p-type GaAs contact layer 111 having a thickness of 1 μm are sequentially formed. Further, a front surface electrode (p-side electrode in this case) 115 is formed on the contact layer 111, and a back surface electrode (n-side electrode in this case) is formed on the surface of the substrate 100 opposite to the semiconductor layer growth surface.
116 is formed. From the above, ZnCdSe system L
The ED is configured.

In this LED, the cladding layer 105,
Reference numeral 108 is transparent to light generated in the light emitting layer 106, and includes the substrate 100, the buffer layer 101, and the contact layer 11.
1 is opaque to the light generated in the light emitting layer 106.
Further, the refractive indices of the total reflection layers 104 and 108 are smaller than the refractive indices of the cladding layers 105 and 107.

This LED can be manufactured as follows.

First, MB is formed on the n-type GaAs substrate 100.
N type GaAs buffer layer 101, n type Al by E method
_0.5 Ga _0.5 As first intermediate bandgap layer 102, n-type AlAs second intermediate bandgap layer 103, n-type ZnC
dS total reflection layer 104, n-type ZnSSe cladding layer 10
5, undoped ZnCdS (X = 0.2) strained quantum well light emitting layer 106, p-type ZnSSe cladding layer 107, p-type ZnCdS total reflection layer 108, n-type AlAs second intermediate bandgap layer 109, n-type Al _0.5 Ga _0.5. An As first intermediate bandgap layer 110 and a p-type GaAs contact layer 111 are sequentially stacked.

Then, the front surface electrode 115 and the back surface electrode 1
16 is formed and divided into chips of 140 μm square, and the chips are horizontally mounted on a printed board in the same manner as in Example 1.

Therefore, in the LED of this embodiment, since the total reflection layers 104 and 108 are formed, it is possible to prevent light from being absorbed by the buffer layer 101 and the substrate 100 downward from the light emitting layer 106. And again,
It is also possible to prevent absorption from the light emitting layer 106 toward the upper part in the vicinity of the contact layer 111 and the electrodes. In addition to the light rays that directly reach the side surfaces, the light rays i and the light rays j that are reflected by the total reflection layers 104 and 108 and are guided to the side surfaces in addition to the light rays that directly reach the side surfaces are also light transmitting layers. Since the light is emitted to the outside from the side surfaces of the clad layers 105 and 107, it is possible to enhance the efficiency of external emission.

Further, this LED emits blue light having a wavelength of 492 nm, which is indispensable for full-color display, and can obtain a luminous intensity about 2.2 times that of a conventional top emission LED.

In this embodiment, the ZnCdS layer is used as a total reflection layer by utilizing the fact that the refractive index of ZnCdS is smaller than that of ZnSSe forming the cladding layers 105 and 107. However, the mixed crystal ratio of ZnCdS and ZnSSe is set so as to be lattice-matched with the GaAs substrate 100.

As the total reflection layers 104 and 108,
ZnCdS, ZnCdSSe, ZnMgSSe, or the like having a lower refractive index than that of the light transmitting layer can be used.

Moreover, ZnSe, ZnSSe or ZnMgSSe can be used as the cladding layers 105 and 107 which are the medium on the light incident side with respect to the total reflection layers 104 and 108. Even if the clad layer is made of ZnMgSSe, the total reflection layers 104 and 108 are clad layers 105 and 1.
It is possible to use ZnCdS, ZnCdSSe, or ZnMgSSe having a refractive index lower than 07. ZnMg
When SSe is used, one having a Mg mixed crystal ratio or an S mixed crystal ratio higher than that of the light transmitting layer can be used. The cladding layers 105 and 107 are made of ZnS / ZnSe, respectively.
It may be a strained superlattice layer.

Further, the mixed crystal ratio x of the light emitting layer 106 is not particularly limited, and may be ZnSe (x = 0). Also,
The light emitting layer 106 may have a ZnSe / ZnCdSe multiple quantum well structure, for example.

Further, as the material of each of the semiconductor layers 104 to 108, Vd such as Cd, Zn, Mg as a group II element is used.
II-VI using Te, Se, S, etc. as a group I element
Group semiconductors can be used.

In addition to the MBE method, the growth of each semiconductor layer is performed by MOCVD method, MOMBE method, gas source MBE method,
It may be performed by the CBE method or the like, and the same mesa shape as that in the second embodiment may be formed.

In addition, the modifications as shown in Examples 1 to 3 are possible.

(Embodiment 5) FIG. 11 is a sectional view of an AlGaInN LED of Embodiment 5 in this embodiment.

In FIG. 11, an AlN buffer layer 301 and an n-type GaN cladding layer 3 are formed on a sapphire substrate 300.
02, an n-type GaInN light emitting layer 303, a p-type GaN cladding layer 304, and a p-type AlGaN total reflection layer 305 are sequentially formed. From these n-type cladding layers 302 to p
The type total reflection layer 305 is partially removed so that the n-type cladding layer 302 is exposed. Furthermore, the p-type total reflection layer 30
5, a p-side electrode 306 made of Au is formed, and an n-side electrode 307 made of Al is formed on the exposed portion of the n-type cladding layer 302. From the above, AlGa
An InN LED is constructed.

In this LED, the cladding layer 302,
304 is transparent to the light generated in the light emitting layer 303, and the electrodes 306 and 307 are opaque to the light generated in the light emitting layer 303. The refractive index of the total reflection layer 305 is smaller than that of the cladding layer 304.

This LED can be manufactured as follows.

First, the MOC is formed on the sapphire substrate 300.
The AlN buffer layer 301, the n-type GaN cladding layer 302, the n-type GaInN light emitting layer 303, and the p-type Ga are formed by the VD method.
N-clad layer 304, and p-type AlGaN total reflection layer 3
05 is sequentially laminated.

Next, part of the device is etched until the n-type GaN cladding layer 302 is exposed. Then, the p-side electrode 306 is formed on the p-type total reflection layer 305, and the n-side electrode 307 is formed on the exposed portion of the n-type cladding layer 302.

Thereafter, the chip is divided into 250 μm square chips by dicing, mounted on a stem, wire bonded to the p-side electrode 306 and the n-side electrode 307, and resin-sealed.

In the conventional AlGaInN-based LED, it is difficult to reduce the resistance of the p-type GaN layer and it is p-type Ga.
Current could not be sufficiently diffused in the N-clad layer, and light emission was mainly generated under the p-side electrode. Therefore, there is a problem that the light traveling toward the p-side electrode is absorbed there and cannot be effectively used.

In the LED of this embodiment, the p-side electrode 3
Since the p-type total reflection layer 305 is formed under 06,
Light can be prevented from being absorbed by the p-side electrode 306 from the light emitting layer 303 toward the upper side. A light ray t generated from the light emitting layer 303 and traveling toward the p-side electrode 306 is a total reflection layer 305.
Since the light is reflected on the side surface and guided to the side surface and is emitted to the outside from the side surface of the cladding layer 303, the external emission efficiency can be improved.

As the total reflection layer 305, AlGaInN whose refractive index is lower than that of the cladding layer 304 can be used. When AlGaInN is used as the cladding layer 304, the total reflection layer 305 has a lower refractive index than that of the cladding layer 304 (provided that the Al mixed crystal ratio is larger than that of the transparent layer or the In mixed ratio is smaller than that of the transparent layer). ) Is preferably used.

Other than the above, the same changes as those in Examples 1 to 4 can be made.

The present invention is not limited to those shown in Examples 1 to 5 above, and includes a light emitting region, a transparent layer transparent to light emitted from the light emitting region, and light emitted from the light emitting region. On the other hand, if the LED has a structure in which an opaque layer or an opaque substrate that is opaque and absorbs the emission wavelength is formed,
It can also be applied to various LEDs having other materials and structures.

[0115]

As described above, according to the present invention, the total reflection layer is formed between the light-transmitting layer (clad layer, etc.) and the non-light-transmitting layer (buffer layer, contact layer, substrate, electrode, etc.). As a result, the light that has hitherto been obliquely incident on the opaque layer and absorbed can be effectively extracted from the side surface of the LED chip, etc., and high external emission efficiency can be obtained with a small and simple structure. As a result, the current utilization efficiency can be improved. Further, since a large amount of light can be extracted from the side surface of the LED chip, a simple mounting method of horizontally mounting the LED chip on the printed circuit board can be performed.

Therefore, the LED of the present invention is made of AlGa
InP system, AlGaAs system, GaAsP system, AlGaI
It is possible to exert a great effect on high brightness, high efficiency, and improvement in productivity of various LEDs such as nN group III-V group LEDs or II-VI group LEDs.

[Brief description of drawings]

FIG. 1 is an AlGaInP-based L of Example 1 of the present invention.
It is sectional drawing which shows ED.

FIG. 2 is a top view showing a state in which the LEDs of FIG. 1 are horizontally mounted in a matrix.

FIG. 3 is a cross-sectional view for explaining the operation principle of the present invention.

FIG. 4 is a graph showing the relationship between the reflection layer thickness d and the reflectance R for explaining the principle of the present invention.

FIG. 5 is a schematic diagram for explaining the principle of the present invention,
(A) is a diagram showing a range of light emitted from the upper surface of the element,
(B) is a diagram showing a range of light emitted from the side surface of the element.

FIG. 6 is an AlGaInP-based L of Example 2 of the present invention.
It is a top view which shows ED.

7 is a cross-sectional view showing the AlGaInP-based LED of FIG.

8 is a cross-sectional view showing a state in which the AlGaInP LED of FIG. 7 is resin-sealed.

FIG. 9 is a GaAsP-based LED of Example 3 of the present invention.
FIG.

FIG. 10 is a ZnCdSe system L of Example 4 of the present invention.
It is sectional drawing which shows ED.

FIG. 11 is a sectional view showing an AlGaInN-based LED of Example 5 of the present invention.

FIG. 12 is a cross-sectional view of a conventional LED.

13A and 13B are diagrams for explaining a lateral mounting method of an LED, FIG. 13A is a perspective view of an LED chip, and FIG.
FIG. 3 is a sectional view showing a mounted state.

[Explanation of symbols]

10, 50, 70, 100, 300 Substrate 11, 51, 101, 301 Buffer layer 12, 20, 52, 60, 102, 103, 109, 1
10 Intermediate Band Gap Layer 14, 18, 53, 59, 75, 104, 108, 30
5 Total reflection layer 15, 17, 55, 57, 105, 107, 302, 3
04 clad layer 16, 56, 106, 303 light emitting layer 21, 61, 111 contact layer 25, 26, 65, 66, 76, 77, 115, 11
6,306,307 electrode 71 graded buffer layer 72 GaAsP layer 73,74 GaAsP: N layer

Claims (9)

[Claims] 1. A light emitting region, a light transmissive layer transparent to light generated in the light emitting region, and a non-transparent layer or an opaque substrate opaque to light generated in the light emitting region are arranged in this order. A total reflection layer having a smaller refractive index than the transparent layer is provided between the transparent layer and the non-transparent layer or the opaque substrate, the total reflection layer having a smaller refractive index than the transparent layer. A light emitting diode in which at least a part of light reflected by the layer is emitted to the outside from the side surface of the light transmitting layer and the light emitting region. 2. A first translucent layer transparent to light generated in the light emitting region and a first opaque layer opaque to light generated in the light emitting region on one wide surface of the light emitting region. A light layer or an opaque substrate is arranged in this order from the light emitting region side, and a second light transmitting layer transparent to light generated in the light emitting region is provided on the side of the light emitting region opposite to the first light transmitting layer. A layer and a second opaque layer opaque to the light generated in the light emitting region are arranged in this order from the light emitting region side, and the first light transmitting layer and the first light permeable layer or A first total reflection layer having a refractive index smaller than that of the first transparent layer is provided between the opaque substrate and the first transparent layer so as to be in contact with the first transparent layer, and the second transparent layer and the second transparent layer are provided. A second total reflection layer having a refractive index smaller than that of the second light transmitting layer is provided between the light transmitting layer and the second light transmitting layer, and the second total reflection layer is generated in the light emitting region to generate the first total reflection layer. all At least a part of the light reflected by at least one of the reflective layer and the second total reflection layer is emitted to the outside from the side surfaces of the first transparent layer, the second transparent layer and the light emitting region. Light emitting diode. 3. The light emitting diode according to claim 1, wherein the product of the film thickness and the refractive index of the total reflection layer is 1.41 times or more the center emission wavelength of the light emitting diode. 4. The translucent layer is AlGaAs or AlG
AlAs, AlGaAs, AlInP or Al, which is made of aInP and in which the total reflection layer has a lower refractive index than the translucent layer.
The light emitting diode according to claim 1, which is made of GaInP. 5. The light-transmitting layer is made of GaAsP, and the total reflection layer is made of GaP or GaAs having a refractive index lower than that of the light-transmitting layer.
The light emitting diode according to claim 1, which is made of P or AlGaAs. 6. The translucent layer is made of ZnSe, ZnSSe, or ZnMgSSe, and the total reflection layer has a lower refractive index than ZnCdS, ZnCdSSe, or Zn.
The light emitting diode according to claim 1, which is made of MgSSe. 7. The transparent layer is GaN or AlGaIn
3. The light emitting diode according to claim 1, wherein the total reflection layer is made of N and the total reflection layer is made of AlGaInN having a refractive index lower than that of the light transmission layer. 8. The light emitting diode according to claim 1, wherein a protective film is formed on side surfaces of the light emitting region and the light transmitting layer. 9. A first electrode and a second electrode are formed on the surface of a substrate, and a first conductivity type electrode and a second conductivity type electrode of a light emitting diode are provided in the vicinity of the first electrode and the second electrode. The light emitting diode is arranged such that the surface thereof and the side surfaces of the first electrode and the second electrode opposite to the base body are substantially orthogonal to each other, and the first electrode, the first conductivity type electrode, and the second electrode. 3. The light emitting diode according to claim 1, wherein the electrode and the second conductivity type electrode are electrically connected to each other.