JP2011086856A - Light emitting diode element, light emitting diode lamp, and lighting apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a large-size light emitting diode element allowing light intensity to be easily adjusted, capable of carrying a large drive current without concentrating the current during high current conduction, and excelling in a luminance characteristic. <P>SOLUTION: In this light emitting diode element including first and second electrodes arranged to interpose a light emitting portion including a luminescent layer, the first electrode includes three pads for wire bonding which make a light emission amount from the luminescent layer adjustable, and the area of a light emitting surface is ≥0.64 mm<SP>2</SP>. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a light-emitting element, and more particularly to a high-power light-emitting diode element used for plant growth and security using infrared light.

  A light emitting diode (hereinafter also referred to as an LED) using a GaAlAs compound semiconductor is widely used as a light source for infrared to red. Infrared LEDs are often used for optical communication and space transmission, but in recent years, demand for plant growth and security has increased. These applications are required to have high output from the viewpoint of energy saving.

  As conventionally known, in a GaAlAs-based LED, a double heterostructure (hereinafter referred to as a DH structure) has a higher output than a single heterostructure. Further, higher output is achieved by removing the substrate (see, for example, Patent Documents 1 to 7).

  Furthermore, when producing an epitaxial wafer of the type that removes the substrate (hereinafter referred to as a DDH structure), only a normal DH structure, that is, a three-layer structure of a p-type cladding layer, a light emitting layer, and an n-type cladding layer is epitaxially grown. When the substrate is removed, the thickness of the product becomes thin and handling in the device fabrication process becomes difficult. At the same time, the height from the bottom surface of the device manufactured from this epitaxial wafer to the pn junction decreases, and the device is bonded to the base. When this occurs, the side surface of the device rises and the pn junction is short-circuited. In order to prevent this, it is a standard structure in the DDH structure that a fourth epitaxial layer is added to the DH structure in order to increase the total thickness after the substrate removal and the distance from the element bottom to the junction. . The fourth epitaxial layer has a wider band gap than the light emitting layer and is designed not to absorb light emitted from the light emitting layer.

  In the case of such a GaAlAs substrate removal type LED, light can be extracted also from the side surface when it is made into a chip. Since the fourth epitaxial layer is conductive, the electrode is generally a so-called “1-wire” type element in which ohmic electrodes having different polarities are provided on the upper surface side and the back surface side of the chip, respectively.

  It is desirable that the front surface side electrode be as small as possible within the range where wire bonding is possible in order to increase the extraction of light from the upper surface.

  In order to produce a light-emitting diode with a large light-emitting output, it is necessary to pass a large current, but there is a limit to the current that can be passed per unit area. If an excessive current is passed, the light-emitting output decreases due to heating of the chip. In addition, the service life is remarkably shortened. Therefore, in order to use the chip for a large current, it is necessary to increase the size of the chip.

  However, when a large chip is manufactured using such an AlGaAs-based LED having a DDH structure, when there is only one bonding electrode on the front side as in the prior art, the current may not easily spread over the entire chip. This is particularly noticeable in the case of a thick AlGaAs mixed crystal having a DDH structure. If the current does not spread in the chip when a high current is applied, the current concentrates directly under the ohmic electrode, and the light emission efficiency and reliability may be reduced by heating. Further, the light generated inside the chip is reabsorbed in the chip before coming out of the chip, and the light extraction efficiency is lowered. Such internal absorption is particularly large when p-type AlGaAs is used as the fourth epitaxial layer.

  Further, when adjusting the amount of light of the LED for large current, the current is adjusted as variable or the time is adjusted by a pulse in pulse driving, but there is a problem that the circuit becomes complicated.

JP 2001-339100 A JP-A-6-302857 JP 2002-246640 A Japanese Patent No. 2588849 JP 2001-57441 A JP 2007-81010 A JP 2006-32952 A JP 2006-108259 A

  The present invention has been made in view of the above circumstances, and in a large-sized light emitting diode element that allows a large current to flow, it is easy to adjust the amount of light and has a configuration in which no current is concentrated when a high current is applied, and has excellent output characteristics. An object of the present invention is to provide a light emitting diode device.

In order to achieve the above object, the present invention employs the following configuration. That is,
(1) A light-emitting diode element including first and second electrodes arranged so as to sandwich a light-emitting portion including a light-emitting layer, and the first electrode can adjust the amount of light emitted from the light-emitting layer. A light-emitting diode element comprising three wire bonding pads and having a light-emitting surface area of 0.64 mm ² or more.
Here, the light emitting surface is the uppermost surface of the light emitting portion, and refers to the surface indicated by reference numeral 5a in FIG. This is the main light extraction surface for light emission.
(2) The light emitting diode element according to (1), wherein the pads are connected by a thin wire electrode.
(3) The light-emitting diode element according to any one of (1) and (2), wherein a transparent conductive film is provided between the first electrode and the light-emitting portion.
(4) The light-emitting diode element according to any one of (1) to (3), wherein the light-emitting portion is made of AlGaAs.
(5) The light emitting unit includes a first p-type layer (Ga _{1 -X1} Al _X1 As, 0 ≦ X1 ≦ 1) and a p-type cladding layer (Ga ₁ ) arranged in order from the second electrode side. and _{-X2 Al X2 as, 0 ≦ X2} ≦ 1), p -type light-emitting layer emitting wavelength is in the range of 700~900nm and _{(Ga 1-X3 Al X3 as} , 0 ≦ X3 ≦ 1), n -type clad layer _{(Ga 1-X4 Al X4 as} , 0 ≦ X4 ≦ 1) and the light emitting diode device according to any one of items (1) to (4), which comprises a.
(6) The light emitting diode element as described in (5) above, wherein the n-type cladding layer has a thickness of 5 to 50 μm.
(7) The light-emitting diode element according to any one of (1) to (6) is provided, and one of the three wire bonding pads of the first electrode is a first terminal. The other two pads are connected to the second terminal, and the second electrode is connected to the third terminal.
(8) The light emitting diode lamp according to (7), wherein a terminal area of the third terminal is larger than a total area of the terminal area of the first terminal and the terminal area of the second terminal. .
(9) The method of driving a light emitting diode lamp according to any one of (7) and (8) above, wherein the number of wire bonding pads connected to the first terminal and the second terminal is set. A method for driving a light-emitting diode lamp, characterized in that the light output is varied by passing a substantially proportional current.
(10) At least one light emitting diode element and / or light emitting diode lamp among the light emitting diode elements according to (1) to (6) and the light emitting diode lamps according to (7) and (8) above. A lighting device comprising:
(11) The illumination device as set forth in (10) above, comprising a control circuit capable of changing the light output by the driving method of the light emitting diode lamp as set forth in (9).

According to said structure, in a large sized light emitting diode element, light quantity adjustment can be easily performed by switching electric current value, and since a high electric current can be sent, high output is ensured and also electric current supply is 3 Since it can be distributed to individual pads, the burden on the terminals and pads connected to it is reduced and the life is extended. In addition, since the current supply is distributed in the plane, the uniformity of light emission is ensured. A light emitting diode element can be provided.
That is, since one electrode has three wire bonding pads, current supply from the outside can be distributed to the three pads, and current can be supplied to the three pads simultaneously. Alternatively, when high output is not required, the amount of light can be adjusted by supplying current only to one or two pads. In addition, in the large light emitting diode element targeted by the present invention, it is necessary to flow a large drive current. However, since the current can be supplied by being distributed to three pads, the large current is concentrated on the pads. Can be avoided. Therefore, the burden on the terminals when packaged is reduced. Thereby, the terminal connected to the pad can be reduced in size (reduced area), and instead, the area of the common terminal effective for heat dissipation of the element can be increased to improve the heat dissipation.
Furthermore, since the drive current is dispersed and flows into the element from the three pads, light emission can be generated in the entire light emitting layer, and uniform and stable luminance can be secured in the plane.

It is a cross-sectional schematic diagram which shows the structure of the epitaxial wafer for light emitting elements which is embodiment of this invention. It is a cross-sectional schematic diagram of the slide boat type growth apparatus which produced the epitaxial wafer for light emitting elements which is embodiment of this invention. (A) It is a plane schematic diagram of the light emitting diode element which is embodiment of this invention. (B) It is the cross-sectional schematic diagram. It is a schematic diagram which shows the light emitting diode lamp which is one Embodiment of this invention, Comprising: It is (a) top view, (b) sectional drawing, (c) back view. It is a plane schematic diagram of the light emitting diode element which is embodiment of this invention. It is a plane schematic diagram which shows the example of the arrangement pattern of the pad for three wire bonding which is embodiment of this invention. It is a schematic diagram which shows the light emitting diode lamp which is other embodiment of this invention, Comprising: It is (a) top view, (b) sectional drawing, (c) back view. 5 is a graph showing the relationship between the layer thickness of an n-type GaAlAs cladding layer and the light emission output for the light-emitting diode lamp shown in FIG. It is a schematic diagram which shows the conventional light emitting diode lamp, Comprising: (a) Top view, (b) Sectional drawing, (c) Back view.

  Hereinafter, a light-emitting diode element according to an embodiment to which the present invention is applied will be described in detail with reference to the drawings. In addition, in the drawings used in the following description, in order to make the features easy to understand, there are cases where the portions that become the features are enlarged for the sake of convenience, and the dimensional ratios of the respective components are not always the same as the actual ones. Absent.

(First embodiment)
The semiconductor wafer used for the light-emitting diode element of the present invention is an epitaxial wafer for LED in which a pn junction is formed by growing a p-type semiconductor or an n-type semiconductor on a commonly used light-emitting diode semiconductor substrate such as GaAs or GaP. Can be used. As the structure of the LED, it can be applied to a GaAs or GaP homojunction or a heterojunction such as GaAlAs / GaAs used in ordinary LEDs. Usually, it is more effective to place the crystal so that the GaAs or GaP substrate side is on the back side of the element, and to select a substrate that absorbs as little as possible with respect to the wavelength of light emitted from the epitaxial layer. In particular, it is more preferable for an epi-wafer that does not include a substrate that is self-absorbing with respect to the emission wavelength and can extract light from the entire side surface when a chip is formed. Further, a substrate removal type GaAlAs light emitting diode is desirable, and a GaAs substrate may be removed to produce and use a wafer consisting only of an epitaxial layer. The epitaxial growth method is optimal in terms of cost by the liquid phase epitaxial growth method, but can also be produced by a halide vapor phase epitaxial growth method, a so-called MOCVD method or MBE method using an organic metal.
The present invention is particularly effective for large-sized infrared light-emitting diodes, but the same effect is also applied to visible AlGaInP light-emitting layers (yellow green to red) and ultraviolet and visible InGaN light-emitting layers (ultraviolet to green). is there.
Furthermore, an n-side-up type light emitting diode is desirable because it facilitates current diffusion.

In FIG. 1, the cross-sectional schematic diagram of the structure of the epitaxial wafer for light emitting elements of this invention used for preparation of infrared light emitting LED is shown.
In the epitaxial wafer for a light emitting device shown in FIG. 1, each epitaxial layer includes a first p-type Ga _1-X1 Al _X1 As layer 2 (0 ≦ X1 ≦ 1), p-type Ga on a p-type GaAs single crystal substrate 1. _1-X2 Al _X2 As cladding layer (0 ≦ X2 ≦ 1), p-type Ga _1-X3 Al _X3 As light emitting layer 4 (0 ≦ X3 ≦ 1), and n-type Ga _1-X4 Al _X4 As cladding layer 5 The light emitting unit 6 is configured by stacking in the order of (0 ≦ X4 ≦ 1).

Regarding the Al mixed crystal ratio of each epitaxial layer, the light-emitting layer 4 is selected so as to be infrared light having a light emission wavelength of 700 to 940 nm, and the first p-type layer 2, the p-type cladding layer 3, and the n-type. The cladding layer 5 is selected so that the band gap is wider than that of the light emitting layer 4 so as not to absorb light emitted from the light emitting layer 4.
In the case where GaAlAs is used as the light emitting layer, in order to obtain a high output, it is desirable to be in the infrared light region rather than the visible light. Zn, Mg, or Ge is used as a dopant for the first p-type layer 2, the p-type cladding layer 3, and the p-type light emitting layer 4, and Te is used as a dopant for the n-type cladding layer 5. Here, the doping amount to the light emitting layer is selected so that the light emission intensity and the response speed of the light emitting element are optimized.

For example, the epitaxial wafer for a light emitting device of the present invention can be produced by a liquid phase epitaxial growth method using a slide boat type growth apparatus shown in FIG.
Reference numeral 11 is a substrate holder, reference numeral 12 is a substrate storage groove, reference numerals 13 to 17 are raw material crucibles (15 is a retracting crucible), reference numeral 18 is a crucible base, and reference numeral 19 is a crucible lid.
In the production of the light emitting device of the present invention, after epitaxial growth of each GaAlAs layer as shown in FIG. 1 on a GaAs substrate, the epitaxial wafer is taken out and the surface of the n-type GaAlAs cladding layer 5 is protected with an acid resistant sheet. The GaAs substrate can be selectively removed with an ammonia-hydrogen peroxide etchant.

  In the present invention, the thickness of the n-type cladding layer is preferably 5 μm or more and 50 μm or less. Regarding the layer thickness of the n-type clad layer, it is preferable that the n-type clad layer is thin because it absorbs less light from the light emitting layer. However, if the layer thickness of the n-type clad layer is less than 5 μm, the element of the present invention has The flowing current concentrates in the center without spreading to the periphery of the element, resulting in an element with low light emission output and large deterioration of energization. On the other hand, when the layer thickness is greater than 50 μm, the absorption of the emitted light is increased, resulting in a decrease in output. Therefore, when the thickness range of the n-type cladding layer is preferably 5 μm or more and 50 μm or less, more preferably 15 μm or more and 40 μm or less, an infrared LED having a high light emission output can be manufactured.

FIG. 3A shows a schematic plan view of the light-emitting diode element 10 of the present embodiment. FIG. 3B is a schematic cross-sectional view along AA ′ shown in FIG.
As shown in FIG. 3, the first electrode (n-type electrode) is formed on the light extraction surface (light-emitting surface) 5 a that is the uppermost surface of the light-emitting portion 6 and is the surface opposite to the light-emitting layer of the n-type cladding layer 5. ) 7 is formed, and the second electrode (p-type) 8 having a different polarity is formed on the back surface of the light-emitting portion 6 on the opposite surface 2a of the light-emitting layer of the first p-type layer 2. Yes.
Of the surface electrode (first electrode) 7, wire bonding pads 7 aa, 7 ab, and 7 ac are shown in a circle, and are in ohmic contact with the LED chip surface (the uppermost surface of the light emitting unit 6). In order to perform good bonding, the diameter is desirably 100 μm or more.
The other thin wire is a thin wire electrode 7b that connects them. These are preferably in ohmic contact with the LED chip surface (the uppermost surface of the light-emitting portion 6) for current diffusion, but the effects of the invention can be obtained even if they are not.
The present invention is characterized in that the first electrode includes three wire bonding pads (bonding electrodes), and the arrangement pattern of the three pads can be various.

  4A to 4C are a plan view, a cross-sectional view, and a rear view showing, in order, an example of wire bonding of the light-emitting diode element (chip) 10 of the present invention. This is an embodiment of a light-emitting diode lamp in which the chip is mounted on a PLCC 6 (6-pin) package 20. Six pins (terminals: 21a to 21f) cover a part of the front surface, side surface, and back surface of the mount substrate 23.

  A rectangular parallelepiped wall member 24 is fixed on the mount substrate 23. At the center of the wall member 24, a bowl-shaped hole 24a for holding the light emitting diode element (chip) 10 is formed. The inclined surface 24b of the hole 24a is formed of a white or metallic glossy surface having a high visible light reflectivity, and its curved surface shape is determined in consideration of the light reflection direction to extract light forward. A reflecting surface (reflector surface) is used.

  A light-emitting diode element (chip) 10 disposed inside the hole 24a is covered with a transparent sealing resin (mold) 25 in a dome shape. The transparent sealing resin (mold) 25 may include not only a portion 25a filling the hole 24a but also a lens-like portion 25b thereon.

The material of the sealing resin 25 is preferably a silicone resin having high heat resistance, but may be other resin such as polycarbonate resin or epoxy resin, or a transparent material such as glass. It is preferable to select a material with as little deterioration by ultraviolet light as possible.
As the sealing resins 25a and 25b, the same resin may be used or different resins may be used. However, it is preferable to use the same resin from the viewpoint of ease of manufacture and good adhesiveness.

  The mount substrate 23 and / or the wall surface member 24 preferably includes a resin member or a ceramic member. Resin members are inexpensive and can reduce manufacturing costs. In particular, by using a thermosetting resin, it can be made excellent in heat resistance. As the resin, for example, high heat resistance and high reflectance nylon resin, white silicone resin, or the like is used. Moreover, since the ceramic member is very excellent in heat resistance, it can be made excellent in heat resistance.

  Of the 6 pins (terminals), 4 pins (21a, 21c, 21d, 21f; these terminals are connected to form a common terminal (third terminal)) are back electrode (first terminals) using silver paste. 2 electrodes) 8. This also serves as a heat dissipation function. Out of the three pads of the first electrode 7, the outer two 7aa and 7ac are connected to pin 1 (21e: second terminal) using bonding wires 22a and 22c, and the center one 7ab is bonded. It is connected to the remaining 1 pin (21b: first terminal) using a wire 22b. About the area of the terminal (metal part) of the side surface part and back surface part of a package, in order to improve heat dissipation, the side surface part (21ab, 21cb, 21db, 21fb) and back surface part (21ac (21cc), 21dc (21fc)) of the common terminal ) Is larger than the sum of the area of the side surface portion (21bb) and back surface portion (21bc) of the first terminal and the area of the side surface portion (21eb) and back surface portion (21ec) of the second terminal. desirable.

  In this state, as an example of light output adjustment (variable) with large current drive, a case where adjustment is performed in three stages of Low (middle) and Middle (high) will be described. The current supplied to each stage is set to Low = 100 mA, Middle = 200 mA, and High = 300 mA. When low, it is 100 mA for the center pad 7ab, when middle it is 200 mA for the two outer pads 7aa and 7ac, and when it is high, it is 100 mA for the center pad 7ab and two outer pads 7aa and 7ac. Energize 300 mA by multiplying 200 mA. By energizing in this way, light amount adjustment (dimming) can be performed by on / off (on / off), which is convenient. Further, at each current value, the current distribution is not biased to one side of the chip, which is effective for light extraction efficiency. Also, the load on the package pin can be reduced. Actually, it is difficult to flow 300 mA to 1 pin (terminal) of a small package.

As described above, the light output diode drive method according to the present invention can vary the light output by passing a current approximately proportional to the number of wire bonding pads connected to the first terminal and the second terminal. Can be implemented.
By including the control circuit capable of changing the light output as described above and including the light-emitting diode element or the light-emitting diode lamp of the present invention, it is possible to manufacture the lighting device according to the embodiment of the present invention.

  The wire bonding pads are preferably connected by thin wires. However, they can be used without being connected, and in that case, it is preferable to provide a transparent conductive film 9 between the first electrode 7 and the light emitting portion 6 as shown in FIG.

  FIG. 6 schematically shows examples of various arrangement patterns of the three wire bonding pads. When a spatial distribution is required in the light emission direction, a pad arrangement pattern suitable for the spatial distribution can be applied. When a normal uniform light emission spatial distribution is required, considering the symmetry of the current distribution at the time of current switching, (a), (b), (c), (d), (h), (i), (K) is desirable.

  The manufacturing process of the light emitting diode element can employ a normal manufacturing process of the light emitting diode element including the formation of the electrode.

  As the second electrode 8 on the back surface of the semiconductor epitaxial wafer (light emitting portion) configured as described above, a p-type ohmic electrode made of, for example, a gold / zinc (Au / Zn) alloy is vacuumed to a thickness of 1 μm. It is formed by vapor deposition.

  Further, in order to form the first electrode 7 on the front surface (uppermost surface) of the light emitting portion, first, a gold / germanium alloy film made of an alloy of 93 wt% Au and 7 wt% Ge having a thickness of about 50 nm. Is once deposited on the entire front surface by a general vacuum deposition method. As the material of the electrode, any material can be used as long as an ohmic characteristic can be obtained. However, in the case of a compound semiconductor, AuGe and AuGeNi are used for the n-side ohmic contact, and the p-side ohmic contact is used. In general, Au-based alloys such as AuZn and AuBe can be used. Next, a gold (Au) film having a thickness of about 1 μm is deposited on the surface of the gold / germanium alloy film. Next, patterning is performed using a general photolithography means so that a two-layered multilayer film composed of a gold / germanium alloy film and a gold film becomes a wire bonding pad and a fine wire electrode. A first electrode 7 comprising a bonding pad and a fine wire electrode is formed. For the pattern formation of the electrode, a photolithography method using a photosensitive resin is optimal with high pattern accuracy, but an electrode pattern formation method using a metal mask method is also possible. The thin wire electrode may be formed separately after the bonding electrode is formed separately from the bonding electrode.

  After the formation of the electrode, an alloying heat treatment is performed at 500 ° C. for 15 minutes in an argon (Ar) stream to form an ohmic contact between the electrode and the surface of the GaAlAs.

Furthermore, when a thin wire electrode is not provided, a transparent conductive film such as a film made of indium tin oxide (ITO) may be provided thereon. At that time, for example, a film 9 made of indium tin oxide (ITO) is deposited as a transparent conductive film by a general magnetron sputtering method so as to cover the surface of the n-clad layer and the first electrode. The film thickness of the transparent conductive film 9 may be about 300 nm. When ITO is attached, a general photoresist material is applied to the entire surface of the transparent conductive film, and then the region on the bonding pad electrode is patterned using a known photolithography technique. Further, while leaving the patterned resist material left, a gold (Au) film is deposited on the entire surface by a vacuum deposition method, and is limited to the above on the bonding electrode by a known lift-off means. Gold electrodes may be further stacked by leaving a gold film.
The epitaxial wafer on which the electrodes are formed by the method as described above is then cut into element shapes by a normal scribing method or dicing method, and individually divided into LED chips (light-emitting diode elements). It is desirable to roughen the surface for higher output.

Further, this LED chip is die-bonded to the common terminal of the package with silver paste, and then the three bonding pads of the first electrode are connected to the first and second terminals with gold wires (bonding wires).
Thereafter, sealing is performed with a transparent epoxy resin, silicone resin, or the like. If necessary, the lens shape can be obtained.

(Second Embodiment)
7A to 7C are a plan view, a cross-sectional view, and a back view showing an embodiment of a light-emitting diode lamp in which the chip 10 is mounted on a PLCC 4 (4-pin) package 30 in order. The four pins (31a to 31d) cover a part of the front surface, side surface, and back surface of the mount substrate 33.

Of the four pins (31a to 31d), 2pins (31a, 31c; these terminals are connected to form a common terminal (third terminal)) are back electrodes (second terminals) using silver paste. The outer two 7aa and 7ac of the three pads of the first electrode 7 are connected to one pin (31d: second terminal) using bonding wires 32a and 32c, and are connected to the center. The one 7ab is connected to the remaining 1 pin (31b: first terminal) using a bonding wire 32b. Regarding the area of the terminal (metal part) on the side surface portion and the back surface portion of the package, the area of the side surface portion (31ab, 31cb) and the back surface portion (31ac, 31cc) of the common terminal is as follows. It is desirable that it is larger than the sum of the area of the side surface portion (31bb) and the back surface portion (31bc) and the area of the side surface portion (31db) and the back surface portion (31dc) of the second terminal.
The optical output can be varied in the same manner as in the first embodiment.

Example 1
In the example, the epitaxial wafer for a light emitting device having the laminated structure shown in FIG. 1 was performed using the slide boat type growth apparatus shown in FIG.
The p-type GaAs substrate 1 is set in the substrate storage groove 12 of the slide boat type growth apparatus, and each of the crucibles 13, 14, 16, 17 at the time of epitaxial growth is Ga metal, GaAs polycrystal, metal Al, and dopant. Put. A slide boat type growth apparatus in which these raw materials are set is set in a quartz reaction tube (not shown), heated to 950 ° C. in a hydrogen stream, dissolved in raw materials, and then the ambient temperature is lowered to 910 ° C. After pressing the slider to the right and bringing it into contact with the raw material solution (melt), the temperature is lowered at a rate of 0.5 ° C./min. 1 and finally contact with the 4th melt, and then the ambient temperature is lowered to 703 ° C. to grow the n-clad layer in FIG. 1, and then the slider is pushed to separate the raw material solution from the wafer for epitaxial growth. Was terminated.

The structure of the obtained epitaxial layer is as follows: the first p-type layer has an Al composition X1 = 0.3 to 0.4, the layer thickness is 64 μm, the carrier concentration is 3 × 10 ¹⁷ cm ⁻³ , and the p-type cladding layer is Al Composition X2 = 0.4 to 0.5, layer thickness 79 μm, carrier concentration 5 × 10 ¹⁷ cm ⁻³ , p-type active layer has a composition with an emission wavelength of 760 nm, layer thickness 1 μm, carrier concentration 1 × 10 ¹⁸ cm ⁻³ , the n-type cladding layer had an Al composition X4 = 0.4 to 0.5, a layer thickness of 25 μm, and a carrier concentration of 5 × 10 ¹⁷ cm ⁻³ .

After the epitaxial growth was completed, the epitaxial substrate was taken out, the surface of the n-type GaAlAs cladding layer in FIG. 1 was protected with an acid resistant sheet, and the p-type GaAs substrate was selectively removed with an ammonia-hydrogen peroxide-based etchant. Thereafter, gold electrodes were formed on both sides of the epitaxial wafer, and a surface electrode on which three wire bonding pads having a diameter of 100 μm were arranged was formed using an electrode mask having a long side of 1000 μm. A back electrode was formed on the back electrode using a grid electrode mask. Then, by separating by dicing, a 1000 μm square LED in which the n-type GaAlAs layer was on the surface side was produced.
FIG. 6A is used for the surface electrode pattern.
A light-emitting diode lamp was fabricated by mounting in the 6-terminal package of FIG. The area of the side surface portion and the back surface portion of the common terminal of this package was about 8 times the total area of the side surface portion and the back surface portion of the first and second terminals.

Table 1 shows the results of measuring the light emission output and peak wavelength of each of the 20 lamps at current values of 100 mA, 200 mA, and 300 mA.
It was found that the proportional relationship between the output and current was maintained even at high current, and that the current spread in the element and the heat dissipation of the package were good.

(Example 2)
By the same method as in the above example, epitaxial growth was performed by changing the layer thickness of the n-type cladding layer to produce an LED. When changing the layer thickness of the n-type cladding layer, the separation temperature of the crucible 5 and the temperature drop rate were adjusted so that the Al composition was the same as in Example 1 .
The structure of the obtained epitaxial layer is as follows: the first p-type layer has an Al composition X1 = 0.3 to 0.4, the layer thickness is 65 μm, the carrier concentration is 4 × 10 ¹⁷ cm ⁻³ , and the p-type cladding layer is Al Composition X2 = 0.4 to 0.5, layer thickness 77 μm, carrier concentration 4 × 10 ¹⁷ cm ⁻³ , p-type active layer has a composition with an emission wavelength of 760 nm, layer thickness 1 μm, carrier concentration 1 × 10 ¹⁸ cm ⁻³ , the n-type cladding layer had an Al composition X4 = 0.4 to 0.5, a layer thickness of 20 μm, and a carrier concentration of 4 × 10 ¹⁷ cm ⁻³ .

Table 1 shows the results of measuring the light emission output and peak wavelength of each of the 20 lamps at current values of 100 mA, 200 mA, and 300 mA.
Similarly to Example 1, in Example 2, it was found that the proportional relationship between output and current was maintained at a high current, the current in the element spread, and the heat dissipation of the package was good.

For the LED of Example 2, the relationship between the layer thickness of the n-type GaAlAs cladding layer and the light emission output at 300 mA was examined. FIG. 8 shows the result.
As is apparent from FIG. 8, it was found that when the thickness of the nGaAlAs cladding layer was 50 μm or less, the light emission output was higher than 78 mW, which is the target output. Furthermore, it was confirmed that the output was improved as the layer thickness was reduced, and the peak was around 20 μm. However, it was also confirmed that the output decreased from 78 mW when the layer thickness was 5 μm or less. In particular, the light emission output was 85 mW or more when the layer thickness was in the range of 15 to 40 μm.
Therefore, it has been found that the LED has a high output when the thickness of the n-type GaAlAs cladding layer is in the range of 5 μm to 50 μm, preferably in the range of 15 to 40 μm.

(Comparative Example 1)
A light emitting layer was formed by the same method as in Example 1. The difference is that one surface electrode (first electrode) having a diameter of 170 μm is formed at the center. The same package as in Example 1 was used, and the surface electrode was wired only to the first terminal 21b.
Table 1 shows the results of measuring the light emission output and peak wavelength of each of the 20 lamps at current values of 100 mA, 200 mA, and 300 mA.
At high currents, the output decreases and the peak wavelength becomes longer. This is considered to be caused by a current flowing in a part of the light emitting layer due to insufficient current diffusion and a decrease in light emission efficiency and a longer wavelength due to temperature rise.

(Comparative Example 2)
The element of the comparative example 1 was used, and the difference was that a general PLCC 6 (6 pin) package having an equivalent area for all 6 terminals was used.
As shown in FIG. 9, the front surface electrode (first electrode) is connected to the first terminal 41b, and the back surface electrode (second electrode) is connected to the second terminal 41e. Since the six terminals (41a to 41f) have an equivalent area, the areas of the first terminal and the second terminal to which the front electrode (first electrode) and the back electrode (second electrode) are connected are equal. .

Table 1 shows the results of measuring the light emission output and peak wavelength of each of the 20 lamps at current values of 100 mA, 200 mA, and 300 mA.
At high currents, there was a noticeable decrease in output and a longer peak wavelength. This is considered to be caused by a decrease in luminous efficiency and a longer wavelength due to a temperature rise due to insufficient current diffusion and insufficient heat dissipation of the package.

  The light-emitting diode element of the present invention is easy to adjust the amount of light, and does not concentrate current even when a high current is applied, and can use a package with good heat dissipation, so it has excellent output linearity. It can be used for lamps and lighting fixtures to be used. In particular, it can be used for high-power light-emitting diode elements used in plant growth using infrared light, which has recently been attracting attention, and security-related lighting devices, and can be used in industries that manufacture and use these.

DESCRIPTION OF SYMBOLS 1 Board | substrate 2 1st p-type layer 3 p-type clad layer 4 p-type light emitting layer 5 n-type clad layer 5a Light emission surface 6 Light emission part 7 1st electrode 7aa, 7ab, 7ac Wire bonding pad 7b Fine wire electrode 8 2nd Electrode 9 Transparent conductive film 10 Light-emitting diode element 20 Light-emitting diode lamp 21a, 21c, 21d, 21f Common terminal (third terminal)
21b 1st terminal 21e 2nd terminal 23 Mount substrate 24 Wall-shaped member 25 Sealing resin 30 Light emitting diode lamp 31a, 31c Common terminal (3rd terminal)
31b First terminal 31e Second terminal 33 Mount substrate 34 Wall-shaped member 35 Sealing resin

Claims (11)

A light-emitting diode element including first and second electrodes arranged so as to sandwich a light-emitting portion including a light-emitting layer,
The first electrode includes three wire bonding pads that can adjust the amount of light emitted from the light emitting layer.
A light emitting diode element having an area of a light emitting surface of 0.64 mm ² or more.   2. The light emitting diode element according to claim 1, wherein the pads are connected by a thin line electrode.   The light-emitting diode element according to claim 1, further comprising a transparent conductive film between the first electrode and the light-emitting portion.   The light emitting diode element according to any one of claims 1 to 3, wherein the light emitting portion is made of AlGaAs. The light emitting section includes a first p-type layer (Ga _{1 -X1} Al _X1 As, 0 ≦ X1 ≦ 1) and a p-type cladding layer (Ga _{1 -X2} Al) arranged in order from the second electrode side. _X2 As, 0 ≦ X2 ≦ 1), a p-type light emitting layer (Ga ₁ -X3 Al _X3 As, 0 ≦ X3 ≦ 1) having an emission wavelength in the range of 700 to 900 nm, and an n-type cladding layer (Ga _{1 -X4 Al X4 as, 0 ≦ X4} ≦ 1) and the light emitting diode device according to claim 1, any one of 4, which comprises a.   6. The light emitting diode device according to claim 5, wherein the n-type cladding layer has a thickness of 5 to 50 [mu] m.   7. The light-emitting diode element according to claim 1, wherein one of the three wire bonding pads of the first electrode is connected to a first terminal, and the other The two pads are connected to a second terminal, and the second electrode is connected to a third terminal.   8. The light emitting diode lamp according to claim 7, wherein a terminal area of the third terminal is larger than a total area of a terminal area of the first terminal and a terminal area of the second terminal.   9. The method for driving a light-emitting diode lamp according to claim 7, wherein a current substantially proportional to the number of wire bonding pads connected to the first terminal and the second terminal is supplied to the first terminal and the second terminal. A method for driving a light-emitting diode lamp, characterized in that the light output is varied accordingly.   A light emitting diode element according to claim 1 and a light emitting diode lamp according to claims 7 and 8, comprising at least one light emitting diode element and / or a light emitting diode lamp. .   The lighting device according to claim 10, further comprising a control circuit capable of changing a light output by the driving method of the light-emitting diode lamp according to claim 9.

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