JP2004363382A - Oxide semiconductor light-emitting element and manufacturing method thereof - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an oxide semiconductor light-emitting element capable of improving light-emitting efficiency and reliability, and to provide a manufacturing method thereof. <P>SOLUTION: A main body 100 has an n-type ZnO single crystal substrate 101, an n-type Mg<SB>0.1</SB>Zn<SB>0.9</SB>O cladding layer 102, a non-doped quantum well light-emitting layer 103, a p-type Mg<SB>0.1</SB>Zn<SB>0.9</SB>O cladding layer 104, a p-type ZnO contact layer 105, and a p-type ohmic electrode 106. An Mn-doped Zn<SB>2</SB>SiO<SB>4</SB>phosphor 109 is deposited on the top surface of the main body 100. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a light-emitting device such as a light-emitting diode device and a method for manufacturing the same, and more particularly to a method for manufacturing an oxide semiconductor light-emitting device including a phosphor that emits light by converting the wavelength of light emitted from an oxide semiconductor. .
[0002]
[Prior art]
LED (Light Emitting Diode) elements are excellent in power saving and reliability, and are therefore widely used as various indicators and light sources. In recent years, the performance improvement of LEDs using compound semiconductors has been remarkable, and ultra-high-brightness LEDs exceeding 1 cd have been developed one after another. As a result, a high-luminance, high-definition, large-area multicolor display using the three primary colors of RGB has been put to practical use.
[0003]
On the other hand, as a method of realizing multicolor, there is a method of performing color conversion of light emitted from an LED using a phosphor, in addition to a method of mixing colors using individual LED chips of RGB. The method of converting the color of light emitted from the LED by the fluorescent material can realize a very simple and low-cost multicolor light emitting device. As the LED for exciting the phosphor, an LED using a wide-gap semiconductor capable of emitting blue to ultraviolet light is suitable, and blue to red light required for multicoloring can be obtained.
[0004]
A multicolor display using an ultra-high-brightness LED having the above-described phosphor must secure long-term reliability under a severe driving environment. However, there is a problem that the phosphor is liable to undergo reduction corrosion due to moisture, and is likely to be deteriorated due to a temperature rise due to heat generated from the LED.
[0005]
In order to solve this problem, a mold material containing a gallium nitride-based body provided with a light-emitting layer having a high energy band gap, and a yttrium-aluminum-garnet-based phosphor activated with cerium, which is a photoluminescence phosphor A multicolor LED combining the above is devised and disclosed in Japanese Patent No. 2927279 (Patent Document 1).
[0006]
[Patent Document 1]
Japanese Patent No. 2927279
[0007]
[Problems to be solved by the invention]
However, the multicolor LED has a problem that the luminous efficiency and the reliability are not yet sufficient for the following first and second reasons.
[0008]
The first reason is that the gallium nitride LED used as a phosphor excitation light source has low quantum efficiency. That is, the gallium nitride-based LED uses an interband transition via an impurity level, and the quantum efficiency is about ten and several percent even when a light emitting layer having a multiple quantum well structure is used. Furthermore, when carriers are highly injected to increase the emission intensity, the emission intensity tends to be saturated. Therefore, the temperature of the gallium nitride-based LED rises during driving, so that the phosphor deteriorates, and the luminous efficiency decreases and color shift occurs.
[0009]
The second reason is that the phosphor is added to the molding material. In other words, the light emitted from the main body of the gallium nitride LED is scattered and absorbed in the mold material before the phosphor is excited, and the wavelength-converted light is also subjected to the same loss. Is greatly reduced as compared with a mold material to which no phosphor is added. In particular, when a diffusing agent or the like is added to the molding material, the light extraction efficiency is further reduced. Further, when a phosphor is added to the molding material, the resistance of the molding material to temperature, moisture, ultraviolet rays, and the like deteriorates.
[0010]
Therefore, an object of the present invention is to provide an oxide semiconductor light emitting device that can improve luminous efficiency and reliability, and a method for manufacturing the same.
[0011]
[Means for Solving the Problems]
The present inventors have conducted intensive studies on an excitation source LED having high quantum efficiency, a phosphor having excellent environmental resistance, a combination thereof, and an element structure. The present inventors have found that the above objects can be achieved by covering the body, and have reached the present invention.
[0012]
In the present specification, the “ZnO-based semiconductor” includes ZnO and a mixed crystal represented by MgZnO, CdZnO, or the like based on ZnO.
[0013]
An oxide semiconductor light-emitting device according to the present invention includes a main body made of a ZnO-based semiconductor, a phosphor covering at least a part of a main surface composed of an upper surface of the main body and a side surface of the main body, and a phosphor formed on the upper surface of the main body. And provided electrodes.
[0014]
According to the oxide semiconductor light-emitting element having the above structure, a light-emitting element using a ZnO-based semiconductor can use an exciton transition with high emission efficiency, and thus consumes lower power than a light-emitting element using a group III nitride semiconductor. . Therefore, since the main body made of the ZnO-based semiconductor generates less heat, the deterioration of the phosphor due to the heat is small. As a result, a power-saving oxide semiconductor light-emitting element having excellent luminous efficiency and reliability can be obtained.
[0015]
In one embodiment, the main body has a first conductivity type clad layer, an active layer, a second conductivity type clad layer, and a second conductivity type contact layer laminated on a substrate.
[0016]
According to the oxide semiconductor light emitting device of the embodiment, the active layer is sandwiched between the first conductive type clad layer and the second conductive type clad layer, so that the luminous efficiency can be increased.
[0017]
The “active layer” is referred to as a “light-emitting layer” in the case of a light-emitting diode element, but has the same meaning in the sense of a layer that controls light emission, and is not particularly distinguished below.
[0018]
In one embodiment, in the oxide semiconductor light-emitting element, the phosphor covers all regions of the main surface other than the region where the electrodes are formed.
[0019]
According to the oxide semiconductor light emitting device of the above embodiment, the side surface of the main body is a portion having high light extraction efficiency. Therefore, the color conversion efficiency of the phosphor can be improved by coating the side surface of the main body with the phosphor.
[0020]
In one embodiment, the phosphor is in direct contact with the main surface.
[0021]
According to the oxide semiconductor light emitting device of the above embodiment, since the phosphor is in direct contact with the main surface, the color conversion efficiency of the phosphor can be further improved.
[0022]
In one embodiment, an intermediate layer is formed between the main body and the phosphor.
[0023]
According to the oxide semiconductor light emitting device of the embodiment, the heat generated by the main body is transmitted to the phosphor through the intermediate layer, so that the heat conduction from the main body to the phosphor is reduced. Therefore, the phosphor is less likely to deteriorate, and the life of the phosphor can be further improved.
[0024]
In one embodiment, the intermediate layer includes an oxide insulator.
[0025]
According to the oxide semiconductor light emitting device of the embodiment, the oxide insulator has an excellent affinity for a ZnO-based semiconductor that is the same oxide. Therefore, when the intermediate layer contains an oxide insulator, defects at the interface between the intermediate layer and the main body can be extremely reduced.
[0026]
Further, when the intermediate layer contains an oxide insulator, current leakage from the main body to the phosphor is suppressed, so that the life of the phosphor can be further improved.
[0027]
Further, since the oxide insulator does not absorb light emitted from the main body, it is possible to prevent the excitation efficiency of the phosphor from lowering.
[0028]
In one embodiment, the oxide insulator includes Mg, Sc, Y, Ti, Zr, Hf, Ce, V, Nb, Ta, Mo, W, Re, Al, Ga, Si and At least one of Ge oxides is included.
[0029]
According to the oxide semiconductor light-emitting device of the embodiment, if the intermediate layer is amorphous or single crystal, the amorphous or single crystal does not include a crystal grain boundary, so that the growth of defects in the intermediate layer is suppressed. I can do it. Therefore, the oxides of Mg, Sc, Y, Ti, Zr, Hf, Ce, V, Nb, Ta, Mo, W, Re, Al, Ga, Si and Ge have an amorphous or single crystal structure. It is preferable because it is easy.
[0030]
In one embodiment, the phosphor includes a zinc oxide to which an additive to be a luminescent center is added.
[0031]
According to the oxide semiconductor light emitting device of the embodiment, when the phosphor contains zinc oxide, the affinity between the phosphor and the ZnO-based semiconductor can be improved. Therefore, by including zinc oxide in the phosphor, the proliferation of defects in the phosphor can be suppressed.
[0032]
In one embodiment, the zinc oxide is ZnO, Zn ₂ SiO ₄ , ZnGa ₂ O ₄ And ZnWO ₄ And the additive includes at least one of Zn, Mn, Cr and Ti.
[0033]
According to the oxide semiconductor light emitting device of the embodiment, the zinc oxide contained in the phosphor is ZnO, ZnO ₂ SiO ₄ , ZnGa ₂ O ₄ And ZnWO ₄ And the zinc oxide contains at least one of Zn, Mn, Cr and Ti, so that red to blue light can be emitted with high efficiency.
[0034]
In one embodiment, the phosphor is not added to the sealing resin for sealing the main body.
[0035]
According to the oxide semiconductor light emitting device of the embodiment, since the main body is sealed with the sealing resin, the phosphor can be protected from the outside air.
[0036]
In addition, since no phosphor is added to the sealing resin, the light emission of the main body is not scattered and absorbed by the sealing resin, so that a decrease in emission intensity can be prevented.
[0037]
Further, since no phosphor is added to the sealing resin, adverse effects on the environment can be reduced. That is, the environmental resistance is improved.
[0038]
Further, the method for manufacturing an oxide semiconductor light emitting device according to the present invention is the method for manufacturing an oxide semiconductor light emitting device, wherein the phosphor is continuously formed in the film forming apparatus on which the main body is formed. Is formed.
[0039]
According to the method for manufacturing an oxide semiconductor light-emitting element having the above-described configuration, the formation of the main body to the phosphor is continuously performed in the same film forming apparatus, so that water causing reduction corrosion adheres to the phosphor. Can be prevented.
[0040]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, an oxide semiconductor light emitting device of the present invention and a method of manufacturing the same will be described in detail with reference to the illustrated embodiments.
[0041]
(Embodiment 1)
In the first embodiment, an example in which the present invention is applied to a ZnO-based light emitting diode element will be described.
[0042]
FIG. 1 shows a schematic cross-sectional view of the ZnO-based light-emitting diode element of the first embodiment.
[0043]
The light-emitting diode element has a Ga content of 3 × 10 ¹⁸ cm ^-3 N-type Mg doped at a concentration of 1 μm _0.1 Zn _0.9 O cladding layer 102, non-doped quantum well light emitting layer 103, N is 5 × 10 ¹⁹ cm ^-3 P-type Mg doped at a concentration of 1 μm _0.1 Zn _0.9 O cladding layer 104, N is 1 × 10 ²⁰ cm ^-3 The p-type ZnO contact layer 105 having a thickness of 0.5 μm and doped at a concentration of 0.5 μm is stacked in this order.
[0044]
In the first embodiment, the n-type ZnO single crystal substrate 101 is an example of _0.1 Zn _0.9 The O-cladding layer 102 is an example of a first conductivity type cladding layer, and the quantum well light emitting layer 103 is an example of an active layer. _0.1 Zn _0.9 The O cladding layer 104 corresponds to an example of the second conductivity type cladding layer.
[0045]
The quantum well light emitting layer 103 includes a ZnO well layer having a thickness of 5 nm and a MgO layer having a thickness of 4 nm. _0.05 Zn _0.95 It is constituted by alternate lamination with an O barrier layer. While there are seven ZnO well layers, MgO _0.05 Zn _0.95 There are eight O barrier layers.
[0046]
On the entire surface of the main surface of the p-type ZnO contact layer 105, a 15-nm-thick translucent p-type ohmic electrode 106 made of Ni is formed. On the p-type ohmic electrode 106, a bonding Au pad electrode 107 having a thickness of 100 nm as an example of an electrode is formed with an area smaller than that of the p-type ohmic electrode 106.
[0047]
On the back surface of the n-type ZnO single crystal substrate 101, Al having a thickness of 100 nm is laminated as an n-type ohmic electrode.
[0048]
The main body 100 of the light emitting diode element according to the first embodiment includes an n-type ZnO single crystal substrate 101, an n-type MgO _0.1 Zn _0.9 O cladding layer 102, non-doped quantum well light emitting layer 103, p-type Mg _0.1 Zn _0.9 It has an O clad layer 104, a p-type ZnO contact layer 105 and a p-type ohmic electrode 106. The surface of the p-type ohmic electrode 106 on the pad electrode 107 side becomes the upper surface of the main body 100.
[0049]
On the upper surface of the main body 100, Mn-added Zn having a thickness of 500 nm as an example of a phosphor is provided. ₂ SiO ₄ The phosphor 109 is deposited. That is, Mn as an example of an additive to be a luminescent center is replaced with Zn as an example of a zinc oxide. ₂ SiO ₄ The upper surface of the main body 100 is covered with the phosphor 109 obtained by adding the phosphor. The phosphor 109 is formed on a region other than the region where the pad electrode 107 is formed on the upper surface of the main body 100. Therefore, the pad electrode 107 is made of Mn-added Zn. ₂ SiO ₄ Not covered by the phosphor 109.
[0050]
The oxide semiconductor light emitting device of the present invention can be manufactured by a crystal growth technique such as MBE (molecular beam epitaxy), laser MBE, MOCVD (metal organic chemical vapor deposition) using a solid or gaseous raw material. The light emitting diode element of the first embodiment was formed by a laser MBE apparatus as an example of the film forming apparatus shown in FIG.
[0051]
The laser MBE apparatus includes a growth chamber 201 that can be evacuated to an ultra-high vacuum. A substrate holder 202 for holding a substrate 203 is arranged in an upper part in the growth chamber 201. Above the substrate holder 202, a heater 204 for heating the back surface of the substrate holder 202 (the surface opposite to the substrate 203) is arranged. On the other hand, a target table 205 is disposed directly below the substrate holder 202 at an appropriate distance from the substrate holder 202. This target table 205 can carry a plurality of raw material targets 206. A view port 207 through which a pulse laser beam 208 applied to the raw material target 206 passes is provided on one side wall of the growth chamber 201. On the other side wall of the growth chamber 201, there are provided a radical cell 209 connected to the gas introduction pipe 213 and a driving unit 212 for driving the shielding mask 211. The shielding mask 211 is located between the substrate 203 and the target table 205 and can cover a predetermined area of the substrate 203. A plurality of gas introduction pipes 210 (only one is shown in FIG. 2) penetrate the other side wall of the growth chamber 201, and gas is introduced into the growth chamber 201 through the gas introduction pipes 210. You. Although not shown, the target table 205 has a rotating mechanism.
[0052]
When the laser MBE apparatus having the above configuration performs crystal growth, first, the back surface of the substrate holder 202 is heated by the heater 204. Thereby, the heat of the substrate holder 202 is transmitted to the substrate 203, and the substrate 203 is heated.
[0053]
Next, the source laser 206 is irradiated with the pulse laser beam 208 through the view port 207. Then, the raw material of the raw material target 206 is instantaneously evaporated and deposited on the substrate 203. As a result, a thin film made of the raw material grows on the substrate 203.
[0054]
At the time of crystal growth by the laser MBE apparatus, the target table 205 is rotated by a rotating mechanism, and the rotation of the target table 205 is controlled in synchronization with the irradiation sequence of the pulsed laser beam 208, so that the raw material of a different raw material target 206 is deposited on the substrate 203. Can be laminated.
[0055]
Further, the substrate 203 can be irradiated with the atomic beam activated by the radical cell 209.
[0056]
In addition, in the crystal growth using the laser MBE apparatus, the deviation between the composition of the raw material target 206 and the composition of the thin film obtained on the substrate 203 is small. ₂ O ₄ It is preferable because generation of unintended by-products such as the above can be suppressed.
[0057]
Hereinafter, a method for manufacturing the light emitting diode element of the first embodiment will be described with reference to FIGS. 3A and 3B and FIGS. 4C and 4D.
[0058]
First, the cleaned ZnO substrate 101 is introduced into the laser MBE apparatus 200, and heated at a temperature of 600 ° C. for 30 minutes to be cleaned.
[0059]
Next, the substrate temperature is lowered to 500 ° C., the raw material target 206 is used as the raw material target 206, and the driving cycle of the target table 205 by the rotating mechanism and the pulse irradiation cycle of the KrF excimer laser are synchronized by an external control device (not shown). Let it. Then, the two material targets 206 are alternately laser ablated at a ratio at which a desired Mg composition ratio and a Ga doping concentration can be obtained, and as shown in FIG. _0.1 Zn _0.9 The O cladding layer 102 is grown.
[0060]
The KrF excimer laser has a wavelength of 248 nm, a pulse number of 10 Hz, and an output of 1 J / cm. ² belongs to. The n-type Mg _0.1 Zn _0.9 During the growth of the O-clad layer 102, O ₂ A gas is introduced into the growth chamber 201.
[0061]
Next, the non-doped ZnO single crystal and the MgZnO sintered body were alternately laser-ablated using the ZnO well layer and the MgZnO sintered body as raw material targets 206. _0.05 Zn _0.95 A quantum well light emitting layer 103 composed of an O barrier layer is grown.
[0062]
Next, N introduced through the gas introduction pipe 213 ₂ While the gas is turned into plasma in the radical cell 209 and irradiated, the non-doped ZnO single crystal and the non-doped MgZnO sintered body are alternately laser-ablated using the raw material target 206 to form p-type Mg. _0.1 Zn _0.9 The O-clad layer 104 is grown.
[0063]
Next, N introduced through the gas introduction pipe 213 ₂ While the gas is turned into plasma in the radical cell 209 and irradiated, the non-doped ZnO single crystal is used as a raw material target 206 by laser ablation to grow the p-type ZnO contact layer 105.
[0064]
Next, O ₂ Gas and N ₂ The introduction of gas was stopped, and the pressure in the growth chamber 201 was reduced to 1 × 10 ^-4 The pressure is adjusted to Pa, and laser ablation is performed using the Ni tablet as the raw material target 206 to form the p-type ohmic electrode 106.
[0065]
Next, O is introduced through the gas introduction pipe 210. ₂ The gas is introduced again, and Mn-added Zn ₂ SiO ₄ Laser ablation using the sintered body as the raw material target 206 ₂ SiO ₄ : Zn for forming Mn phosphor 109 ₂ SiO ₄ : Mn layer 1109 is deposited.
[0066]
Next, the ZnO substrate 101 was taken out of the laser MBE apparatus, ₂ SiO ₄ : After forming a resist mask 110 as shown in FIG. 3B on the Mn layer 1109, an etching process is performed. Thereby, Zn having an opening with a diameter of 100 μm ₂ SiO ₄ : Mn phosphor 109 is obtained. This Zn ₂ SiO ₄ : The ohmic electrode 106 is exposed from the opening of the Mn phosphor 109.
[0067]
Next, the Zn ₂ SiO ₄ : An Au layer 1107 for forming the pad electrode 107 is formed by a vacuum deposition method so as to fill the opening of the Mn phosphor 109 as shown in FIG.
[0068]
Next, when the Au layer 1107 deposited on the resist mask 110 is lifted off together with the resist mask 110 and removed, a pad electrode 107 as shown in FIG. 4D is obtained.
[0069]
Finally, Al is vapor-deposited on the back surface of the ZnO substrate 101 by a vacuum vapor deposition method to form an n-type ohmic electrode 108, and then the ZnO substrate 101 is separated into chips to obtain the light-emitting diode element of Embodiment 1. Can be
[0070]
After mounting the light emitting diode element on a lead frame and wiring to the pad electrode 107, the light emitting diode element was sealed with an epoxy mold resin containing no phosphor and a diffusing agent to emit light. Yellow light emission was obtained. At this time, the operating current for obtaining a light output of 4 mW in the light emitting diode element was 10 mA. When the light emitting diode element was continuously driven at an optical output of 4 mW, the driving time required for the emission intensity to decrease by 20% was 100,000 hours.
[0071]
As Comparative Example 1, Zn was applied to the upper surface of the main body of a group III nitride light-emitting diode device using an InGaN quantum well light-emitting layer, similarly to the first embodiment. ₂ SiO ₄ : A light emitting diode element was prepared by depositing a Mn phosphor. When the group III nitride light-emitting diode device of Comparative Example 1 was caused to emit light, yellow light emission having an emission peak wavelength of 550 nm was obtained, but the operating current for obtaining an optical output of 4 mW was 20 mA. When the group III nitride light-emitting diode device of Comparative Example 1 was continuously driven at an optical output of 4 mW, the driving time required for the emission intensity to decrease by 20% was 10,000 hours.
[0072]
The reason why the ZnO-based light-emitting diode device of Embodiment 1 is more reliable than the Group III nitride light-emitting diode device of Comparative Example 1 is that it has excellent luminous efficiency and power saving, so that the temperature rise during driving is reduced This is probably because the deterioration of the phosphor was suppressed.
[0073]
That is, a ZnO-based semiconductor has a strong exciton binding energy of 60 meV and can generate highly efficient light emission using an exciton transition at room temperature, whereas a group III nitride semiconductor has Since the exciton binding energy is only 24 meV, the contribution to emission at room temperature is small, excitons are dissociated until sufficient light output is obtained, and inter-band transition via impurity levels, which are inferior in emission efficiency, is mainly performed. It is because it becomes.
[0074]
FIG. 5 shows the light-emitting diode element of the present embodiment with Zn ₂ SiO ₄ : Emission spectrum when the deposited film thickness of Mn phosphor 109 is changed.
[0075]
At an emission wavelength of 500 nm, Zn ₂ SiO ₄ : Yellow emission from the Mn phosphor 109 is mainly used, but at an emission wavelength of about 50 nm, light from the ZnO emission layer is transmitted and mixed with yellow emission, so that white emission can be obtained. On the other hand, if the thickness of the phosphor layer is 5 nm or less, the light emission from the phosphor 109 is too weak, and the ultraviolet light from the ZnO light emitting layer (quantum well light emitting layer 103) is mainly used. preferable. Further, it is preferable that the thickness of the phosphor layer be 10 μm or less, since the phosphor layer can emit light uniformly and the production cost can be suppressed.
[0076]
As Comparative Example 2, a light emitting diode element in which the phosphor 109 was made of ZnS: Tb was manufactured. In the light-emitting diode device of Comparative Example 2, yellow light emission with a light emission peak wavelength of 550 nm was obtained, but the operating current for obtaining a light output of 4 mW was 12 mA. When the light emitting diode device of Comparative Example 2 was continuously driven at an optical output of 4 mW, the driving time required for the emission intensity to decrease by 20% was 50,000 hours.
[0077]
Compared with the ZnS-based phosphor, the ZnO-based phosphor of the first embodiment is made of the same zinc oxide as the main body 100 of the light-emitting diode element, and therefore has a higher affinity even when directly deposited on the surface of the main body 100, Less likely to peel or deteriorate. The base material of such a ZnO-based phosphor includes Zn used in the first embodiment. ₂ SiO ₄ In addition, ZnGa ₂ O ₄ , ZnWO ₄ And ZnO can be used. In addition, Zn, Mn, Cr, Ti, and the like can be used as additives to be added to the base material of the ZnO-based phosphor.
[0078]
As Comparative Example 3, Zn ₂ SiO ₄ : Without depositing the Mn phosphor 109 on the surface of the main body 100 of the ZnO-based light emitting diode element, ₂ SiO ₄ : A light emitting diode element was prepared by dispersing a Mn phosphor. In the light-emitting diode element of Comparative Example 3, yellow light emission with a light emission peak wavelength of 550 nm was obtained, but the operating current for obtaining a light output of 4 mW was 24 mA. When the light emitting diode device of Comparative Example 3 was continuously driven at a light output of 4 mW, the driving time required until the light emission intensity decreased by 20% was 5000 hours.
[0079]
In the light-emitting diode element of Comparative Example 3, both the light emission and the excited fluorescence are scattered and absorbed in the mold resin, and the light emission efficiency is greatly reduced. Therefore, when the light-emitting diode element of Comparative Example 3 is driven at a constant light output, the temperature rise is larger than that of the light-emitting diode element of Embodiment 1. As a result, it is considered that the light emitting diode element of Comparative Example 3 was deteriorated in a short time.
[0080]
As Comparative Example 4, after the p-type ohmic electrode 106 was formed, the ZnO substrate 101 was taken out of the laser MBE apparatus, and Zn was deposited by another sputtering apparatus (not shown). ₂ SiO ₄ : Mn phosphor 109 was formed to produce a light emitting diode element. The light emitting diode element of Comparative Example 4 emitted yellow light with a light emission peak wavelength of 550 nm, but the operating current for obtaining a light output of 4 mW was 12 mA. When the light emitting diode device of Comparative Example 4 was continuously driven at a light output of 4 mW, the driving time required for the emission intensity to decrease by 20% was 30,000 hours.
[0081]
In the light-emitting diode element of Comparative Example 4, since the ZnO substrate 101 was taken out of the laser MBE apparatus before depositing the phosphor 109, the moisture adsorbed on the surface of the main body in the manufacturing process up to resin sealing caused the phosphor 109 to be removed. The phosphor 109 deteriorates, and the deterioration of the phosphor 109 multiplies due to heat generated by light emission. As a result, it is considered that the light-emitting diode element of Comparative Example 4 was deteriorated in a shorter time than the light-emitting diode element of Embodiment 1.
[0082]
Since the light emitting diode element of the first embodiment does not expose the main body 100 to the outside air until the phosphor 109 is deposited, it is considered that the phosphor is protected from the reducing atmosphere and the life is improved.
[0083]
In the manufacturing method of the first embodiment, the desired Mg composition and the Ga doping concentration are controlled by alternately laser ablating the two material targets 206 of the ZnO single crystal and the Ga-doped MgZnO sintered body. The control may be performed by a method such as punching out three raw material targets 206 of a crystal, a non-doped MgZnO sintered body and a Ga-doped ZnO sintered body.
[0084]
Instead of using a MgZnO sintered body, a ZnO single crystal and a MgO single crystal may be alternately laser ablated to obtain a MgZnO mixed crystal having a desired composition.
[0085]
Ga ₂ O ₃ Instead of using the additive sintered body, metal Ga may be doped using an evaporation cell.
[0086]
Further, Au which is a raw material of the pad electrode 107 and Al which is a raw material of the n-type ohmic electrode 108 may be formed by a laser MBE apparatus like the p-type ohmic electrode 106 and the phosphor 109.
[0087]
(Embodiment 2)
FIG. 6 shows a schematic cross-sectional view of the light emitting diode element of the second embodiment.
[0088]
In the light emitting diode element, the upper surface of the main body 300 (the upper surface of the p-type ohmic electrode 306) is formed of Zn as an example of a phosphor. ₂ SiO ₄ : The side surface of the main body 300 except for the side surface of the n-type ZnO single crystal substrate 301 as an example of the substrate is coated with Zn and covered with the Mn phosphor 309. ₂ SiO ₄ : Except for coating with Mn phosphor 309, it was produced in the same manner as in the first embodiment.
[0089]
The above Zn ₂ SiO ₄ : The Mn phosphor 309 also covers the upper surface of the exposed n-type ZnO single crystal substrate 301. In addition, the Zn ₂ SiO ₄ : The Mn phosphor 309 is not formed on the bonding Au pad electrode 307 as an example of the electrode.
[0090]
6, reference numeral 302 denotes n-type Mg as an example of a first conductivity type cladding layer. _0.1 Zn _0.9 O cladding layer, 303 is a non-doped quantum well light emitting layer as an example of an active layer, 304 is p-type Mg as an example of a second conductivity type cladding layer. _0.1 Zn _0.9 An O clad layer 305 is a p-type ZnO contact layer as an example of a second conductivity type contact layer, and 308 is an n-type ohmic electrode.
[0091]
Hereinafter, a method for manufacturing the light-emitting diode element of the third embodiment will be described with reference to FIGS. 7A and 7B and FIGS. 8C to 8E.
[0092]
First, the cleaned ZnO substrate 301 is introduced into the laser MBE apparatus shown in FIG. 2 and is heated at a temperature of 600 ° C. for 30 minutes to be cleaned.
[0093]
Next, as shown in FIG. 9, a shielding mask 311 having a plurality of 300 μm square openings 311 a at 50 μm intervals is arranged between the ZnO substrate 303 and the raw material target 206. Since the crystal is grown through the shielding mask 311, the light emitting diode elements are selectively formed on the ZnO substrate 303 to have a size of 300 μm square.
[0094]
Next, in the same manner as in the first embodiment, as shown in FIG. _0.1 Zn _0.9 A p-type ohmic electrode 306 is formed from the O clad layer 302.
[0095]
Next, the shielding mask 311 is moved from directly below the ZnO substrate 301, and as shown in FIG. ₂ SiO ₄ : Zn for forming Mn phosphor 309 ₂ SiO ₄ : Mn layer 1309 is deposited on the entire surface.
[0096]
After that, the same method as in the first embodiment is performed. In other words, using a resist mask 310 as shown in FIG. ₂ SiO ₄ After forming the Mn phosphor 309, a pad electrode 307 as shown in FIG. 8D is formed, and further, an n-type ohmic electrode 308 as shown in FIG. 8E is formed.
[0097]
Finally, when the ZnO substrate 301 is separated into chips, a light emitting diode device of the second embodiment is obtained.
[0098]
After attaching the light emitting diode element to a lead frame and wiring to the pad electrode 307, the light emitting diode element is sealed with an epoxy mold resin containing no phosphor and a diffusing agent. When the light-emitting diode element was caused to emit light in this state, yellow light emission with a light emission peak wavelength of 550 nm was obtained, and the operating current for obtaining a light output of 4 mW was 7.5 mA. When the light emitting diode element was continuously driven at a light output of 4 mW, the driving time required for the emission intensity to decrease by 20% was 200000 hours.
[0099]
The light emitting diode element of Embodiment 2 has Zn ₂ SiO ₄ : Since the Mn phosphor 109 was deposited, the efficiency of the fluorescent light emission was improved as compared with the light emitting diode element of the first embodiment, and the operating current and the element life were improved.
[0100]
(Embodiment 3)
FIG. 10 shows a schematic sectional view of the light emitting diode element of the present embodiment. In FIG. 10, the same components as those shown in FIG. 6 are denoted by the same reference numerals as those in FIG. 6, and the description will be omitted.
[0101]
The light emitting diode element according to the third embodiment uses Zn as an example of a phosphor. ₂ SiO ₄ : Fabricated in the same manner as in Embodiment 2 except that an MgO intermediate layer 410 made of MgO was formed between the Mn phosphor 409 and the main body 300.
[0102]
After attaching the light emitting diode element of the third embodiment to a lead frame and wiring to the pad electrode 307, the light emitting diode element is sealed with an epoxy mold resin not containing a phosphor and a diffusing agent. When the light emitting diode element was caused to emit light in this state, yellow light emission with a light emission peak wavelength of 550 nm was obtained, and the operating current for obtaining a light output of 4 mW was 5 mA. When the device was continuously driven at an optical output of 4 mW, the driving time required for the emission intensity to decrease by 20% was 500,000 hours.
[0103]
The MgO intermediate layer 410 according to the third embodiment has a function of improving the adhesion between the main body 300 and the phosphor 409 and suppressing a reactive current from flowing from the main body 300 to the phosphor. Therefore, in the light emitting diode element of the third embodiment, the luminous efficiency and the life of the phosphor are remarkably improved.
[0104]
The intermediate layer having such a function is preferably the same oxide as the light-emitting diode element, and is preferably an insulator that can electrically separate the light-emitting diode element and the phosphor without absorbing light emission. . Furthermore, in order for the intermediate layer itself to be excellent in reliability, it is preferable that the intermediate layer be amorphous or single crystal that does not include a crystal grain boundary. As such an intermediate layer, in addition to Mg of the third embodiment, Sc, Y, Ti, Zr, Hf, Ce, V, Nb, Ta, Mo, W, Re, Al, Ga, Si and Ge are oxidized. It is preferable to include at least one of the objects.
[0105]
In Embodiments 1 to 3, the n-type clad layer, the active layer, the p-type clad layer, the p-type contact layer, and the p-type ohmic electrode are laminated on the substrate in this order to obtain a light emitting diode element. A p-type clad layer, an active layer, an n-type clad layer, an n-type contact layer, and an n-type ohmic electrode may be stacked in this order on a substrate to obtain a light emitting diode element. That is, in the light emitting diode elements of the first to third embodiments, the n-type layer may be changed to the p-type layer and the p-type layer may be changed to the n-type layer.
[0106]
Needless to say, the present invention may be applied to a semiconductor laser device.
[0107]
【The invention's effect】
As is clear from the above, since the main body of the oxide semiconductor light emitting device of the present invention is made of the ZnO-based semiconductor, the heat generation from the main body is small, and the phosphor covering at least a part of the main surface of the main body is deteriorated. Hateful. Therefore, luminous efficiency and power saving can be improved.
[Brief description of the drawings]
FIG. 1 is a schematic sectional view of a light-emitting diode element according to Embodiment 1 of the present invention.
FIG. 2 is a schematic configuration diagram of a laser MBE apparatus used for manufacturing the light emitting diode element.
FIGS. 3A and 3B are views for explaining a method for manufacturing the light emitting diode element.
FIGS. 4C and 4D are views for explaining a method of manufacturing the light emitting diode element.
FIG. 5 is a view showing an emission spectrum of the above-mentioned light emitting diode element when the deposited film thickness of the phosphor is changed.
FIG. 6 is a schematic sectional view of a light-emitting diode element according to Embodiment 2 of the present invention.
FIGS. 7A and 7B are diagrams for explaining a method of manufacturing the light-emitting diode element according to the second embodiment.
FIGS. 8C to 8E are views for explaining a method for manufacturing the light-emitting diode element according to the second embodiment.
FIG. 9 is a schematic top view of a shielding mask used in manufacturing the light-emitting diode element of the second embodiment.
FIG. 10 is a schematic sectional view of a light-emitting diode element according to Embodiment 3 of the present invention.
[Explanation of symbols]
100,300 body
101,301 n-type ZnO single crystal substrate
102,302 n-type Mg _0.1 Zn _0.9 O clad layer
103,303 Quantum well light emitting layer
104,304 p-type Mg _0.1 Zn _0.9 O clad layer
105,305 p-type ZnO contact layer
107,307 Au pad electrode for bonding
109,309,409 Mn added Zn ₂ SiO ₄ Phosphor

Claims (11)

A body made of a ZnO-based semiconductor;
A phosphor that covers at least a part of a main surface including the upper surface of the main body and the side surface of the main body,
An electrode formed on the upper surface of the main body. The oxide semiconductor light emitting device according to claim 1,
An oxide semiconductor light emitting device, wherein the main body has a first conductivity type clad layer, an active layer, a second conductivity type clad layer, and a second conductivity type contact layer laminated on a substrate. The oxide semiconductor light emitting device according to claim 1,
The oxide semiconductor light-emitting device, wherein the phosphor covers all regions other than the region where the electrode is formed on the main surface. The oxide semiconductor light emitting device according to claim 1,
An oxide semiconductor light emitting device, wherein the phosphor is in direct contact with the main surface. The oxide semiconductor light emitting device according to claim 1,
An oxide semiconductor light emitting device, wherein an intermediate layer is formed between the main body and the phosphor. The oxide semiconductor light emitting device according to claim 5,
An oxide semiconductor light-emitting element, wherein the intermediate layer includes an oxide insulator. The oxide semiconductor light emitting device according to claim 6,
The oxide insulator includes at least one of oxides of Mg, Sc, Y, Ti, Zr, Hf, Ce, V, Nb, Ta, Mo, W, Re, Al, Ga, Si, and Ge. An oxide semiconductor light-emitting element comprising: The oxide semiconductor light emitting device according to claim 1,
An oxide semiconductor light-emitting element, wherein the phosphor includes a zinc oxide to which an additive to be a luminescent center is added. The oxide semiconductor light emitting device according to claim 8,
The zinc oxide includes at least one of ZnO, Zn ₂ SiO ₄ , ZnGa ₂ O ₄ and ZnWO ₄ ,
The oxide semiconductor light-emitting device, wherein the additive includes at least one of Zn, Mn, Cr, and Ti. The oxide semiconductor light emitting device according to claim 1,
An oxide semiconductor light emitting device, wherein a phosphor is not added to a sealing resin for sealing the main body. It is a manufacturing method of the oxide semiconductor light emitting element of Claim 1, Comprising:
A method for manufacturing an oxide semiconductor light emitting device, wherein the phosphor is formed in a film forming apparatus in which the main body is formed, continuously with the formation of the main body.

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