JP2004228401A - Oxide semiconductor light emitting element and its manufacturing method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an oxide semiconductor light emitting element exhibiting excellent adhesion to an n-type oxide semiconductor layer and provided with a low resistance ohmic electrode. <P>SOLUTION: In the oxide semiconductor light emitting element 1 comprising a growth layer of an n-type ZnO contact layer 3 (n-type oxide semiconductor layer), an n-type clad layer 4, a light emitting layer 5, a p-type clad layer 6, and a p-type contact layer 7 formed on a sapphire substrate 2 (substrate), an n-type ohmic electrode 10 composed of an oxide of a transition metal not containing Ni, Cu and Ag is provided on the n-type ZnO contact layer 3 exposed by etching the growth layer partially. <P>COPYRIGHT: (C)2004,JPO&NCIPI

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to an oxide semiconductor light emitting device having a low-resistance ohmic electrode for an n-type oxide semiconductor layer and a method for manufacturing the same.
[0002]
[Prior art]
Prior art documents related to the present invention include the following.
[0003]
[Patent Document 1]
International Publication No. 00/16411 pamphlet
[Non-patent document 1]
"Japanese Journal of Applied Physics", Vol. 36, November 1, 1997, p. 1453-1455
[Non-patent document 2]
"Japanese Journal of Applied Physics", Vol. 40, March 1, 2001, p. 177-180
[0004]
Oxide materials have many properties such as dielectric properties, magnetism, and superconductivity, and also have properties that are far more than the properties of existing materials as semiconductor materials.
[0005]
Among them, zinc oxide (ZnO) is a direct transition type semiconductor having a band gap energy of about 3.4 eV, has an extremely high exciton binding energy of 60 meV, is inexpensive in raw materials, is harmless to the environment and the human body, and is formed of a film. It has features such as a simple method. In addition, zinc oxide can realize a light-emitting device with high efficiency, low power consumption, and excellent environmental performance. In the following, the ZnO-based semiconductor includes ZnO and a mixed crystal represented by MgZnO or CdZnO, which is based on ZnO.
[0006]
The technique of forming a low-resistance p-type ohmic electrode on the ZnO-based semiconductor is extremely important for uniformly and efficiently injecting carriers into the light emitting layer. However, since ZnO has a self-compensation effect due to strong ionicity, it has been difficult to control the p-type conductivity. In order to solve this drawback, a p-type ohmic electrode has been realized by using nitrogen (N) as an acceptor impurity (for example, see Non-Patent Document 1). In addition, many studies have been made to manufacture a highly efficient light-emitting element using a ZnO-based semiconductor (for example, see Non-Patent Document 2).
[0007]
However, not only the p-type ohmic electrode but also an n-type ohmic electrode that can obtain a stable ohmic contact still has room for improvement. For example, a Ti-Al electrode used in an n-type group III nitride semiconductor has poor adhesion between a metal thin film and an oxide semiconductor, so that it is difficult to obtain complete ohmic contact with an n-type ZnO-based semiconductor layer, and Ohmic resistance was high.
[0008]
As means for solving this problem, an n-type ohmic electrode in which Ti or Cr is in contact with the n-type ZnO layer and Al is not in contact with the n-type ZnO layer is disclosed (for example, see Patent Document 1).
[0009]
[Problems to be solved by the invention]
However, even if Ti or Cr is used for the electrode, the ohmic resistance does not significantly decrease, and the metal electrode formed by a manufacturing method such as a vacuum evaporation method or a sputtering method is easily peeled or deteriorated during wire bonding or energization. There was also a problem.
[0010]
Accordingly, an object of the present invention is to provide an oxide semiconductor light-emitting element which has excellent adhesion to an n-type oxide semiconductor layer and realizes excellent light-emitting characteristics by using a low-resistance ohmic electrode in view of the conventional problem. The task is to provide
[0011]
[Means for Solving the Problems]
The present invention has conducted intensive studies on an ohmic electrode material having both adhesion and low resistance to an n-type oxide semiconductor layer and a structure and a manufacturing method thereof. As a result, a transition metal containing no transition metals Ni, Cu, Ag, In particular, the above object is achieved by using an oxide of at least one transition metal selected from transition metals Ti, Cr, V, Hf, Zr, Nb, Ta, Mo, and W for the ohmic electrode.
[0012]
The oxide semiconductor light emitting device according to the present invention, as means for solving the above problems,
An oxide semiconductor light-emitting element in which a growth layer including an n-type oxide semiconductor layer, an n-type clad layer, a light-emitting layer, a p-type clad layer, and a p-type contact layer is stacked on a substrate,
An ohmic electrode made of a transition metal oxide that does not contain transition metals Ni, Cu, and Ag is provided on the n-type oxide semiconductor layer exposed by etching a part of the growth layer.
[0013]
According to the invention, the transition metal oxide is more excellent in adhesion to the oxide semiconductor than the metal, so that the ohmic electrode is not peeled off by wire bonding or energization, and is excellent in reliability. Further, it is not preferable that the ohmic electrode contains any of transition metals Ni, Cu, and Ag, because the ohmic electrode becomes a p-type ohmic electrode and the resistance is increased by diffusion of these elements.
[0014]
The oxide semiconductor light-emitting device according to the present invention, as another means for solving the above problems,
An oxide semiconductor light-emitting element in which a growth layer including at least an n-type cladding layer, a light-emitting layer, a p-type cladding layer, and a p-type contact layer is stacked on a substrate including an n-type oxide semiconductor,
An ohmic electrode made of a transition metal oxide not containing transition metals Ni, Cu, and Ag is provided on the back surface of the substrate.
[0015]
It is preferable that the ohmic electrode is made of an oxide of at least one transition metal selected from transition metals Ti, Cr, V, Hf, Zr, Nb, Ta, Mo, and W. The oxides of the transition metals Ti, Cr, V, Hf, Zr, Nb, Ta, Mo, and W have good conductor or n-type semiconductor properties, and can form a stable and low-resistance ohmic electrode. Thus, an oxide semiconductor light-emitting element having excellent reliability and low operating voltage can be provided.
[0016]
It is preferable that the ohmic electrode has a layer thickness of 1 nm or more and 100 nm or less, and has a property of transmitting light from the light emitting layer. Accordingly, the ohmic electrode has a light-transmitting property, light from the light-emitting layer can be extracted to the outside, and the luminance of the light-emitting element can be improved. Specifically, when an ohmic electrode is formed on an n-type oxide semiconductor layer of an oxide semiconductor light-emitting element using an insulating substrate, when light reflected on the bottom surface of the substrate enters the ohmic electrode, light is extracted to the outside. Therefore, it is effective to make the ohmic electrode translucent. When the thickness of the ohmic electrode is in the range of 1 nm or more and 100 nm or more, a sufficiently low ohmic contact can be ensured, and light transmission efficiency is high and light extraction efficiency is improved.
[0017]
It is preferable that a pad electrode made of Al or Au is formed on the ohmic electrode. Al and Au are suitable for use as a pad electrode for bonding a wire with low resistance. In particular, since Al does not act as an acceptor impurity for an oxide semiconductor, the electrode can be formed even on an n-type ohmic electrode. Does not increase resistance.
[0018]
At this time, an intermediate layer containing a transition metal not containing transition metals Ni, Cu, and Ag and at least one element selected from Ga and In may be formed between the ohmic electrode and the pad electrode. By providing this intermediate layer between the ohmic electrode and the pad electrode, the adhesion between the ohmic electrode and the pad electrode is improved.
[0019]
Further, the transition metal of the intermediate layer is preferably made of at least one transition metal selected from Ti, Cr, V, Hf, Zr, Nb, Ta, Mo, and W.
[0020]
Preferably, a reflective layer containing at least one of Al and Pt is formed between the ohmic electrode and the pad electrode. The light incident on the ohmic electrode is reflected with high efficiency, and multiple reflection inside the light emitting element improves light extraction efficiency. Further, the resistance of the ohmic electrode can be reduced. Such a reflective layer can improve light extraction efficiency both when the ohmic electrode and the pad electrode are formed on the surface of the light emitting element or when the ohmic electrode and the pad electrode are formed on the back surface of the substrate.
[0021]
It is preferable that the ohmic electrode formed on the back surface of the substrate is patterned, and the back surface of the substrate is electrically connected to a lead frame with a conductive material containing Ag. Ag has a high reflectance to light in the blue to ultraviolet region, and the n-type ohmic electrode on the back surface of the substrate is patterned and connected to the lead frame with a conductive material containing Ag, so that light incident on the bottom surface of the substrate is absorbed. Since the light is reflected by the conductive material containing Ag without light, the light extraction efficiency is improved.
[0022]
The method for manufacturing an oxide semiconductor light-emitting device according to the present invention, as means for solving the above problems,
A growth layer including an n-type oxide semiconductor layer, an n-type cladding layer, a light-emitting layer, a p-type cladding layer, and a p-type contact layer is stacked on a substrate,
An ohmic electrode is formed by evaporating or scattering an oxide of a transition metal containing no transition metal, Ni, Cu, or Ag, on the n-type oxide semiconductor layer exposed by etching a part of the growth layer. Is formed as a thin film.
[0023]
According to the invention, the transition metal oxide is used as a raw material of the ohmic electrode, so that, for example, O ₂ There is no need to introduce a gas, and the ohmic electrode of the present invention can be easily formed.
[0024]
The method for manufacturing an oxide semiconductor light emitting device according to the present invention includes, as another means for solving the above-described problems,
A growth layer including an n-type oxide semiconductor layer, an n-type cladding layer, a light-emitting layer, a p-type cladding layer, and a p-type contact layer is stacked on a substrate,
The transition metal excluding transition metals Ni, Cu, and Ag is evaporated or scattered on the n-type oxide semiconductor layer exposed by etching a part of the growth layer, and oxygen is introduced to reduce the raw material. The ohmic electrode is formed into a thin film by deposition.
[0025]
According to the invention, a high-purity raw material of the transition metal can be obtained at a low cost. By using this as a raw material for an ohmic electrode, an ohmic electrode having excellent characteristics can be manufactured at low cost. Further, an oxide thin film can be easily formed by vapor deposition in an oxygen atmosphere, so that a low-resistance ohmic electrode having excellent adhesion can be formed.
[0026]
The method for manufacturing an oxide semiconductor light emitting device according to the present invention includes, as another means for solving the above-described problems,
A growth layer including at least an n-type clad layer, a light-emitting layer, a p-type clad layer, and a p-type contact layer is stacked on a substrate formed of an n-type oxide semiconductor,
On the back surface of the substrate, an oxide of a transition metal not containing transition metals Ni, Cu, and Ag is evaporated or scattered and deposited to form an ohmic electrode as a thin film.
[0027]
The method for manufacturing an oxide semiconductor light emitting device according to the present invention includes, as another means for solving the above-described problems,
A growth layer including at least an n-type clad layer, a light-emitting layer, a p-type clad layer, and a p-type contact layer is stacked on a substrate formed of an n-type oxide semiconductor,
On the rear surface of the substrate, a transition metal containing no transition metals Ni, Cu, and Ag is evaporated or scattered, and oxygen is introduced to deposit the raw material to form an ohmic electrode as a thin film.
[0028]
It is preferable that the ohmic electrode is made of an oxide of at least one transition metal selected from transition metals Ti, Cr, V, Hf, Zr, Nb, Ta, Mo, and W.
[0029]
The thin film forming method is preferably any one of an electron beam evaporation method, a sputtering method, and a laser ablation method. These thin film formation methods are high in mass productivity and can easily form a high-quality oxide thin film, and a light-emitting element having excellent characteristics can be manufactured at low cost.
[0030]
After forming the ohmic electrode, it is preferable to perform a heat treatment on the oxide semiconductor light emitting device in an oxygen atmosphere or the air. By performing the heat treatment or the annealing treatment, the adhesion of the ohmic electrode to the oxide semiconductor and the ohmic characteristics are significantly improved. In particular, by performing the annealing treatment in an oxygen atmosphere, it is possible to suppress the escape of oxygen from the electrode and improve the adhesion while maintaining a low ohmic resistance.
[0031]
The heat treatment temperature is preferably in the range of 300 to 450 ° C. When the temperature is 300 ° C. or higher, the adhesiveness of the ohmic electrode and the ohmic resistance reduction effect can be improved. When the temperature is 450 ° C. or lower, the oxide semiconductor light-emitting element does not deteriorate and has excellent characteristics. Can be manufactured.
[0032]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings.
[0033]
(1st Embodiment)
FIG. 1 is a sectional view of an oxide semiconductor light emitting device 1 according to the first embodiment of the present invention. In this oxide semiconductor light emitting device 1, Ga is placed on a sapphire substrate 2 having a c-plane as a main surface. ¹⁸ cm ^-3 N-type ZnO contact layer 3 (n-type oxide semiconductor layer) having a thickness of 0.2 μm and doped with Ga ¹⁸ cm ^-3 N-type Mg doped at a concentration of 1 μm _0.1 Zn _0.9 O-clad layer 4, non-doped Cd of 0.1 μm thickness _0.1 Zn _0.9 O light emitting layer 5, N is 1 × 10 ²⁰ cm ^-3 P-type Mg doped at a concentration of 1 μm _0.1 Zn _0.9 O clad layer 6, N is 5 × 10 ²⁰ cm ^-3 A p-type ZnO contact layer 7 having a thickness of 0.3 μm and doped at a concentration of 0.1 μm is laminated.
[0034]
On the entire surface of the main surface of the p-type ZnO contact layer 7, a light-transmitting p-type ohmic electrode 8 is formed by laminating 10 nm-thick NiO. Au pad electrodes 9 are stacked.
[0035]
Further, the n-type Mg _0.1 Zn _0.9 A part of the epitaxial layer from the O-cladding layer 4 to the p-type ZnO contact layer 7 is etched, and a part of the n-type ZnO contact layer 3 is exposed. On the exposed surface of the n-type ZnO contact layer 3, a 10 nm thick TiO ₂ Are laminated, and a bonding Al pad electrode 11 having a diameter of 80 μm and a thickness of 500 nm is laminated thereon.
[0036]
Next, a method for manufacturing the oxide semiconductor light emitting device 1 will be described.
[0037]
The oxide semiconductor light emitting device 1 of the present embodiment is manufactured by a laser molecular beam epitaxy (hereinafter referred to as a laser MBE) device 20 shown in FIG. In the laser MBE apparatus 20, a substrate holder 22 that holds the substrate 2 at a lower surface position is disposed above a growth chamber 21 that can be evacuated to an ultra-high vacuum. The substrate holder 22 is configured such that the back surface of the substrate holder 22 is heated by a heater 23 disposed above the substrate holder 22, whereby the substrate 2 is heated by heat conduction from the substrate holder 22. A fan-shaped target table 24 is disposed below the substrate 2, and a plurality of targets 25 are disposed on the outer edge of the upper surface of the target table 24. The surface of the target 25 is ablated by the pulsed laser beam 26a irradiated through the view port 26 provided on the side wall of the growth chamber 21, so that the material on the surface of the target 25 evaporates instantaneously. A thin film is formed on the substrate 2 by depositing the evaporated raw material of the target 25 on the lower surface of the substrate 2 (laser ablation method). The rotation of the target table 24 is controlled by a rotation mechanism (not shown) in synchronization with the irradiation sequence of the pulsed laser light 26a, so that different materials of the target 25 can be stacked on the substrate 2. Further, the growth chamber 21 is provided with gas introduction pipes 27 a and 27 b so that gas can be introduced into the growth chamber 21. Further, it is possible to irradiate the substrate 2 with the atomic beam activated by the radical cell 28 provided in the gas introduction pipe 27b.
[0038]
In the laser MBE method using the laser MBE device 20, first, the cleaned sapphire substrate 2 is attached and fixed to the lower surface of the substrate holder 22 in the laser MBE device 20. Next, O ₂ Inlet gas and internal pressure 5 × 10 ^-3 The pressure is adjusted to Pa and the sapphire substrate 2 is cleaned by heating at a temperature of 600 ° C. for 30 minutes, and then the substrate temperature is lowered to 550 ° C.
[0039]
Next, the rotation driving cycle of the target table 24 by the rotation mechanism is synchronized with the pulse irradiation cycle of the pulse laser beam 26a, and the non-doped ZnO single crystal and Ga ₂ O ₃ Are alternately ablated with a target 25 made of a ZnO sintered body to which Ga is added to obtain a desired Ga doping concentration (3 × 10 ¹⁸ cm ^-3 ) Is grown to a thickness of 0.2 μm. At this time, a KrF excimer laser (wavelength: 248 nm, pulse number: 10 Hz, output: 1 J / cm) was used as the pulse laser beam 26a for performing ablation. ² ) Was used. Also, during the formation of the n-type ZnO contact layer 3, O gas is introduced through the gas introduction pipe 27a. ₂ Gas was introduced into the growth chamber 21.
[0040]
Next, a non-doped ZnO single crystal and Ga ₂ O ₃ Are alternately ablated to obtain a desired Mg composition and a Ga doping concentration (1 × 10 3). ¹⁸ cm ^-3 N-type Mg having) _0.1 Zn _0.9 The O cladding layer 4 is grown to a thickness of 1 μm.
[0041]
Further, a target 25 made of a non-doped ZnO single crystal and a non-doped CdO single crystal is alternately ablated to form a non-doped CdO single crystal. _0.1 Zn _0.9 The O light emitting layer 5 is grown to a thickness of 0.1 μm.
[0042]
Also, the N introduced through the gas introduction pipe 27b ₂ The target 25 made of a non-doped ZnO single crystal and a non-doped MgZnO sintered body is alternately ablated while irradiating the gas with a plasma in a radical cell 28 to obtain a desired N doping concentration (1 × 10 4 ²⁰ cm ^-3 P-type Mg having) _0.1 Zn _0.9 The O clad layer 6 is grown to a thickness of 1 μm.
[0043]
Also, the N introduced through the gas introduction pipe 27b ₂ The target 25 made of a non-doped ZnO single crystal is ablated while irradiating the gas with plasma in a radical cell 28 to obtain a desired N doping concentration (5 × 10 5 ²⁰ cm ^-3 ) Is grown to a thickness of 0.3 μm.
[0044]
And O ₂ The pressure inside the growth chamber 21 is adjusted to 1 × 10 ^-3 The pressure is adjusted to Pa and the target 25 made of Ni is ablated. At this time, the metal Ni evaporated by the ablation causes O in the growth chamber 21. ₂ It becomes NiO by the gas and is laminated on the substrate 2. Thereby, the p-type ohmic electrode 8 made of NiO is formed to a thickness of 10 nm. Furthermore, O ₂ The introduction of gas was stopped and the pressure in the growth chamber 21 was reduced to 1 × 10 ^-4 The pressure is adjusted to Pa, the target 25 made of Au is ablated, and the Au pad electrode 9 is laminated to a thickness of 500 nm.
[0045]
Next, the sapphire substrate 2 is taken out of the laser MBE device 20, and a part of the upper surface of the sapphire substrate 2 is covered with a resist mask (not shown). Then, the sapphire substrate 2 is n-type Mg-based by an ion milling device (not shown). _0.1 Zn _0.9 A part of the growth layer from the O cladding layer 4 to the Au pad electrode 9 is etched to expose a part of the n-type ZnO contact layer 3.
[0046]
Next, the sapphire substrate 2 is taken out of the ion milling device, the resist mask is removed, and the sapphire substrate 2 is introduced into the laser MBE device 20 again. And O ₂ The pressure inside the growth chamber 21 is adjusted to 1 × 10 ^-3 The pressure is adjusted to Pa, and the target 25 made of metal Ti as a raw material is ablated. At this time, the metal Ti evaporated by the ablation causes O in the growth chamber 21. ₂ TiO by gas ₂ And a film is formed on the surface of the n-type ZnO contact layer 3. Thereby, TiO ₂ Is stacked to a thickness of 10 nm. Furthermore, O ₂ The introduction of gas was stopped and the pressure in the growth chamber 21 was reduced to 1 × 10 ^-4 The pressure is adjusted to Pa, the target 25 made of Al is ablated, and the Al pad electrode 11 is laminated to a thickness of 500 nm.
[0047]
Then, the sapphire substrate 2 is taken out of the laser MBE device 20 and TiO deposited on the portion other than the exposed portion of the n-type ZnO contact layer 3 ₂ And Al are removed by etching. The Au pad electrode 9 and the Al pad electrode 11 are each processed to a diameter of 80 μm.
[0048]
Finally, the sapphire substrate 2 is introduced into an annealing furnace (not shown), and an annealing process (heat treatment) is performed at 350 ° C. for 1 minute in the atmosphere. After that, it is divided into 300 μm square chips.
[0049]
In the laser MBE method described above, the composition deviation between the raw material of the target 25 and the thin film formed is small, and the ZnGa ₂ O ₄ It is preferable because generation of unintended compounds such as the above can be suppressed. Further, the oxide semiconductor light emitting device 1 of the present invention is not limited to the laser MBE method, but may be a crystal growth method such as a molecular beam epitaxy (MBE) method using a solid or gaseous raw material, and a metal organic chemical vapor deposition (MOCVD) method. May be manufactured. The method for forming the thin film is not limited to the laser ablation method, but may be any of an electron beam evaporation method and a sputtering method.
[0050]
After the Au pad electrode 9 and the Al pad electrode 11 of the manufactured oxide semiconductor light emitting device 1 were wire-bonded to the lead frame, the oxide semiconductor light emitting device 1 was molded with resin to emit light. Blue light emission having an emission peak wavelength of 410 nm was obtained. The operating voltage at an operating current of 20 mA was 3.6V. In addition, when 100 oxide semiconductor light emitting devices 1 were mounted on a lead frame, none of the oxide semiconductor light emitting devices 1 suffered electrode peeling during wire bonding. When 300 oxide semiconductor light-emitting elements 1 were mounted on a lead frame, five of the oxide semiconductor light-emitting elements 1 suffered electrode peeling during wire bonding.
[0051]
(Comparative Example 1)
On the other hand, as described above, TiO ₂ Instead of forming the n-type ohmic electrode 10 made of ₂ When 100 oxide semiconductor light-emitting elements each having the n-type ohmic electrode 10 made of Ti formed thereon without flowing gas into the growth chamber 21 were mounted on a lead frame, electrode peeling occurred during wire bonding to the Al pad electrode 11. There were 25 oxide semiconductor light-emitting elements in which occurred. In addition, there were 20 oxide semiconductor light-emitting elements whose operating voltage was 5 V or more.
[0052]
That is, the ohmic electrode made of metal (Ti) and the oxide semiconductor (the n-type ZnO contact layer 3) have low adhesion and the production yield is low, whereas the ohmic electrode 10 of the present invention has the transition metal oxide ( TiO ₂ ), The adhesion is strong and the reliability is dramatically improved. In particular, oxides of transition metals Ti, Cr, V, Hf, Zr, Nb, Ta, Mo, and W have good conductor or n-type semiconductor properties, and can form a stable and low-resistance ohmic electrode. .
[0053]
FIG. ₂ The relationship between the layer thickness (nm) of the ohmic electrode 10 made of and the operating voltage (V) and the light emission intensity (arbitrary unit) of the oxide semiconductor light emitting device 1 is shown. TiO ₂ When the thickness of the ohmic electrode 10 exceeds 1 nm, the operating voltage decreases, and becomes almost saturated at 100 nm or more. On the other hand, if the layer thickness is 100 nm or more, TiO ₂ Since the translucency of the ohmic electrode 10 also decreases, the light emission intensity sharply decreases. From the above results, it is preferable that the layer thickness of the n-type ohmic electrode 10 be 1 nm or more and 100 nm or less in order to keep the operating voltage of the oxide semiconductor light-emitting element 1 low and achieve high emission intensity.
[0054]
(Comparative Example 2)
When 100 oxide semiconductor light emitting devices without the Al pad electrode 11 were mounted on a lead frame, it was found that TiO 2 ₂ There were 60 oxide semiconductor light emitting elements in which electrode peeling occurred during wire bonding to the ohmic electrode 10 made of. In addition, there were 20 oxide semiconductor light emitting elements in which the bonding wire was disconnected from the ohmic electrode 10 during energization.
[0055]
That is, in order to maximize the effects of the low ohmic resistance and strong adhesion of the present invention, TiO ₂ It is preferable to form an Al pad electrode 11 on the ohmic electrode 10 made of and perform wire bonding.
[0056]
(Comparative Example 3)
When 100 oxide semiconductor light emitting devices manufactured without annealing in the manufacturing process were mounted on a lead frame, 15 oxide semiconductor light emitting devices in which electrode peeling occurred during wire bonding to the Al pad electrode 11 were found. There were pieces. In addition, there were 10 oxide semiconductor light-emitting elements having an operation voltage of 5 V or more.
[0057]
That is, by performing an annealing process (heat treatment), the oxide semiconductor (the n-type ZnO contact layer 3) and the metal oxide (TiO 2) are formed. ₂ Adhesion with the ohmic electrode 10) and ohmic characteristics are significantly improved. Note that when the temperature of the annealing treatment is 300 ° C. or higher, the adhesion and the resistance can be reduced, and when the temperature is 450 ° C. or lower, the oxide semiconductor element 1 is hardly deteriorated. The atmosphere in the annealing process is O ₂ Alternatively, it is preferably in an air atmosphere. ₂ On the contrary, the resistance increases in the atmosphere.
[0058]
In the case where Al that is easily oxidized is used for the Al pad electrode 11 on the n-type ohmic electrode 10 as in the present embodiment, the surface of the Al pad electrode 11 is non-conductive when subjected to high-temperature annealing in an oxidizing atmosphere. Al ₂ O ₃ May be formed, and the adhesiveness and conductivity of the bonding wire may be degraded. In order to prevent this, it is preferable that the pad electrode 11 be made of Au or that the annealing atmosphere be air.
[0059]
In this embodiment, the p-type ohmic electrode 8 made of NiO and the TiO ₂ An n-type ohmic electrode 10 made of O is formed by using a target 25 made of metal Ni and metal Ti. ₂ It was formed by ablation in an atmosphere. Targets and tablets of this elemental metal (Ni and Ti) are highly pure and inexpensive at about 4N to 5N. Therefore, an oxide ohmic electrode with high purity and low resistance can be easily formed at low cost. On the other hand, the p-type ohmic electrode 8 and the n-type ohmic electrode 10 are made of metal NiO and metal TiO. ₂ When forming by ablation using the target which uses as a raw material, metal oxide (NiO and TiO ₂ Although it is difficult to obtain a high-purity target or tablet (about 3N to 4N), the target or tablet is ₂ There is no need to introduce a gas, and the p-type ohmic electrode 8 and the n-type ohmic electrode 10 can be easily formed.
[0060]
Further, by using the laser MBE apparatus 20 of the present embodiment, a high-purity O ₂ A metal oxide thin film can be formed using a gas, and further, a layer from a growth layer to an electrode can be formed consistently in the vacuum growth chamber 21. Therefore, it is possible to easily form an oxide ohmic electrode having excellent purity.
[0061]
Further, it is preferable that the p-type ohmic electrode 8 also has a light-transmitting property like the n-type ohmic electrode 10. Further, as a material of the p-type ohmic electrode 8, it is preferable to use Ni, Ag, and Cu, and Ni is particularly preferable. Further, as the material of the pad electrode 9 on the p-type ohmic electrode 8, Au is preferable as in the present embodiment, and the use of Al is not preferable because the resistance of the p-type ohmic electrode 8 is easily increased.
[0062]
As the acceptor impurity to be doped into the p-type ZnO contact layer 7, it is preferable to use a group I element such as Li, Cu, Ag or a group V element such as N, As, or P, so that the effect of the present invention is maximized. In order to obtain, N, Li and Ag having a high activation rate are particularly preferable. Further, when doping N, N ₂ Is more preferable because a high-concentration doping can be performed while maintaining good crystallinity by irradiating during the crystal growth by turning into a plasma.
[0063]
Further, as a donor impurity to be doped into the n-type ZnO contact layer 3, it is preferable to use a group III element such as B, Al, Ga, In, and particularly, Ga or Al having a high activation rate in a ZnO-based semiconductor. Is preferred.
[0064]
In addition, as described in the present embodiment, it is preferable to form the ohmic electrode 8 on the cladding layers 4 and 6 via the contact layer 7 so as to reduce the resistance and improve the luminous efficiency of the oxide semiconductor light emitting element 1. . As the material of the contact layer 7, it is preferable to use ZnO which is excellent in crystallinity and can increase the carrier concentration. If the ZnO contact layer is excessively doped with impurities, the crystallinity is remarkably deteriorated and the effect of the present invention is reduced. ¹⁶ ~ 5 × 10 ¹⁹ cm ^-3 It is preferable to adjust the doping concentration so as to be within the carrier concentration range.
[0065]
Other configurations are arbitrary and are not limited by the present embodiment.
[0066]
As a modification of the above embodiment, as shown in FIG. ₂ An intermediate layer 12 made of Zr and having a thickness of 50 nm may be formed between the n-type ohmic electrode 10 made of and the Al pad electrode 11. After wire bonding the oxide semiconductor light emitting device 1 to a lead frame, the oxide semiconductor light emitting device 1 was molded with a resin and emitted light. As a result, blue light emission having an emission peak wavelength of 410 nm was obtained. The operating voltage at an operating current of 20 mA was 3.4 V, which was lower than that of the embodiment. Further, when 300 pieces of the oxide semiconductor light emitting elements 1 were mounted on a lead frame, none of the oxide semiconductor light emitting elements 1 suffered electrode peeling during wire bonding.
[0067]
As described above, between the oxide ohmic electrode 10 and the Al pad electrode 11, the intermediate layer 12 containing a transition metal not containing transition metals Ni, Cu, and Ag and at least one element (Zr) selected from Ga and In. Is formed, the adhesion between the oxide ohmic electrode 10 and the Al pad electrode 11 can be improved, and the operating voltage can be reduced.
[0068]
When the intermediate layer 12 was formed using Ni, electrode peeling did not occur during wire bonding, but the operating voltage of the oxide semiconductor light emitting device 1 was 5 V or more. It is considered that the reason for the increase in the operating voltage is that Ni acts as an ohmic electrode for the p-type ZnO semiconductor, so that the electric conduction was hindered by diffusing into the n-type ohmic electrode 10 and the n-type ZnO contact layer 3. . As described above, it is preferable that the intermediate layer 12 does not include Ni, Cu, and Ag that are p-type ohmic electrode materials. In particular, as the material of the intermediate layer 12, transition metals Ti, Cr, V, Hf, Zr, Nb, Ta, Mo, and W are preferable. Similarly, it is preferable that the n-type ohmic electrode 10 also does not contain Ni, Cu, and Ag which are p-type ohmic electrode materials.
[0069]
As a modification of the above-described embodiment, TiO 2 shown in FIG. ₂ The intermediate layer 12 between the n-type ohmic electrode 10 and the Al pad electrode 11 may be made of Pt having a thickness of 50 nm. After the oxide semiconductor light emitting device 1 was wire-bonded to a lead frame, the oxide semiconductor light emitting device 1 was molded with a resin to emit light. As a result, the light emission intensity was increased by 10% as compared with the above embodiment. This is because the intermediate layer 12 made of Pt has a high reflectance with respect to light having a wavelength in the blue to ultraviolet range, and thus acts as a reflective layer, and reflects light incident on the pad electrode 11 with high efficiency. This is because multiple reflection inside allows the light to be extracted from the side surface of the oxide semiconductor light emitting device 1 to the outside. If such a light reflecting layer is formed as the intermediate layer 12, even if the pad electrode 11 is made of a material (such as Au) having a low reflectance for light having a wavelength in the blue to ultraviolet range, the light extraction efficiency is reduced. I can't. Of course, if the intermediate layer 12 is formed of a laminated structure of Zr and Pt, both the effect of improving the adhesion and the effect of the light reflecting layer can be obtained. In particular, it is preferable to stack the Zr layer so as to be in contact with the Al pad electrode 11 and the Pt layer so as to be in contact with the n-type ZnO contact layer 3, since both effects can be surely obtained.
[0070]
As a modification of the above-described embodiment, the n-type ohmic electrode 10 is made of HfO ₂ HfO by electron beam evaporation using a tablet ₂ May be configured. After wire bonding the oxide semiconductor light emitting device 1 to a lead frame, the oxide semiconductor light emitting device 1 was molded with a resin and emitted light. As a result, blue light emission having an emission peak wavelength of 410 nm was obtained. The operating voltage and the light emission intensity at an operating current of 20 mA were almost the same as those in the embodiment. In addition, when 100 oxide semiconductor light emitting devices 1 were mounted on a lead frame, none of the oxide semiconductor light emitting devices 1 suffered electrode peeling during wire bonding.
[0071]
This electron beam evaporation method is a film-forming technique that has high mass productivity and can easily form a high-quality oxide thin film (ohmic electrode 10), and is advantageous in that an excellent oxide semiconductor light-emitting element 1 can be manufactured at low cost. preferable. In addition, HfO ₂ By using a tablet, O 2 is introduced into the growth chamber 21 of the laser MBE apparatus 20. ₂ An oxide ohmic electrode (HfO ₂ An ohmic electrode 10) can be formed, which is excellent in the simplicity of the manufacturing process and is suitable when a vacuum film forming apparatus or the like which does not like oxygen is used.
[0072]
(2nd Embodiment)
FIG. 5 is a sectional view of an oxide semiconductor light emitting device 1 ′ according to the second embodiment of the present invention. This oxide semiconductor light emitting device 1 ′ has an n-type Mg _0.1 Zn _0.9 O clad layer 4, Cd _0.1 Zn _0.9 O light emitting layer 5, p-type Mg _0.1 Zn _0.9 It is formed by laminating a growth layer including an O-cladding layer 6, a p-type ZnO contact layer 7, a p-type ohmic electrode 8, and an Au pad electrode 9. Unlike the first embodiment, the n-type ZnO contact layer 3 is not formed. In addition, TiO is provided on the back surface of the ZnO single crystal substrate 2 '. ₂ An n-type ohmic electrode 10 and an Al pad electrode 11 are formed. The n-type ohmic electrode 10 and the Al pad electrode 11 are patterned into a lattice having a width of 30 μm as shown in FIG. The portions having the same and similar functions as those of the first embodiment are denoted by the same reference numerals, and detailed description is omitted.
[0073]
In order to manufacture the oxide semiconductor light emitting device 1 'having the above-described configuration, the growth layer is formed on the substrate 2' by using the laser MBE device 20, and then the substrate 2 ' , An n-type ohmic electrode 10 and an Al pad electrode 11 are laminated. Next, the substrate 2 'is taken out from the laser MBE apparatus 20, the Au pad electrode 9 is processed to a diameter of 80 μm, and the n-type ohmic electrode 10 and the Al pad electrode 11 are patterned by etching as shown in FIG.
[0074]
In addition, the TiO ₂ An n-type ohmic electrode 10 made of O is formed by using a target 25 made of metal Ti as in the first embodiment. ₂ It was formed by ablation in an atmosphere. Since the target and the tablet of the element metal (Ti) are high-purity and inexpensive, it is possible to easily and inexpensively form an oxide ohmic electrode having high purity and low resistance. On the other hand, the TiO ₂ N-type ohmic electrode 10 made of metal NiO and metal TiO ₂ When the laser MBE apparatus 20 is formed by ablation using a target made of ₂ There is no need to introduce a gas, and the n-type ohmic electrode 10 can be easily formed.
[0075]
This oxide semiconductor light emitting device 1 ′ is separated into a chip shape of 300 μm square, the back surface of the substrate 2 ′ is bonded to a lead frame with an Ag paste, the Au pad electrode 9 is wire-bonded to the other of the lead frame, and then molded with a resin. As a result, blue light emission having an emission peak wavelength of 410 nm was obtained in the same manner as in the first embodiment. The operating voltage at an operating current of 20 mA was 3.3 V, which was lower than that of the first embodiment. The reason why the operating voltage was reduced was that the use of the conductive ZnO substrate 2 ′ improved the crystallinity, improved the luminous efficiency, and increased the area through which current flowed, thereby reducing the element resistance. Conceivable.
[0076]
When 100 oxide semiconductor light emitting devices 1 'were mounted on a lead frame, none of the oxide semiconductor light emitting devices 1' suffered electrode peeling during wire bonding. Further, as in the present embodiment, the n-type oxide ohmic electrode 10 formed on the back surface of the ZnO single-crystal substrate 2 ′, which is an n-type substrate, is connected to a lead frame by a conductive paste (Ag) as a conductive material. Therefore, no load is applied at the time of wire bonding, so that there is no peeling.
[0077]
(Comparative Example 4)
On the other hand, when the n-type ohmic electrode 10 and the Al pad electrode 11 were not patterned in a grid pattern, the oxide semiconductor light emitting device was mounted on a lead frame and emitted light. It was reduced to about 70% as compared with the case of pattern processing.
[0078]
Further, in the present embodiment, the electrode pattern shape of the n-type ohmic electrode 10 and the Al pad electrode 11 on the back surface of the substrate 2 ′ is a lattice shape, but the electrode pattern shape is not limited thereto, and may be a dot shape or a dot shape. It may be striped. Furthermore, it is not necessary to process the n-type ohmic electrode 10 and the Al pad electrode 11 in the same shape, and the two may have different pattern shapes.
[0079]
(Comparative Example 5)
When the back surface of the substrate 2 'of the oxide semiconductor light emitting element 1' is bonded to a lead frame, when a Cu paste and a carbon paste are used instead of the Ag paste, the operating voltage at an operating current of 20 mA is the same as that of the Ag paste. Same as when used, but the emission intensity dropped to 50% and 20%, respectively. It is considered that the light emission intensity was reduced because the Cu paste and the carbon paste absorbed light incident on the bottom surface of the substrate 2 '. On the other hand, an Ag paste having a high reflectance for light having a wavelength in the blue to ultraviolet range reflects light incident on the bottom surface of the substrate 2 ′ with high efficiency and can be extracted to the outside of the oxide semiconductor light emitting element 1 ′. It is preferred in that respect.
[0080]
In this embodiment, the n-type ZnO contact layer 3 is not formed between the substrate 2 'and the n-type cladding layer 4, but the ZnO contact layer 3 may be formed and used as a buffer layer.
[0081]
As a modification of the above embodiment, as shown in FIG. ₂ An intermediate layer 12 ′ made of Zr and having a thickness of 50 nm may be formed between the n-type ohmic electrode 10 made of and the Al pad electrode 11. As described above, by forming the intermediate layer 12 ′ containing the transition metal not containing the transition metals Ni, Cu, and Ag and at least one element (Zr) selected from Ga and In, the oxide ohmic electrode 10 and the Al The adhesion of the pad electrode 11 can be improved, and the operating voltage can be reduced. In particular, as the material of the intermediate layer 12, transition metals Ti, Cr, V, Hf, Zr, Nb, Ta, Mo, and W are preferable. When the intermediate layer 12 'was formed using Ni, no electrode peeling occurred during wire bonding, but the operating voltage of the oxide semiconductor light emitting element 1' was 5 V or more. This is considered to be because, as described above, Ni acts as an ohmic electrode with respect to the p-type ZnO semiconductor, so that electric conduction was hindered, and the intermediate layer 12 'and the n-type ohmic electrode 10 become p-type ohmic electrode materials. It is preferable not to contain Ni, Cu, and Ag.
[0082]
As a modification of the above embodiment, as shown in FIG. ₂ A 50 nm-thick intermediate layer 12 ′ made of Pt may be formed between the n-type ohmic electrode 10 made of and the Al pad electrode 11. After this oxide semiconductor light emitting device 1 'was wire-bonded to a lead frame, the oxide semiconductor light emitting device 1' was molded with a resin and emitted light. As a result, blue light emission having an emission peak wavelength of 410 nm was obtained. Further, the light emission intensity was increased by 10% as compared with the embodiment.
[0083]
This is because the intermediate layer 12 ′ made of Pt has a high reflectance for light having a wavelength in the blue to ultraviolet range, and thus acts as a reflective layer, and reflects light incident on the bottom surface of the substrate 2 ′ with high efficiency. This is because the reflected light is extracted outside from the side surface of the oxide semiconductor light emitting device 1 '. Thereby, the light extraction efficiency of the oxide semiconductor light emitting element 1 'is improved. The material of the intermediate layer 12 'may be Al.
[0084]
(Third embodiment)
FIG. 8 is a perspective view of a ZnO-based semiconductor laser device 31 to which the present invention is applied. This ZnO-based semiconductor laser device 31 has a structure in which Ga is placed on an n-type ZnO single-crystal substrate 32 having a zinc surface as a main surface by 1 × 10 ¹⁸ cm ^-3 Buffer layer 33 having a thickness of 0.1 μm and doped with Ga ¹⁸ cm ^-3 1.0 μm thick n-type Mg doped at a concentration of _0.1 Zn _0.9 O cladding layer 34, 5 × 10 Ga ¹⁷ cm ^-3 30 nm thick n-type ZnO light guide layer 35, non-doped quantum well active layer 36 and N ¹⁸ cm ^-3 30 nm thick p-type ZnO light guide layer 37 doped with a concentration of ²⁰ cm ^-3 1.2 μm thick p-type Mg doped at a concentration of _0.1 Zn _0.9 O cladding layer 38, 1 × 10 N ²⁰ cm ^-3 A p-type ZnO contact layer 39 having a thickness of 0.5 μm and doped at a concentration of 0.5 μm is laminated.
[0085]
The quantum well active layer 36 includes two ZnO barrier layers having a thickness of 5 nm and three Cd layers having a thickness of 6 nm. _0.1 Zn _0.9 O-well layers, which are alternately stacked. The p-type Mg _0.1 Zn _0.9 A part of the O clad layer 38 and the p-type ZnO contact layer 39 is etched into a ridge stripe shape, and Ga ¹⁸ cm ^-3 -Type Mg doped at a concentration of _0.3 Zn _0.7 The O current block layer 40 is embedded.
[0086]
On the lower surface of the n-type ZnO substrate 32, a 100-nm-thick n-type Cr ₂ O ₃ An ohmic electrode 41 is formed, under which an Al pad electrode 42 is formed. p-type ZnO contact layer 39 and n-type Mg _0.3 Zn _0.7 A NiO ohmic electrode 43 having a thickness of 100 nm is formed on the O current block layer 40, and an Au pad electrode 44 is formed thereon.
[0087]
The semiconductor laser element 31 performs crystal growth by the laser MBE method, ₂ O ₃ The ohmic electrode 41, the Al pad electrode 42, the NiO ohmic electrode 43 and the Au pad electrode 44 ₂ O ₃ , Al, NiO and Au were formed by a sputtering method using a target 25 made of raw materials. The sputtering method is a film-forming method that has high mass productivity and can easily form a high-quality oxide thin film similarly to the electron beam evaporation method, and can manufacture a light-emitting element having excellent characteristics at low cost. Further, since the semiconductor laser device of the present embodiment is of the edge emission type, ₂ O ₃ The ohmic electrode 41 and the p-type NiO ohmic electrode 43 do not need to have translucency, and are formed thick to sufficiently reduce ohmic resistance. In addition, no electrode pattern processing is required, so that the process is not performed. After manufacturing the above structure, the ZnO single crystal substrate 32 was cleaved to form an end face mirror (not shown), a protective film was formed by vacuum deposition, and then the semiconductor laser element 31 was separated into 300 μm.
[0088]
When the manufactured ZnO-based semiconductor laser device 31 was caused to emit light as described above, blue oscillation light having an emission peak wavelength of 405 nm was obtained from the end face. When driven at an optical output of 5 mW, the operating voltage and operating current were 3.5 V and 25 mA. When 100 semiconductor laser elements 31 were die-bonded to a heat sink made of a Cu material on a stem (not shown), none of the semiconductor laser elements 31 suffered electrode peeling during bonding.
[0089]
(Comparative Example 6)
On the other hand, n-type Cr ₂ O ₃ When the ohmic electrode 41 is made of metal Cr, 100 semiconductor laser elements 31 are die-bonded to a heat sink made of a Cu material on the stem. There were pieces. In addition, the operating voltage of the twenty semiconductor laser elements 31 when driven at an optical output of 5 mW exceeded 5 V, and the heat generated thereby significantly shortened the element life. As described above, the oxide ohmic electrode 41 of the present invention has a sufficient adhesiveness and a resistance reduction effect even when applied to the semiconductor laser element 31.
[0090]
【The invention's effect】
As is clear from the above description, the oxide semiconductor light-emitting device according to the present invention has an n-type oxide semiconductor layer, an n-type clad layer, a light-emitting layer, a p-type clad layer, In an oxide semiconductor light emitting device in which a growth layer including a contact layer is stacked, a transition metal containing no transition metals Ni, Cu, and Ag is formed on an n-type oxide semiconductor layer exposed by etching a part of the growth layer. Since the ohmic electrode made of the oxide is provided, it is possible to provide an oxide semiconductor light emitting element having excellent adhesion without the ohmic electrode being peeled off from the oxide semiconductor layer. Further, an oxide semiconductor light-emitting element including a stable and low-resistance ohmic electrode and having a low operating voltage can be provided.
[0091]
Further, the oxide semiconductor light-emitting device according to the present invention is a growth layer including at least an n-type clad layer, a light-emitting layer, a p-type clad layer, and a p-type contact layer on a substrate made of an n-type oxide semiconductor. Is provided on the back surface of the substrate, an ohmic electrode made of a transition metal oxide containing no transition metals Ni, Cu, and Ag is provided, so that the ohmic electrode may be peeled off from the substrate made of the oxide semiconductor. An oxide semiconductor light-emitting element having excellent adhesion can be provided without performing the method. Further, an oxide semiconductor light-emitting element including a stable and low-resistance ohmic electrode and having a low operating voltage can be provided.
[0092]
In particular, since the ohmic electrode is made of an oxide of at least one transition metal selected from transition metals Ti, Cr, V, Hf, Zr, Nb, Ta, Mo, and W, it has good conductor or n-type semiconductor properties. And a stable and low-resistance ohmic electrode can be formed. Thus, an oxide semiconductor light-emitting element having excellent reliability and low operating voltage can be provided.
[0093]
In addition, the method for manufacturing an oxide semiconductor light-emitting element according to the present invention includes the steps of: forming an n-type oxide semiconductor layer, an n-type cladding layer, a light-emitting layer, a p-type cladding layer, and a p-type contact layer on a substrate. On the n-type oxide semiconductor layer exposed by etching a part of the growth layer, and depositing the transition metal oxide containing no transition metal Ni, Cu, or Ag by evaporation or scattering. The ohmic electrode is formed as a thin film by performing ₂ An ohmic electrode can be easily manufactured without introducing a gas.
[0094]
In addition, the method for manufacturing an oxide semiconductor light-emitting element according to the present invention includes the steps of: forming an n-type oxide semiconductor layer, an n-type cladding layer, a light-emitting layer, a p-type cladding layer, and a p-type contact layer on a substrate. A transition metal containing no transition metals Ni, Cu, and Ag is evaporated or scattered on the n-type oxide semiconductor layer exposed by etching a part of the growth layer, and oxygen is removed. Since the ohmic electrode is formed into a thin film by introducing and depositing the raw material, the ohmic electrode can be manufactured at low cost. In addition, since vapor deposition is performed in an oxygen atmosphere, there is an effect that an oxide thin film can be easily formed and a low-resistance ohmic electrode having excellent adhesion can be formed.
[0095]
In addition, the method for manufacturing an oxide semiconductor light-emitting element according to the present invention includes the step of forming at least an n-type clad layer, a light-emitting layer, a p-type clad layer, and a p-type contact layer on a substrate made of an n-type oxide semiconductor. Are formed on the back surface of the substrate by evaporating or scattering an oxide of a transition metal that does not contain transition metals Ni, Cu, and Ag to form a thin ohmic electrode. O in the MBE device ₂ An ohmic electrode can be easily manufactured without introducing a gas.
[0096]
In addition, the method for manufacturing an oxide semiconductor light-emitting element according to the present invention includes the step of forming at least an n-type clad layer, a light-emitting layer, a p-type clad layer, and a p-type contact layer on a substrate made of an n-type oxide semiconductor. A transition layer containing no transition metals Ni, Cu, and Ag is evaporated or scattered on the back surface of the substrate, and oxygen is introduced to deposit a raw material to form a thin ohmic electrode. Therefore, an ohmic electrode can be manufactured at low cost. In addition, since vapor deposition is performed in an oxygen atmosphere, there is an effect that an oxide thin film can be easily formed and a low-resistance ohmic electrode having excellent adhesion can be formed.
[Brief description of the drawings]
FIG. 1 is a sectional view of an oxide semiconductor light emitting device according to a first embodiment of the present invention.
FIG. 2 is a schematic view showing a laser MBE apparatus used in manufacturing the oxide semiconductor light emitting device of FIG.
FIG. 3 n-type TiO ₂ FIG. 5 is a diagram illustrating a relationship between a layer thickness (nm) of an ohmic electrode layer, an operating voltage (V), and emission intensity (arbitrary unit) of an oxide semiconductor light emitting element.
FIG. 4 is a cross-sectional view illustrating a modification of the oxide semiconductor light emitting device of FIG.
FIG. 5 is a sectional view of an oxide semiconductor light emitting device according to a second embodiment of the present invention.
FIG. 6 is a bottom view of FIG. 5;
FIG. 7 is a cross-sectional view illustrating a modification of the oxide semiconductor light emitting device of FIG.
FIG. 8 is a sectional view of an oxide semiconductor light emitting device according to a third embodiment of the present invention.
[Explanation of symbols]
1: oxide semiconductor light-emitting element,
2. Sapphire substrate (substrate)
3. n-type ZnO contact layer (n-type oxide semiconductor layer),
4 ... n-type cladding layer,
5 ... light-emitting layer,
6 ... p-type cladding layer,
7 ... p-type contact layer,
10 ... n-type ohmic electrode (ohmic electrode).

Claims (17)

An oxide semiconductor light-emitting element in which a growth layer including an n-type oxide semiconductor layer, an n-type clad layer, a light-emitting layer, a p-type clad layer, and a p-type contact layer is stacked on a substrate,
An ohmic electrode made of a transition metal oxide that does not contain transition metals Ni, Cu, and Ag is provided on the n-type oxide semiconductor layer exposed by etching a part of the growth layer. An oxide semiconductor light-emitting element. An oxide semiconductor light-emitting element in which a growth layer including at least an n-type cladding layer, a light-emitting layer, a p-type cladding layer, and a p-type contact layer is stacked on a substrate including an n-type oxide semiconductor,
An oxide semiconductor light emitting device, wherein an ohmic electrode made of a transition metal oxide not containing transition metals Ni, Cu, and Ag is provided on the back surface of the substrate. 3. The method according to claim 1, wherein the ohmic electrode is made of an oxide of at least one transition metal selected from transition metals Ti, Cr, V, Hf, Zr, Nb, Ta, Mo, and W. An oxide semiconductor light emitting device. The oxide semiconductor light emitting device according to claim 1, wherein a thickness of the ohmic electrode is 1 nm or more and 100 nm or less, and has a property of transmitting light from the light emitting layer. . 3. The oxide semiconductor light emitting device according to claim 1, wherein a pad electrode made of Al or Au is formed on the ohmic electrode. An intermediate layer containing a transition metal not containing transition metals Ni, Cu, and Ag and at least one element selected from Ga and In is formed between the ohmic electrode and the pad electrode. 6. The oxide semiconductor light emitting device according to 5. The oxide semiconductor light emitting device according to claim 6, wherein the transition metal comprises at least one transition metal selected from Ti, Cr, V, Hf, Zr, Nb, Ta, Mo, and W. The oxide semiconductor light emitting device according to claim 5, wherein a reflection layer containing at least one of Al and Pt is formed between the ohmic electrode and the pad electrode. 3. The oxide semiconductor according to claim 2, wherein the ohmic electrode formed on the back surface of the substrate is patterned, and the back surface of the substrate is electrically connected to a lead frame with a conductive material containing Ag. Light emitting element. A growth layer including an n-type oxide semiconductor layer, an n-type cladding layer, a light-emitting layer, a p-type cladding layer, and a p-type contact layer is stacked on a substrate,
An ohmic electrode is formed by evaporating or scattering a transition metal oxide containing no transition metal Ni, Cu, or Ag on the n-type oxide semiconductor layer exposed by etching a part of the growth layer. A method for manufacturing an oxide semiconductor light-emitting device, in which a thin film is formed. A growth layer including an n-type oxide semiconductor layer, an n-type cladding layer, a light-emitting layer, a p-type cladding layer, and a p-type contact layer is stacked on a substrate,
The transition metal excluding transition metals Ni, Cu, and Ag is evaporated or scattered on the n-type oxide semiconductor layer exposed by etching a part of the growth layer, and oxygen is introduced to reduce the raw material. A method for manufacturing an oxide semiconductor light-emitting device in which an ohmic electrode is formed as a thin film by depositing. A growth layer including at least an n-type clad layer, a light-emitting layer, a p-type clad layer, and a p-type contact layer is stacked on a substrate formed of an n-type oxide semiconductor,
A method of manufacturing an oxide semiconductor light-emitting device, wherein an ohmic electrode is formed as a thin film by evaporating or scattering an oxide of a transition metal that does not contain transition metals Ni, Cu, and Ag on the back surface of the substrate. A growth layer including at least an n-type clad layer, a light-emitting layer, a p-type clad layer, and a p-type contact layer is stacked on a substrate formed of an n-type oxide semiconductor,
A method for manufacturing an oxide semiconductor light emitting device, wherein a transition metal not containing transition metals Ni, Cu, and Ag is evaporated or scattered on the back surface of the substrate, and an ohmic electrode is formed as a thin film by depositing the raw material by introducing oxygen. . 14. The method according to claim 10, wherein the ohmic electrode is made of an oxide of at least one transition metal selected from transition metals Ti, Cr, V, Hf, Zr, Nb, Ta, Mo, and W. 13. A method for manufacturing an oxide semiconductor light-emitting device according to 14. The method for manufacturing an oxide semiconductor light emitting device according to claim 10, wherein the thin film forming method is any one of an electron beam evaporation method, a sputtering method, and a laser ablation method. 16. The method according to claim 10, wherein the heat treatment is performed on the oxide semiconductor light emitting device in an oxygen atmosphere or in the air after forming the ohmic electrode. . The method according to claim 16, wherein the heat treatment temperature is in a range of 300 to 450C.

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