JP2006120764A - Gallium nitride system light-emitting diode equipped with high reverse reactive voltage and high static electricity preventing function - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a gallium nitride system light-emitting diode, having high reverse reactive voltage and high static electricity preventing function. <P>SOLUTION: On one side surface of a substrate 10, a buffer layer 20 is constituted with nitride aluminum gallium indium of a specific composition (Al<SB>a</SB>Ga<SB>b</SB>In<SB>1-a-b</SB>N, 0≤a, b<1, a+b≤1). Thereafter, an n-type contact layer 30 and an active layer 40 are formed thereon, and moreover a negative electrode 42, a p-type clad layer 50, a p-type contact layer 60, a static electricity preventing thin layer 70, a non-superimposed positive electrode 80, and a transparent conductive layer 82 are sequentially formed on the non-covered portion. This antistatic thin layer clearly improves the inverse reactive voltage and antistatic capability of the gallium nitride system light-emitting diode, and thereby the operating lifetime of the gallium nitride system light-emitting diode can be prolonged. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a kind of gallium nitride light emitting diode, and more particularly, to a gallium nitride light emitting diode having a high reverse anti-resistance voltage and a high antistatic ability.

  Gallium nitride (GaN) light-emitting diodes can form light-emitting diodes of various colors by controlling the composition of the materials, and related technologies have recently become the focus of active research and development in the industry. In addition to traditional applications of display functions of various electronic devices such as electronic watches and mobile phones, gallium nitride-based light-emitting diodes are increasingly used for outdoor signboards due to technological reforms in terms of their brightness and luminous efficiency. It has come to be applied to areas such as car lighting equipment.

  When applied to outdoor lighting display equipment, in addition to high brightness and high luminous efficiency, gallium nitride-based light emitting diodes have extremely high requirements, such as Reverse Withstand Voltage and Electrostatic Discharge; ESD) capability is required in order to be able to operate in harsh environments outdoors for long periods of time and have practical value.

  Traditional gallium nitride-based light-emitting diodes, according to their well-known structure, have a gallium nitride-based nitride epitaxial layer grown on a substrate typically made of sapphire. The lattice constants of gallium nitride-based nitride and sapphire substrate are mismatched and tend to form excessive stress accumulation. Therefore, the epitaxial crystal quality of known gallium nitride-based light-emitting diodes is poor, and its antistatic ability An impact has occurred.

  At present, the most widely adopted method for solving this problem employs a flip chip process, and integrates a gallium nitride light emitting diode and a Zener diode composed of silicon. It is a method of combining. Although this method can reliably solve the problem of antistatic ability that gallium nitride light emitting diodes are subjected to, the manufacturing process of such a flip chip is very complicated compared to the manufacturing process of known gallium nitride light emitting diodes. .

  The gallium nitride light emitting diode provided by the present invention solves the limitations and disadvantages of the related art described above.

  The main difference between the gallium nitride-based light-emitting diodes provided by the present invention and known gallium nitride-based light-emitting diodes is that they are undoped indium gallium nitride (InGaN) or low-bandgap (Eg <3.4 eV). A single antistatic thin layer is formed on the p-type contact layer of a well-known gallium nitride light emitting diode using aluminum indium gallium nitride, and this antistatic thin layer is used to reverse the gallium nitride light emitting diode. The directional repulsion voltage and antistatic ability are clearly improved, thereby extending the service life of the gallium nitride light emitting diode.

FIG. 1 and FIG. 2 are experimental data diagrams for antistatic thin layer thicknesses having different antistatic voltages and reverse resistance voltages of antistatic thin layers of three different materials. As shown in FIGS. 1 and 2, an antistatic thin layer formed of undoped indium gallium nitride (In _0.2 Ga _0.8 N) and having a thickness of between 5 and 100 mm is clearly similarly In _0.2 Ga. Adopting _0.8 N, it has good antistatic ability and reverse repulsion voltage compared to the same antistatic thin layer of the same thickness, but doped with silicon (Si) and magnesium (Mg).

  In addition to the above-mentioned advantages, the antistatic thin layer formed of undoped indium gallium nitride or low bandgap undoped aluminum indium gallium nitride is further reduced by the low bandgap characteristics of such materials. The ohmic contact can be easily formed because the electrical resistance between the metal electrode or the transparent conductive electrode and the transparent conductive electrode is lower than that of the metal electrode or the transparent conductive electrode and the p-type contact layer.

The invention of claim 1 is a gallium nitride based light emitting diode,
A substrate formed of sapphire, 6H—SiC, 4H—SiC, Si, ZnO, GaAs, spinel, (MgAl ₂ O ₄ ), or a single crystal oxide whose lattice constant approaches a nitride semiconductor;
A buffer layer which is located on one side of the substrate and is made of aluminum gallium indium nitride (Al _a Ga _b In _1-ab N, 0 ≦ a, b <1, a + b ≦ 1) having a specific composition;
An n-type contact layer located on the buffer layer and formed of a gallium nitride (GaN) -based material;
An active layer located on the n-type contact layer and covering an upper surface of a part of the n-type contact layer and formed of indium gallium nitride;
A negative electrode formed on an uncoated upper surface by an active layer on the upper surface of the n-type contact layer;
A p-type cladding layer made of a p-type gallium nitride-based material located on the active layer; a p-type contact layer located on the p-type cladding layer and made of p-type gallium nitride; Undoped indium gallium nitride, undoped aluminum indium gallium nitride with a band gap of less than 3.4 eV, and undoped indium gallium nitride and undoped aluminum nitride with a band gap of less than 3.4 eV located on the p-type contact layer An antistatic thin layer composed of one of three types of materials with a superlattice structure formed of indium gallium;
It is either a metal conductive layer or a transparent oxide layer that is located on the antistatic thin layer and covers a part of the surface, and the metal conductive layer is made of Ni / Au alloy, Ni / Pt alloy, Ni / Pd Alloy, Pd / Au alloy, Pt / Au alloy, Cr / Au alloy, Ni / Au / Be alloy, Ni / Cr / Au alloy, Ni / Pt / Au alloy, Ni / Pd / Au alloy and other similar materials The transparent oxide layer formed of any one of ITO, CTO, ZnO: Al, ZnGa ₂ O ₄ , SnO ₂ : Sb, Ga ₂ O ₃ : Sn, AgInO ₂ : Sn, In ₂ O ₃ : Zn, CuAlO ₂ A transparent conductive layer formed of any one of LaCuOS, NiO, CuGaO ₂ , and SrCu ₂ O ₂ ;
Located on the surface of the antistatic thin layer, which is uncoated with a transparent conductive layer, Ni / Au alloy, Ni / Pt alloy, Ni / Pd alloy, Ni / Co alloy, Pd / Au alloy, Pt / A positive electrode formed of any one of Au alloy, Ti / Au alloy, Cr / Au alloy, Sn / Au alloy, Ta / Au alloy, TiN, TiWN _x (x ≧ 0), and WSi _y (y ≧ 0); ,
A gallium nitride-based light-emitting diode characterized by comprising:
According to a second aspect of the present invention, in the gallium nitride based light-emitting diode according to the first aspect, the antistatic thin layer is undoped and has a specific composition (In _d Ga _1-d N, 0 <d ≦ 1). The gallium nitride light-emitting diode is characterized in that the thickness is between 5 and 100 mm.
The invention according to claim 3, in claim 1, wherein the gallium nitride based light-emitting diodes, antistatic thin layer, an undoped, having a specific composition, the aluminum band gap 3.4eV smaller indium gallium nitride (Al _e The gallium nitride based light-emitting diode is composed of In _f Ga _{1 -ef} N, 0 <e, f <1, e + f <1), and has a thickness of 5 to 100 mm.
According to a fourth aspect of the present invention, in the gallium nitride based light-emitting diode according to the first aspect, the antistatic thin layer is a superlattice in which indium gallium nitride thin layers and aluminum indium gallium nitride thin layers are alternately stacked. And the number of overlaps is at least 2 and the total thickness is 200 mm or less. Each indium gallium nitride thin layer has a thickness between 5 mm and 20 mm, and both are undoped. Each of the thin layers of aluminum indium gallium nitride has a thickness of 5 to 20 Å, each of which is composed of indium gallium nitride (In _k Ga _1-k N, 0 <k ≦ 1) having the specific composition. Aluminum nitride indium gallium nitride, both of which are undoped, each having a specific composition and a band gap of less than 3.4 eV. Characterized in that it consists of um _{(Al p In q Ga 1-} pq N, 0 <p, q <1, p + q <1), and a gallium nitride based light-emitting diode.

  The gallium nitride-based light emitting diode provided by the present invention uses undoped indium gallium nitride (InGaN) or undoped aluminum indium gallium nitride with a low band gap (Eg <3.4 eV). An antistatic thin layer is formed on the p-type contact layer, and this antistatic thin layer clearly improves the reverse resistance voltage and antistatic ability of the GaN-based light emitting diode, thereby nitriding Extend the service life of gallium-based light-emitting diodes.

FIG. 3 is a display diagram of the first embodiment of the gallium nitride light emitting diode of the present invention. As shown in FIG. 3, this embodiment uses C-Plane, R-Plane, or A-Plane sapphire or silicon carbide (6H-SiC or 4H-SiC) as a substrate 10, and other materials that can be used for the substrate 10. Examples include Si, ZnO, GaAs, spinel (MgAl ₂ O ₄ ), or a single crystal oxide having a lattice constant close to that of a nitride semiconductor. Thereafter, a buffer layer 20 composed of aluminum gallium indium nitride (Al _a Ga _b In _1-ab N, 0 ≦ a, b <1, a + b ≦ 1) having a specific composition is formed on one side of the substrate 10. An n-type contact layer 30 is formed on the buffer layer, and the n-type contact layer 30 is made of a gallium nitride (GaN) -based material. Thereafter, an active layer 40 is formed on the n-type contact layer 30. The active layer 40 is made of indium gallium nitride and covers the upper surface of a part of the n-type contact layer 30. In addition to this, a negative electrode 42 is formed on the uncovered portion of the upper surface of the n-type contact layer 30.

In this embodiment, a p-type cladding layer 50 is subsequently formed on the active layer 40, and the p-type cladding layer 50 is made of a gallium nitride material. A p-type contact layer 60 is formed on the p-type cladding layer 50 using p-type gallium nitride as a material. On this p-type contact layer 60, an antistatic thin layer 70 which is an important point of the present invention is formed. In this embodiment, the antistatic thin layer 70 is undoped and is composed of indium gallium nitride having a specific composition (In _d Ga _1-d N, 0 <d ≦ 1), and its thickness is between 5 and 100 mm. The growth temperature is between 600 degrees Celsius and 1100 degrees Celsius.

In this embodiment, a positive electrode 80 and a transparent conductive layer 82 that do not overlap each other are further formed above the antistatic thin layer 70. The positive electrode 80 is made of Ni / Au alloy, Ni / Pt alloy, Ni / Pd alloy, Ni / Co alloy, Pd / Au alloy, Pt / Au alloy, Ti / Au alloy, Cr / Au alloy, Sn / Au alloy, It is made of any one of Ta / Au alloy, TiN, TiWN _x (x ≧ 0), WSi _y (y ≧ 0), or other similar metal materials. The transparent conductive layer 82 is a metal conductive layer or a transparent oxide layer. This metal conductive layer is made of Ni / Au alloy, Ni / Pt alloy, Ni / Pd alloy, Pd / Au alloy, Pt / Au alloy, Cr / Au alloy, Ni / Au / Be alloy, Ni / Cr / Au alloy, Ni / Pt / Au alloy, Ni / Pd / Au alloy and other similar materials. This transparent oxide layer is made of ITO, CTO, ZnO: Al, ZnGa ₂ O ₄ , SnO ₂ : Sb, Ga ₂ O ₃ : Sn, AgInO ₂ : Sn, In ₂ O ₃ : Zn, CuAlO ₂ , LaCuOS, NiO, It is composed of either CuGaO ₂ or SrCu ₂ O ₂ .

FIG. 4 is a display diagram of a second embodiment of the gallium nitride light emitting diode of the present invention. As shown in FIG. 4, this embodiment has the same structure and growth method as the first embodiment. The only difference is in the materials used for the antistatic thin layer. In this embodiment, the antistatic thin layer 72 is undoped, has a specific composition, and an aluminum indium gallium nitride (Al _e In _f Ga _{1 -ef} N, 0 <e, f <) whose band gap is smaller than 3.4 eV. 1, e + f <1), the thickness is between 5 and 100 and the growth temperature is between 600 and 1100 degrees Celsius.

FIG. 5 is a display diagram of a third embodiment of the gallium nitride light emitting diode of the present invention. As shown in FIG. 5, this embodiment and the first and second embodiments have the same structure and growth method. The only difference is in the structure, material and growth method of the antistatic thin layer. In this embodiment, the antistatic thin layer 74 has a superlattice structure in which indium gallium nitride thin layers 741 and aluminum indium gallium nitride thin layers 742 are alternately stacked. Each indium gallium nitride thin layer 741 is made of undoped indium gallium nitride having a specific composition (In _g Ga _1-g N, 0 <g ≦ 1), and has a thickness between 5 and 20 mm. Is between 600 and 1100 degrees Celsius. The indium gallium nitride composition (that is, the parameter g in the above molecular formula) of the different indium gallium nitride thin layers 741 is not necessarily the same. Each of the aluminum indium gallium nitride thin layers 742 is undoped, has a specific composition, and has a band gap of less than 3.4 eV (Al _h In _i Ga _1-hi N, 0 <h, i <1 , H + i <1), the thickness is between 5 and 20 and the growth temperature is between 600 and 1100 degrees Celsius. The different aluminum indium gallium nitride thin layers 742 have different indium gallium nitride composition (that is, the parameters h and i in the above-described molecular formula) are not necessarily the same.

  In this antistatic thin layer 74, the bottom layer (that is, the layer directly on the p-type contact layer) can be an indium gallium nitride thin layer 741, and further an aluminum indium gallium nitride thin layer 742 thereon. A thin layer of indium gallium nitride 741 is deposited, and is assumed to be analogized by this, or the bottom layer is an aluminum indium gallium nitride thin layer 742, on which a thin layer of indium gallium nitride 741 and aluminum nitride are further formed. A thin layer of indium gallium 742 is deposited and will continue to be analogized. The indium gallium nitride thin layer 741 and the aluminum indium gallium nitride thin layer 742 are alternately and repeatedly deposited in this manner, and the number of overlaps is two or more (that is, the number of indium gallium nitride thin layers 741 and the thickness of the aluminum indium gallium nitride thin layer The number of the layers 742 is 2 or more). The total thickness of the antistatic thin layer 74 does not exceed 200 mm.

  The above is a description of the preferred embodiments of the present invention, and does not limit the scope of the present invention. Any modification or alteration in detail that can be made based on the above embodiments falls within the scope of the present invention. Shall.

It is an experimental data figure with respect to the antistatic thin layer thickness from which the antistatic voltage of the antistatic thin layer of three types of different materials and a reverse repulsive voltage differ. It is an experimental data figure with respect to the antistatic thin layer thickness from which the antistatic voltage of the antistatic thin layer of three types of different materials and a reverse repulsive voltage differ. It is a display figure of the 1st example of the gallium nitride system light emitting diode of the present invention. It is a display figure of 2nd Example of the gallium nitride type light emitting diode of this invention. It is a display figure of 3rd Example of the gallium nitride type light emitting diode of this invention.

Explanation of symbols

10 substrate 20 buffer layer 30 n-type contact layer 40 active layer 42 negative electrode 50 p-type cladding layer 60 p-type contact layer 70 antistatic thin layer 72 antistatic thin layer 74 antistatic thin layer 741 indium gallium nitride thin layer 742 Aluminum indium gallium nitride thin layer 80 positive electrode 82 Transparent conductive layer Minium indium gallium thin layer 80 Positive electrode 82 Transparent conductive layer

Claims (4)

In gallium nitride based light-emitting diodes,
A substrate formed of sapphire, 6H—SiC, 4H—SiC, Si, ZnO, GaAs, spinel, (MgAl ₂ O ₄ ), or a single crystal oxide whose lattice constant approaches a nitride semiconductor;
A buffer layer which is located on one side of the substrate and is made of aluminum gallium indium nitride (Al _a Ga _b In _1-ab N, 0 ≦ a, b <1, a + b ≦ 1) having a specific composition;
An n-type contact layer located on the buffer layer and formed of a gallium nitride (GaN) -based material;
An active layer located on the n-type contact layer and covering an upper surface of a part of the n-type contact layer and formed of indium gallium nitride;
A negative electrode formed on an uncoated upper surface by an active layer on the upper surface of the n-type contact layer;
A p-type cladding layer made of a p-type gallium nitride-based material located on the active layer; a p-type contact layer located on the p-type cladding layer and made of p-type gallium nitride; undoped indium gallium nitride, undoped aluminum indium gallium nitride with a band gap of less than 3.4 eV, and undoped indium gallium nitride and undoped aluminum nitride with a band gap of less than 3.4 eV located on the p-type contact layer An antistatic thin layer composed of one of three types of materials with a superlattice structure formed of indium gallium;
It is either a metal conductive layer or a transparent oxide layer that is located on the antistatic thin layer and covers a part of the surface, and the metal conductive layer is made of Ni / Au alloy, Ni / Pt alloy, Ni / Pd Alloy, Pd / Au alloy, Pt / Au alloy, Cr / Au alloy, Ni / Au / Be alloy, Ni / Cr / Au alloy, Ni / Pt / Au alloy, Ni / Pd / Au alloy and other similar materials The transparent oxide layer formed of any one of ITO, CTO, ZnO: Al, ZnGa ₂ O ₄ , SnO ₂ : Sb, Ga ₂ O ₃ : Sn, AgInO ₂ : Sn, In ₂ O ₃ : Zn, CuAlO ₂ A transparent conductive layer formed of any one of LaCuOS, NiO, CuGaO ₂ , and SrCu ₂ O ₂ ;
Located on the surface of the antistatic thin layer, which is uncoated with a transparent conductive layer, Ni / Au alloy, Ni / Pt alloy, Ni / Pd alloy, Ni / Co alloy, Pd / Au alloy, Pt / A positive electrode formed of any one of Au alloy, Ti / Au alloy, Cr / Au alloy, Sn / Au alloy, Ta / Au alloy, TiN, TiWN _x (x ≧ 0), and WSi _y (y ≧ 0); ,
A gallium nitride-based light-emitting diode comprising: In claim 1 GaN-based light emitting diode according, antistatic thin layer, an undoped, is composed of indium gallium nitride having a specific composition _{(In d Ga 1-d N} , 0 <d ≦ 1), the thickness A gallium nitride based light-emitting diode characterized by having a thickness of 5 to 100 cm. 2. The gallium nitride based light-emitting diode according to claim 1, wherein the antistatic thin layer is undoped, has a specific composition, and has a band gap of less than 3.4 eV (Al _e In _f Ga _{1 -ef} N). , 0 <e, f <1, e + f <1), and its thickness is between 5 and 100 mm. 2. The gallium nitride-based light-emitting diode according to claim 1, wherein the antistatic thin layer has a superlattice structure in which indium gallium nitride thin layers and aluminum indium gallium nitride thin layers are alternately and repeatedly deposited, and the number of overlaps. Is at least twice and has a total thickness of 200 mm or less, each indium gallium nitride thin layer has a thickness between 5 mm and 20 mm, and is undoped, each having its specific composition Indium gallium nitride (In _k Ga _1-k N, 0 <k ≦ 1), and each aluminum indium gallium nitride thin layer has a thickness of between 5 and 20 mm. Undoped aluminum indium gallium nitride (Al _p In _q) with each specific composition and a band gap of less than 3.4 eV A gallium nitride based light-emitting diode comprising Ga _1-pq N, 0 <p, q <1, p + q <1).

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