EXHIBIT 1027
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`Japanese Patent Application Publication No.
`H4-321280 to Nakamura
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`(“Nakamura II”)
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`

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`Kingbright Elec. Co. Ltd., Kingbright Corp., SunLED Corp.,
`Kingbright Co. LLC, SunLED Co. LLC and Sunscreen Co. Ltd.
`Exhibit - 1027 Page 1
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`

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`Kingbright Elec. Co. Ltd., Kingbright Corp., SunLED Corp.,
`Kingbright Co. LLC, SunLED Co. LLC and Sunscreen Co. Ltd.
`Exhibit - 1027 Page 2
`
`

`
`Kingbright Elec. Co. Ltd., Kingbright Corp., SunLED Corp.,
`Kingbright Co. LLC, SunLED Co. LLC and Sunscreen Co. Ltd.
`Exhibit - 1027 Page 3
`
`

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`(19) Japan Patent Office (JP)
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`(12) Unexamined Patent Application Publication (A)
`(11) Pat. Application Pub. No.
`Unexamined Patent Application Publication No. H4-321280
` (43) Publication Date: November 11, 1992
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`ID No.
`Internal Reference No.
`FI
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`
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`Technical Indications
`(51) Int.Cl.5
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`H01L
`33/00
`C
`8934-4M
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`21/20
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`9171-4M
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`21/86
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`7739-4M
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`(21) Application No.: Patent Application H3-116912
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`(22) Application Date: April 19, 1991
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`Request for examination: Not filed yet. Number of claims: 1
`(71) Applicant: 000226057
` Nichia Corporation
` Oka 491-100, Kaminaka-cho, Anan-shi, Tokushima-ken
`(72) Inventor: Shuji Nakamura
` c/o Nichia Corporation
` Oka 491-100, Kaminaka-cho, Anan-shi, Tokushima-ken
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`(Total 3 pages)
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`Active layer
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`Electrode
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`buffer layer
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`-441-
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`(54) [Title of the Invention] BLUE LIGHT EMITTING DIODE
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`(57)[Abstract]
`[Purpose] To provide a blue light emitting diode with high
`efficiency, high brightness and good light emitting properties
`such as color purity.
`[Constitution] A blue light emitting diode consisting of a
`sapphire substrate laminated with a buffer layer made of
`GaXAl1-XN (where 0<X≦1), an n-type cladding layer doped
`with Si, a light emitting active layer doped with Zn, and a p-
`type cladding layer doped with Mg.
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`
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`Kingbright Elec. Co. Ltd., Kingbright Corp., SunLED Corp.,
`Kingbright Co. LLC, SunLED Co. LLC and Sunscreen Co. Ltd.
`Exhibit - 1027 Page 4
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`

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`Unexamined Patent Application Publication H4-321280
`2
`[0008] The present invention was made in light of the above-
`described circumstances, and its purpose is to provide a blue
`light emitting diode with high efficiency, high brightness and
`superior light emitting properties including color purity, by
`realizing a blue light emitting diode structured with the above-
`mentioned i-type layer sandwiched by a p-type layer and an n-
`type layer.
`[0009]
`[Means for Solving the Problems] The present invention provides
`a blue light emitting diode structured as a sapphire substrate
`laminated with gallium nitride-based compound semiconductors
`whose general formula is expressed as GaXAl1-XN (0≦X≦1),
`characterized by having a buffer layer made of GaXAl1-XN (0<X≦
`1), a light emitting active layer doped with Zn, an n-type cladding
`layer doped with Si, and furthermore a p-type cladding layer
`doped with Mg.
`[0010] An example of that structure is shown in Figure 1. A blue
`light emitting diode under the present invention is structured as
`a sapphire substrate 1 laminated with a buffer layer made of
`GaXAl1-XN (0<X≦1) 12, an Si-doped n-type GaXAl1-XN layer 3 as
`the n-type cladding layer doped with Si (hereafter referred to as
`the n-type cladding layer), a Zn-doped GaXAl1-XN layer 14 as the
`light emitting active layer doped with Zn (hereafter referred to as
`the active layer), and an Mg-doped p-type GaXAl1-XN layer 5 as
`the p-type cladding layer doped with Mg (hereafter referred to
`as the p-type cladding layer), in this order, with electrodes
`provided on 3 and 5.
`[0011] The buffer layer 12 is needed to improve the crystallinity
`of the gallium nitride-based compound semiconductor to be
`laminated on top of it, and is normally formed with a thickness of
`several nm to several hundred nm. Also, the buffer layer 12 may
`be formed on top of the n-type cladding layer 3 and/or the active
`layer 14 in addition to the sapphire substrate.
`[0012] The active layer 14 has Zn as the emission center, and the
`peak of the emission wavelength is approximately 470-480 nm.
`[0013]
`[Operation] The operation of the buffer layer 12 in a blue light
`emitting diode under the present invention has been described
`in detail in Patent Application No. H3-32259 which had been
`submitted by the present inventor. To simply put, as the material
`for the buffer layer, GaXAl1-XN (0<X≦1) is better than the
`conventionally used AlN because the crystallinity of the gallium
`nitride-based compound semiconductor to be grown on top of
`the buffer layer improves markedly and it becomes easier to turn
`the Mg-doped GaXAl1-XN to be grown on top of it into a p-type
`layer.
`[0014] Also, when GaXAl1-XN (0<X≦1) is used as the material for
`the buffer layer, even the crystallinity of the active layer 14
`improves markedly in comparison to the conventional i-type
`GaXAl1-XN layer 4 with the buffer layer made of AlN, and the
`specific resistance becomes 105 Ω・cm or lower.
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`(2)
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`[Claims]
`[Claim 1] A blue light emitting diode characterized by having a
`buffer layer made of GaXAl1-XN (where 0<X≦1), a light emitting
`active layer doped with Zn, an n-type cladding layer doped with
`Si, and furthermore a p-type cladding layer doped with Mg.
`[Detailed Description of the Invention]
`[0001]
`[Industrial Field of Application] The present invention relates to a
`blue light emitting diode made of gallium nitride-based
`compound semiconductors whose general formula is expressed
`as GaXAl1-XN (0≦X≦1), and particularly to a blue light emitting
`diode with high efficiency, high brightness and good color purity.
`[0002]
`[Prior Art] With regard to blue light emitting diodes that utilize
`gallium nitride-based compound semiconductors, those with the
`MIS structure, as shown in Figure 2, are well known.
`[0003] In general, a MIS structure blue light emitting diode is
`basically structured as a sapphire substrate 1 laminated with a
`buffer layer 2 made of AlN, an Si-doped n-type GaXAl1-XN layer 3,
`and a Zn-doped i-type GaXAl1-XN layer 4, in this order, with
`electrodes provided on 3 and 4. Such MIS structure blue light
`emitting diodes with gallium nitride-based compound
`semiconductors have lower efficiency and brightness compared
`to red light emitting diodes and green light emitting diodes made
`of other semiconductor materials with p-n junctions such as
`GaAlAs and GaP, and therefore are not suitable for practical
`applications.
`[0004]
`[Problems To Be Solved by the Invention] The reason why only
`the above-described MIS structure blue light emitting diodes
`have been put to practical use is that, even if a gallium nitride-
`based compound semiconductor is doped with Zn as a p-type
`dopant, it does not become a p-type semiconductor and instead
`becomes a high-resistance i-type semiconductor. Here, the high-
`resistance i-type semiconductor is defined as a semiconductor
`with a specific resistance of 108Ω・cm or higher.
`[0005] Attempts have been made to obtain a p-type layer by
`using Mg instead of Zn as a p-type dopant, and a low-resistance
`p-type layer can be obtained by Mg doping. However, the
`emission wavelength of that p-type layer is shorter than blue
`light and the color of light is purple. For this reason, it has been
`impossible to obtain a blue light emitting diode with good color
`purity with a p-n junction structured with Mg as the emission
`center.
`[0006] As described above, it is very difficult to obtain a p-n
`junction blue light emitting diode by using gallium nitride-based
`compound semiconductors. Therefore, as it stands at the
`present time, only MIS structure blue light emitting diode are
`being made.
`[0007] It is widely and commonly known that the p-n junction
`has advantages over the MIS structure in terms of light emitting
`output and other key light emitting properties and reliability, etc.
`Therefore, an early realization of p-n junction blue light emitting
`diodes is strongly desired.
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`-442-
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`Kingbright Elec. Co. Ltd., Kingbright Corp., SunLED Corp.,
`Kingbright Co. LLC, SunLED Co. LLC and Sunscreen Co. Ltd.
`Exhibit - 1027 Page 5
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`[0015] Therefore, when a light emitting diode is made with the
`above-described structure, the p-type cladding layer 5 on top can
`easily become a p-type layer. For this reason, when an electric
`current is applied with the p-type cladding layer 5 as the + (plus)
`side and the n-type cladding layer 3 as the - (minus) side, for
`example, holes are injected from the p-type cladding layer 5 to
`the active layer 4 and, at the same time, electrons are injected
`from the n-type cladding layer 3, and holes and electrons are
`recombined in the active layer 4 which is the light emitting layer,
`and blue light with good color purity with Zn as the emission
`center is emitted.
`[0016] As described above, without this buffer layer 12, the p-
`type layer cannot be obtained, and therefore the blue light
`emitting diode with the present invention's structure cannot be
`obtained.
`[0017]
`[Effects of the Invention] As described above, the blue light
`emitting diode under the present invention has the same light
`emitting mechanism as a light emitting diode with a double
`hetero structure, for example, which has a light emitting active
`layer sandwiched between a p-type gallium nitride-based
`compound semiconductor and an n-type gallium nitride-based
`compound semiconductor and makes the active layer emit light
`by injecting electrons and holes into it. It can realize a blue light
`emitting diode with higher efficiency, higher brightness and
`better color purity than a MIS structure blue light emitting diode.
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`(2)
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`Unexamined Patent Application Publication H4-321280
`4
`[0018] Furthermore, since the blue light emitting diode under
`the present invention contains GaXAl1-XN (0<X≦1) in the buffer
`layer, the crystallinity of the compound semiconductor
`laminated onto the sapphire substrate improves markedly.
`Therefore, the crystallinity of a p-type cladding layer 5 laminated
`on an AlN buffer layer differs markedly from that of a p-type
`cladding layer 5 formed on top of a GaXAl1-XN (0<X≦1) buffer
`layer which is a constituent factor of the present invention.
`Therefore, with superior crystallinity, the blue light emitting
`diode under the present invention naturally has higher
`brightness.
`[Brief Description of the Figures]
`[Figure 1] A cross section diagram showing the structure of a
`blue light emitting diode under the present invention.
`[Figure 2] A cross section diagram showing the structure of a
`conventional blue light emitting diode.
`[Explanations of Symbols]
`1: sapphire substrate
`2: AlN buffer layer
`3: n-type cladding layer
`4: i-type GaXAl1-XN layer
`5: p-type cladding layer
`12: GaXAl1-XN (0<X≦1) buffer layer
`14: active layer
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`[Figure 1]
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`[Figure 2]
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`Electrode
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`Electrode
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`Active layer
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`buffer layer
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`-443-
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`
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`Kingbright Elec. Co. Ltd., Kingbright Corp., SunLED Corp.,
`Kingbright Co. LLC, SunLED Co. LLC and Sunscreen Co. Ltd.
`Exhibit - 1027 Page 6
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`CERTIFICATION OF TRANSLATION
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`International Litigation Services, a company specializing in international cases and foreign language
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`document processing, certifies the following:
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`into English document. The document is referred to as:
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`"JPH04321280A-Nakamura_eng"
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`translation in English of the corresponding Japanese document.
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`attached document.
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`Joseph Thorpe
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`International Litigation Services, Inc.
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`Kingbright Elec. Co. Ltd., Kingbright Corp., SunLED Corp.,
`Kingbright Co. LLC, SunLED Co. LLC and Sunscreen Co. Ltd.
`Exhibit - 1027 Page 7