(19)
(11)EP 2 613 368 B1

(12)EUROPEAN PATENT SPECIFICATION

(45)Mention of the grant of the patent:
06.05.2020 Bulletin 2020/19

(21)Application number: 13150060.5

(22)Date of filing:  02.01.2013
(51)Int. Cl.: 
H01L 33/32  (2010.01)
H01L 33/04  (2010.01)
H01L 33/38  (2010.01)
F21K 9/23  (2016.01)
H01L 33/42  (2010.01)
H01L 33/20  (2010.01)
H01L 33/44  (2010.01)
F21Y 115/10  (2016.01)

(54)

LIGHT EMITTING DIODE

LEUCHTDIODE

DIODE ÉLECTROLUMINESCENTE


(84)Designated Contracting States:
AL AT BE BG CH CY CZ DE DK EE ES FI FR GB GR HR HU IE IS IT LI LT LU LV MC MK MT NL NO PL PT RO RS SE SI SK SM TR

(30)Priority: 03.01.2012 KR 20120000622

(43)Date of publication of application:
10.07.2013 Bulletin 2013/28

(73)Proprietor: LG Innotek Co., Ltd.
Seoul, 04637 (KR)

(72)Inventors:
  • Jeong, Jong Pil
    100-714 Seoul (KR)
  • Hwang, Jung Hyun
    100-714 Seoul (KR)
  • Kim, Chong Cook
    100-714 Seoul (KR)

(74)Representative: Zardi, Marco 
M. Zardi & Co. SA Via Pioda 6
6900 Lugano
6900 Lugano (CH)


(56)References cited: : 
EP-A2- 1 005 123
US-A1- 2007 228 385
US-A1- 2009 085 056
US-A1- 2010 019 247
US-A1- 2007 105 260
US-A1- 2008 277 682
US-A1- 2009 250 684
US-A1- 2011 168 977
  
      
    Note: Within nine months from the publication of the mention of the grant of the European patent, any person may give notice to the European Patent Office of opposition to the European patent granted. Notice of opposition shall be filed in a written reasoned statement. It shall not be deemed to have been filed until the opposition fee has been paid. (Art. 99(1) European Patent Convention).


    Description

    BACKGROUND



    [0001] The present disclosure relates to light emitting diodes (LEDs), a method of manufacturing a light emitting diode, a light emitting diode package, and a lighting system.

    [0002] A light emitting diode (LED) includes a p-n junction diode having a characteristic of converting electric energy into light energy. The p-n junction diode can be formed by combining group III-V elements of the periodic table. The LED may represent various colors by adjusting the compositional ratio of compound semiconductors.

    [0003] When forward voltage is applied to the LED, electrons of an n layer are bonded with holes of a p layer, so that energy corresponding to an energy gap between a conduction band and a valence band may be generated. This energy is mainly realized as heat or light, and the LED emits the energy as the light.

    [0004] A nitride semiconductor represents superior thermal stability and wide band gap energy so that the nitride semiconductor has been spotlighted in the field of optical devices and high-power electronic devices. In particular, blue, green, and UV light emitting devices employing the nitride semiconductor have already been developed and extensively used.

    [0005] In a GaN-based light emitting diode (LED) according to the related art, in order to improve light emitting efficiency, light efficiency is further improved through a design of an active layer, and then a work of improving extraction efficiency is performed so that optimization is achieved.

    [0006] According to the related art, such as the prior art document US 2008/0277682 A1, a patterned sapphire substrate (PSS) using a pattern on a substrate is used at a lower portion of a light emitting diode chip, and roughening is used at an upper portion of the light emitting diode chip so that light extraction efficiency may be improved. However, according to the demand of a high output light emitting diode, the improvement in the light extraction efficiency is required.

    [0007] Further examples of light emitting diodes according to the related prior art are known from each of the documents: US 2010/0019247 A1, US 2007/0105260 A1, US 2007/0228385 A1, and US 2009/0250684 A1.

    SUMMARY



    [0008] The present invention provides a light emitting diode according to the appended claim 1, capable of improving light extraction efficiency.

    [0009] Advantageous, further embodiments of the present invention are the object of the appended dependent claims.

    [0010] Although not being embodiments of the present invention as defined by the appended claims, also disclosed are: a method of manufacturing a light emitting diode, a light emitting diode package, and a lighting system.

    [0011] The present invention provides a light emitting diode capable of increasing optical efficiency. Also disclosed are: a method of manufacturing a light emitting diode, a light emitting diode package, and a lighting system.

    [0012] The light emitting diode in accordance with the present invention includes: a substrate; a first conductivity type semiconductor layer on the substrate; an active layer on the first conductivity type semiconductor layer; a second conductivity type semiconductor layer on the active layer; a nitride semiconductor layer, having a refractive index less than a refractive index of the second conductivity type semiconductor layer, on the second conductivity type semiconductor layer; and a light transmissive ohmic layer between the second conductivity type semiconductor layer and the nitride semiconductor layer.

    BRIEF DESCRIPTION OF THE DRAWINGS



    [0013] 

    FIG. 1 is a sectional view illustrating a light emitting diode according to a first illustrative example, not forming part of the present invention as defined by the claims, but illustrating its context.

    FIG. 2 is a partially enlarged view illustrating the light emitting diode according to the first illustrative example.

    FIG. 3 is a sectional view illustrating a light emitting diode according to a second illustrative example, also not forming part of the present invention as defined by the claims, but illustrating its context.

    FIG. 4 is a sectional view illustrating a light emitting diode according to an embodiment of the present invention.

    FIGS. 5 to 8 are sectional views illustrating a manufacturing process of the light emitting diode according to the second illustrative example.

    FIG. 9 is a sectional view illustrating a light emitting diode package according to the present disclosure.

    FIG. 10 is an exploded perspective view of an example of a lighting system including a light emitting diode according to the present disclosure.


    DETAILED DESCRIPTION



    [0014] Hereinafter, a light emitting diode, a light emitting diode package, and a lighting system according to the present disclosure will be described with reference to the accompanying drawings.

    [0015] In the following detailed description, it will be understood that when a layer (or film) is referred to as being 'on' another layer or substrate, it can be directly on another layer or substrate, or intervening layers may also be present. Further, it will be understood that when a layer is referred to as being 'under' another layer, it can be directly under another layer, and one or more intervening layers may also be present. In addition, it will also be understood that when a layer is referred to as being 'between' two layers, it can be the only layer between the two layers, or one or more intervening layers may also be present.

    [0016] FIG. 1 is a sectional view illustrating a light emitting diode 100 according to a first illustrative example, and FIG. 2 is a partially enlarged view illustrating a nitride semiconductor layer 130 of the light emitting diode 100 according to the first illustrative example.

    [0017] The light emitting diode 100 may include a substrate 105, a first conductivity type (abbreviated in the rest of the description: first conductive) semiconductor layer 112 on the substrate 150, an active layer 114 on the first conductive semiconductor layer 112, a second conductivity type (abbreviated in the rest of the description: second conductive) semiconductor layer 112 on the active layer 114, and a nitride semiconductor layer 130 having a refractive index less than that of the second conductive semiconductor layer 116 on the second conductive semiconductor layer 116.

    [0018] The nitride semiconductor layer 130 may include AlxGa1-xN (0≤x≤1).

    [0019] The present disclosure provides a light emitting diode, a method of manufacturing the same, a light emitting diode package, and a lighting system capable of improving light extraction efficiency.

    [0020] The present disclosure also provides a light emitting diode, a method of manufacturing the same, a light emitting diode package, and a lighting system capable of improving optical efficiency.

    [0021] To accomplish the above object, a material having a low refractive index is grown in-situ during the growth of a light emitting diode (LED) to improve the light extraction efficiency.

    [0022] For example, the refractive index n of the nitride semiconductor layer 130 may become gradually reduced from the active layer 114 to the second conductive semiconductor layer 116.

    [0023] The nitride semiconductor layer 130 may make contact with the second conductive semiconductor layer 116.

    [0024] The first illustrative example may control the refractive index of the nitride semiconductor layer by controlling a composition of A1 contained in the nitride semiconductor layer 130. For example, the composition x of A1 contained in the nitride semiconductor layer 130 may become gradually increased from the active layer 114 to the second conductive semiconductor layer 116.

    [0025] Accordingly, the refractive index n of the nitride semiconductor layer 130 may become gradually reduced from the active layer 114 to the second conductive semiconductor layer 116 so that the light extraction efficiency of the light emitted from the active layer 114 may be increased in the upward direction rather than the lateral direction.

    [0026] The nitride semiconductor layer 130 may include a first nitride semiconductor layer 131, a second nitride semiconductor layer 132, a third nitride semiconductor layer 133, a fourth nitride semiconductor layer 134, a fifth nitride semiconductor layer 135, a sixth nitride semiconductor layer 136, a seventh nitride semiconductor layer 137, an eighth nitride semiconductor layer 138, and a ninth nitride semiconductor layer 139, the first nitride semiconductor layer 131 may include GaN, and the ninth nitride semiconductor layer 139 may include AlN, but the first illustrative example is not limited thereto.

    [0027] Accordingly, the refractive index n of the nitride semiconductor layer 130 may become gradually reduced from the active layer 114 to the second conductive semiconductor layer 116 from about 2.4 to about 2.0, but the first illustrative example is not limited thereto.

    [0028] According to the present disclosure, the nitride semiconductor layer 130 may include an n type nitride semiconductor layer doped with n type dopant. For example, the nitride semiconductor layer 130 may be doped with Si, but the present disclosure is not limited thereto.

    [0029] Since the nitride semiconductor layer 130 is doped with an n type dopant, even if a second electrode 152 is formed on the nitride semiconductor layer 130 without making contact with the second conductive semiconductor layer 116, a carrier may be easily injected.

    [0030] The nitride semiconductor layer 130 may have a thickness sufficient for enabling the tunneling of a carrier, but the first illustrative example is not limited thereto.

    [0031] The first illustrative example may further include a transmissive ohmic layer 140 having a refractive index less than that of the nitride semiconductor layer 130 on the nitride semiconductor layer 130. The second electrode 152 may be formed on the transmissive ohmic layer 140.

    [0032] A horizontal width of the first transmissive ohmic layer 140 may be substantially the same as a horizontal width of the nitride semiconductor layer 130 so that uniform current spreading may be achieved at the nitride semiconductor layer 130. Meanwhile, the horizontal width of the first transmissive ohmic layer 140 may be less than the horizontal width of the nitride semiconductor layer 130.

    [0033] The transmissive ohmic layer 140 may have a single or multi-layer structure of metal oxide capable of facilitating the carrier injection. The transmissive ohmic layer 140 may include at least one selected from the group consisting of ITO(indium tin oxide), IZO(indium zinc oxide), IZTO(indium zinc tin oxide), IAZO(indium aluminum zinc oxide), IGZO(indium gallium zinc oxide), IGTO(indium gallium tin oxide), AZO(aluminum zinc oxide), ATO(antimony tin oxide), GZO(gallium zinc oxide), IZON(IZO Nitride), AGZO(Al-Ga ZnO), IGZO(In-Ga ZnO), ZnO, IrOx, RuOx, NiO, RuOx/ITO, Ni/IrOx/Au, and Ni/IrOx/Au/ITO, and the present disclosure is not limited thereto.

    [0034] Accordingly, the refractive index n of the nitride semiconductor layer 130 may become gradually reduced from the active layer 114 to the second conductive semiconductor layer 116 from about 2.4 to about 2.0.

    [0035] Since the refractive index is controlled from about 2.0 to about over 1.0 in the transmissive ohmic layer 140, the refractive index becomes gradually reduced in the direction of the second conductive semiconductor layer 116, the nitride semiconductor layer 130, and the transmissive ohmic layer 140 so that light emitted from the active layer 114 may be efficiently extracted in the upward direction.

    [0036] FIG. 3 is a sectional view illustrating a light emitting diode 102 according to a second illustrative example.

    [0037] The second example may adopt the technical features and effects of the first example.

    [0038] According to the second illustrative example, the second electrode 152 may make contact with the second conductive semiconductor layer 116 through the nitride semiconductor layer 130.

    [0039] According to the second example, there is no limitation in the thickness of the nitride semiconductor layer 130 for the tunneling of the carrier.

    [0040] According to the second example, the nitride semiconductor layer 130 may include a p type nitride semiconductor layer doped with a p type element. For example, after formation of the second conductive semiconductor layer 116, the nitride semiconductor layer 130 including a p type nitride semiconductor layer doped with a p type element may be formed in-situ.

    [0041] The nitride semiconductor layer 130 may include an undoped nitride semiconductor layer which is not doped with an element. Upon the formation of the nitride semiconductor layer 130, a process may be performed without doping an n or p type conductive element to form the nitride semiconductor layer 130 including the undoped nitride semiconductor layer.

    [0042] The second illustrative example may further include a transparent insulating layer having a refractive index less than that of the nitride semiconductor layer 130 on the nitride semiconductor layer 130.

    [0043] The transparent insulating layer 142 may include silicon oxide or silicon nitride, but the present example is not limited thereto.

    [0044] According to the second example, the refractive index n of the nitride semiconductor layer 130 may become gradually reduced from the active layer 114 to the second conductive semiconductor layer 116 from about 2.4 to about 2.0, and the refractive index becomes gradually reduced in the direction of the second conductive semiconductor layer 116, the nitride semiconductor layer 130, and the transparent insulating layer 142 by controlling the refractive index of the transparent insulating layer 142 from about 2.0 to about over 1.0 so that light emitted from the active layer 114 may be more efficiently extracted in the upward direction rather than the lateral direction.

    [0045] FIG. 4 is a sectional view illustrating a light emitting diode 103 according to an embodiment of the present invention.

    [0046] The present third embodiment may adopt the technical features and effects of the first and second illustrative examples.

    [0047] The present embodiment includes further a light transmissive ohmic layer 140b between the second conductive semiconductor layer 116 and the nitride semiconductor layer 130.

    [0048] The light transmissive ohmic layer 140b has a refractive index between the refractive index of the second conductive layer 116 and the refractive index of the nitride semiconductor layer 130 so that light extraction efficiency may be maximized.

    [0049] The second electrode 152 formed above the second conductive semiconductor layer 116 may be formed on the light transmissive ohmic layer 140b.

    [0050] Reference numerals which are not described in FIGS. 1 to 4 will be illustrated in a following manufacturing method.

    [0051] According to the present disclosure, spreading of light may be improved and the present disclosure is easily applied to a product by controlling the content (%) of Al.

    [0052] According to the light diode, the method of manufacturing the same, the light emitting diode package, and the lighting system of the present disclosure, light extraction efficiency can be increased. Further, according to the present disclosure, optical efficiency can be increased.

    [0053] Hereinafter, a method of manufacturing the light emitting diode of the second illustrative example will be described with reference to FIGS. 5 to 8.

    [0054] First, the substrate 105 as shown in FIG. 5 may be prepared. The substrate 105 may include a conductive substrate or an insulating substrate. For instance, the substrate 105 may include at least one of Al2O3, SiC, Si, GaAs, GaN, ZnO, GaP, InP, Ge, and Ga2O3. A concave-convex structure can be formed on the substrate 105, but the present disclosure is not limited thereto. The substrate 105 can be subject to the wet cleaning to remove impurities from the surface of the substrate 105.

    [0055] A light extraction structure, for example, a PSS (not shown) may be formed on the substrate 105, but the present disclosure is not limited thereto.

    [0056] Then, the light emitting structure 110 including the first conductive semiconductor layer 112, the active layer 114 and the second semiconductor layer 116 may be formed on the substrate 105.

    [0057] A buffer layer (not shown) may be formed on the substrate 105. The buffer layer may attenuate lattice mismatch between the light emitting structure 110 and the substrate 105. The buffer layer may include the group III-V compound semiconductor. For instance, the buffer layer may include at least one of GaN, InN, AlN, InGaN, AlGaN, InAlGaN, and AlInN.

    [0058] An undoped semiconductor layer (not shown) may be formed on the buffer layer, but the present disclosure is not limited thereto.

    [0059] A first conductive layer 112 may be formed on the substrate 105 or the semiconductor layer.

    [0060] The first conductive semiconductor layer 112 may include a group III-V compound semiconductor doped with a first conductive dopant. If the first conductive semiconductor layer 112 is an N type semiconductor layer, the first conductive dopant is an N type dopant, such as Si, Ge, Sn, Se, or Te, but the present disclosure is not limited thereto.

    [0061] The first conductive semiconductor layer 122 may include semiconductor material having the compositional formula of InxAlyGa1-x-yN (0≤x≤1, 0≤y≤1, 0≤x+y≤1).

    [0062] The first conductive semiconductor layer 112 may include at least one of GaN, InN, AlN, InGaN, AlGaN, InAlGaN, AlInN, AlGaAs, InGaAs, AlInGaAs, GaP, AlGaP, InGaP, AlInGaP, and InP.

    [0063] The first conductive semiconductor layer 112 may include an N type GaN layer, which is formed through the CVD, MBE, sputtering or HVPE. In addition, the first conductive semiconductor layer 112 may be formed by injecting trimethyl gallium (TMGa) gas, ammonia (NH3) gas, nitrogen (N2) gas and silane (SiH4) gas including n type impurities, such as silicon, into the chamber.

    [0064] Next, a current spreading layer 122 may be formed on the first conductive semiconductor layer 112. The current spreading layer 122 may be an undoped GaN layer, but the present disclosure is not limited thereto.

    [0065] After that, according to the present disclosure, an electron injection layer 124 may be formed on the current spreading layer 122. The electron injection layer 124 may be a first conductive GaN layer. Electrons may be effectively injected into the electron injection layer 124 by doping the electron injection layer 124 with an N type doping element at a concentration of 6.0x1018atoms/cm3∼8.0x1018atoms/cm3.

    [0066] According to the present disclosure, a strain control layer (not shown) may be formed on the electron injection layer 124. For example, a strain control layer including InyAlxGa(1-x-y)N (0≤x≤1, 0≤y≤1)/GaN may be formed on the electron injection layer 124.

    [0067] The strain control layer may efficiently attenuate the stress resulting from lattice mismatch between the first conductive semiconductor layer 112 and the active layer 114.

    [0068] Since the strain control layer is repeatedly laminated in at least 6 periods having the compositional formula of a first Inx1GaN and a second Inx2GaN, more electrons are collected at a low energy level of the active layer 114 so that a recombination probability of electrons and holes is increased, thereby improving light emission efficiency.

    [0069] After that, the active layer 114 may be formed on the first conductive semiconductor layer 112.

    [0070] The active layer 114 may include at least one of a single quantum well structure, a multiple quantum well (MQW) structure, a quantum wire structure and a quantum dot structure. For instance, the active layer 114 can be formed with the MQW structure by injecting TMGa gas, NH3 gas, N2 gas, and trimethyl indium (TMIn) gas, but the present disclosure is not limited thereto.

    [0071] The active layer 114 may have a well/barrier layer including at least one of InGaN/GaN, InGaN/InGaN, AlGaN/GaN, InAlGaN/GaN, GaAs/AlGaAs (InGaAs) and GaP/AlGaP (InGaP), but the present disclosure is not limited thereto. The well layer may include material having the bandgap energy lower than that of the barrier layer.

    [0072] According to the present disclosure, an electron blocking layer 126 may be formed on the active layer 114 for the purpose of electron blocking and MQW cladding of an active layer so that light emitting efficiency may be improved. For example, the electron blocking layer 126 may include an AlxInyGa(1-x-y)N (0≤x≤1,0≤y≤1)-based semiconductor having the energy bandgap higher than that of the active layer 114. The electron blocking layer 126 may have a thickness in the range of about 100 Å to about 600 Å, but the present disclosure is not limited thereto.

    [0073] The electron blocking layer 126 may have an AlzGa(1-z)N/GaN (0≤z≤1) super lattice, but the present disclosure is not limited thereto.

    [0074] A p type ion may be implanted into the electron blocking layer 126 to efficiently block overflow of electrons and increase injection efficiency of holes. An Mg ion is implanted into the electron blocking layer 126 at the concentration in the range of about 1018/ cm3 to about 1020/cm3 to efficiently block overflow electrons and increase injection efficiency of holes.

    [0075] Next, a second conductive semiconductor layer 116 may be formed on the electron blocking layer 126.

    [0076] The second conductive semiconductor layer 116 may include the group III-V compound semiconductor doped with the second conductive dopant. For instance, the second conductive semiconductor layer 116 may include the semiconductor material having the compositional formula of InxAlyGa1-x-yN (0≤x≤1, 0≤y≤1, 0≤x+y≤1). In detail, the second conductive semiconductor layer 126 may include one selected from the group consisting of GaN, AlN, AlGaN, InGaN, InN, InAlGaN, AlInN, AlGaAs, GaP, GaAs, GaAsP, and AlGaInP. If the second conductive semiconductor layer 126 is a P type semiconductor layer, the second conductive dopant includes the P type dopant such as Mg, Zn, Ca, Sr, or Ba. The second conductive semiconductor layer 126 can be prepared as a single layer or a multiple layer, but the present disclosure is not limited thereto.

    [0077] The second conductive semiconductor layer 116 may include a p type GaN layer, which can be formed by injecting TMGa gas, NH3 gas, N2 gas and (EtCp2Mg){Mg(C2H5C5H4)2} gas including p type impurities (for example, Mg) into the chamber, but the present disclosure is not limited thereto.

    [0078] According to the present disclosure, the first conductive semiconductor layer 112 may include an N type semiconductor layer and the second conductive semiconductor layer 126 may include a P type semiconductor layer, but the present disclosure is not limited thereto. In addition, a semiconductor layer, such as an N type semiconductor layer (not shown) having polarity opposite to that of the second conductive semiconductor layer 126, can be formed on the second conductive semiconductor layer 126. Thus, the light emitting structure 110 may include one of an N-P junction structure, a P-N junction structure, an N-P-N junction structure, and a P-N-P junction structure.

    [0079] Thereafter, as shown in FIG. 6, a nitride semiconductor layer 130 having a refractive index less than that of the second conductive semiconductor layer 116 is formed on the second conductive semiconductor layer 116. The nitride semiconductor layer 130 may include AlxGa1-xN (0≤x≤1).

    [0080] Light extraction efficiency may be improved by growing a material of a low refractive index in-situ during the growth of a light emitting diode (LED). For example, the refractive index n of the nitride semiconductor layer 130 may become gradually reduced from the active layer 114 to the second conductive semiconductor layer 116.

    [0081] The present disclosure may control the refractive index of the nitride semiconductor layer by controlling a composition of Al contained in the nitride semiconductor layer 130. For example, the composition x of Al contained in the nitride semiconductor layer 130 may become gradually increased from the active layer 114 to the second conductive semiconductor layer 116.

    [0082] Accordingly, the refractive index n of the nitride semiconductor layer 130 may become gradually reduced from the active layer 114 to the second conductive semiconductor layer 116 so that light emitted from the active layer 114 may increase light extraction efficiency in the upward direction rather than the lateral direction.

    [0083] For example, the refractive index n of the nitride semiconductor layer 130 may become gradually reduced from the active layer 114 to the second conductive semiconductor layer 116 from about 2.4 to about 2.0, but the present disclosure is not limited thereto.

    [0084] According to the present disclosure, the nitride semiconductor layer 130 may include an N type nitride semiconductor layer doped with an N type dopant. For example, the nitride semiconductor layer 130 may be doped with Si, but the present disclosure is not limited thereto.

    [0085] Since the nitride semiconductor layer 130 is doped with an N type dopant, even if a second electrode 152 is formed on the nitride semiconductor layer 130 without making contact with the second conductive semiconductor layer 116, a carrier may be easily injected.

    [0086] The nitride semiconductor layer 130 may have a thickness sufficient for enabling the tunneling of a carrier, but the present disclosure is not limited thereto.

    [0087] As shown in FIG. 1, the first illustrative example may further include a transmissive ohmic layer 140 having a refractive index less than that of the nitride semiconductor layer 130 on the nitride semiconductor layer 130. The second electrode 152 may be formed on the transmissive ohmic layer 140. The transmissive ohmic layer 140 may have a single or multi-layer structure of metal oxide capable of facilitating the carrier injection. The transmissive ohmic layer 140 may include at least one selected from the group consisting of ITO(indium tin oxide), IZO(indium zinc oxide), IZTO(indium zinc tin oxide), IAZO(indium aluminum zinc oxide), IGZO(indium gallium zinc oxide), IGTO(indium gallium tin oxide), AZO(aluminum zinc oxide), ATO(antimony tin oxide), GZO(gallium zinc oxide), IZON(IZO Nitride), AGZO(Al-Ga ZnO), IGZO(In-Ga ZnO), ZnO, IrOx, RuOx, NiO, RuOx/ITO, Ni/IrOx/Au, and Ni/IrOx/Au/ITO, and the present disclosure is not limited thereto.

    [0088] Accordingly, the refractive index n of the nitride semiconductor layer 130 may become gradually reduced from the active layer 114 to the second conductive semiconductor layer 116 from about 2.4 to about 2.0. Since the refractive index is controlled from about 2.0 to about over 1.0 in the transmissive ohmic layer 140, the refractive index becomes gradually reduced in the direction of the second conductive semiconductor layer 116, the nitride semiconductor layer 130, and the transmissive ohmic layer 140 so that light emitted from the active layer 114 may be efficiently extracted in the upward direction.

    [0089] As shown in FIG. 6, the second illustrative example may further include a transparent insulating layer 142 having a refractive index less than that of the nitride semiconductor layer 130 on the nitride semiconductor layer. The transparent insulating layer 142 may include silicon oxide or silicon nitride, but the present disclosure is not limited thereto.

    [0090] According to the second illustrative example, the refractive index n of the nitride semiconductor layer 130 may become gradually reduced from the active layer 114 to the second conductive semiconductor layer 116 from about 2.4 to about 2.0. Since the refractive index is controlled from about 2.0 to about over 1.0 in the transmissive ohmic layer 140, the refractive index becomes gradually reduced in the direction of the second conductive semiconductor layer 116, the nitride semiconductor layer 130, and the transmissive ohmic layer 140 so that light emitted from the active layer 114 may be efficiently extracted in the upward direction.

    [0091] According to the second illustrative example, the second electrode 152 may make contact with the second conductive semiconductor layer 116 through the nitride semiconductor layer 130. According to the second illustrative example, there is no limitation in the thickness of the nitride semiconductor layer 130 for the tunneling of the carrier.

    [0092] As shown in FIG. 4, the embodiment of the present invention further includes a light transmissive ohmic layer 140b between the second conductive semiconductor layer 116 and the nitride semiconductor layer 130.

    [0093] The light transmissive ohmic layer 140b has a refractive index between the refractive index of the second conductive layer 116 and the refractive index of the nitride semiconductor layer 130 so that light extraction efficiency may be maximized.

    [0094] According to the present invention, spreading of light may be improved and the embodiment of the present invention is easily applied to a product by controlling the content (%) of Al.

    [0095] To this end, as shown in FIG. 7, according to the present disclosure, the second conductive semiconductor layer 116 may be exposed by partially removing the transparent insulating layer 142 and the nitride semiconductor layer 130.

    [0096] The first conductive semiconductor layer 112 may be exposed by partially removing the transparent insulating layer 142, the nitride semiconductor layer 130, the second conductive semiconductor layer, the electron blocking layer, a strain control layer, and the electron injection layer 124, and the current spreading layer 122.

    [0097] After that, as shown in FIG. 8, a second electrode 152 and a first electrode 151 may be formed on the second exposed conductive semiconductor layer 116 and the first exposed conductive semiconductor layer 112, respectively.

    [0098] According to the light emitting diode, the method of manufacturing the same, the light emitting diode package, and the lighting system of the present disclosure, light extraction efficiency can be increased.

    [0099] Further, according to the present disclosure, optical efficiency can be increased.

    [0100] FIG. 9 is a sectional view illustrating a light emitting diode package 200 according to the present disclosure.

    [0101] The light emitting diode package 200 according to the present disclosure includes a package body 205, third and fourth electrode layers 213 and 214 formed on the package body 205, the light emitting diode 100 provided on the package body 205 and electrically connected to the third and fourth electrode layers 213 and 214, and a molding member 240 that surrounds the light emitting diode 100.

    [0102] The package body 205 may include silicon, synthetic resin or metallic material. An inclined surface may be formed around the light emitting diode 100.

    [0103] The third and fourth electrode layers 213 and 214 may be electrically isolated from each other to supply power to the light emitting diode 100. In addition, the third and fourth electrode layers 213 and 214 reflect the light emitted from the light emitting diode 100 to improve the light efficiency and dissipate heat generated from the light emitting diode 100 to the outside.

    [0104] The lateral type light emitting diode shown in FIG. 1, 3, or 4 can be employed as the light emitting diode 100, but the present disclosure is not limited thereto.

    [0105] The light emitting diode 100 may be installed on the package body 205 or the third and fourth electrode layers 213 and 214.

    [0106] The light emitting diode 100 is electrically connected to the third electrode layer 213 and/or the fourth electrode layer 214 through at least one of a wire bonding scheme, a flip chip bonding scheme and a die bonding scheme. According to the present disclosure, the light emitting diode 100 is electrically connected to the third electrode layer 213 through a wire and electrically connected to the fourth electrode layer 214 through the die bonding scheme, but the present disclosure is not limited thereto.

    [0107] The molding member 230 surrounds the light emitting diode 100 to protect the light emitting diode 100. In addition, the molding member 230 may include phosphors to change the wavelength of the light emitted from the light emitting diode 100.

    [0108] A plurality of light emitting diode packages according to the present disclosure may be arrayed on a substrate, and an optical member including a light guide plate, a prism sheet, a diffusion sheet or a fluorescent sheet may be provided on the optical path of the light emitted from the light emitting diode package. The light emitting diode package, the substrate, and the optical member may serve as a backlight unit or a lighting unit. For instance, the lighting system may include a backlight unit, a lighting unit, an indicator, a lamp or a streetlamp.

    [0109] FIG. 10 is an exploded perspective view an example of a lighting system including the light emitting diode according to the present disclosure.

    [0110] As shown in FIG. 10, the lighting system according to the present disclosure may include a cover 2100, a light source module 2200, a radiator 2400, a power supply part 2600, an inner case 2700, and a socket 2800. The lighting system according to the present disclosure may further include at least one of a member 2300 and a holder 2500. The light source module 2200 may include the light emitting diode 100 or the light emitting diode package 200 according to the present disclosure.

    [0111] For example, the cover 2100 may have a bulb shape, a hemisphere shape, a partially-open hollow shape. The cover 2100 may be optically coupled with the light source module 2200. For example, the cover 2100 may diffuse, scatter, or excite light provided from the light source module. The cover 2100 may be a type of optical member. The cover 2100 may be coupled with the radiator 2400. The cover 2100 may include a coupling part which is coupled with the radiator 2400.

    [0112] The cover 2100 may include an inner surface coated with a milk-white paint. The milk-white paint may include a diffusion material to diffuse light. The cover 2100 may have the inner surface of which surface roughness is greater than that of the outer surface thereof. The surface roughness is provided for the purpose of sufficiently scattering and diffusing the light from the light source module 2200.

    [0113] For example, a material of the cover 2100 may include glass, plastic, polypropylene (PP), polyethylene (PE), and polycarbonate (PC). The polycarbonate (PC) has the superior light resistance, heat resistance and strength among the above materials. The cover 2100 may be transparent so that a user may view the light source module 2200 from the outside, or opaque. The cover 2100 may be formed through a blow molding scheme.

    [0114] The light source module 2200 may be disposed at one surface of the radiator 2400. Accordingly, the heat from the light source module 2200 is transferred to the radiator 2400.
    The light source module 2200 may include a light source 2210, a connection plate 2230, and a connector 2250.

    [0115] The member 2300 is disposed at a top surface of the radiator 2400, and includes guide grooves 2310 into which a plurality of light sources 2210 and the connector 2250 are inserted. The guide grooves 2310 correspond to a substrate of the light source 2210 and the connector 2250.

    [0116] A surface of the member 2300 may be coated with a light reflective material. For example, the surface of the member 2300 may be coated with white paint. The member 2300 again reflects light, which is reflected by the inner surface of the cover 2100 and is returned to the direction of the light source module 2200, to the direction of the cover 2100. Accordingly, the light efficiency of the lighting system according to the present disclosure may be improved.

    [0117] For example, the member 2300 may include an insulating material. The connection plate 2230 of the light source module 2200 may include an electrically conductive material. Accordingly, the radiator 2400 may be electrically connected to the connection plate 2230. The member 2300 may be configured by an insulating material, thereby preventing the connection plate 2230 from being electrically shorted with the radiator 2400. The radiator 2400 receives heat from the light source module 2200 and the power supply part 2600 and radiates the heat.

    [0118] The holder 2500 covers a receiving groove 2719 of an insulating part 2710 of an inner case 2700. Accordingly, the power supply part 2600 received in the insulating part 2710 of the inner case 2700 is closed. The holder 2500 includes a guide protrusion 2510. The guide protrusion 2510 has a hole through a protrusion of the power supply part 2600.

    [0119] The power supply part 2600 processes or converts an electric signal received from the outside and provides the processed or converted electric signal to the light source module 2200. The power supply part 2600 is received in the receiving groove of the inner case 2700, and is closed inside the inner case 2700 by the holder 2500.

    [0120] The power supply part 2600 may include a protrusion 2610, a guide part 2630, a base 2650, and an extension part 2670.

    [0121] The guide part 2630 has a shape protruding from one side of the base 2650 to the outside. The guide part 2630 may be inserted into the holder 2500. A plurality of components may be disposed above one surface of the base 2650. For example, the components may include a DC converter converting AC power provided from an external power supply into DC power, a driving chip controlling driving of the light source module 2200, and an electrostatic discharge (ESD) protection device protecting the light source module 2200, but the present disclosure is not limited thereto.

    [0122] The extension part 2670 has a shape protruding from an opposite side of the base 2650 to the outside. The extension part 2670 is inserted into an inside of the connection part 2750 of the inner case 2700, and receives an electric signal from the outside. For example, a width of the extension part 2670 may be smaller than or equal to a width of the connection part 2750 of the inner case 2700. First terminals of a "+ electric wire" and a "- electric wire" are electrically connected to the extension part 2670 and second terminals of the "+ electric wire" and the "- electric wire" may be electrically connected to a socket 2800.

    [0123] The inner case 2700 may include a molding part therein together with the power supply part 2600. The molding part is prepared by hardening molding liquid, and the power supply part 2600 may be fixed inside the inner case 2700 by the molding part.

    [0124] According to the light emitting diode of the present invention, the method of manufacturing the same, the light emitting diode package, and the lighting system of the present disclosure, the light extraction efficiency can be increased.

    [0125] In addition, according to the present invention, the optical efficiency can be increased.

    [0126] Any reference in this specification to "one embodiment," "an embodiment," etc., means that a particular feature, structure, or characteristic described in connection with the embodiment is included in at least one embodiment of the present invention, whose scope is defined by the appended claims.

    [0127] Although embodiments have been described with reference to a number of illustrative embodiments thereof, it should be understood that numerous other modifications and embodiments can be devised by those skilled in the art that will fall within the scope of the present invention as defined by the appended claims.


    Claims

    1. A light emitting diode (103) comprising:

    a substrate (105);

    a first conductivity type semiconductor layer (112) on the substrate (105);

    an active layer (114) on the first conductivity type semiconductor layer (112);

    a second conductivity type semiconductor layer (116) on the active layer (114); and

    a nitride semiconductor layer (130), having a refractive index less than a refractive index of the second conductivity type semiconductor layer (116), on the second conductivity type semiconductor layer (116),

    characterised by further comprising:

    a light transmissive ohmic layer (140b) between the second conductivity type semiconductor layer (116) and the nitride semiconductor layer (130).


     
    2. The light emitting diode of claim 1, wherein the refractive index of the nitride semiconductor layer (130) becomes gradually reduced as the nitride semiconductor layer (130) is located away from the second conductivity type semiconductor layer (116).
     
    3. The light emitting diode of any one of claims 1 to 2, wherein the nitride semiconductor layer (130) comprises an AlxGa1-xN layer (0≤x≤1).
     
    4. The light emitting diode of claim 3, wherein a composition of Al in the nitride semiconductor layer (130) becomes gradually increased as the nitride semiconductor layer (130) is located away from the second conductivity type semiconductor layer (116).
     
    5. The light emitting diode of claim 3, wherein a composition of Al in the nitride semiconductor layer (130) at a region close to the second conductivity type semiconductor layer (116) is less than the composition of Al in the nitride semiconductor layer (130) at a region away from the second conductivity type semiconductor layer (116).
     
    6. The light emitting diode of any one of claims 1 to 5, wherein the nitride semiconductor layer (130) comprises an n type nitride semiconductor layer; and wherein the n type nitride semiconductor layer has a thickness sufficient for enabling tunneling.
     
    7. The light emitting diode of any one of claims 1 to 5, wherein the nitride semiconductor layer (130) comprises a p type nitride semiconductor layer.
     
    8. The light emitting diode of any one of claims 1 to 5, wherein the nitride semiconductor layer (130) comprises an undoped nitride semiconductor layer.
     
    9. The light emitting diode of any one of claims 1 to 8, further comprising a transparent insulating layer (142), having a refractive index less than the refractive index of the nitride semiconductor layer (130), on the nitride semiconductor layer (130).
     
    10. The light emitting diode of any one of claims 1 to 9, wherein the light transmissive ohmic layer (140b) has a refractive index between a refractive index of the second conductivity type semiconductor layer (116) and the refractive index of the nitride semiconductor layer (130).
     
    11. The light emitting diode of any one of claims 1 to 10, further comprising an electrode (152) on the light transmissive ohmic layer (140b).
     
    12. The light emitting diode of claim 11, wherein the electrode (152) is through the nitride semiconductor layer (130) and is directly in-contact with the light transmissive ohmic layer (140b).
     
    13. The light emitting diode of claim 11, wherein a top surface of the electrode (152) is lower than a top surface of the nitride semiconductor layer (130).
     


    Ansprüche

    1. Leuchtdiode (103) umfassend:

    ein Substrat (105);

    eine Halbleiterschicht eines ersten Leitfähigkeitstyps (112) auf dem Substrat (105);

    eine aktive Schicht (114) auf der Halbleiterschicht des ersten Leitfähigkeitstyps (112);

    eine Halbleiterschicht eines zweiten Leitfähigkeitstyps (116) auf der aktiven Schicht (114); und

    eine Nitridhalbleiterschicht (130), die einen Brechungsindex aufweist, der geringer als ein Brechungsindex der Halbleiterschicht des zweiten Leitfähigkeitstyps (116) ist, auf der Halbleiterschicht des zweiten Leitfähigkeitstyps (116),

    dadurch gekennzeichnet, dass sie ferner umfasst:
    eine lichtdurchlässige ohmsche Schicht (140b) zwischen der Halbleiterschicht des zweiten Leitfähigkeitstyps (116) und der Nitridhalbleiterschicht (130).


     
    2. Leuchtdiode nach Anspruch 1, wobei sich der Brechungsindex der Nitridhalbleiterschicht (130) allmählich verringert, wenn sich die Nitridhalbleiterschicht (130) entfernt von der Halbleiterschicht des zweiten Leitfähigkeitstyps (116) befindet.
     
    3. Leuchtdiode nach einem der Ansprüche 1 bis 2, wobei die Nitridhalbleiterschicht (130) eine AlxGa1-xN-Schicht (0≤x≤1) umfasst.
     
    4. Leuchtdiode nach Anspruch 3, wobei eine Zusammensetzung von Al in der Nitridhalbleiterschicht (130) allmählich zunimmt, wenn sich die Nitridhalbleiterschicht (130) entfernt von der Halbleiterschicht des zweiten Leitfähigkeitstyps (116) befindet.
     
    5. Leuchtdiode nach Anspruch 3, wobei eine Zusammensetzung von Al in der Nitridhalbleiterschicht (130) an einem Bereich nahe bei der Halbleiterschicht des zweiten Leitfähigkeitstyps (116) geringer als die Zusammensetzung von Al in der Nitridhalbleiterschicht (130) an einem Bereich entfernt von der Halbleiterschicht des zweiten Leitfähigkeitstyps (116) ist.
     
    6. Leuchtdiode nach einem der Ansprüche 1 bis 5, wobei die Nitridhalbleiterschicht (130) eine n-Typ-Nitridhalbleiterschicht umfasst; und
    wobei die n-Typ-Nitridhalbleiterschicht eine Dicke aufweist, die ausreichend ist, um Tunneln zu ermöglichen.
     
    7. Leuchtdiode nach einem der Ansprüche 1 bis 5, wobei die Nitridhalbleiterschicht (130) eine p-Typ-Nitridhalbleiterschicht umfasst.
     
    8. Leuchtdiode nach einem der Ansprüche 1 bis 5, wobei die Nitridhalbleiterschicht (130) eine undotierte Nitridhalbleiterschicht umfasst.
     
    9. Leuchtdiode nach einem der Ansprüche 1 bis 8, ferner umfassend eine transparente Isolierschicht (142), die einen Brechungsindex aufweist, der geringer als der Brechungsindex der Nitridhalbleiterschicht (130) ist, auf der Nitridhalbleiterschicht (130).
     
    10. Leuchtdiode nach einem der Ansprüche 1 bis 9, wobei die lichtdurchlässige ohmsche Schicht (140b) einen Brechungsindex zwischen einem Brechungsindex der Halbleiterschicht des zweiten Leitfähigkeitstyps (116) und dem Brechungsindex der Nitridhalbleiterschicht (130) aufweist.
     
    11. Leuchtdiode nach einem der Ansprüche 1 bis 10, ferner umfassend eine Elektrode (152) auf der lichtdurchlässigen ohmschen Schicht (140b).
     
    12. Leuchtdiode nach Anspruch 11, wobei die Elektrode (152) durch die Nitridhalbleiterschicht (130) hindurchgeht und direkt in Kontakt mit der lichtdurchlässigen ohmschen Schicht (140b) ist.
     
    13. Leuchtdiode nach Anspruch 11, wobei eine obere Oberfläche der Elektrode (152) niedriger als eine obere Oberfläche der Nitridhalbleiterschicht (130) ist.
     


    Revendications

    1. Une diode électroluminescente (103) comprenant :

    un substrat (105);

    une couche semi-conductrice (112) d'un premier type de conductivité située sur le substrat (105);

    une couche active (114) située sur la couche semi-conductrice (112) du premier type de conductivité ;

    une couche semi-conductrice (116) d'un deuxième type de conductivité située sur la couche active (114); et

    une couche semi-conductrice de nitrure (130), ayant un indice de réfraction inférieur à un indice de réfraction de la couche semi-conductrice (116) du deuxième type de conductivité, située sur la couche semi-conductrice (116) du deuxième type de conductivité,

    caractérisée par le fait de comprendre en outre :
    une couche ohmique (140b) transmettant la lumière, située entre la couche semi-conductrice (116) du deuxième type de conductivité et la couche semi-conductrice de nitrure (130).


     
    2. La diode électroluminescente selon la revendication 1, dans laquelle l'indice de réfraction de la couche semi-conductrice de nitrure (130) diminue progressivement au fur et à mesure que la couche semi-conductrice de nitrure (130) s'éloigne de la couche semi-conductrice (116) du deuxième type de conductivité.
     
    3. La diode électroluminescente selon l'une quelconque des revendications 1 à 2, dans laquelle la couche semi-conductrice de nitrure (130) comprend une couche de AlxGa1-xN (0≤x≤1).
     
    4. La diode électroluminescente selon la revendication 3, dans laquelle la composition d'Al dans la couche semi-conductrice de nitrure (130) augmente progressivement au fur et à mesure que la couche semi-conductrice de nitrure (130) s'éloigne de la couche semi-conductrice (116) du deuxième type de conductivité.
     
    5. La diode électroluminescente selon la revendication 3, dans laquelle une composition d'Al dans la couche semi-conductrice de nitrure (130) dans une zone proche de la couche semi-conductrice (116) du deuxième type de conductivité est inférieure à la composition d'Al dans la couche semi-conductrice de nitrure (130) dans une zone éloignée de la couche semi-conductrice (116) du deuxième type de conductivité.
     
    6. La diode électroluminescente selon l'une quelconque des revendications 1 à 5, dans laquelle la couche semi-conductrice de nitrure (130) comprend une couche semi-conductrice de nitrure de type n ; et
    dans lequel la couche semi-conductrice de nitrure de type n a une épaisseur suffisante pour permettre un effet tunnel.
     
    7. La diode électroluminescente selon l'une quelconque des revendications 1 à 5, dans laquelle la couche semi-conductrice de nitrure (130) comprend une couche semi-conductrice de nitrure de type p.
     
    8. La diode électroluminescente selon l'une quelconque des revendications 1 à 5, dans laquelle la couche semi-conductrice de nitrure (130) comprend une couche semi-conductrice de nitrure non dopée.
     
    9. La diode électroluminescente selon l'une quelconque des revendications 1 à 8, comprenant en outre une couche isolante transparente (142), ayant un indice de réfraction inférieur à l'indice de réfraction de la couche semi-conductrice de nitrure (130), située sur la couche semi-conductrice de nitrure (130).
     
    10. La diode électroluminescente selon l'une quelconque des revendications 1 à 9, dans laquelle la couche ohmique transmettant la lumière (140b) a un indice de réfraction compris entre un indice de réfraction de la couche semi-conductrice (116) du deuxième type de conductivité et l'indice de réfraction de la couche semi-conductrice de nitrure (130).
     
    11. La diode électroluminescente selon l'une quelconque des revendications 1 à 10, comprenant en outre une électrode (152) sur la couche ohmique (140b) transmettant la lumière.
     
    12. La diode électroluminescente selon la revendication 11, dans laquelle l'électrode (152) traverse la couche semi-conductrice de nitrure (130) et est directement en contact avec la couche ohmique (140b) transmettant la lumière.
     
    13. La diode électroluminescente selon la revendication 11, dans laquelle une surface supérieure de l'électrode (152) est plus basse qu'une surface supérieure de la couche semi-conductrice de nitrure (130).
     




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    REFERENCES CITED IN THE DESCRIPTION



    This list of references cited by the applicant is for the reader's convenience only. It does not form part of the European patent document. Even though great care has been taken in compiling the references, errors or omissions cannot be excluded and the EPO disclaims all liability in this regard.

    Patent documents cited in the description