KR102355604B1 - Light emitting device and light unit having thereof - Google Patents

Abstract

The embodiment relates to a light emitting device.
The light emitting device disclosed in the embodiment, the first conductive semiconductor layer; an active layer disposed on the first conductive semiconductor layer and having a plurality of barrier layers and a plurality of well layers; a plurality of superlattice layers disposed under the first conductive semiconductor layer; and a second conductive semiconductor layer on the active layer, wherein the plurality of superlattice layers include a first superlattice layer and a second superlattice layer disposed between the first superlattice layer and the first conductive semiconductor layer, , The first superlattice layer includes a plurality of pairs of first and second layers, the second superlattice layer includes a plurality of pairs of third and fourth layers, the first layer includes AlN, wherein the second to fourth layers include an AlGaN-based semiconductor, the third and fourth layers have an aluminum composition higher than that of the second layer, and the active layer emits an ultraviolet wavelength.

Description

A light emitting device and a light unit having the same

The embodiment relates to a light emitting device.

The embodiment relates to an ultraviolet light emitting device.

The embodiment relates to a light unit having an ultraviolet light emitting device.

In general, a nitride semiconductor material including a Group V source such as nitrogen (N) and a Group III source such as gallium (Ga), aluminum (Al), or indium (In) has excellent thermal stability and is a direct transition type energy source. Since it has a band structure, it is widely used as a material for a nitride-based semiconductor device, for example, a nitride-based semiconductor light emitting device in the ultraviolet region and a solar cell.

Nitride-based materials have a wide energy bandgap of 0.7eV to 6.2eV, and are often used as materials for solar cell devices due to their characteristics matching the solar spectrum region. In particular, the ultraviolet light emitting device is used in various industrial fields such as curing device, medical analyzer and treatment device, sterilization, water purification, and purification system, and is attracting attention as a material that can be used for general lighting as a semiconductor lighting light source in the future.

The embodiment provides a light emitting device having a plurality of superlattice layers under a first conductive semiconductor layer and a light unit having the same.

The embodiment provides a light emitting device capable of reducing defects by disposing a plurality of superlattice layers between a first conductive semiconductor layer and a substrate, and a light unit having the same.

The embodiment provides a light emitting device and a light unit having the same, in which the composition of aluminum of at least one layer of each pair of a plurality of superlattice layers gradually increases as it approaches the active layer.

The embodiment provides a light emitting device emitting an ultraviolet wavelength, for example, a UV (Ultraviolet) wavelength, and a light unit having the same.

A light emitting device according to an embodiment includes a first conductive semiconductor layer; an active layer disposed on the first conductive semiconductor layer and having a plurality of barrier layers and a plurality of well layers; a plurality of superlattice layers disposed under the first conductive semiconductor layer; and a second conductive semiconductor layer on the active layer, wherein the plurality of superlattice layers include a first superlattice layer and a second superlattice layer disposed between the first superlattice layer and the first conductive semiconductor layer, , The first superlattice layer includes a plurality of pairs of first and second layers, the second superlattice layer includes a plurality of pairs of third and fourth layers, the first layer includes AlN, wherein the second to fourth layers include an AlGaN-based semiconductor, the third and fourth layers have an aluminum composition higher than that of the second layer, and the active layer emits ultraviolet wavelengths.

A light unit according to an embodiment includes the light emitting device.

According to the light emitting device according to the embodiment, it is possible to remove the defect transferred to the active layer.

According to the light emitting device according to the embodiment, it is possible to improve the internal quantum efficiency.

The embodiment may improve the reliability of the ultraviolet light emitting device for sterilization.

The embodiment may provide a light emitting device package having an ultraviolet light emitting device and a light unit such as an ultraviolet lamp.

1 is a view showing a light emitting device according to an embodiment.
FIG. 2 is a view for explaining a plurality of superlattice layers of FIG. 1 .
FIG. 3 is an example in which electrodes are disposed in the light emitting device of FIG. 1 .
FIG. 4 is another example in which electrodes are disposed in the light emitting device of FIG. 1 .
5 is a cross-sectional view illustrating a light emitting device package including the light emitting device of FIG. 3 .
6 is a view showing another example of a light emitting device according to an embodiment.
7 is an example in which electrodes are disposed in the light emitting device of FIG. 6 .
8 is a cross-sectional view illustrating a light emitting device package including the light emitting device of FIG. 6 .
9 is a view showing a light unit having a light emitting device according to an embodiment.

In the description of the embodiment, each layer (film), region, pattern or structure is “on/over” or “under” the substrate, each layer (film), region, pad or patterns. )", "on/over" and "under/under" are "directly" or "indirectly" formed through another layer. includes all that is In addition, the criteria for the upper / upper or lower / lower of each layer will be described with reference to the drawings.

<Light emitting element>

1 is a cross-sectional view of a light emitting device according to an embodiment, and FIG. 2 is a detailed configuration diagram of a superlattice layer of the light emitting device of FIG. 1 .

1 and 2, the light emitting device according to the embodiment includes a substrate 21, a plurality of superlattice layers 31 and 35 disposed on the substrate 21, and the plurality of superlattice layers ( 31 and 35) a first conductive semiconductor layer 41 disposed on, an active layer 51 disposed on the first conductive semiconductor layer 41, and an electron blocking layer disposed on the active layer 51 ( 61 ) and a second conductive semiconductor layer 71 disposed on the electron blocking layer 61 .

The light emitting device emits light having an ultraviolet wavelength. The light emitting device may emit light at a wavelength of 300 nm or less, for example, in a range of 280 nm to 320 nm. The light emitting device may be a device that emits UV-B wavelengths.

The substrate 21 may be, for example, a light-transmitting, conductive, or insulating substrate. For example, the substrate 21 may include at least one _{of AlN, Al 2} O ₃ , SiC, Si, GaAs, GaN, ZnO, GaP, InP, Ge, and Ga ₂ O _{3 .} The substrate 21 may be, for example, an AlN template. A plurality of protrusions (not shown) may be formed on the upper and/or lower surfaces of the substrate 21, and each of the plurality of protrusions includes at least one of a hemispherical shape, a polygonal shape, and an elliptical shape and has a side cross-section. It may be arranged in a form or a matrix form. The protrusion may improve light extraction efficiency.

A plurality of compound semiconductor layers may be grown on the substrate 21 , and equipment for growing the plurality of compound semiconductor layers is an electron beam evaporator, physical vapor deposition (PVD), chemical vapor deposition (CVD), or plasma laser deposition (PLD). , a dual-type thermal evaporator may be formed by sputtering, metal organic chemical vapor deposition (MOCVD), or the like, but is not limited thereto.

A plurality of superlattice layers 31 and 35 may be disposed between the substrate 21 and the first conductive semiconductor layer 41 . An active layer 51 may be disposed on the first conductive semiconductor layer 41 .

The plurality of superlattice layers 31 and 35 may include at least two superlattice layers or more superlattice layers. Each of the plurality of superlattice layers 31 and 35 may include at least two different layers as one pair and include a plurality of pairs. In the plurality of superlattice layers 31 and 35, one layer of each pair may be implemented as, for example, a group II-VI or group III-V compound semiconductor, and the other layer is, for example, a group II-VI It may be implemented as a group or group III-V compound semiconductor.

At least one first semiconductor layer 33 may be disposed between the plurality of superlattice layers 31 and 35 . The first semiconductor layer 33 may be implemented as a group II-VI or group III-V compound semiconductor, and may have the same aluminum composition as any one of the superlattice layers 31 and 35 .

Referring to FIG. 2 , the plurality of superlattice layers 31 and 35 include first and second superlattice layers 31 and 35 , and the first superlattice layer 31 is a different AlN-based semiconductor. The layers may be alternately repeated, and the second superlattice layer 35 may be alternately repeated with different AlN-based semiconductor layers having an aluminum composition different from that of the aluminum of the first superlattice layer 31 . .

The first superlattice layer 31 is disposed between the substrate 21 and the second superlattice layer 35 , and the second superlattice layer 35 includes the first superlattice layer 31 and the second superlattice layer 35 . It may be disposed between the first conductive semiconductor layers 41 .

The first superlattice layer 31 includes a plurality of pairs of the first layer 11 and the second layer 12, and the pair may include 8 to 20 pairs, for example, 10 to 15 pairs. The first layer 11 may be AlN, and the second layer 12 may be a semiconductor having a composition formula _{of Al x} Ga _{1-x N (0.5≤x<0.6).} In the first superlattice layer 31 , a difference in aluminum composition between the first layer 11 and the second layer 12 may have a difference of 40% or more.

The thickness T1 of the first layer 11 in the first superlattice layer 31 is 15 nm or less, for example, in the range of 5 nm to 10 nm. The thickness T2 of the second layer 12 in the first superlattice layer 31 is 15 nm or less, and includes a range of 5 nm to 10 nm. By providing the thicknesses T1 and T2 of the first layer 11 and the second layer 12 of the first superlattice layer 31 in the above-described range, the lattice constant difference with the substrate 21 is Defects may be reduced and stress transferred to the second superlattice layer 35 may be reduced. The thicknesses T1 and T2 of the first layer 11 and the second layer 12 of the first superlattice layer 31 may be the same thickness or different thicknesses, but are not limited thereto.

Looking at the AlN/AlGaN stack structure of the first superlattice layer 31, the a-axis lattice constant values are arranged in the order of AlN>AlGaN>GaN, and when AlN is grown on AlGaN with a small a-axis lattice constant value, Compressive stress is applied, and when AlGaN is grown on AlN again, tensile stress is applied. By periodically repeating such AlGaN/AlN, compressive stress and tensile stress, which are opposite stresses, are offset. In addition, AlGaN and AlN can provide a stable superlattice structure because they have a crystallographically identical wurzite crystal structure.

The first semiconductor layer 33 may be formed of an AlGaN semiconductor on the first superlattice layer 31 . The first semiconductor layer 33 may have, for example, the same aluminum composition as that of the second layer 12 . The aluminum composition of the first semiconductor layer 33 may be between the aluminum composition of the second layer 12 of the first superlattice layer 31 and the aluminum composition of the second superlattice layer 35 .

The second superlattice layer 35 includes a plurality of pairs of the third layer 13 and the fourth layer 14, and the pair may include 8 to 20 pairs, for example, 10 to 15 pairs. The third layer 13 and the fourth layer 14 may be formed of an AlGaN-based semiconductor. The third layer 13 and the fourth layer 14 may have different aluminum compositions, and may have a higher aluminum composition than that of the second layer 12 . Since the third layer 13 and the fourth layer 14 have a difference in composition with the aluminum of the second layer 12 in the range of 0.5% to 20%, the first superlattice layer 33 ) can prevent the laser irradiated from being transmitted.

In the second superlattice layer 35 , the third layer 13 is _{a semiconductor material having a composition formula of Al y} Ga _1-y N (0.6<y<1), and the fourth layer 14 is Al _z Ga It can be formed of a semiconductor material having a compositional formula of _{1-z N (0.6<z<1).} In the second superlattice layer 33, the difference in the aluminum composition of the third layer 13 and the fourth layer 14 may have a difference of 10% or more, for example, under the condition of 0.6<z<y<1 and The condition of 0.1≤yz may be satisfied. Here, y may be 0.8≤y or less.

When the aluminum composition of the third and fourth layers 13 and 14 of the second superlattice layer 35 is less than 60%, there is a problem that light of a wavelength of 320 nm is not transmitted, and the aluminum composition is 80% If it is exceeded, a defect may occur in the surface adjacent to the active layer 51 . By setting the aluminum composition of the second superlattice layer 35 to more than 60%, light having a UV-B wavelength or a wavelength of 320 nm or less can be transmitted and the occurrence of defects can be suppressed.

The thickness T3 of the third layer 13 in the second superlattice layer 35 is 15 nm or less, for example, in the range of 5 nm to 10 nm, and the thickness T4 of the fourth layer 14 is 15 nm or less, for example 5 nm to 10 nm. By providing the thickness (T3, T4) of the third layer 13 and the fourth layer 14 of the second superlattice layer 35 in the above-described range, it is transmitted through the first superlattice layer 31 . It is possible to reduce the defects and reduce the stress transferred to the active layer 51 . The thickness T3 of the third layer 13 of the second superlattice layer 33 may be the same as or different from the thickness T4 of the fourth layer 14, but is not limited thereto.

The second superlattice layer 35 may be formed in a DBR (Distributed Bragg Reflector) structure due to a difference in aluminum composition between the third layer 13 and the fourth layer 14 . Among the second layer 12 , the third layer 13 , and the fourth layer 14 of the plurality of superlattice layers 33 and 35 , the layer adjacent to the active layer 51 has a higher aluminum composition.

Since the first superlattice layer 31 is an AlN/AlGaN pair and the second superlattice layer 33 is disposed as an AlGaN/AlGaN pair, it is possible to improve transmittance with respect to ultraviolet wavelengths.

In the embodiment, by disposing a plurality of superlattice layers 31 and 35 on the substrate 21 , it is possible to effectively block dislocation compared to a case in which a single n-type semiconductor layer is disposed on the substrate 21 and , it is possible to prevent deterioration in quality due to differences in lattice constants.

The plurality of superlattice layers 31 and 35 may include dopants of the first conductivity type, for example, n-type dopants such as Si, Ge, Sn, Se, and Te. The plurality of superlattice layers 31 and 35 may be n-type semiconductor layers, for example, the first to fourth layers 11, 12, 13, and 14 of each superlattice layer 31 and 35 are n-type semiconductor layers. this can be

Referring to FIG. 1 , the first conductive semiconductor layer 41 may be disposed on the plurality of superlattice layers 31 and 35 . The first conductive semiconductor layer 41 may be disposed on the second superlattice layer 35 . The first conductive semiconductor layer 41 may be disposed on the second layer 14 of the second superlattice layer 35 .

The first conductive semiconductor layer 41 may be formed of an AlGaN-based semiconductor, and the aluminum composition may be 60% or more.

The thickness T5 of the first conductive semiconductor layer 41 is thicker than the thickness T4 of the fourth layer 14 of the second superlattice layer 35 adjacent to the first conductive semiconductor layer 41, for example, It can be 10 times or more thick. The first conductive semiconductor layer 41 may have, for example, a composition of aluminum in a range of 60% to 80%, and a thickness in a range of 20 nm to 1000 nm. The aluminum of the first conductive semiconductor layer 41 has a difference of about 40% from the aluminum composition of AlN and is provided thickly, thereby reducing polarization and defects transmitted to the active layer 51 .

The first conductive semiconductor layer 41 may include other semiconductors including aluminum, for example, at least one of InAlGaN, AlInN, AlGaAs, and AlGaInP materials. The first conductive semiconductor layer 41 may be an n-type semiconductor layer doped with a first conductive dopant, for example, an n-type dopant such as Si, Ge, Sn, Se, or Te.

The active layer 51 may be formed of at least one of a single well, a single quantum well, a multiple well, a multi quantum well (MQW) structure, a quantum wire (Quantum-Wire) structure, or a quantum dot structure. can

In the active layer 51, electrons (or holes) injected through the first conductive semiconductor layer 41 and holes (or electrons) injected through the second conductive semiconductor layer 71 meet each other, and the active layer ( 51) is a layer that emits light due to the difference in the band gap of the energy band according to the forming material.

The active layer 51 may be implemented with a compound semiconductor. The active layer 51 may be implemented, for example, by at least one of a group II-VI group and a group III-V compound semiconductor.

When the active layer 51 is implemented as a multi-well structure, the active layer 51 includes a plurality of well layers (not shown) and a plurality of barrier layers (not shown). In the active layer 51, well layers and barrier layers are alternately disposed. A pair of the well layer and the barrier layer may be formed in 2 to 30 cycles.

The well layer may be formed of, for example, _{a semiconductor material having a compositional formula of In x} Al _y Ga _1-xy N (0≤x≤1, 0≤y≤1, 0≤x+y≤1). The barrier layer may be formed of, for example, _{a semiconductor material having a compositional formula of In x} Al _y Ga _1-xy N (0≤x≤1, 0≤y≤1, 0≤x+y≤1).

The period of the well layer/barrier layer is, for example, InGaN/GaN, GaN/AlGaN, AlGaN/AlGaN, InGaN/AlGaN, InGaN/InGaN, AlGaAs/GaAs, InGaAs/GaAs, InGaP/GaP, AlInGaP/InGaP, InP contains at least one of the pairs of /GaAs.

The well layer of the active layer 51 according to the embodiment may be implemented with AlGaN, and the barrier layer may be implemented with AlGaN. The active layer 51 may emit ultraviolet light, for example, in a range of 200 nm to 290 nm.

The aluminum composition of the barrier layer has a higher composition than that of the aluminum of the well layer. The aluminum composition of the well layer may be in the range of 20% to 40%, and the aluminum composition of the barrier layer may be in the range of 40% to 95%. The barrier layer may include a dopant, for example, an n-type dopant.

The electron blocking layer 61 may be disposed on the active layer 51 . The electron blocking layer 61 may be formed of an AlGaN semiconductor, and may have a higher aluminum composition than the barrier layer of the active layer. The composition of aluminum of the electron blocking layer 61 may be 50% or more.

The electron blocking layer 61 may have a multilayer structure, for example, may include a plurality of semiconductor layers having different aluminum compositions, and at least one layer may have an aluminum composition of 50% or more.

The second conductive semiconductor layer 71 is disposed on the electron blocking layer 61 . The second conductive semiconductor layer 71 may include an AlGaN-based semiconductor. The second conductive semiconductor layer 71 may be a p-type semiconductor layer having a dopant of a second conductivity type, for example, a p-type dopant. As another example, the second conductive semiconductor layer 71 may include at least one of AlN, InAlGaN, AlInN, AlGaAs, and AlGaInP, and may include a p-type dopant such as Mg, Zn, Ca, Sr, or Ba. can The second conductive semiconductor layer 71 may be formed of an AlGaN-based semiconductor to prevent absorption of ultraviolet wavelengths.

The second conductive semiconductor layer 71 may be multi-layered, but is not limited thereto.

Although the embodiment has been described as n-type as the first conductivity type and p-type as the second conductivity type, as another example, the first conductivity type may be p-type and the second conductivity type may be n-type. Alternatively, the light emitting device may include any one of an np junction structure, a pn junction structure, an npn junction structure, and a pnp junction structure.

FIG. 3 shows an example in which electrodes are disposed in the light emitting device of FIG. 1 . In the description of FIG. 3 , the same parts as those of the above-described configuration will be referred to in the description of the above-described embodiment.

Referring to FIG. 3 , the light emitting device 101 includes a first electrode 91 and a second electrode 95 . The first electrode 91 is electrically connected to a first conductive semiconductor layer, for example, any one of the plurality of superlattice layers 31 and 35, and the second electrode 95 is a second conductive semiconductor layer. (71) may be electrically connected.

The first electrode 91 may be disposed on the first conductive semiconductor layer, for example, on at least one of the plurality of superlattice layers 31 and 35 and the first conductive semiconductor layer 41 , and the second The electrode 95 may be disposed on the second conductive semiconductor layer 71 .

At least one or both of the first electrode 91 and the second electrode 95 may further have a current diffusion pattern having an arm structure or a finger structure. The first electrode 91 and the second electrode 95 may be made of non-transmissive metal having characteristics of an ohmic contact, an adhesive layer, and a bonding layer, but is not limited thereto. The first electrode 93 and the second electrode 95 are selected from Ti, Ru, Rh, Ir, Mg, Zn, Al, In, Ta, Pd, Co, Ni, Si, Ge, Ag and Au, and their selections. alloys can be selected.

An electrode layer (not shown) may be disposed between the second electrode 95 and the second conductive semiconductor layer 71, and the electrode layer is a transmissive material that transmits 70% or more of light or reflects 70% or more of light. It may be formed of a material having reflective properties, for example, it may be formed of a metal or a metal oxide. The electrode layer includes indium tin oxide (ITO), indium zinc oxide (IZO), indium zinc tin oxide (IZTO), indium aluminum zinc oxide (IAZO), indium gallium zinc oxide (IGZO), indium gallium tin oxide (IGTO), and AZO. (aluminum zinc oxide), antimony tin oxide (ATO), gallium zinc oxide (GZO), ZnO, IrOx, RuOx, NiO, Al, Ag, Pd, Rh, Pt, and Ir may be selectively formed. The electrode layer may have a laminate structure of a light-transmitting layer/reflective metal layer.

In addition, the substrate 21 may be provided with a thickness of 20 μm or less in order to reduce absorption of ultraviolet wavelengths. In addition, the substrate 21 may be separated from the light emitting device, but is not limited thereto. The light emitting device 101 according to the embodiment may emit light of an ultraviolet wavelength, for example, a UV-B wavelength.

FIG. 4 is a view showing an example of a vertical light emitting device using the light emitting device of FIG. 1 . In the description of FIG. 4 , the same parts as those of the above-described configuration will be referred to in the description of the above-described embodiment.

Referring to FIG. 4 , the light emitting device 102 includes a plurality of superlattice layers 31 and 35 , and at least one of the plurality of superlattice layers 31 and 35 , for example, a first on the first superlattice layer 31 . An electrode 91 is disposed, a first conductive semiconductor layer 41 and an active layer 51 are disposed under the plurality of superlattice layers 31 and 35 , and a plurality of conductive semiconductor layers 71 are disposed under the second conductive semiconductor layer 71 . and a second electrode having conductive layers 96 , 97 , 98 , 99 .

A first electrode 91 may be disposed on the upper surface 11A of the first superlattice layer 31 , and the first layer 11 or the second layer 12 of FIG. 2 is the first electrode 91 . ) can be in contact with The upper surface 11A may have a rough uneven structure, but is not limited thereto.

The second electrode is disposed under the second conductive semiconductor layer 71 , and includes a contact layer 96 , a reflective layer 97 , a bonding layer 98 , and a support member 99 . The contact layer 96 is in contact with a semiconductor layer, for example, the second conductive semiconductor layer 71 . The contact layer 96 may be formed of a low-conductivity material such as ITO, IZO, IZTO, IAZO, IGZO, IGTO, AZO, ATO, or a metal of Ni or Ag. A reflective layer 97 is disposed under the contact layer 96, and the reflective layer 97 is composed of Ag, Ni, Al, Rh, Pd, Ir, Ru, Mg, Zn, Pt, Au, Hf, and combinations thereof. It may be formed into a structure comprising at least one layer made of a material selected from the group. The reflective layer 97 may be in contact under the second conductive semiconductor layer 71 , but is not limited thereto.

A bonding layer 98 is disposed under the reflective layer 97, and the bonding layer 98 may be used as a barrier metal or a bonding metal, and the material is, for example, Ti, Au, Sn, Ni, Cr, at least one of Ga, In, Bi, Cu, Ag and Ta and an optional alloy.

A channel layer 83 and a current blocking layer 85 are disposed between the second conductive semiconductor layer 71 and the second electrode.

The channel layer 83 is formed along the lower edge of the second conductive semiconductor layer 71 and may be formed in a ring shape, a loop shape, or a frame shape. The channel layer 83 includes a transparent conductive material or an insulating material, for example, ITO, IZO, IZTO, IAZO, IGZO, IGTO, AZO, ATO, SiO ₂ , SiO _x , SiO _x N _y , Si ₃ N ₄ , At least one of Al ₂ O ₃ and TiO _{2 may be included.} An inner portion of the channel layer 163 is disposed under the second conductive semiconductor layer 71 , and an outer portion of the channel layer 163 is disposed more outside than a side surface of the light emitting structure.

The current blocking layer 85 may be disposed between the second conductive semiconductor layer 71 and the contact layer 96 or the reflective layer 97 . The current blocking layer 85 includes an insulating material, and may include, for example, at least one of _{SiO 2} , SiO _x , SiO _x N _y , Si ₃ N ₄ , Al ₂ O ₃ , and TiO _{2 .} As another example, the current blocking layer 85 may be formed of a metal for a Schottky contact.

The current blocking layer 85 is disposed to correspond to the first electrode 91 in a vertical direction. The current blocking layer 85 may block the current supplied from the second electrode and spread it to another path. One or a plurality of the current blocking layers 85 may be disposed, and at least a portion or an entire region of the first electrode 91 may overlap in a vertical direction.

A support member 99 is formed under the bonding layer 98 , and the support member 99 may be formed of a conductive member, and the material is copper (Cu-copper), gold (Au-gold), or nickel. It may be formed of a conductive material such as (Ni-nickel), molybdenum (Mo), copper-tungsten (Cu-W), or a carrier wafer (eg, Si, Ge, GaAs, ZnO, SiC, etc.). As another example, the support member 99 may be implemented as a conductive sheet.

Here, in order to provide the vertical light emitting device, the substrate of FIG. 1 is removed. In the method of removing the growth substrate, as shown in FIG. 5 , when a laser (eg, KrF) of a predetermined wavelength (248 nm) is irradiated onto the surface of the substrate 21 on the substrate 21, the The second layer 12 at a predetermined position in the first superlattice layer 31, that is, the layer having an aluminum composition of 60% or less is melted, and the substrate ( 21) can be lifted off.

In this case, the wavelength of the laser may not be transmitted by the DBR structure of the second superlattice layer 35 , and thus the active layer 51 may be protected.

Accordingly, the first superlattice layer 31 can be divided into a separated second region 31A and the remaining first region 31B, and the uppermost layer of the remaining first region 31B is the first It can be layer 11 or it can be part of the second layer 12 . Here, the surface of the first region 31B of the first superlattice layer 31 may be polished to expose the first layer 11 or the second layer 12 .

In addition, isolation etching may be performed in the direction in which the substrate 21 is removed, and the first electrode 91 may be formed on the first superlattice layer 31 and separated into individual chips.

Accordingly, the light emitting device 102 having a vertical electrode structure including the first electrode 91 on the light emitting structure and the support member 99 below may be manufactured. The light emitting device 102 according to the embodiment may emit light of an ultraviolet wavelength, for example, a UV-B wavelength.

<Light emitting device package>

FIG. 5 is a view showing a light emitting device package including the light emitting device of FIG. 4 .

Referring to FIG. 5 , the light emitting device package includes a support member 110 , a reflective member 111 having a cavity 112 on the support member 110 , an upper portion of the support member 110 and within the cavity 112 . The light emitting device 101 according to the embodiment includes a transparent window 115 on the cavity 112 .

The support member 110 is a resin-based printed circuit board (PCB), silicon-based such as silicon or silicon carbide (SiC), ceramic-based such as aluminum nitride (AlN), polyphthalic It may be formed of at least one of a resin series such as amide (polyphthalamide: PPA), liquid crystal polymer, and a metal core PCB (MCPCB) having a metal layer on the bottom, but is not limited to these materials.

The support member 110 includes a first metal layer 131 , a second metal layer 133 , a first connection member 138 , a second connection member 139 , a first electrode layer 135 , and a second electrode layer 137 . includes The first metal layer 131 and the second metal layer 132 are disposed on the bottom of the support member 110 to be spaced apart from each other. The first electrode layer 135 and the second electrode layer 137 are disposed on the upper surface of the support member 110 to be spaced apart from each other. The first connection member 138 may be disposed inside or on the first side surface of the support member 110 , and connects the first metal layer 131 and the first electrode layer 135 to each other. The second connection member 139 may be disposed inside or on the second side surface of the support member 110 , and connects the second metal layer 133 and the second electrode layer 137 to each other.

The first metal layer 131 , the second metal layer 133 , the first electrode layer 135 , and the second electrode layer 137 are made of a metal material, for example, titanium (Ti), copper (Cu), or nickel (Ni). , may be formed of at least one of gold (Au), chromium (Cr), tantalum (Ta), platinum (Pt), tin (Sn), silver (Ag), phosphorus (P), or a selective alloy thereof, It may be formed of a single metal layer or a multi-layered metal layer.

The first connecting member 138 and the second connecting member 139 include at least one of a via, a via hole, and a through hole.

The reflective member 111 is disposed around the cavity 112 on the support member 110 , and may reflect the ultraviolet light emitted from the light emitting device 101 .

The reflective member 111 is a resin-based printed circuit board (PCB), silicon-based such as silicon or silicon carbide (SiC), ceramic-based such as AlN (aluminum nitride; AlN), polyphthalamide It may be formed of at least one of a resin series such as (polyphthalamide: PPA) and a liquid crystal polymer, but is not limited to these materials. The support member 110 and the reflective member 111 may include a ceramic-based material, and the ceramic-based material has a higher heat dissipation efficiency than a resin material.

The light emitting device 101 may be disposed on the second electrode layer 137 or on the support member 110 , and may be electrically connected to the first electrode layer 135 and the second electrode layer 137 . do. The light emitting device 101 may be connected with a wire 121 . As another example, the light emitting device 101 may be bonded using a flip chip method.

The light emitting device 101 may emit ultraviolet light, or when a phosphor layer is disposed on the light emitting device 101, light of a different wavelength may be emitted.

The transparent window 115 is disposed on the cavity 112 and emits a peak wavelength emitted from the light emitting device 101 . The transparent window 115 may include a glass material, a ceramic material, or a light-transmitting resin material.

In addition, an optical lens or a phosphor layer may be further disposed on the cavity 112 , but the present disclosure is not limited thereto.

The light emitting device or the light emitting device package according to the embodiment may be applied to a light unit. The light unit is an assembly including one or a plurality of light emitting devices or light emitting device packages, and may include an ultraviolet lamp.

6 is a side cross-sectional view illustrating another example of a light emitting device according to the embodiment. In describing FIG. 6 , the same configuration as that of the first embodiment will be referred to with reference to the description of the first embodiment.

Referring to FIG. 6 , the light emitting device according to the embodiment includes a substrate 21 , a plurality of superlattice layers 31 and 35 disposed on the substrate 21 , and the plurality of superlattice layers 31 and 35 . ) a first conductive semiconductor layer 41 disposed on, an active layer 51 disposed on the first conductive semiconductor layer 41 , an electron blocking layer 61 disposed on the active layer 51 , and , a second conductive semiconductor layer 71 disposed on the electron blocking layer 61 , and a third conductive semiconductor layer 73 disposed on the second conductive semiconductor layer 71 .

The light emitting device emits light having an ultraviolet wavelength. The light emitting device may emit light at a wavelength of 320 nm or less, for example, in a range of 280 nm to 320 nm. The light emitting device may be a device that emits UV-B wavelengths.

A plurality of superlattice layers 31 and 35 may be disposed between the substrate 21 and the first conductive semiconductor layer 41 . An active layer 51 may be disposed on the first conductive semiconductor layer 41 .

The plurality of superlattice layers 31 and 35 includes first and second superlattice layers 31 and 35 as shown in FIG. 2 . The first superlattice layer 31 includes a pair of the first layer 11 and the second layer 12, and the pair may include 8 to 20 pairs, for example, 10 to 15 pairs. The first layer 11 may be AlN, and the second layer 12 may be a semiconductor having a composition formula _{of Al x} Ga _{1-x N (0.5≤x<0.6).} In the first superlattice layer 31 , a difference in aluminum composition between the first layer 11 and the second layer 12 may have a difference of 40% or more.

The first semiconductor layer 33 may be formed of an AlGaN semiconductor on the first superlattice layer 31 . The first semiconductor layer 33 may have, for example, the same aluminum composition as that of the second layer 12 . The aluminum composition of the first semiconductor layer 33 may be between the aluminum composition of the second layer 12 of the first superlattice layer 31 and the aluminum composition of the second superlattice layer 35 .

The second superlattice layer 35 includes a pair of the third layer 13 and the fourth layer 14, and the pair may include 8 to 20 pairs, for example, 10 to 15 pairs. The third layer 13 and the fourth layer 14 may be formed of an AlGaN-based semiconductor. The third layer 13 and the fourth layer 14 may have different aluminum compositions, and may have a higher aluminum composition than that of the second layer 12 . Since the third layer 13 and the fourth layer 14 have a difference in composition with the aluminum of the second layer 12 in the range of 0.5% to 20%, the first superlattice layer 33 ) can prevent the laser irradiated from being transmitted.

In the second superlattice layer 35 , the third layer 13 is _{a semiconductor material having a composition formula of Al y} Ga _1-y N (0.6<y<1), and the fourth layer 14 is Al _z Ga It can be formed of a semiconductor material having a compositional formula of _{1-z N (0.6<z<1).} In the second superlattice layer 33, the difference in the aluminum composition of the third layer 13 and the fourth layer 14 may have a difference of 10% or more, for example, under the condition of 0.6<z<y<1 and The condition of 0.1≤yz may be satisfied. Here, y may be 0.8≤y or less.

When the aluminum composition of the third and fourth layers 13 and 14 of the second superlattice layer 35 is less than 60%, there is a problem that light of a wavelength of 320 nm is not transmitted, and the aluminum composition is 80% If it is exceeded, a defect may occur in the surface adjacent to the active layer 51 . By setting the aluminum composition of the second superlattice layer 35 to more than 60%, light having a UV-B wavelength or a wavelength of 320 nm or less can be transmitted and the occurrence of defects can be suppressed.

The second superlattice layer 35 may be formed in a DBR (Distributed Bragg Reflector) structure due to a difference in aluminum composition between the third layer 13 and the fourth layer 14 . Among the second layer 12 , the third layer 13 , and the fourth layer 14 of the plurality of superlattice layers 33 and 35 , the layer adjacent to the active layer 51 has a higher aluminum composition.

Since the first superlattice layer 31 is an AlN/AlGaN pair and the second superlattice layer 33 is disposed as an AlGaN/AlGaN pair, it is possible to improve transmittance with respect to ultraviolet wavelengths.

The plurality of superlattice layers 31 and 35 may include dopants of the first conductivity type, for example, n-type dopants such as Si, Ge, Sn, Se, and Te. The plurality of superlattice layers 31 and 35 may be n-type semiconductor layers, for example, the first to fourth layers 11, 12, 13, and 14 of each superlattice layer 31 and 35 are n-type semiconductor layers. this can be The plurality of superlattice layers 31 and 35 will be described with reference to FIG. 2 .

A first conductive semiconductor layer 41 is disposed on the plurality of superlattice layers 31 and 35 , an active layer 51 is disposed on the first conductive semiconductor layer 41 , and an electron blocking layer is disposed on the active layer 51 . A layer 61 may be disposed, a second conductive semiconductor layer 71 may be disposed on the electron blocking layer 61 , and a third conductive semiconductor layer 73 may be disposed on the second conductive semiconductor layer 71 . have.

The second and third conductive semiconductor layers 71 and 73 may be formed of an AlGaN-based semiconductor, for example, AlGaN. The second conductive semiconductor layer 71 may have an aluminum composition of 50% or more, and a p-type dopant may be added thereto. The p-type dopant concentration may be in the range of 1E16cm-3 to 1E21cm-3, and when the p-type dopant concentration is lower than the range, hole injection efficiency is lowered, and when the p-type dopant concentration is higher than the range, the crystal quality may be lowered, and the third conductive semiconductor The electrical properties of the layer 73 may be affected.

When the third conductive semiconductor layer 73 is GaN, an ultraviolet wavelength is absorbed, so that light extraction efficiency may be reduced. In addition, when an oxide layer such as ITO is disposed on the third conductive semiconductor layer 73 , light extraction efficiency may be reduced due to absorption of ultraviolet wavelengths. The embodiment may provide a layer capable of ohmic contact with the second electrode 95 by the aluminum composition of the third conductive semiconductor layer 73 . To this end, the third conductive semiconductor layer 73 may be an electrode contact layer or an ohmic contact layer in contact with the second electrode 95 , and may be in ohmic contact with the second electrode 95 .

The aluminum composition of the third conductive semiconductor layer 73 may be 40% or less, for example, 20% to 40%. When the composition of the aluminum of the third conductive semiconductor layer 73 is out of the above range, the contact resistance with the second electrode 95 is increased. The third conductive semiconductor layer 73 may include a second conductive dopant, for example, a p-type dopant, and the p-type dopant concentration may be in the range of 1 Ecm-18 or more, for example, 1 Ecm-18 to 1 Ecm-21. , when the p-type dopant concentration is lower than the above range, the contact resistance is rapidly increased, and when it is higher than the above range, there is a problem in that the film quality is deteriorated and the ohmic characteristics are changed.

The third conductive semiconductor layer 73 may have a thickness of 50 nm or less, for example, a thickness of 40 nm or less, which may vary according to the transmittance of an ultraviolet wavelength according to the material and thickness of the third conductive semiconductor layer 73 .

The second electrode 95 is formed of a metal in contact with the third conductive semiconductor layer 73 , for example, Ti, Ru, Rh, Ir, Mg, Zn, Al, In, Ta, Pd, Co, Ni, Si, Ge. , Ag and Au and their optional alloys. By providing the second and third conductive semiconductor layers 73 and 75 , contact resistance with the second electrode 95 can be lowered and light transmittance can be improved.

FIG. 7 is an example in which electrodes are disposed in the light emitting device of FIG. 6 .

Referring to FIG. 7 , the light emitting device includes a substrate 21 , a plurality of superlattice layers 31 and 35 according to an embodiment, a first conductive semiconductor layer 41 , an active layer 51 , an electron blocking layer 61 , The second and third conductive semiconductor layers 73 and 75 according to the second embodiment are included.

The light emitting device includes a first electrode 91 and a second electrode 95 , and the first electrode 91 includes at least one of a plurality of superlattice layers 31 and 35 and a first conductive semiconductor layer 41 . It may be disposed under one, and the second electrode 95 may be disposed under the third conductive semiconductor layer 75 .

A contact layer and a reflective layer are included between the second electrode 95 and the third conductive semiconductor layer 75 , and the contact layer includes indium tin oxide (ITO), indium zinc oxide (IZO), and indium zinc tin (IZTO). 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), ZnO, At least one or a mixture of IrOx, RuOx, NiO, Al, Ag, Pd, Rh, Pt, and Ir is included, and the reflective layer may include at least one of Al, Ag, Pd, Rh, Pt, and Ir. have.

The substrate 21 may have a thickness of 20 μm or less to minimize light absorption and improve light transmittance. In addition, a light extraction structure 21A such as roughness may be disposed on the upper surface of the substrate 21 .

The substrate 21 may be a bulk AlN substrate or a sapphire substrate for growth of AlGaN, which is the first layer 11 , 13 , 15 , and 17 of the first superlattice layer 31 .

The light emitting device 103 may be arranged in a flip structure to extract light in the direction of the substrate. For example, the light emitting device of FIG. 7 may be mounted in a flip-chip structure as shown in FIG. 8 .

9 may provide a light source module having a light emitting device or a light emitting device package according to an embodiment. The light source module according to the embodiment may be a light unit.

Referring to FIG. 9 , the light source module according to the embodiment includes a light emitting device package 201 having a light emitting device 103 disclosed in the embodiment, a circuit board 301 on which the light emitting device package 201 is disposed, and the light emitting device. It includes a device package 201 and a moisture-proof film 275 covering the circuit board 301 .

The light emitting device package 201 includes a body 210 having a cavity 211 , a plurality of electrodes 221 and 225 disposed in the cavity 211 , and a light emitting device disposed on at least one of the plurality of electrodes 221 and 225 . 103 , a transparent window 261 disposed on the cavity 111 .

The light emitting device 103 may include a selective peak wavelength within a range from an ultraviolet wavelength to a visible light wavelength. The light emitting device 103 may emit, for example, a UV-B wavelength, that is, an ultraviolet wavelength in the range of 280 nm to 320 nm.

The body 210 includes an insulating material, for example, a ceramic material. The ceramic material includes a co-fired low temperature co-fired ceramic (LTCC) or a high temperature co-fired ceramic (HTCC). The material of the body 210 may be, for example, AlN, and may be formed of a metal nitride having a thermal conductivity of 140 W/mK or more.

The upper periphery of the body 210 includes a stepped structure 215 . The stepped structure 215 is a region lower than the upper surface of the body 210 and is disposed around the upper portion of the cavity 211 . The depth of the stepped structure 215 is a depth from the upper surface of the body 210 , and may be formed to be deeper than the thickness of the transparent window 261 , but is not limited thereto.

The cavity 211 is a region in which a part of the upper region of the body 210 is open, and may be formed to a predetermined depth from the upper surface of the body 210 .

The electrodes 221 and 225 in the cavity 211 and the body 210 may be electrically connected to electrode pads 241,245 disposed on the lower surface of the body 210 . The materials of the electrodes 221 and 225 and the electrode pads 241,245 are metal, for example, platinum (Pt), titanium (Ti), copper (Cu), nickel (Ni), gold (Au), tantalum (Ta), aluminum ( Al) may be optionally included.

The light emitting device 103 may be mounted on the electrodes 221 and 225 in the cavity 211 in a flip-chip method without a separate wire. The light emitting device 103 is an ultraviolet light emitting diode according to the first and second embodiments, and may be an ultraviolet light emitting device having a wavelength in the range of 280 nm to 320 nm.

The transparent window 261 is disposed on the cavity 211 . The transparent window 261 includes a glass material, for example, quartz glass. Accordingly, the transparent window 261 may be defined as a material that can transmit the light emitted from the light emitting device 103 without damage such as breakage of bonds between molecules by, for example, ultraviolet wavelengths.

The transparent window 261 has an outer circumference coupled to the stepped structure 215 of the body 210 . An adhesive layer 263 is disposed between the transparent window 261 and the stepped structure 215 of the body 210 , and the adhesive layer 263 includes a resin material such as silicone or epoxy.

The transparent window 261 may be spaced apart from the light emitting device 103 . Since the transparent window 261 is spaced apart from the light emitting device 103 , it is possible to prevent expansion due to heat generated by the light emitting device 103 .

The circuit board 301 includes a plurality of bonding pads 304 and 305 , and the plurality of bonding pads 304 and 305 may be electrically connected to pads 241,245 disposed on the lower surface of the body 210 .

The circuit board 301 may be connected to signal cables 311 and 313 through external connection terminals 307 and 308, and the signal cables 311 and 313 supply power from the outside.

The moisture barrier film 275 is disposed on the upper surface and side surfaces of the light emitting device package 201 and the upper surface of the circuit board 301 . The moisture-proof film 275 is disposed on the upper surface of the transparent window 261 of the light emitting device package 201 , and on the upper surface and side surfaces of the body 210 . The extension portion 271 of the moisture-proof film 275 is disposed to extend from a side surface of the body 210 to an upper surface of the circuit board 301 .

The moisture-proof film 275 is a fluororesin-based material, and may transmit the light without being destroyed by the light emitted from the light emitting device 103 . The moisture-proof film 275 may be used as at least one of polychlorotrifluoroethylene (PCTFE), ethylene + tetrafluoroethylene (ETFE), fluorinated ethylene propylene copoly-mer (FEP), and perfluoroalkoxy (PFA).

The moisture-proof film 275 may block not only moisture or moisture penetrating into the circuit board 301 , but also moisture or moisture penetrating through the side and top surfaces of the light emitting device package 201 . The thickness of the moisture-proof film 275 may be formed in the range of 0.5 μm-10 μm, and when the thickness of the moisture-proof film 275 exceeds the above range, the light transmittance is significantly reduced, and if it is less than the range, the Habits drop.

The moisture-proof film 275 may be spaced apart from bonding regions of the external connection terminals 307 and 308 and the signal cables 311 and 313 . As another example, the moisture-proof film 275 may cover the external connection terminals 307 and 308 . In this case, the moisture-proof film 275 may prevent penetration of moisture or moisture through the external connection terminals 307 and 308 .

Features, structures, effects, etc. described in the above embodiments are included in at least one embodiment of the present invention, and are not necessarily limited to only one embodiment. Furthermore, features, structures, effects, etc. illustrated in each embodiment can be combined or modified for other embodiments by those of ordinary skill in the art to which the embodiments belong. Accordingly, the contents related to such combinations and modifications should be interpreted as being included in the scope of the present invention.

In addition, although the embodiment has been described above, it is merely an example and does not limit the present invention, and those of ordinary skill in the art to which the present invention pertains are exemplified above in a range that does not depart from the essential characteristics of the present embodiment. It can be seen that various modifications and applications that have not been made are possible. For example, each component specifically shown in the embodiment can be implemented by modification. And differences related to such modifications and applications should be construed as being included in the scope of the present invention defined in the appended claims.

11,13,15,17: first floor 12,14,16,18: second floor
21: substrate 31, 35: superlattice layer
33: first semiconductor layer 41: first conductive semiconductor layer
51: active layer 61: electron blocking structure layer
71: second conductive semiconductor layer 73: third conductive semiconductor layer
75: contact layer 77: reflective layer
91: first electrode 95: second electrode

Claims (12)

a first conductive semiconductor layer;
an active layer disposed on the first conductive semiconductor layer and having a plurality of barrier layers and a plurality of well layers;
a plurality of superlattice layers disposed under the first conductive semiconductor layer; and
A second conductive semiconductor layer is included on the active layer,
The plurality of superlattice layers includes a first superlattice layer and a second superlattice layer disposed between the first superlattice layer and the first conductive semiconductor layer,
The first conductive semiconductor layer and the second conductive semiconductor layer include an AlGaN-based semiconductor,
The first superlattice layer has a plurality of pairs of first and second layers,
The second superlattice layer has a plurality of pairs of third and fourth layers,
The first layer is AlN,
The second to fourth layers include an AlGaN-based semiconductor,
The third and fourth layers have an aluminum composition higher than that of the second layer,
The first layer and the second layer have a composition difference of 40% or more of aluminum,
The third layer and the fourth layer have an aluminum composition of more than 60%, and have different compositions,
The active layer is a light emitting device that emits ultraviolet wavelengths. The method of claim 1,
The difference in the composition of aluminum between the third layer and the fourth layer is 10% or more,
The third layer has an aluminum composition of 80% or less, and the light emitting device is disposed closer to the first superlattice layer than the fourth layer. 3. The method of claim 2,
A first semiconductor layer having the same aluminum composition as that of the second layer of the first superlattice layer is further included between the first superlattice layer and the second superlattice layer,
The first semiconductor layer is a light emitting device formed of an AlGaN semiconductor. 4. The method according to any one of claims 1 to 3,
The first conductive semiconductor layer and the plurality of superlattice layers include an n-type dopant,
The second conductive semiconductor layer includes a p-type dopant,
Including an AlN substrate disposed under the plurality of superlattice layers,
The active layer is a light emitting device that emits UV-B wavelength. a body having a cavity;
The light emitting device of claim 4 disposed in the cavity;
a transparent window over the cavity; and
Having a moisture-proof film disposed on the transparent window and the body,
The light emitting device includes a first electrode under any one of the plurality of superlattice layers; and a second electrode having a reflective layer on the second conductive semiconductor layer. delete delete delete delete delete delete delete

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