In the description of the embodiment according to the invention, in the case where it is described as being formed on the "top" or "bottom" of each component, the top (bottom) or the bottom (bottom) is that the two components are It includes both direct contact or one or more other components disposed between and formed between the two components. In addition, when expressed as "up (up) or down (down)" may include the meaning of the down direction as well as the up direction based on one component.
1 is a plan view showing a light emitting device according to the first embodiment, Figure 2 is a cross-sectional view showing a light emitting device according to the first embodiment.
1 and 2, the light emitting device 1 according to the first embodiment may include a first light emitting structure 11, a plurality of second light emitting structures 21, and first to third electrodes 23, 25, 27).
The light emitting device 1 according to the first embodiment may include a lateral type light emitting device.
The first light emitting structure 11 may be grown on the growth substrate 3.
Although not shown, the light emitting device 1 according to the first embodiment may further include a buffer layer disposed between the growth substrate 3 and the first light emitting structure 11, but is not limited thereto.
The light emitting device 1 according to the first embodiment may further include an electrode layer 13 disposed between the first light emitting structure 11 and the plurality of second light emitting structures 21, but is not limited thereto. Do not.
The first light emitting structure 11 and the plurality of second light emitting structures 21 may be electrically connected to each other with the electrode layer 13 therebetween.
When the electrode layer 13 is not formed, the plurality of second light emitting structures 21 may be in contact with the first light emitting structure 11, but is not limited thereto.
The first electrode 23 may be disposed on one side of the first light emitting structure 11, and the second electrode 25 may be disposed on the other side of the first light emitting structure 11.
One side of the plurality of light emitting structures may be in contact with the electrode layer 13, and the other side of the plurality of light emitting structures may be electrically connected to the third electrode 27.
The buffer layer, the first light emitting structure 11 and the plurality of second light emitting structures 21 may be formed of Al x In y Ga (1-xy) N (0 ) made of a II-VI or III-V compound semiconductor material. <x <1, 0 <y <1, 0 <x + y <1). For example, the buffer layer, the first light emitting structure 11 and the plurality of second light emitting structures 21 may include at least one selected from the group consisting of InAlGaN, GaN, AlGaN, InGaN, AlN, InN, and AlInN. This is not limitative.
The growth substrate 3 may serve to grow the first light emitting structure 11. In addition, the growth substrate 3 may serve to support a layer disposed thereon, for example, the first light emitting structure 11. Therefore, the material of the growth substrate 3 may be selected in consideration of a difference in thermal expansion rate, a lattice constant difference, or a support strength with respect to the first light emitting structure 11. For example, the growth substrate 3 may be one of a conductive substrate, a compound semiconductor substrate, and an insulating substrate, but is not limited thereto. For example, the growth substrate 3 may be formed of at least one selected from the group consisting of sapphire (Al 2 O 3 ), SiC, Si, GaAs, GaN, ZnO, GaP, InP, and Ge.
The growth substrate 3 may include a dopant to have conductivity, but is not limited thereto. Therefore, the growth substrate 3 may be used as the electrode layer 13, but is not limited thereto.
If the difference in lattice constant and thermal expansion coefficient between the growth substrate 3 and the first light emitting structure 11 is still large, a buffer layer between the growth substrate 3 and the first light emitting structure 11 may be used. May be formed, but is not limited thereto.
The buffer layer may alleviate the lattice constant difference between the growth substrate 3 and the first light emitting structure 11. In addition, the buffer layer prevents recesses from being formed on the top surface of the growth substrate 3 by a melt-back phenomenon or controls stress to the first light emitting structure 11. Although cracks can be prevented or the growth substrate 3 is broken, the present invention is not limited thereto.
The buffer layer may be formed of a compound semiconductor material including Al to satisfy various functions described above. For example, the buffer layer may include AlN, AlGaN or InAlGaN, but is not limited thereto.
The first light emitting structure 11 may be disposed on the growth substrate 3 or the buffer layer.
The first light emitting structure 11 may include a plurality of compound semiconductor layers. The first light emitting structure 11 may include at least a first conductive semiconductor layer 5, a first active layer 7, and a second conductive semiconductor layer 9.
The first conductivity type semiconductor layer 5 may be disposed on the growth substrate 3 or the buffer layer. The first active layer 7 may be disposed on the first conductivity type semiconductor layer 5. The second conductivity type semiconductor layer 9 may be disposed on the first active layer 7.
The first conductive semiconductor layer 5 and the second conductive semiconductor layer 9 may include a dopant. The first active layer 7 may or may not include a dopant.
The dopant of the first conductive semiconductor layer 5 and the dopant of the second conductive semiconductor layer 9 may have opposite polarities. For example, the first conductivity-type semiconductor layer 5 may include an n-type dopant, and the second conductivity-type semiconductor layer 9 may include a p-type dopant, but is not limited thereto. The n-type dopant includes at least one of Si, Ge, Sn, Se, and Te, and the p-type dopant includes, but is not limited to, at least one of Mg, Zn, Ca, Sr, and Ba.
For example, the first conductivity type semiconductor layer 5 generates a first carrier, that is, electrons, is provided to the first active layer 7, and the second conductivity type semiconductor layer 9 is a second carrier, that is, a hole. And may be provided to the first active layer 7.
In the first active layer 7, electrons from the first conductivity-type semiconductor layer 5 and holes from the second conductivity-type semiconductor layer 9 may be recombined. By such recombination, light having a wavelength corresponding to an energy band gap determined by the material for forming the first active layer 7 may be emitted.
The first active layer 7 may include any one of a single quantum well structure (SQW), a multiple quantum well structure (MQW), a quantum dot structure, or a quantum line structure. In the first active layer 7, the well layer and the barrier layer may be repeatedly formed by using the well layer and the barrier layer as one cycle. Since the repetition period of the well layer and the barrier layer can be modified according to the characteristics of the light emitting device 1, the present invention is not limited thereto. The first active layer 7 may be formed, for example, with a period of InGaN / GaN, a period of InGaN / AlGaN, or a period of InGaN / InGaN.
The first active layer 7 may generate first light having a first wavelength. For example, the first light of the first wavelength may include one of ultraviolet light, visible light, and infrared light.
Another compound semiconductor layer may be disposed in a single layer or multiple layers below the first conductive semiconductor layer 5 or above the second conductive semiconductor layer 9, but is not limited thereto.
The electrode layer 13 may be disposed on the second conductive semiconductor layer 9 of the first light emitting structure 11. The electrode layer 13 may be formed of a material that can facilitate current spreading and current injection. In order to improve the current injection, the electrode layer 13 may be formed of a material having excellent ohmic contact characteristics with the second conductive semiconductor layer 9 of the first light emitting structure 11. The electrode layer 13 may be formed of a material having excellent light transmittance. The electrode layer 13 may include, for example, ITO, IZO (In-ZnO), GZO (Ga-ZnO), AZO (Al-ZnO), AGZO (Al-Ga ZnO), IGZO (In-Ga ZnO), IrOx, RuOx. At least one selected from the group consisting of RuOx / ITO, Ni / IrOx / Au, and Ni / IrOx / Au / ITO may be included, but is not limited thereto. From this, the electrode layer 13 may include at least one or more of a current spreading layer, an ohmic contact layer, and a light transmitting layer, but is not limited thereto.
Therefore, the current supplied to the electrode layer 13 is rapidly spread into the entire region of the electrode layer 13 and the second conductivity type semiconductor layer of the first light emitting structure 11 in contact with the electrode layer 13. It can be injected rapidly into (9).
The first electrode 23 may be disposed on a portion of the upper surface of the first conductive semiconductor layer 5 of the first light emitting structure 11. To this end, the first light emitting structure 11 may be etched to expose a portion of the upper surface of the first conductive semiconductor layer 5 of the first light emitting structure 11 to the outside. The first electrode 23 may be disposed on a portion of the upper surface of the second conductive semiconductor layer 9 exposed to the outside.
Although not shown, the first electrode 23 may be disposed in each of a plurality of regions of the top surface of the first conductivity-type semiconductor layer 5 of the first light emitting structure 11, but is not limited thereto.
The second electrode 25 may be disposed on a portion of the upper surface of the second conductive semiconductor layer 9 of the first light emitting structure 11. The second electrode 25 may be disposed on a portion of the upper surface of the electrode layer 13.
The second electrode 25 may be in contact with the top surface of the second conductive semiconductor layer 9 through the electrode layer 13, but is not limited thereto. The second electrode 25 may include a protrusion protruding downward from the lower surface of the second electrode 25, but is not limited thereto. The lower surface of the protrusion may contact the second conductive semiconductor layer 9, and the side surface of the protrusion may contact the inner surface of the recess of the electrode layer 13. The recess may include, but is not limited to, a hole penetrating the upper and lower surfaces of the electrode layer 13. The lower surface of the second electrode 25 except for the protrusion may contact a portion of the upper surface of the electrode layer 13 around the recess.
Meanwhile, the second electrode 25 may be in contact with the upper surface of the electrode layer 13 without penetrating the electrode layer 13, but the embodiment is not limited thereto.
The first electrode 23 and the second electrode 25 may be formed of a metal material having excellent electrical conductivity, barrier properties, bonding properties, and / or reflection properties. The first electrode 23 and the second electrode 25 may include, for example, one or a multilayer structure selected from the group consisting of Al, Ti, Cr, Ni, Pt, Au, W, Cu, and Mo. This is not limitative.
The second electrode 25 may be used as a common electrode for supplying power to the first light emitting structure 11 and the plurality of second light emitting structures 21. The current supplied to the second electrode 25 is supplied to the second conductive semiconductor layer 9 of the first light emitting structure 11, while the electrode layer 13 or the first light emitting structure 11 is The second conductive semiconductor layer 9 may be supplied to the third conductive semiconductor layer 15 of the plurality of second light emitting structures 21.
The plurality of second light emitting structures 21 may be disposed on the electrode layer 13. When the electrode layer 13 is not formed, the plurality of second light emitting structures 21 may be formed on the second conductive semiconductor layer 9 of the first light emitting structure 11.
Each of the plurality of second light emitting structures 21 may have a nanorod shape, but is not limited thereto. The second light emitting structure 21 may be formed long in the longitudinal direction of the second light emitting structure 21.
The plurality of second light emitting structures 21 may be spaced apart from each other. The separation distance between the plurality of second light emitting structures 21 may or may not be constant. The plurality of second light emitting structures 21 may be spaced apart from each other at regular intervals or at random intervals from each other.
When viewed from above, the second light emitting structure 21 may be a polygon, such as a triangle, a rectangle, a circle, or an oval, but is not limited thereto.
The second light emitting structure 21 may be formed using a growth method or an etching method, but is not limited thereto.
The height of the second light emitting structure 21 may be about 10nm to 5㎛. Specifically, the height of the second light emitting structure 21 may be about 100nm to about 3㎛, but is not limited thereto. The height of the second light emitting structure 21 may be approximately 500 nm to 2 μm, but is not limited thereto.
Growth above the upper limit of the height of the second light emitting structure 21 is difficult and it is difficult to expect an excellent quantum effect (quantum effect). Below the lower limit of the height of the second light emitting structure 21, the amount of electrons or holes generated in the second light emitting structure 21 is reduced, the light efficiency may be lowered.
The height of the second light emitting structure 21 may be at least the sum of the height of the third conductive semiconductor layer 15, the height of the second active layer 17, and the height of the fourth conductive semiconductor layer 19. However, this is not limitative.
The diameter of the second light emitting structure 21 may be about 5nm to about 2㎛. Specifically, the diameter of the second light emitting structure 21 may be about 200nm to about 2㎛, but is not limited thereto. More specifically, the diameter of the second light emitting structure 21 may be about 700 nm to about 1 μm, but is not limited thereto.
The diameter of the second light emitting structure 21 is at least one of the diameter of the third conductive semiconductor layer 15, the diameter of the second active layer 17, and the diameter of the fourth conductive semiconductor layer 19. It may be a diameter, but is not limited thereto.
Each of the plurality of second light emitting structures 21 may include a plurality of compound semiconductor layers. The second light emitting structure 21 may include at least a third conductive semiconductor layer 15, a second active layer 17, and a fourth conductive semiconductor layer 19.
The third conductive semiconductor layer 15 may be disposed on the second conductive semiconductor layer 9 or the electrode layer 13 of the first light emitting structure 11. The second active layer 17 may be disposed on the third conductive semiconductor layer 15. The fourth conductive semiconductor layer 19 may be disposed on the second active layer 17.
The third conductive semiconductor layer 15 and the fourth conductive semiconductor layer 19 may include a dopant. The second active layer 17 may or may not include a dopant.
The dopant of the third conductive semiconductor layer 15 and the dopant of the fourth conductive semiconductor layer 19 may have opposite polarities. For example, the third conductivity-type semiconductor layer 15 may include a p-type dopant, and the fourth conductivity-type semiconductor layer 19 may include an n-type dopant, but is not limited thereto. The n-type dopant includes at least one of Si, Ge, Sn, Se, and Te, and the p-type dopant includes, but is not limited to, at least one of Mg, Zn, Ca, Sr, and Ba.
For example, the third conductivity type semiconductor layer 15 generates holes and is provided to the second active layer 17, and the fourth conductivity type semiconductor layer 19 generates electrons to form the second active layer 17. It may be provided as.
In the second active layer 17, holes from the third conductive semiconductor layer 15 and electrons from the fourth conductive semiconductor layer 19 may be recombined. By such recombination, light having a wavelength corresponding to an energy band gap determined by the material for forming the second active layer 17 may be emitted.
Since the specific structure of the second active layer 17 is the same as that of the first active layer 7 of the first light emitting structure 11, further description thereof will be omitted.
The second active layer 17 may generate second light having a second wavelength. For example, the second light of the second wavelength may include one of ultraviolet light, visible light, and infrared light.
For example, the first light generated in the first active layer 7 of the first light emitting structure 11 and the second light generated in the second active layer 17 of the second light emitting structure 21 are different from each other. It may have a band. For example, the first light may include ultraviolet rays, and the second light may include visible rays.
Another compound semiconductor layer may be disposed under the third conductive semiconductor layer 15 or above the fourth conductive semiconductor layer 19 in a single layer or multiple layers, but is not limited thereto.
All of the plurality of second light emitting structures 21 may be in contact with the top surface of the electrode layer 13 or the top surface of the second conductive semiconductor layer 9 of the first light emitting structure 11 for electrical connection. .
The electrode layer 13 may be formed in a plate shape having a size similar to that of the second light emitting structure 21.
Although not shown, the electrode layer 13 may be formed in a matrix shape, but is not limited thereto. That is, the electrode layer 13 may include a plurality of first electrode 23 lines formed along one direction and a plurality of second electrode 25 lines formed to cross the plurality of first electrode 23 lines. have. The lines of the first electrode 23 may be spaced apart from each other, and the lines of the second electrode 25 may be spaced apart from each other. In this case, the third conductive semiconductor layer 15 of each of the plurality of second light emitting structures 21 may be formed on an intersection area of the first electrode 23 line and the second electrode 25 line. However, this is not limitative.
The third electrode 27 may be disposed on the plurality of second light emitting structures 21. The third electrode 27 may be formed in a plate shape having a size similar to that of the first light emitting structure 11.
The third electrode 27 may be in contact with all of the plurality of second light emitting structures 21 for electrical connection. The third electrode 27 may be in contact with the top surface of the fourth conductive semiconductor layer 19 of each of the second light emitting structures 21. Therefore, the current supplied to the third electrode 27 may be supplied to the fourth conductive semiconductor layer 19 of the plurality of second light emitting structures 21.
The third electrode 27 may transmit both the first light of the first wavelength generated by the first light emitting structure 11 and the second light of the second wavelength generated by the second light emitting structure 21. It may be formed of a transparent conductive material, but is not limited thereto. The third electrode 27 may be formed of the same material as the electrode layer 13. The third electrode 27 may be formed of a graphene material. The third electrode 27 may be formed of a metal material having a very thin thickness such that light is transmitted. The third electrode 27 may include one of a light transmitting layer, a graphene layer, and a metal layer.
Although not shown, the third electrode 27 may be formed in a matrix shape, but is not limited thereto. The third electrode 27 may include a plurality of first electrode 23 lines formed along one direction and a plurality of second electrode 25 lines formed to intersect the plurality of first electrode 23 lines. have. The lines of the first electrode 23 may be spaced apart from each other, and the lines of the second electrode 25 may be spaced apart from each other. In this case, the fourth conductive semiconductor layer 19 of each of the plurality of second light emitting structures 21 may be formed under an intersection area of the first electrode 23 line and the second electrode 25 line. However, this is not limitative.
According to the first embodiment, as the second light emitting structure 21 is formed long in one direction, the electric field inherently present in the second light emitting structure 21, that is, the internal electric field is greatly reduced. Therefore, the light efficiency can be improved.
According to the first embodiment, since the diameter of the second light emitting structure 21 is very small, the light generated in the second active layer 17 of the second light emitting structure 21 is directed to the side of the second light emitting structure 21. The distance to reach is short. Therefore, the light generated in the second light emitting structure 21 is less likely to be lost in the second light emitting structure 21 and the likelihood of being extracted from the second light emitting structure 21 to the outside becomes high. The efficiency can be improved.
According to the first embodiment, at least two lights having different wavelengths can be produced in a single light emitting element 1, and white or other desired color can be obtained by mixing these at least two lights. Therefore, a separate phosphor is not used, and color rendering index (CRI) may be improved. In addition, the area occupied by the light emitting device can be reduced and manufacturing cost can be reduced as compared with the light emitting device that generates a single light.
3 to 11 illustrate a process of manufacturing the light emitting device according to the first embodiment.
Referring to FIG. 3, the first light emitting structure 11 may be grown on the growth substrate 3. The first light emitting structure 11 may include a plurality of compound semiconductor layers. The first light emitting structure 11 may include at least a first conductive semiconductor layer 5, a first active layer 7, and a second conductive semiconductor layer 9.
The first conductive semiconductor layer 5, the first active layer 7, and the second conductive semiconductor layer 9 may be sequentially formed on the growth substrate 3.
The first conductive semiconductor layer 5, the first active layer 7, and the second conductive semiconductor layer 9 may be formed by metal organic chemical vapor deposition (MOCVD) or chemical vapor deposition (CVD). Formation using one of Vapor Deposition, Plasma-Enhanced Chemical Vapor Deposition (PECVD), Molecular Beam Epitaxy (MBE) and Hydride Vapor Phase Epitaxy (HVPE) But it is not limited thereto.
The first conductive semiconductor layer 5 may be an n-type semiconductor layer including an n-type dopant, and the second conductive semiconductor layer 9 may be a p-type semiconductor layer including a p-type dopant, but is not limited thereto. I never do that.
4A and 4B, an electrode layer 13 may be formed on the second conductive semiconductor layer 9 of the first light emitting structure 11. The electrode layer 13 may be formed of a material capable of facilitating current spreading and current injection. In order to improve the current injection, the electrode layer 13 may be formed of a material having excellent ohmic contact characteristics with the second conductive semiconductor layer 9 of the first light emitting structure 11.
The first light emitting structure 11 may be etched to expose a portion of the top surface of the first conductive semiconductor layer 5. For example, the right edge region of the first light emitting structure 11 is etched in the vertical direction. Accordingly, the second conductive semiconductor layer 9 and the first active layer 7 of the first light emitting structure 11 are removed to expose a portion of the upper surface of the first conductive semiconductor layer 5 to the outside. Can be.
A portion of the electrode layer 13 may be selectively etched to form a recess 29 through which the top and bottom surfaces of the electrode layer 13 penetrate. A portion of the top surface of the second conductive semiconductor layer 9 of the first light emitting structure 11 may be exposed to the outside by the recess 29.
The first electrode 23 may be formed on a portion of the upper surface of the first conductive semiconductor layer 5 exposed to the outside from the first light emitting structure 11. The second electrode 25 may be formed on a portion of the upper surface of the second conductive semiconductor layer 9 exposed to the outside in the first light emitting structure 11. The second electrode 25 is in contact with the upper portion of the second conductive semiconductor layer 9 in the recess 29 and in contact with the upper portion of the electrode layer 13 around the recess 29. Can be.
The first electrode 23 and the second electrode 25 may be formed of a metal material having excellent electrical conductivity, barrier properties, bonding properties, and / or reflection properties.
5A and 5B, a plurality of second light emitting structures 21 may be grown on the growth substrate 31.
The growth substrate 31 may be formed of an oxide-based material such as Al 2 O 3 , Ga 2 O 3 , or a semiconductor material such as Si, SiC, GaAs, but is not limited thereto.
Each of the plurality of second light emitting structures 21 may include a fourth conductive semiconductor layer 19, a second active layer 17, and a third conductive semiconductor layer 15.
The fourth conductive semiconductor layer 19, the second active layer 17, and the third conductive semiconductor layer 15 may be sequentially formed on the growth substrate 31.
The fourth conductive semiconductor layer 19, the second active layer 17, and the third conductive semiconductor layer 15 may be formed by metal organic chemical vapor deposition (MOCVD) or chemical vapor deposition (CVD). Formation using one of Vapor Deposition, Plasma-Enhanced Chemical Vapor Deposition (PECVD), Molecular Beam Epitaxy (MBE) and Hydride Vapor Phase Epitaxy (HVPE) But it is not limited thereto.
The fourth conductive semiconductor layer 19 may be an n-type semiconductor layer including an n-type dopant, and the third conductive semiconductor layer 15 may be a p-type semiconductor layer including a p-type dopant, but is not limited thereto. I never do that.
By controlling growth conditions, such as growth temperature, gas flow rate, and the like, the plurality of fourth conductivity-type semiconductor layers 19 may be grown only in the vertical direction on the growth substrate 31. In this case, each of the plurality of fourth conductive semiconductor layers 19 may be spaced apart from each other.
Subsequently, a plurality of second light emitting structures 21 may be formed by sequentially growing the second active layer 17 and the third conductive semiconductor layer 15 on the fourth conductive semiconductor layer 19. .
The plurality of second light emitting structures 21 do not contact each other and may be grown independently.
Referring to FIG. 6, a support substrate 33 may be attached onto the plurality of second light emitting structures 21. The support substrate 33 may serve to support the plurality of second light emitting structures 21. The support substrate 33 may be formed of a conductive material or an insulating material having excellent support strength.
Referring to FIG. 7, after inverting the growth substrate 31, the growth substrate 31 may be removed.
The support substrate 33 may be disposed downward, and a plurality of second light emitting structures 21 may be positioned on the support substrate 33.
Referring to FIG. 8, a third electrode 27 may be attached onto the plurality of second light emitting structures 21. The third electrode 27 may be bonded to the plurality of second light emitting structures 21 using, for example, a bonding process, but is not limited thereto. A bonding layer (not shown) may be formed between the plurality of second light emitting structures 21 and the third electrodes 27 by a bonding process, but is not limited thereto. The bonding layer may include, for example, a metal material including at least one selected from the group consisting of Ti, Au, Sn, Ni, Nb, Cr, Ga, In, Bi, Cu, Ag, and Ta. .
The third electrode 27 may be formed of the same material as the electrode layer 13 illustrated in FIG. 4B. The third electrode 27 may be formed of a graphene material. The third electrode 27 may be formed of a metal material having a very thin thickness such that light is transmitted.
Referring to FIG. 9, after supporting the support substrate 33, the support substrate 33 is removed. The third electrode 27 may be disposed downward, and a plurality of second light emitting structures 21 may be positioned on the third electrode 27.
Referring to FIG. 10, the third electrode 27 illustrated in FIG. 9 may be positioned on the growth substrate 3 illustrated in FIGS. 4A and 4B. A plurality of second light emitting structures 21 may be positioned below the third electrode 27.
Referring to FIG. 11, a plurality of second light emitting structures 21 positioned below the third electrode 27 are attached onto the electrode layer 13, so that the light emitting device according to the first embodiment may be manufactured. . The plurality of second light emitting structures 21 may be attached onto the electrode layer 13 by using a bonding process, but is not limited thereto.
A bonding layer (not shown) may be formed between the plurality of second light emitting structures 21 and the third electrodes 27 by a bonding process, but is not limited thereto. The bonding layer may include, for example, a metal material including at least one selected from the group consisting of Ti, Au, Sn, Ni, Nb, Cr, Ga, In, Bi, Cu, Ag, and Ta. .
It has been described that the plurality of second light emitting structures 21 are grown in the shape of nanorods using a growth method.
In an embodiment, a plurality of second light emitting structures 21 may be formed using an etching method. That is, the third conductive semiconductor layer 15, the second active layer 17, and the fourth conductive semiconductor layer 19 are collectively formed, and then the fourth conductive semiconductor layer 19 and the mask are formed by using a mask. By selectively etching the second active layer 17 and the third conductive semiconductor layer 15, a plurality of second light emitting structures 21 may be formed.
12 is a plan view of the light emitting device according to the second embodiment, and FIG. 13 is a cross-sectional view of the light emitting device according to the second embodiment.
The second embodiment is similar to the first embodiment except that the diameters of each of the plurality of second light emitting structures 21 are different from each other. Therefore, in the second embodiment, the same reference numerals are assigned to components having the same function, the same kind of material, and / or the same shape as the first embodiment, and detailed description thereof will be omitted.
12 and 13, the light emitting device 1A according to the second embodiment may include a growth substrate 3, a first light emitting structure 11, a plurality of second light emitting structures 21, and first to third layers. It may include electrodes 23, 25, 27.
The light emitting device 1A according to the second embodiment may further include, but is not limited to, an electrode layer 13 disposed between the first light emitting structure 11 and the plurality of second light emitting structures 21. Do not.
Although not shown, the light emitting device 1A according to the second embodiment may further include a buffer layer disposed between the first light emitting structure 11 and the growth substrate 3, but is not limited thereto.
The first light emitting structure 11 may be disposed on the growth substrate 3. The plurality of second light emitting structures 21 may be disposed on the first light emitting structure 11.
The electrode layer 13 may or may not be disposed between the first light emitting structure 11 and the plurality of second light emitting structures 21.
When the electrode layer 13 is disposed between the first light emitting structure 11 and the plurality of second light emitting structures 21, an upper surface of the first light emitting structure 11 is formed on a lower surface of the electrode layer 13. The bottom surface of the plurality of second light emitting structures 21 may be in contact with the top surface of the electrode layer 13.
When the electrode layer 13 is not disposed between the first light emitting structure 11 and the plurality of second light emitting structures 21, a lower surface of the plurality of second light emitting structures 21 may be formed in the first light emitting structure. It may be in contact with the upper surface of (11).
The first light emitting structure 11 may include at least a first conductive semiconductor layer 5, a first active layer 7, and a second conductive semiconductor layer 9. The first conductivity type semiconductor layer 5 is disposed on the growth substrate 3 or the buffer layer, and the first active layer 7 is disposed on the first conductivity type semiconductor layer 5. The second conductivity-type semiconductor layer 9 may be disposed on the first active layer 7.
The first conductive semiconductor layer 5 may be an n-type semiconductor layer, and the second conductive semiconductor layer 9 may be a p-type semiconductor layer, but is not limited thereto.
Each of the plurality of second light emitting structures 21 may include at least a third conductive semiconductor layer 15, a second active layer 17, and a fourth conductive semiconductor layer 19. The third conductive semiconductor layer 15 is disposed on the electrode layer 13 or the second conductive semiconductor layer 9 of the first light emitting structure 11, and the second active layer 17 is formed of the first conductive layer 17. The fourth conductive semiconductor layer 19 may be disposed on the third conductive semiconductor layer 15, and the fourth conductive semiconductor layer 19 may be disposed on the second active layer 17.
The third conductive semiconductor layer 15 may be a p-type semiconductor layer, and the fourth conductive semiconductor layer 19 may be an n-type semiconductor layer, but is not limited thereto.
For example, the first conductive semiconductor layer 5 and the fourth conductive semiconductor layer 19 include dopants having the same polarity, that is, n-type dopants, and the second conductive semiconductor layer 9 and the second conductive semiconductor layer 19 The three conductive semiconductor layer 15 may include a dopant having the same polarity, that is, a p-type dopant, but is not limited thereto.
The first electrode 23 is disposed on a portion of the top surface of the first conductive semiconductor layer 5 of the first light emitting structure 11, and the second electrode 25 is formed of the first light emitting structure 11. The second conductive semiconductor layer 9 may be disposed on a portion of the upper surface. The third electrode 27 may be disposed on an upper surface of each of the fourth conductive semiconductor layers 19 of the plurality of second light emitting structures 21.
When the electrode layer 13 is disposed between the first light emitting structure 11 and the plurality of second light emitting structures 21, the second electrode 25 penetrates the electrode layer 13 to allow the first light emitting structure to pass through the first light emitting structure 11. The upper surface of the second conductivity-type semiconductor layer 9 of the light emitting structure 11 may be in contact with the portion. The electrode layer 13 may include a recess to allow the second electrode 25 to pass therethrough. Therefore, the second electrode 25 may be in contact with a portion of the top surface of the second conductive semiconductor layer 9 of the first light emitting structure 11 through the recess of the electrode layer 13.
Unlike the first embodiment, in the second embodiment, the second plurality of light emitting structures may have different diameters.
As shown in FIG. 14, it can be seen that as the diameter d decreases in diameter, 1 / d increases, and as 1 / d increases, the change width ΔEg of the energy band gap increases. As the change width ΔEg of the energy bandgap is increased, the wavelength of light may be shortened.
For example, the plurality of second light emitting structures 21 may include a plurality of second light emitting structures 21a having a first diameter D1, a plurality of second light emitting structures 21b having a second diameter D2, and a plurality of second light emitting structures 21b having a first diameter D1. A plurality of second light emitting structures 21c having three diameters D3 may be included, but are not limited thereto.
The first diameter D1 may be smaller than the second diameter D2, and the second diameter D2 may be smaller than the third diameter D3.
For example, when the second light emitting structure 21b having the second diameter D2 is set to generate light having a green wavelength (about 450 nm to 500 nm), the first diameter D1 smaller than the second diameter D2 The second light emitting structure 21a having the second light emitting structure 21a is set to generate light having a blue wavelength (about 450 nm to 500 nm) and has a third diameter D1 larger than the second diameter D2. Set to produce light of this red wavelength (about 610 nm to about 700 nm),
The first to third light emitting structures 21a, 21b, and 21c may be regularly or randomly disposed on the electrode layer 13 or the first light emitting structure 11. For example, another second light emitting structure 21b or another second light emitting structure 21c may be disposed adjacent to the second light emitting structure 21a. For example, another second light emitting structure 21b may be disposed adjacent to the second light emitting structure 21b.
The second light emitting structure 21a having the first diameter D1, the second light emitting structure 21b having the second diameter D2, and the third light emitting structure 21c having the third diameter D3. When each of the blue light, the green light, and the red light, the first light emitting structure 11 may generate ultraviolet light or visible light, but is not limited thereto.
In the second embodiment, a single light emitting element 1A having light of red wavelength, light of green wavelength and white light by light of blue wavelength is possible.
For example, when the first light emitting structure 11 generates light having a blue wavelength, the second light emitting structure 21 may have a second light emitting structure 21b and a third diameter D3 having a second diameter D2. It may include a second light emitting structure (21c) having, but is not limited to this. The second light emitting structure 21b having the second diameter D2 may generate light having a green wavelength, and the second light emitting structure 21c having the third diameter D3 may generate light having a red wavelength. have. Therefore, white light may be realized by the first foot and the structure, the second light emitting structure 21b having the second diameter D2, and the second light emitting structure 21c having the third diameter D3.
15 is a plan view illustrating a light emitting device according to a third embodiment, and FIG. 16 is a cross-sectional view showing a light emitting device according to a third embodiment.
15 and 16, the light emitting device 1B according to the third embodiment may include a first light emitting structure 55, a plurality of second light emitting structures 63, and first to third electrodes 47, 67, 69).
The light emitting device 1B according to the third embodiment may be a vertical type light emitting device.
The first electrode 47 is disposed below the first light emitting structure 55, the second electrode 67 is disposed on a portion of the first light emitting structure 55, and the third electrode 69. ) May be disposed on the plurality of second light emitting structures 63.
The first light emitting structure 55 may include at least a first conductivity type semiconductor layer 49, a first active layer 51, and a second conductivity type semiconductor layer 53.
The first conductive semiconductor layer 49 is disposed on the first electrode 47, the first active layer 51 is disposed on the first conductive semiconductor layer 49, and the second conductive layer is disposed on the first conductive layer 51. The type semiconductor layer 53 may be disposed on the first active layer 51.
The first conductivity type semiconductor layer 49 may be a p-type semiconductor layer, and the second conductivity type semiconductor layer 53 may be an n-type semiconductor layer, but is not limited thereto.
The plurality of second light emitting structures 63 may be disposed on the first light emitting structure 55. The second light emitting structure 63 may include at least a third conductive semiconductor layer 57, a second active layer 59, and a fourth conductive semiconductor layer 61. The third conductive semiconductor layer 57 is disposed on the second conductive semiconductor layer 53 of the first light emitting structure 55, and the second active layer 59 is the third conductive semiconductor layer ( The fourth conductive semiconductor layer 61 may be disposed on the second active layer 59.
The third conductive semiconductor layer 57 may be an n-type semiconductor layer, and the fourth conductive semiconductor layer 61 may be a p-type semiconductor layer, but is not limited thereto.
For example, the first conductivity type semiconductor layer 49 and the fourth conductivity type semiconductor layer 61 include dopants having the same polarity, that is, a p type dopant, and the second conductivity type semiconductor layer 53 and the first conductivity type. The three conductive semiconductor layer 57 may include a dopant having the same polarity, that is, an n-type dopant, but is not limited thereto.
The first electrode 47 may be disposed under the first conductive semiconductor layer 49 of the first light emitting structure 55. The first electrode 47 may be an electrode layer having excellent electrical conductivity. At least one selected from the group consisting of Au, Ti, Ni, Cu, Al, Cr, Ag, and Pt may be used as the electrode layer. The electrode layer may be formed in a single layer or a multilayer structure. The first electrode 47 may be a reflective layer capable of reflecting light generated by the first light emitting structure 55 or the plurality of second light emitting structures 63. At least one or two or more alloys selected from the group consisting of Ag, Ni, Al, Rh, Pd, Ir, Ru, Mg, Zn, Pt, Au, and Hf may be used as the reflective layer, but is not limited thereto. The first electrode 47 may be an ohmic contact layer to facilitate injection of a current. The ohmic contact layer may be formed of indium tin oxide (ITO), indium zinc oxide (IZO), indium zinc tin oxide (IZTO), indium aluminum zinc oxide (IAZO), indium gallium zinc oxide (IGZO), or IGTO (indium). gallium tin oxide (AZO), aluminum zinc oxide (AZO), antimony tin oxide (ATO), gallium zinc oxide (GZO), IrOx, RuOx, RuOx / ITO, Ni, Ag, Ni / IrOx / Au and Ni / IrOx / Au / At least one selected from the group consisting of ITO can be used.
The first electrode 47 may be a multilayer including an electrode layer, a reflective layer, and an ohmic contact layer.
An area of the first electrode 47 may be larger than an area of the first light emitting structure 55, specifically, at least the first active layer 51, but is not limited thereto. Since the area of the first electrode 47 is larger than that of the first active layer 51, the light generated in the first active layer 51 and reflected in the slant direction can be reflected, thereby improving light extraction efficiency. Can be.
The second electrode 67 may be formed on a portion of the upper surface of the second conductive semiconductor layer 53 of the first light emitting structure 55. One of the metal materials used as the electrode layer of the first electrode 47 may be used as the second electrode 67.
When the second electrode 67 is formed of an opaque metal material, light extraction is prevented by the second electrode 67, so that the second electrode 67 has a pattern shape and the second conductive semiconductor layer. It may be formed on a portion of the upper surface of 53. In this case, the current flows intensively between the second electrode 67 and a portion of the first electrode 47 corresponding to the second electrode 67 perpendicularly, so that light is actively generated. Since the current does not flow well in the first light emitting structure 55 between the region where the second electrode 67 is not formed and the first electrode 47, light is not actively generated. In other words, light is not evenly generated in the entire region of the first light emitting structure 55. To solve this problem, although not shown, a current blocking layer may be formed under the first conductive semiconductor layer 49 corresponding to the second electrode 67 perpendicularly. The current blocking layer may be formed of an insulating material or a material having low electrical conductivity. Due to the current blocking layer, the current does not flow well so that the intensity of the current flowing in the first light emitting structure 55 corresponding to the second electrode 67 is reduced, but instead, the second electrode 67 is formed. The intensity of the current flowing through the first light emitting structure 55 is increased, so that a relatively uniform current flows in the vertical direction over the entire area of the first light emitting structure 55, thereby preventing the first light emitting structure 55. Light can be generated evenly over the entire area.
In order to improve light extraction efficiency of the first light emitting structure 55, a light extraction structure 71 may be formed on an upper surface of the first light emitting structure 55, that is, an upper surface of the second conductive semiconductor layer 53. Can be. The light extracting structure 71 may have roughness or convex-concavo.
The third electrode 69 may be formed in a plate shape. The third electrode 69 may be in contact with the top surface of the fourth conductive semiconductor layer 61 of each of the second light emitting structures 63 for electrical connection. Therefore, the current supplied to the third electrode 69 may be supplied to the fourth conductive semiconductor layer 61 of the plurality of second light emitting structures 63.
The third electrode 69 may transmit both the first light of the first wavelength generated by the first light emitting structure 55 and the second light of the second wavelength generated by the second light emitting structure 63. It may be formed of a transparent material, but is not limited thereto. The third electrode 69 may be formed of one of a transparent conductive material such as ITO, a graphene material, and a metal material having a very thin thickness such that light is transmitted.
Although not shown, the third electrode 69 may be formed in a matrix shape, but is not limited thereto.
A channel layer 45 may be formed between the peripheral area of the first light emitting structure 55 and the peripheral area of the first electrode 47. The channel layer 45 may prevent the electrical short between the first electrode 47 and the active layer or the second conductive semiconductor layer 53 of the first light emitting structure 55. ) And the active layer may further increase the gap.
The channel layer 45 may be formed in a closed-loop structure or an open-loop structure along a peripheral area of the first light emitting structure 55.
The channel layer 45 may include at least one selected from the group consisting of a transparent insulating material such as SiO 2 , SiO x , SiO x N y , Si 3 N 4 , and Al 2 O 3 .
An end of the first electrode 47 may overlap a portion of the bottom surface of the channel layer 45. The first electrode 47 may be embedded by the bonding layer 43 and may not be exposed to the outside. That is, the bonding layer 43 may be formed to surround the first electrode 47 and may contact the lower surface of the channel layer 45. For example, the bonding layer 43 may include a central region having a recess and a peripheral region protruding upward. The first electrode 47 may be disposed in the recess of the central region, and the upper surface of the peripheral region may contact the lower surface of the channel layer 45.
The support member 41 may be disposed below the bonding layer 43.
The bonding layer 43 may include a material capable of easily bonding the support member to the first electrode 47. The bonding layer 43 may include at least one selected from the group consisting of, for example, Ti, Au, Sn, Ni, Nb, Cr, Ga, In, Bi, Cu, Ag, and Ta.
The support member 41 may support a plurality of layers formed thereon. The support member 41 may be a conductive support substrate having conductivity. The support member 41 may be formed of a metal or a metal alloy such as titanium (Ti), chromium (Cr), nickel (Ni), aluminum (Al), platinum (Pt), gold (Au), tungsten (W), It may include at least one of copper (Cu), molybdenum (Mo) and copper-tungsten (Cu-W).
A protective layer 65 may be formed on the first light emitting structure 55. For example, a protective layer 65 may be formed on at least a side surface of the first light emitting structure 55.
The protective layer 65 may prevent electrical short between the light emitting structure and the support member 41, and may protect the light emitting device 1B from an external impact. The protective layer 65 may be formed of a material having excellent transparency and insulation. The protective layer 65 may include the same material as the channel layer 45 and / or the current blocking layer, but is not limited thereto.
Meanwhile, another embodiment in which the second light emitting structures 21a, 21b and 21c having different diameters of the second embodiment and the light emitting device 1B of the third embodiment is also possible.
In addition, the light emitting device according to the embodiment may be applied to a flip-chip type light emitting device, but is not limited thereto.
17 is a cross-sectional view illustrating a light emitting device package according to an embodiment.
Referring to FIG. 17, the light emitting device package according to the embodiment may include a package body 101, a first electrode layer 103 and a second electrode layer 105 installed on the package body 101, and the package body 101. The light emitting device 1 according to the first and second embodiments, which is installed in the first electrode layer 103 and the second electrode layer 105 and receives power, and surrounds the light emitting device 1. The molding member 113 is included.
The package body 101 may include a silicon material, a synthetic resin material, or a metal material, and an inclined surface may be formed around the light emitting device 1.
The first electrode layer 103 and the second electrode layer 105 are electrically separated from each other, and provide power to the light emitting device 1.
In addition, the first and second electrode layers 103 and 105 may increase light efficiency by reflecting light generated from the light emitting device 1, and discharge heat generated from the light emitting device 1 to the outside. It can also play a role.
The light emitting device 1 may be installed on any one of the first electrode layer 103, the second electrode layer 105, and the package body 101. The light emitting device 1 may be formed by a wire method, a die bonding method, or the like. It may be electrically connected to the two electrode layers 103 and 105, but is not limited thereto.
In the exemplary embodiment, the light emitting device 1 is electrically connected to one of the first and second electrode layers 103 and 105 through one wire 109, but is not limited thereto. The light emitting device 1 may be electrically connected to the first and second electrode layers 103 and 15 by using a wire, and the light emitting device 1 may be connected to the first and second electrode layers 103 without using a wire. 105 may be electrically connected.
The molding member 113 may surround the light emitting device 1 to protect the light emitting device 1. In addition, the molding member 113 may include a phosphor to change the wavelength of light emitted from the light emitting device 1.
The light emitting device package according to the embodiment includes a chip on board (COB) type, the top surface of the package body 101 is flat, a plurality of light emitting devices may be installed on the package body 101.
The light emitting device or the light emitting device package according to the embodiment may be applied to the light unit. The light unit may be applied to a unit such as a display device and a lighting device, for example, a lighting lamp, a traffic light, a vehicle headlight, an electric sign, an indicator lamp.
