KR20200014522A - Light emitting device and driving method thereof - Google Patents

Abstract

A light emitting device according to an embodiment of the present invention comprises: a conductive substrate; a plurality of light emitting cells which are arranged on the conductive substrate, include a first conductive semiconductor layer, an active layer, and a second conductive semiconductor layer, and are spaced apart from each other; and a first insulating layer arranged between the light emitting cells and the conductive substrate, wherein the light emitting cells are connected in series, each of the light emitting cells has a wavelength of light having the highest intensity among wavelengths of emitted light in an ultraviolet wavelength region, the first insulating layer includes a first insulating part arranged between the light emitting cells, the first insulating part includes a first protrusion part which protrudes from the conductive substrate toward an upper surface of the light emitting cells, and an upper surface of the first protrusion part may be arranged to be higher than an upper surface of the active layers and to be lower than an upper surface of the first conductive semiconductor layer.

Description

LIGHT EMITTING DEVICE AND DRIVING METHOD THEREOF

An embodiment of the invention relates to a light emitting device.

An embodiment of the present invention relates to an ultraviolet light emitting device having a plurality of light emitting cells.

An embodiment of the invention relates to a light emitting device package having a light emitting device having a plurality of light emitting cells.

An embodiment of the present invention relates to a method of driving a light emitting device having a plurality of light emitting cells.

Light emitting diodes (LEDs) are widely used as one of light emitting devices. Light-emitting diodes use the properties of compound semiconductors to convert electrical signals into light, such as infrared, visible and ultraviolet light.

LED light sources have the advantage of emitting light of various wavelength bands, such as red, green, blue and ultraviolet. Such LED light source lighting field, display field, information and communication technology, agriculture, life, marine, medical fields are used.

In the case of ultraviolet LED, it generates light of 200nm ~ 400nm, in the case of short wavelength ultraviolet light, it is used for sterilization, purification, etc., in the case of long wavelength ultraviolet light can be used in an exposure machine or a curing machine.

Ultraviolet rays can be classified into UV-A (315nm ~ 400nm), UV-B (280nm ~ 315nm), and UV-C (200nm ~ 280nm) in order of long wavelength. The UV-A (315nm ~ 400nm) area is applied to various fields such as industrial UV curing, printing ink curing, exposure machine, forgery discrimination, photocatalyst sterilization, special lighting (aquarium / agriculture, etc.) and UV-B (280nm ~ 315nm). ) Area is used for medical purposes, and UV-C (200nm ~ 280nm) area is applied to air purification, water purification and sterilization products.

An embodiment of the present invention provides a light emitting device having a plurality of light emitting cells.

An embodiment of the present invention provides an ultraviolet light emitting device having a plurality of light emitting cells.

An embodiment of the present invention provides a light emitting device including an electrode that connects adjacent light emitting cells under a plurality of light emitting cells.

Provided is a light emitting device package having a light emitting device according to an embodiment of the present invention.

An embodiment of the present invention can provide a method of driving a light emitting device in which a plurality of light emitting cells are connected in series.

An embodiment of the present invention can provide a method of driving a light emitting device in which a plurality of light emitting cells are connected in series.

A light emitting device according to an embodiment of the present invention includes a conductive substrate; A plurality of light emitting cells disposed on the conductive substrate and including a first conductive semiconductor layer, an active layer, and a second conductive semiconductor layer and spaced apart from each other; And a first insulating layer disposed between the plurality of light emitting cells and the conductive substrate, wherein the plurality of light emitting cells are connected in series, and each of the plurality of light emitting cells has the largest intensity among wavelengths of light emitted. The wavelength of light is an ultraviolet wavelength region, and the first insulating layer includes a first insulating portion disposed between the plurality of light emitting cells, and the first insulating portion is directed toward the top surfaces of the plurality of light emitting cells on the conductive substrate. The protrusion may include a first protrusion, and an upper surface of the first protrusion may be higher than an upper surface of the plurality of active layers and lower than an upper surface of the first conductive semiconductor layer.

According to an embodiment of the present invention, a plurality of first electrodes are disposed between the plurality of light emitting cells and the conductive substrate, and the first electrodes include a second protrusion that overlaps the first insulating portion in a vertical direction. The second protrusion may be higher than a bottom surface of the light emitting cell or a bottom surface of the second conductive semiconductor layer.

According to an embodiment of the present invention, a first recess is disposed in each of the plurality of light emitting cells, and the first recess extends from a lower surface of the second conductive semiconductor layer to a lower portion of the first conductive semiconductor layer. The first electrode may extend through the first recess and be electrically connected to the first conductive semiconductor layer.

According to an embodiment of the present invention, the plurality of light emitting cells include first, second and third light emitting cells spaced apart from each other, and the first to third light emitting cells are electrically connected to a second electrode disposed below. The second electrode connected to the first light emitting cell may be connected to the first electrode connected to the second light emitting cell, and the second electrode connected to the second light emitting cell may be connected to the first electrode connected to the third light emitting cell. have.

In example embodiments, the second light emitting cell may be disposed between the first and third light emitting cells, and the first protrusion may be disposed on at least two side surfaces of the second light emitting cell.

According to an embodiment of the present invention, the second light emitting cell is disposed between the first and third light emitting cells, and the first protrusion is an area in which the second light emitting cell and the first light emitting cell face each other, and the first light emitting cell faces each other. The second light emitting cell and the third light emitting cell may be disposed to face each other.

In example embodiments, the first insulating layer may include a second insulating part disposed in the first recess, and a width of an upper surface of the first insulating part may be wider than a gap between the light emitting cells.

According to an embodiment of the present invention, the outer side of each light emitting cell may include an outer recess having an inclined side surface, and the depth of the outer recess of each of the light emitting cells may be equal to the depth of the first recess.

In example embodiments, the first electrode includes a connection part connected to the first conductive semiconductor layer in the first recess, and the length of the connection part is greater than a distance between the first recesses of the light emitting cells. Can be large.

According to an embodiment of the present invention, the length of the first recess has a long length in one direction, the length direction of the first recess is disposed in the same direction in each of the light emitting cells, and the first recess The longitudinal direction of may be disposed in a direction orthogonal to each other with respect to adjacent light emitting cells.

According to an embodiment of the present invention, the upper surface of the plurality of light emitting cells may include an uneven portion and a reflecting portion disposed in an area between the plurality of light emitting cells.

According to an embodiment of the present invention, each of the plurality of light emitting cells can emit a wavelength of 280 nm or less.

A light emitting device package according to an embodiment of the present invention, the light emitting device disclosed above; A translucent film on the light emitting element; And a support member under the light emitting device.

A light emitting device driving method according to an embodiment of the present invention, a conductive substrate; A plurality of light emitting cells disposed on the conductive substrate and including a first conductive semiconductor layer, an active layer, and a second conductive semiconductor layer and spaced apart from each other; And a first insulating layer disposed between the plurality of light emitting cells and the conductive substrate, wherein the first insulating layer includes a first insulating portion disposed between the plurality of light emitting cells, and the first insulating portion A first protrusion protruding from the conductive substrate toward a top surface of the plurality of light emitting cells, wherein a top surface of the first protrusion is higher than a top surface of the plurality of active layers and lower than a top surface of the first conductive semiconductor layer A light emitting device disposed in the light emitting device, the plurality of light emitting cells being provided in series and being driven by a driving current adjusted to a pulse width of a preset duty cycle; Emitting an ultraviolet wavelength having the greatest intensity among the light wavelengths emitted from each of the light emitting cells by the driving current; The pulse width may be varied by the heating temperature and the fed back voltage according to the driving.

According to an embodiment of the present disclosure, the pulse width may be provided as a minimum pulse width corresponding to a time constant value by a sum of capacitance values of the plurality of light emitting cells.

The embodiment of the present invention can improve the reliability of the high voltage light emitting device by disposing a plurality of light emitting cells.

The embodiment of the present invention can improve the reliability of the high current light emitting device by disposing a plurality of light emitting cells.

The embodiment of the present invention can increase the area of the connection electrode for connecting a plurality of light emitting cells emitting ultraviolet light or a wavelength of 280nm or less in series or in parallel, thereby improving current spreading.

According to an embodiment of the present invention, a plurality of light emitting cells of a light emitting device may be connected in series, thereby reducing overall capacitance of the light emitting device and improving pulse response characteristics.

An embodiment of the present invention can lower the heat generation of the light emitting device by driving the plurality of light emitting cells through pulse driving of the light emitting device.

According to an embodiment of the present invention, current injection may be increased through pulse driving of a light emitting device having a plurality of light emitting cells.

The embodiment of the present invention can increase the light output of a light emitting device having a plurality of light emitting cells through pulse driving.

Embodiment of the present invention can increase the sterilization power according to the improvement of the light output of the light emitting device having a plurality of light emitting cells through the pulse driving.

Embodiment of the present invention can improve the reliability of the ultraviolet light emitting device and the package having the same.

1 is a plan view of a light emitting device having a plurality of light emitting cells according to an embodiment of the present invention.
FIG. 2 is an example of a cross-sectional view at the AA side of the light emitting device of FIG. 1.
3 is a partially enlarged view of the light emitting device of FIG. 2.
FIG. 4 is a diagram illustrating a region of a second connection electrode connecting regions between light emitting cells and adjacent light emitting cells on the light emitting device of FIG. 1.
5 illustrates an example in which a reflector is disposed between light emitting cells in the light emitting device of FIG. 3.
6 is a diagram illustrating edge regions of respective light emitting cells on the light emitting device of FIG. 4.
7 is a plan view illustrating another example of a contact electrode of the light emitting device of FIG. 1.
FIG. 8 is a plan view illustrating a modified example of the contact electrode of the light emitting device of FIG. 7.
9 is a plan view of a light emitting device having a plurality of light emitting cells according to another embodiment of the present invention.
10 is another example of the light emitting device.
11 is an example of a light emitting device package having a light emitting device according to an embodiment of the present invention.
12 is a block diagram illustrating a driving device of a light emitting device according to an exemplary embodiment of the present invention.
13 is a view showing an example of a driving circuit of a light emitting device according to an embodiment of the present invention.
14 is a view showing a pulse example of a light emitting device according to an embodiment of the present invention.
15 is a graph illustrating a relationship between a duty cycle and a rated current in a method of driving a light emitting device according to an exemplary embodiment of the present invention.
16 is a graph illustrating a relationship between charge and discharge of capacitance according to a time constant in a method of driving a light emitting device according to an exemplary embodiment of the present invention.
17 is a flowchart illustrating a method of driving a light emitting device according to an embodiment of the present invention.

 Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings.

However, the technical idea of the present invention is not limited to some embodiments described, but may be implemented in various forms, and within the technical idea of the present invention, one or more of the components may be selectively selected between the embodiments. Can be combined and substituted. In addition, the terms (including technical and scientific terms) used in the embodiments of the present invention may be generally understood by those skilled in the art to which the present invention pertains, unless specifically defined and described. The terms commonly used, such as terms defined in advance, may be interpreted as meanings in consideration of the contextual meaning of the related art. In addition, the terms used in the embodiments of the present invention are intended to describe the embodiments and are not intended to limit the present invention. As used herein, the singular forms may also include the plural unless specifically stated otherwise, and may be combined as A, B, C when described as “and at least one (or more than one) of B and C”. May contain one or more of all possible combinations. In addition, in describing the components of the embodiments of the present disclosure, terms such as first, second, A, B, (a), and (b) may be used. These terms are only for distinguishing the components from other components, and the terms are not determined by the nature, order or order of the components. And when a component is described as being 'connected', 'coupled' or 'connected' to another component, the component is not only connected, coupled or connected directly to the other component, It may also include the case where 'connected', 'coupled' or 'connected' due to another component between the other components. In addition, when described as being formed or placed on the "top (or bottom)" of each component, the top (bottom) or bottom (bottom) is not only when two components are in direct contact with each other, but also one It also includes a case where the above-described further components are formed or disposed between 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.

Hereinafter, a light emitting device according to embodiments will be described in detail with reference to the accompanying drawings.

1 is a plan view of a light emitting device having a plurality of light emitting cells according to an embodiment of the present invention, FIG. 2 is an example of a cross-sectional view of the light emitting device of FIG. 1, and FIG. 3 is a partially enlarged view of the light emitting device of FIG. 2. 4 is a view illustrating a region of a second connection electrode connecting the region between the light emitting cells and adjacent light emitting cells on the light emitting device of FIG. 1.

1 to 4, the light emitting device 100 may include two or more light emitting cells. At least two light emitting cells in the light emitting device 100 may be disposed in the first direction, in the second direction, or in the first and second directions. At least two light emitting cells in the light emitting device 100 may be disposed on a single conductive substrate. At least one of the at least two light emitting cells in the light emitting device 100 may be electrically connected to a single conductive substrate. At least two light emitting cells in the light emitting device 100 may be connected in parallel with each other, or in series with each other. For example, three or four or more light emitting cells may be connected in series or in parallel with each other on a single conductive substrate. The plurality of light emitting cells may be spaced apart from each other at predetermined intervals. The first direction may be a horizontal direction or an X direction, or the second direction may be a vertical direction or a Y direction. The first and second directions may be perpendicular to each other, and the third direction may be a Z direction, a vertical direction, or a thickness direction, and may be perpendicular to the first and second directions.

According to an embodiment of the present invention, a first group having a plurality of light emitting cells and a second group having a plurality of light emitting cells may be disposed on a conductive substrate, and the first group and the second group may be connected in parallel to each other, or It can be driven separately. Each of the first and second groups may include two or more light emitting cells or three or more light emitting cells. Here, the spaced apart light emitting cells are examples in which semiconductor layers of each light emitting cell and semiconductor layers of another light emitting cell are separated from each other. Hereinafter, the light emitting device 100 will be described as three or more light emitting cells for convenience of description, but the present invention is not limited thereto.

The light emitting device 100 may include a plurality of light emitting cells 111, 112, 113, and 114. The plurality of light emitting cells 111, 112, 113, and 114 are examples in which at least four light emitting cells are arranged in first and second directions. That is, at least four light emitting cells may be arranged in a matrix or lattice shape. The plurality of light emitting cells 111, 112, 113, and 114 may be arranged in a first direction and a second direction, and may be connected in series. The light emitting cells 111, 112, 113, and 114 may be driven in groups, for example, simultaneously driven, sequentially driven, or driven in rows or columns. At least one of the plurality of light emitting cells 111, 112, 113, and 114 may be the same size or different size as other light emitting cells.

The light emitting device 100 may include first to fourth side surfaces S1, S2, S3, and S4 disposed outside. In the light emitting device 100, the first and fourth light emitting cells 111 and 114 are adjacent to the first side surface S1, and the second and third light emitting cells 112 and 113 are opposite the second side surface of the first side surface S1. It may be adjacent to (S2). The first and second light emitting cells 111 and 112 may be adjacent to the third side surface S3, and the third and fourth light emitting cells 113 and 114 may be disposed adjacent to the fourth side surface S4. Here, the first and second side surfaces S1 and S2 may be surfaces facing each other or facing each other. The third and fourth side surfaces S3 and S4 may face each other or face each other. The light emitting device 100 may have a top view shape of a polygonal shape such as a square or a rectangle, or a circular shape.

For example, the first light emitting cell 111 is connected in series with the second light emitting cell 112, and the second light emitting cell 112 is connected in series with the third light emitting cell 113. 113 may be connected in series with the fourth light emitting cell 114. The first light emitting cell 111 may be electrically connected to the conductive substrate 81, and the fourth light emitting cell 114 may be electrically connected to the pad 91.

In the light emitting device 100, the pad 91 may be disposed outside at least one of the light emitting cells 111, 112, 113, and 114. The pad 91 may be connected to an output terminal of an array or group of light emitting cells connected in series or to an input terminal. As another example, the pads may be arranged in plurality, and the plurality of pads may be disposed in the same light emitting cell or in different light emitting cells. The plurality of pads may be electrically connected to the same light emitting cells, or may be electrically connected to different light emitting cells.

The first interval d1 between the light emitting cells 111, 112, 113, and 114 may be the same in the first direction and the second direction. The first interval d1 may be 50 micrometers or less, for example, in the range of 10 to 50 micrometers. The gap 115 between the light emitting cells 111, 112, 113, and 114 may have a width of at least a first interval d1, and the maximum width of the gap 115 may be a gap between upper ends of the light emitting cells.

The light emitting device 100 is a device having a plurality of light emitting cells 111, 112, 113, and 114 connected in series and may be driven by a pulse width modulation (PWM) signal. The light emitting device 100 may reduce a heat generation problem generated from each light emitting cell through pulse driving. The light emitting device 100 may be driven by a pulse width modulated signal, thereby increasing current injection and improving light output. In addition, the light emitting device emits an ultraviolet wavelength, for example, a wavelength of 200 nm to 280 nm, and since the ultraviolet light emitting device is pulsed, the sterilizing power according to the light output can be increased. Each of the plurality of light emitting cells 111, 112, 113, and 114 has a wavelength of light having the largest intensity among the wavelengths of emitted light, and may be, for example, in the range of 220 nm to 280 nm.

Referring to FIG. 2, each of the light emitting cells 111, 112, 113, and 114 in the light emitting device 100 may include a light emitting structure. The light emitting structure of each light emitting cell may include the same semiconductor stacked structure. Each of the light emitting cells may include a first conductive semiconductor layer 11, an active layer 12, and a second conductive semiconductor layer 13. In each of the light emitting cells 111, 112, 113, and 114, at least one of a superlattice structure layer and a cladding layer may be disposed between the first conductive semiconductor layer 11 and the active layer 12. At least one of an electron blocking layer and a cladding layer may be disposed between the second conductive semiconductor layer 13 and the active layer 12. The superlattice structure may include a stacked structure in which different semiconductor layers or layers having different refractive indices are alternately arranged.

The active layer 12 may be disposed between the first conductive semiconductor layer 11 and the second conductive semiconductor layer 13. The active layer 12 may be disposed under the first conductive semiconductor layer 11, and the second conductive semiconductor layer 13 may be disposed under the active layer 12.

The first conductivity type semiconductor layer 11 includes a first conductivity type dopant, for example, an n type semiconductor layer to which an n type dopant is added, and the second conductivity type semiconductor layer 13 includes a second conductivity type dopant, It may include a p-type semiconductor layer to which a p-type dopant is added. In addition, the first conductive semiconductor layer 11 may be formed of a p-type semiconductor layer, and the second conductive semiconductor layer 13 may be formed of an n-type semiconductor layer. The first and second conductive semiconductor layers 11 and 13 and the active layer 12 may be implemented as compound semiconductor layers. The compound semiconductor layer may be implemented as at least one of a group II-VI compound semiconductor and a group III-V compound semiconductor.

The first conductive semiconductor layer 11 is _{In x Al y Ga 1 -x- y} N (0≤x≤1, 0≤y≤1, 0≤x + y≤1) or (Al _x Ga _{1 - x} ) _y In _{1 - y} P (0≤x≤1, 0≤y≤1) can be implemented with a semiconductor material. The first conductive semiconductor layer 11 may be selected from GaN, AlN, AlGaN, InGaN, InN, InAlGaN, AlInN, AlGaAs, GaP, GaAs, GaAsP, AlGaInP, and the like, and Si, Ge, Sn, Se, Te, and the like. An n-type dopant may be doped. An upper surface of the first conductive semiconductor layer 11 may be formed as a rough uneven portion f1, and the uneven portion f1 may improve light extraction efficiency.

In the active layer 12, electrons (or holes) injected through the first conductive semiconductor layer 11 and holes (or electrons) injected through the second conductive semiconductor layer 13 meet each other. The layer emits light due to a band gap difference between energy bands of the active layer 12. The active layer 12 may be formed of any one of a single well structure, a multiple well structure, a quantum dot structure, or a quantum line structure, but is not limited thereto.

The active layer 12 may include a pair of a well layer and a barrier layer. When the active layer 12 is implemented in a multi-well structure, the active layer 12 may be implemented by stacking a plurality of well layers and a plurality of barrier layers. The well / barrier layer pair includes InGaN / GaN, GaN / AlGaN, AlGaN / AlGaN, InGaN / AlGaN, InGaN / InGaN, AlGaAs / GaAs, InGaAs / GaAs, InGaP / GaP, AlInGaP / InGaP, InP / GaAs It may include at least one selected from the group.

The second conductive type semiconductor layer 13 is _{In x Al y Ga 1 -x- y} N (0≤x≤1, 0≤y≤1, 0≤x + y≤1) or (Al _x Ga _{1 - x} ) _y In _{1 - y} P (0≤x≤1, 0≤y≤1) can be implemented with a semiconductor material. The second conductive semiconductor layer 13 may be selected from, for example, GaN, AlN, AlGaN, InGaN, InN, InAlGaN, AlInN, AlGaAs, GaP, GaAs, GaAsP, AlGaInP, and Mg, Zn, Ca, P-type dopants such as Sr and Ba may be doped.

The light emitting cells 111, 112, 113, and 114 may have at least one of np, pn, npn, and pnp junction structures. In addition, the doping concentrations of the impurities in the first conductive semiconductor layer 11 and the second conductive semiconductor layer 13 may be uniformly or non-uniformly formed. That is, the structure of the light emitting structure 10 may be formed in various ways, but is not limited thereto. The light emitting cells 111, 112, 113, and 114 may emit light of blue, green, red, or ultraviolet wavelengths. The light emitting cells 111, 112, 113, and 114 may emit the same peak wavelengths. The light emitting cells 111, 112, 113, and 114 may emit ultraviolet light having the largest intensity in the emitted light.

For example, the light emitting cells 111, 112, 113, and 114 may emit an ultraviolet wavelength region having the highest intensity among the emitted wavelengths, or emit an ultraviolet wavelength of 280 nm or less or 200 nm to 280 nm, and the first and second conductive semiconductors. Layers 11 and 13 may include AlGaN based semiconductors. The pair of the well layer and the barrier layer of the active layer 12 according to the embodiment may be implemented with AlGaN / AlGaN. The aluminum composition of the barrier layer may be higher than that of aluminum of the well layer. The aluminum composition of the well layer may range from 20% to 40%, and the aluminum composition of the barrier layer may range from 40% to 95%. The barrier layer may have a band gap wider than the band gap of the well layer. The barrier layer may have a thickness thicker than that of the well layer. The thickness of the well layer may range from 3 nm to 5 nm or from 2 nm to 4 nm. If the thickness of the well layer is thinner than the above range, the confinement efficiency of the carrier is lowered. The barrier layer may have a thickness in the range of 4 nm to 20 nm or in the range of 4 nm to 10 nm. When the thickness of the barrier layer is thinner than the above range, the blocking efficiency of the electrons is lowered, and when the barrier layer is thicker than the above range, the electrons are excessively blocked. According to the thickness of the barrier layer, the wavelength of light and the quantum well structure, each carrier can be effectively confined to the well layer. The barrier layer may comprise a dopant, for example an n-type dopant. The barrier layer may be an n-type semiconductor layer because an n-type dopant is added. When the barrier layer is an n-type semiconductor layer, the injection efficiency of electrons injected into the active layer 12 may be increased.

An electron blocking layer may be disposed between the active layer 12 and the second conductive semiconductor layer. The electron blocking layer may include a band gap wider than the band gap of the barrier layer. The electron blocking layer may include a single layer or a multilayer structure. The electron blocking layer may include at least one of an AlN-based semiconductor and an AlGaN-based semiconductor.

Each of the plurality of light emitting cells 111, 112, 113, and 114 may include one or a plurality of first recesses h1. The first recess h1 may penetrate the upper surface of the active layer 12 through the lower surface of the second conductive semiconductor layer 13 and expose the inside of the first conductive semiconductor layer 11. . The first recess h1 may be disposed in a plurality of light emitting cells. The first recess may decrease in width or diameter from the lower surface of the second conductive semiconductor layer 13 toward the upper surface of the first conductive semiconductor layer 11. The first contact electrode c1 may be disposed in the first recess h1. The first contact electrode c1 may be in contact with the first conductive semiconductor layer 11 in each of the first recesses h1. The first contact electrode c1 may include a metal or a non-metal material. The first contact electrode c1 may include, for example, at least one of Cr, V, W, Ti, Zn, Ni, Cu, Al, Au, and Mo.

An external recess r1 may be disposed below the gap 115 between the light emitting cells 111, 112, 113, and 114. The external recess r1 may be disposed at a second interval d2 that is wider than the first interval d1 between the light emitting cells. The second interval d2 may be larger than the first interval d1. The external recess r1 may be inclined at an angle of 91 degrees or more with respect to a straight line horizontal to the lower side surfaces of the light emitting cells 111, 112, 113, and 114. Upper sides of the light emitting cells 111, 112, 113, and 114 may be inclined at an angle of 91 degrees or more with respect to a horizontal straight line. The first interval d1 may be an interval between adjacent active layers 12 among the light emitting cells 111, 112, 113, and 114, or an interval between lower surfaces of the adjacent first conductive semiconductor layers 11. The first and second recesses h1 and r1 may be formed through the same etching process, and may have the same depth d4. The depth d4 may be a distance from a lower surface of the second conductive semiconductor layer 13 to a lower portion of the first conductive semiconductor layer 11.

The light emitting device 100 includes a conductive substrate 81 supporting a plurality of light emitting cells 111, 112, 113, and 114, and a first electrode 83 and a second electrode between the conductive substrate 81 and the light emitting cells 111, 112, 113, and 114. 60), at least one first connection part c2 and at least one connection electrode 85, 86, and 87. Insulating layers 30, 40, and 50 may be disposed between the light emitting cells 111, 112, 113, and 114 and the conductive substrate 81. The insulating layers 30, 40, and 50 may include the light emitting cells 111, 112, 113, and 114, the first and second electrodes 83 and 60, the first connection part c2 and the connection electrodes 85, 86, and 87, and The conductive substrates 81 can be selectively insulated from each other.

The conductive substrate 81 is a layer supporting the plurality of light emitting cells 111, 112, 113, and 114, and may include a material having thermal conductivity and electrical conductivity. The conductive substrate 81 may include at least one of a metal material, for example, Ti, Cr, Ni, Al, Pt, Au, W, Cu, Mo, and Cu-W. As another example, the light emitting device may be formed in a semiconductor substrate (eg, Si, Ge, GaN, GaAs, ZnO, SiC, SiGe, etc.) implanted with impurities as a supporting member.

The thickness of the conductive substrate 81 is 80% or more of the thickness of the light emitting device, and may be 30 micrometers or more, or 30 to 300 micrometers. The conductive substrate 81 may be formed in a single layer or a multilayer structure.

A bonding layer may be disposed below the conductive substrate 81. The first electrode 83 and the third insulating layer 50 may be disposed on the conductive substrate 81. At least one of a diffusion barrier layer and a bonding layer formed of a metal material may be included between the conductive substrate 81 and the first electrode 83. The diffusion barrier layer and the bonding layer may be formed in a single layer or multiple layers using at least one of Ti, Au, Sn, Ni, Cr, Ga, In, Bi, Cu, Ag, Nb, Pd, or Ta and optional alloys thereof. Can be.

The lower surface area of the conductive substrate 81 may be larger than the sum of the lower surface areas of the plurality of light emitting cells 111, 112, 113, and 114. The upper edge portion of the conductive substrate 81 may protrude outwardly from the side surfaces of the light emitting cells 111, 112, 113, and 114. The conductive substrate 81 may overlap the light emitting cells 111, 112, 113, and 114 and the pad 91 in a vertical direction.

The first electrode 83 may be disposed between at least one light emitting cell and the conductive substrate 81. The second electrode 60 may be disposed between the light emitting cells 111, 112, 113, and 114 and the conductive substrate 81.

The first electrode 83 may be electrically connected to the conductive substrate 81. The first electrode 83 may be electrically connected to the conductive substrate 81 and the first conductive semiconductor layer 11 of the first light emitting cell 111.

The first electrode 83 may be disposed under the first light emitting cell 1111. The first electrode 83 may not overlap with the second, third, and fourth light emitting cells 112, 113, and 114 in the vertical direction. The first electrode 83 may be spaced apart from the second to fourth light emitting cells 112, 113, and 114. As shown in FIG. 4, an upper surface area of the first electrode 83 may be smaller than an area of the lower surface of the first light emitting cell 111. An upper surface area of the first electrode 83 may be 1/4 or less of an upper surface area of the conductive substrate 81. An upper surface area of the first electrode 83 may be smaller than an area of the lower surface of the first light emitting cell 111 to reduce interference with electrodes connected to adjacent light emitting cells.

The first electrode 83 may include at least one of Au, Cu, Ni, Ti, Ti-W, Cr, W, Pt, V, Fe, Mo, and a material of an alloy having at least one of them. . The thickness of the first electrode 83 may be formed in the range of 300 to 900 nm.

The first electrode 83 may include a first connection part c2, and the first connection part c2 extends from the first electrode 83 in the direction of the first conductive semiconductor layer 11. It may protrude. The first connector c2 may be made of the same material as or different from that of the first electrode 83. A lower recess r2 may be disposed below the first connection part c2, and the lower recess r2 is concave in the direction of the first light emitting cell 111. A portion of the conductive substrate 81 may protrude from the lower recess r2.

The second electrode 60 may be disposed under each of the light emitting cells 111, 112, 113, and 114. The second electrode 60 may be disposed under the second conductive semiconductor layer 13 of each of the light emitting cells 111, 112, 113, and 114 and may be electrically connected to the second conductive semiconductor layer 13. The second electrode 60 may include a contact layer 15 and a reflective layer 62. The contact layer 61 is disposed between the reflective layer 62 and the second conductive semiconductor layer 13, and the reflective layer 62 is disposed between the contact layer 61 and the second insulating layer 40. Can be arranged. The contact layer 61 and the reflective layer 62 may be formed of different conductive materials, but are not limited thereto.

The contact layer 61 may be in contact with the second conductivity type semiconductor layer 13. The contact layer 61 may form an ohmic contact with the second conductivity-type semiconductor layer 13. The contact layer 61 may be formed of, for example, a conductive oxide film, a conductive nitride, or a metal. For example, the contact layer 61 may be formed of indium tin oxide (ITO), indium zinc oxide (ITO), indium zinc oxide (IZO), indium zinc oxide (IZON), aluminum zinc oxide (AZO), aluminum gallium zinc oxide (AGZO), Indium Zinc Tin Oxide (IZTO), Indium Aluminum Zinc Oxide (IAZO), Indium Gallium Zinc Oxide (IGZO), Indium Gallium Tin Oxide (IGTO), Antimony Tin Oxide (ATO), Gallium Zinc Oxide (GZO), IZO Nitride ), ZnO, IrOx, RuOx, NiO, Pt, Ag, Ti may be formed of at least one.

The reflective layer 62 may be disposed between the contact layer 61 and each connection electrode 85, 86, 87 and may be electrically connected to the contact layer 61 and each connection electrode 85, 86, 87. . The reflective layer 62 may reflect light incident from the light emitting cells 111, 112, 113, and 114. The reflective layer 62 may be formed of a metal having a light reflectance of 70% or more. For example, the reflective layer 62 may be formed of a metal or an alloy including at least one of Ag, Ni, Al, Rh, Pd, Ir, Ru, Mg, Zn, Pt, Cu, Au, and Hf. In addition, the reflective layer 62 may be formed of the metal or alloy and indium-tin-oxide (ITO), indium-zinc-oxide (IZO), indium-zinc-tin-oxide (IZTO), and indium-aluminum-zinc- (AZO). Light-transmitting materials such as Oxide), Indium-Gallium-Zinc-Oxide (IGZO), Indium-Gallium-Tin-Oxide (IGTO), Aluminum-Zinc-Oxide (AZO), and Antimony-Tin-Oxide (ATO) It can be formed in multiple layers. For example, the reflective layer 62 may include at least one of Ag, Al, Ag-Pd-Cu alloy, or Ag-Cu alloy. For example, the reflective layer 62 may be formed by alternately forming an Ag layer and a Ni layer, and may include a Ni / Ag / Ni, Ti layer, or Pt layer. As another example, the contact layer 61 may be formed under the reflective layer 62, and at least a portion thereof may pass through the reflective layer 62 to be in contact with the second conductive semiconductor layer 13. As another example, the reflective layer 62 may be disposed under the contact layer 61, and a portion thereof may pass through the contact layer 61 to be in contact with the second conductive semiconductor layer 13.

The second electrode 60 may include a capping layer disposed under the reflective layer 62. The capping layer 35 may connect the reflective layer 62 and the connection electrodes 85, 86, and 87. The capping layer may be formed of a metal, and may include, for example, at least one of Au, Cu, Ni, Ti, Ti-W, Cr, W, Pt, V, Fe, and Mo materials. The capping layer may protect the reflective layer 62.

The pad 91 may be disposed on the second electrode 60. The pad 91 may be disposed on the reflective layer 62 of the second electrode 60. The second electrode 60 disposed below the pad 91 may be disposed outside the side surface of the fourth light emitting cell 114. The pad 91 may be formed in a single layer or multiple layers. The pad 91 may include at least one of Ti, Ag, Cu, and Au. For example, the pad 91 may have a stacked structure of Ti / Ag / Cu / Au or a Ti / Cu / Au stacked structure in the case of a multilayer. The pad 91 may be disposed in the recessed area 91A disposed at a corner of the fourth light emitting cell 114. An area of the fourth light emitting cell 114 may be smaller than that of other light emitting cells.

One or more first connection parts c2 of the first electrode 83 may be disposed depending on a connection method of the light emitting cells 111, 112, 113, and 114. For example, when the plurality of light emitting cells 111, 112, 113, and 114 are connected in series, the first connection part c2 may be one, and when connected in parallel, two or more may be provided. When the plurality of light emitting cells 111, 112, 113, and 114 are connected in series, the connection electrodes 85, 86, and 87 may be disposed one smaller than the number of light emitting cells. For example, when four light emitting cells are arranged, three connection electrodes 85, 86, and 87 may be arranged.

Here, the insulating layer may include first to third insulating layers 30, 40, and 50. At least one or all of the first to third insulating layers 30, 40, and 50 may be disposed between the light emitting cells 111, 112, 113, and 114 and the conductive substrate 81.

The first insulating layer 30 may be disposed under and around the light emitting cells 111, 112, 113, and 114, and may be disposed on the first electrode 83 and the connection electrodes 85, 86, and 87. The second insulating layer 40 may be disposed below and around the second electrode 60, and may be disposed on the first electrode 83 and the connection electrodes 85, 86, and 87. The third insulating layer 50 may be disposed between the connection electrodes 85, 86, and 87 and the conductive substrate 81.

The first insulating layer 30 may be disposed around the first connector c2 and the fourth connector c4. The first insulating layer 30 may include a first insulating portion 31 disposed between the plurality of light emitting cells 111, 112, 113, and 114 and a second insulating portion 33 disposed in the first recess h1. Can be. The first and second insulating parts 31 and 33 may be simultaneously formed in the process of forming the first insulating layer 30. The first insulating layer 30 may be formed before the second electrode 60 is formed, or may be formed after the second electrode 60 is formed.

1 and 3, the first insulating portion 31 may include a first protrusion p1 protruding on the conductive substrate 81 in the upper direction of the plurality of light emitting cells 111, 112, 113, and 114. An upper surface of the first protrusion p1 may be higher than an upper surface of the active layer 12 of the light emitting cells. An upper surface of the first protrusion p1 may be lower than an upper surface of the first conductive semiconductor layer 11 of the light emitting cells. An upper surface width of the first protrusion p1 may be greater than a distance d1 between the light emitting cells. The length of the first protrusion p1 is a length extending along adjacent light emitting cells, and may be greater than the length of one side of each light emitting cell.

As illustrated in FIG. 1, the first protrusion p1 may be disposed between the first and second light emitting cells 111 and 112 and between the third and fourth light emitting cells 113 and 114. The first protrusion p1 may be disposed between the second and third light emitting cells 112 and 113 and between the first and fourth light emitting cells 111 and 114. The first protrusion p1 may be disposed on two side surfaces of the light emitting cells 111, 112, 113, and 114. The first protrusion p1 may be disposed between two light emitting cells 111, 112, 113, and 114 facing each other.

For example, the first insulating layer 30 may be formed of oxide or nitride. For example, the first insulating layer 30 may be formed of SiO ₂ , Si _x O _y , Si ₃ N ₄ , Si _x N _y , SiO _x N _y , Al ₂ O ₃ , TiO ₂ , AlN, or the like. At least one may be selected and formed. For example, the thickness of the first insulating layer 30 may be 100 nanometers or more or 100 to 2000 nanometers. If the thickness of the first insulating layer 30 is formed to less than 100 nanometers may cause problems in the insulating properties, if the thickness of the first insulating layer 30 is formed to exceed 2000 nanometers Cracking may occur at the process stage. The first insulating layer 30 may be in contact with the side surface of the first contact electrode c1 and may be in contact with the contact layer 61 and the reflective layer 62. The second insulating portion 33 may be disposed between the reflective layer 62 and the second conductive semiconductor layer 13. The second insulating portion 33 may be in contact with the bottom surface of the second conductive semiconductor layer 13.

In the region between the light emitting cells 111, 112, 113, and 114, a width of an upper surface and a lower surface of the first insulating portion 31 may be greater than a distance d1 between the light emitting cells 111, 112, 113, and 114. An upper surface width of the first insulation portion 31 or an upper surface width of the first protrusion p1 may be greater than a minimum distance d1 between the light emitting cells 111, 112, 113, and 114. Accordingly, both side surfaces of the first insulating part 31 may be disposed inside the side surfaces of the light emitting cells 111, 112, 113, and 114 so as to be in contact with a lower portion of the first conductive semiconductor layer 11 and overlap in a vertical direction. Can be. The first insulating part 31 may be disposed under the lower surface of the first conductive semiconductor layer 11 of each of the light emitting cells 111, 112, 113, and 114 to prevent moisture penetration.

In the first insulating layer 30, the first and second insulating parts 31 and 33 may be formed of the same insulating material or different insulating materials. For example, the first insulating part 31 may be formed of a reflective material having a distributed bragg reflector (DBR) structure.

The first connection part c2 of the first electrode 83 may be in contact with and electrically connected to the first contact electrode c1 disposed in the first light emitting cell 1111. The second insulating part 33 of the first insulating layer 30 may be disposed around the first connection part c2 and the first contact electrode c1. The second insulating part 33 may be disposed on a surface of the first recess h1 and a bottom surface of each of the light emitting cells 111, 112, 113, and 114. The second insulating part 33 may be in contact with the second conductive semiconductor layer 13, the active layer 12, and the first conductive semiconductor layer 11 disposed on the surface of the first recess h1. have. A portion of the second insulating portion 33 may extend on the bottom surface of the second conductive semiconductor layer 13. The second insulating part 33 blocks contact between the first connection part c2, the first contact electrode c1, the active layer 12, and the second conductive semiconductor layer 13. The second insulation portion 33 and the first insulation portion 31 may be connected to the second insulation layer 40. When the first and second insulating layers 30 and 40 are made of the same material, there may be no boundary between the two layers.

The second insulating layer 40 covers the bottom and side surfaces of the second electrode 60. The second insulating layer 40 insulates the bottom and the circumference of the second electrode 60 disposed below the light emitting cells 111, 112, 113, and 114. The second insulating layer 40 blocks the connection between the second electrode 60 and the first electrode 83 or the connection electrodes 83, 85, and 87.

A portion of the second insulating layer 40 may extend on an outer upper portion of the conductive substrate 81 to be exposed to the outer sides of the light emitting cells 111, 112, 113, and 114. An outer portion of the second insulating layer 40 may be in contact with a portion 35 of the first insulating layer 30 disposed around the pad 91. The second insulating layer 40 may be the same material as or different from the first insulating layer 30.

Here, an upper end of the second insulating part 33 of the first insulating layer 30 may be higher than an upper end of the active layer 12. An upper end of the first insulating part 31 may be disposed higher than an upper end of the active layer 12. Upper ends of the first and second insulating parts 31 and 33 may be disposed lower than an upper surface of the first conductive semiconductor layer 11. The first insulating part 31 may be disposed in the gap 115 between two adjacent light emitting cells 111, 112, 113, and 114.

When the first insulating portion 31 of the first insulating layer 30 is disposed higher than the upper end of the active layer 12 and is made of a reflective material, optical interference between adjacent light emitting cells 111, 112, 113, and 114 may be blocked. As shown in FIG. 4, the first insulating part 31 is exposed to the gap 115 between the plurality of light emitting cells 111, 112, 113, and 114, and functions as a sidewall, thereby blocking optical interference between them. As another example, when the material of the second insulating layer 40 is a reflective material, the first insulating part 31 may be a reflective material or a transmissive material. The second protrusions 41 of the second insulating layer 40 may protrude into regions between the light emitting cells 111, 112, 113, and 114. The second protrusion 41 may protrude into the gap 115 and may be in contact with the first insulating part 31. An upper end of the second protrusion 41 may protrude higher than a bottom surface of the second conductive semiconductor layer 13. The first protrusion p1 of the first insulating layer 30 and the second protrusion 41 of the second insulating layer 40 may be integrally formed.

Each of the light emitting cells 111, 112, 113, and 114 may include a light emitting structure having semiconductor layers and first and second electrodes. In this case, the second electrode of the first light emitting cell 111 may be connected to the first electrode of the second light emitting cell 112, and the second electrode of the second light emitting cell 112 may be the third light emitting device. The first electrode of the cell 113 may be connected, and the second electrode of the third light emitting cell 113 may be connected to the first electrode of the fourth light emitting cell 114.

The connection electrodes 85, 86, and 87 connect two adjacent light emitting cells with each other. The connection electrodes 85, 86, and 87 connect two electrodes of different light emitting cells disposed on the connection circuit to each other. The first connection electrode 85 connects the first and second light emitting cells 111 and 112, for example, the second conductive semiconductor layer 13 of the first light emitting cell 111 and the second light emitting cell 112. The first conductive semiconductor layer 11 is connected. Each of the connection electrodes 85, 86, and 87 may function as a first electrode of the second to fourth light emitting cells 112, 113, and 114, or may include a first electrode.

The second connection electrode 86 may connect the second and third light emitting cells 112 and 113. For example, the second connection electrode 86 may include the second conductive semiconductor layer 13 of the second light emitting cell 112 and the first conductive semiconductor layer 11 of the third light emitting cell 113. Connect it. The third connection electrode 87 connects the third and fourth light emitting cells 113 and 114, for example, the second conductive semiconductor layer 13 and the fourth light emitting cell 114 of the third light emitting cell 113. The first conductive semiconductor layer 11 of) is connected.

The first connection electrode 85 is a second electrode 60 connected to the second conductive semiconductor layer 13 of the first light emitting cell 111 and the first conductive semiconductor layer of the second light emitting cell 112. The first contact electrode c1 connected to (11) is connected. The second connection electrode 86 is a second electrode 60 connected to the second conductive semiconductor layer 13 of the second light emitting cell 112 and the first conductive semiconductor layer of the third light emitting cell 113. The first contact electrode c1 connected to (11) is connected. The third connection electrode 87 is a second electrode 60 connected to the second conductive semiconductor layer 13 of the third light emitting cell 113 and the first conductive semiconductor layer of the fourth light emitting cell 114. The first contact electrode c1 connected to (11) is connected.

The connection electrodes 85, 86, and 87 may be disposed under the second insulating layer 40. The connection electrodes 85, 86, and 87 may include a second connection part c3 and a third connection part c4. The second connection part c3 is connected to the second electrode 60 disposed under the first, second, and third light emitting cells 112, 113, and 114, or is disposed under the first, second, third, light emitting cells 112, 113, and 114. It may be connected to the reflective layer 62. The second connector c3 may be connected to the second electrode 60 disposed under the second, third, and fourth light emitting cells 112, 113, and 114 through the second insulating layer 40. The third connector c4 may overlap the first recess h1 of the second to fourth light emitting cells 112, 113, and 114 in a vertical direction.

The third connection part c4 penetrates through the second insulating layer 40 and is disposed in the first recess h1 of the second to fourth light emitting cells 112, 113, and 114 and the first contact electrode c1. Can be connected. In an embodiment, the first and third connectors c2 and c4 may function as first electrodes, extend into the first recess h1 of each light emitting cell, and may be electrically connected to each light emitting cell.

As shown in FIG. 4, the protrusion p2 overlapping the first protrusion p1 in the vertical direction among the connection electrodes 85, 86, and 87 may protrude in the direction of the first protrusion p1. The protrusion p2 may be disposed higher than a lower surface of the light emitting cells 111, 112, 113, and 114 or a lower surface of the second conductive semiconductor layer 13. Since the protrusion p2 is disposed higher than the lower surface of the light emitting cell or the lower surface of the second conductive semiconductor layer, the side leakage light may be reflected. That is, the protrusion p2 may be arranged to surround the lower circumference of the light emitting cells 111, 112, 113, and 114, thereby improving reflection efficiency.

Each of the light emitting cells 111, 112, 113, and 114 including the light emitting structures may act as a resistance and a capacitance in a circuit. When each of the light emitting cells 111, 112, 113, and 114 acts as a capacitance, a circuit of the plurality of light emitting cells 111, 112, 113, and 114 connected in series may be provided as a circuit in which the capacitances are connected in series. In this case, the sum of the plurality of capacitances in the light emitting device 100 may be inversely proportional to the number of connection of the light emitting cells 111, 112, 113, and 114. Referring to FIG. 13, for example, in one light emitting cell LS1, LS2,..., LSn, the value of capacitance C _D1 is 1 / C _D1 , and the sum of capacitances of n light emitting cells is 1 / C _D1 +. 1 / C _D2 +... + 1 / C _Dn It can be calculated as In the light emitting device 100, as the number of light emitting cells connected in series increases, the total capacitance value of the light emitting device decreases in inverse proportion. Since the value of the total capacitance is reduced in the light emitting device 100, the response characteristic of the pulse width modulated signal may be improved.

Referring to FIG. 4, an upper surface area of each of the first to third connection electrodes 85, 86, and 87 may be smaller or larger than an upper surface area of each of the second, third, and fourth light emitting cells 112, 113, and 114. An upper surface area of each of the first to third connection electrodes 85, 86, and 87 may be 50% or more of an upper surface area of each of the second, third, and fourth light emitting cells 112, 113, and 114, for example, 50% to 120%. Can be placed in a range. The width b1 of each of the first to third connection electrodes 85, 86, and 87 may be smaller than the length b2. The width b1 and the length b2 may be lengths in an orthogonal direction. Each of the first to third connection electrodes 85, 86, and 87 may overlap with the adjacent light emitting cells 111, 112, 113, and 114 in a vertical direction. The second connection portion c3 of each of the first to third connection electrodes 85, 86, and 87 may have a length (eg, b1) smaller than the width b0 of the first to third light emitting cells 111, 112, and 113. Can be. The second connection portion c3 of each of the first to third connection electrodes 85, 86, and 87 may be larger than a distance between the first recess h1 disposed in each of the light emitting cells 111, 112, 113, and 114. The second connection portion c3 of each of the first to third connection electrodes 85, 86, and 87 may have a circular shape or a polygonal shape. The length (eg b1) of each of the second connectors c3 may be disposed to be longer than an interval between at least two first recesses h1. Alternatively, the second connector c3 may be 50% or more of the length b0 of one side of the light emitting cells 111, 112, 113, and 114. The second connector c3 may have a plurality of contacts spaced apart from each other under the light emitting cells 111, 112, 113, and 114, and may be connected to the second electrode 60. The second connection portion c3 of the connection electrodes 85, 86, and 87 are disposed in a length corresponding to the length b0 of the light emitting cells 111, 112, 113, and 114, or distributed therein, and thus, through the first recess r1. The current transmitted to the first conductive semiconductor layer 11 may be diffused and transferred through the second electrode 60 and the second connection part c3 in contact with the second conductive semiconductor layer 13.

Therefore, the current is diffused in the lower portions of the light emitting cells 111, 112, 113, and 114, thereby preventing the problem of breakage at different electrode interfaces at high voltage or high current. That is, the current aggregation problem can be prevented at the lower portions of the light emitting cells 111, 112, 113, and 114. In addition, optical interference between the light emitting cells 111, 112, 113, and 114 can be prevented, thereby improving the brightness.

The second connector c3 and the third connector c4 may be made of the same material as or different from those of the connection electrodes 85, 86, and 87. The connection electrodes 85, 86, and 87 may be made of the same material as the first electrode 83. The fourth connector c4 may be connected to the first contact electrode c1 in the first recess h1. The connection electrodes 85, 86, and 87 may be formed after forming the second insulating layer 40. The first connection part c2 and the third connection part c4 may be formed of the same material.

A third insulating layer 50 may be disposed between the connection electrodes 85, 86 and 87 and the conductive substrate 81. A part g1 of the third insulating layer 50 is connected between the first electrode 83 and the connection electrodes 85, 86 and 87, or the protrusions g2 and g3 are connected to the first recess h1. ) And protrude in the gap 115 direction. Here, the protrusions g2 and g3 may be disposed in the lower recesses r2 and r3 of the connection electrodes 85, 86 and 87.

5 is a modified example of FIG. 3.

Referring to FIG. 5, a reflector Ra may be disposed on the gap 115 between the light emitting cells 111, 112, 113, and 114. The reflector Ra may reflect light incident in an area between two adjacent light emitting cells 111, 112, 113, and 114. The reflective part Ra may be disposed on the first insulating part 31 of the first insulating layer 30. A lower surface width of the reflective part Ra may be smaller than an upper surface width of the first insulating part 31 of the first insulating layer 30. The inclined surface of the reflector Ra may be inclined in the range of 40 degrees to 70 degrees, thereby reflecting the incident light upward. The height of the reflector Ra may be arranged in the range of 5 micrometers or more, for example, 5 to 20 micrometers. The height of the reflector Ra may be greater than or equal to 50% of the thickness of the first conductive semiconductor layer 11 to reflect light traveling in the lateral direction of the light emitting cells 111, 112, 113, and 114.

Referring to FIG. 6, an external recess r1 may be disposed in a lower region between the light emitting cells 111, 112, 113, and 114 and an outer lower region of each of the light emitting cells 111, 112, 113, and 114. The external recess r1 is disposed along a lower circumference of each of the light emitting cells 111, 112, 113, and 114, thereby preventing a current leakage problem at an edge portion of the light emitting cells 111, 112, 113, and 114. At least one of the first and second insulating layers 30 and 40 may be disposed in the external recess r1. The structure of the outer recess r1 will be referred to the structures of FIGS. 3 and 5.

7 is a plan view illustrating another example of a contact electrode of the light emitting device of FIG. 1. The configuration of FIG. 7 can be selectively applied to the above configuration.

Referring to FIG. 7, the first contact electrode c1 and the first recess h1 disposed under each of the light emitting cells 111, 112, 113, and 114 may be disposed to have a long length b5 in a second direction perpendicular to the first direction. Can be. The first contact electrode c1 and the first recess h1 may have the same length and may overlap at least a portion in the first direction. Accordingly, the first contact electrode c1 may be uniformly distributed in all areas of the light emitting cells 111, 112, 113, and 114, thereby spreading current. The length b5 of the first contact electrode c1 may be disposed in a range of 10% or more, for example, 10% to 60% of the length b0 of one side of each of the light emitting cells 111, 112, 113, and 114. The length b5 of the first contact electrode c1 may be smaller than the length of the second connection part c3 of each connection electrode.

FIG. 8 is a plan view illustrating a modified example of the contact electrode of the light emitting device of FIG. 7. The configuration of FIG. 8 can be selectively applied to the above configuration.

Referring to FIG. 8, the first contact electrode c1 and the first recess h1 disposed under each of the light emitting cells 111, 112, 113, and 114 may be disposed to have a long length b5 in at least one or two directions. The first contact electrode c1 and the first recess h1 may have the same length and may overlap at least a portion in the first and second directions. Accordingly, the first contact electrode c1 may be uniformly distributed in all areas of the light emitting cells 111, 112, 113, and 114, thereby spreading current. The length b5 of the first contact electrode c1 may be disposed in a range of 10% or more, for example, 10% to 60% of the length b0 of one side of each of the light emitting cells 111, 112, 113, and 114. The length b5 of the first contact electrode c1 may be smaller than the length of the second connection part c3 of each connection electrode.

The first contact electrode c1 and the first recess h1 may be disposed in a direction orthogonal to each other under the light emitting cells 111, 112, 113, and 114. For example, the first contact electrode c1 and the first recess h1 disposed under the first and second light emitting cells 111 and 112 may be disposed in a direction perpendicular to each other, for example, the third and fourth light emitting cells. The first contact electrode c1 and the first recess h1 disposed below the 113 and 114 may be disposed in directions perpendicular to each other. For example, the first contact electrode c1 and the first recess h1 disposed under the second and third light emitting cells 112 and 113 are disposed in a direction perpendicular to each other, for example, the first and fourth light emitting cells. The first contact electrode c1 and the first recess h1 disposed below the 111 and 114 may be disposed in directions perpendicular to each other. A plurality of first contact electrodes c1 disposed on each of the light emitting cells 111, 112, 113, and 114 may be disposed in a direction in which current flows. For example, when the first contact electrode c1 is disposed in the first light emitting cell 111, the first contact electrode c1 may be disposed to have a long length in the direction of the second light emitting cell in the first light emitting cell. The first contact electrode c1 disposed in the last fourth light emitting cell 114 may be disposed to have a long length in the direction of the second light emitting cell 111.

9 is a plan view of a light emitting device having a plurality of light emitting cells according to another embodiment of the present invention. The configuration disclosed in FIGS. 1 to 8 can be applied to FIG. 9.

Referring to FIG. 9, in the light emitting device, a plurality of light emitting cells 131, 132, and 133 may be spaced apart from each other in a first direction x. Each of the light emitting cells 131, 132, and 133 may have a length longer in a second direction than a length in a first direction, and the first contact electrodes c31, c32, c33 and the first recess h1 may have a second length. It can be arranged with a long length in the direction. The second connection portion c3 of the connection electrodes 88 and 89 may be disposed to have a long length in the second direction or longer than the second direction lengths of the first contact electrodes c31, c32, and c33. As a result, current between regions between adjacent light emitting cells 131, 132, and 133 may be diffused.

A lower portion of the gap 115 between the light emitting cells 131, 132, and 133 may be disposed to have a structure in which the first insulating portion 31 of the first insulating layer 30 protrudes, or a reflecting portion may be disposed.

10 is another example of the light emitting device of FIG. 9.

Referring to FIG. 10, the plurality of pads 91 and 92 may be connected in series with a group of the plurality of light emitting cells 131, 132 and 133. When connected in series, the plurality of pads 91 and 92 may be connected to the first and third light emitting cells 131 and 133. As another example, a plurality of pads 91 and 92 may be connected to the second electrode of the third light emitting cell 133 to distribute the power path.

As another example, when the plurality of light emitting cells 131, 132, 133 are connected in parallel to each other, the plurality of pads 91, 92 may be connected in parallel with each of the light emitting cells 131, 132, 133.

When the plurality of pads 91 and 92 are provided, the lower conductive substrate may be connected to any one of the light emitting cells, or may function as a simple heat dissipation member.

<Light emitting device package>

11 is a view showing a light emitting device package having the light emitting device disclosed above.

Referring to FIG. 11, the light emitting device package includes a support member 510, a reflective member 511 having a cavity 512 on the support member 510, a top of the support member 510, and a cavity 512. Light emitting element 100. And a light transmissive film 515 on the support member 510.

The support member 510 may be a resin based printed circuit board (PCB), silicon based on silicon or silicon carbide (SiC), ceramic based on aluminum nitride (AlN), or polyphthal. It may be formed of at least one of a resin series such as amide (Polyphthalamide: PPA), a liquid crystal polymer (PCB), and a metal core PCB (MCPCB) having a metal layer on the bottom thereof, but is not limited thereto.

The support member 510 may include a first pad part 531, a second pad part 533, a first connection member 538, a second connection member 539, a first frame 535, and a second frame ( 537). The first pad part 531 and the second pad part 533 are disposed on the bottom of the support member 510 so as to be spaced apart from each other. The first frame 535 and the second frame 537 are spaced apart from each other on the upper surface of the support member 510. The first connection member 538 may be disposed inside or on the first side surface of the support member 510 and connects the first pad part 531 and the first frame 535 to each other. The second connection member 539 may be disposed inside or on the second side surface of the support member 510, and connects the second pad part 533 and the second frame 537 to each other.

The first pad part 531, the second pad part 533, the first frame 535, and the second frame 537 may be formed of a metal material, for example, titanium (Ti), copper (Cu), or nickel ( Ni, gold (Au), chromium (Cr), tantalum (Ta), platinum (Pt), tin (Sn), silver (Ag), phosphorus (P), or may be formed of an optional alloy thereof. It may be formed of a single metal layer or a multilayer metal layer.

The first connection member 538 and the second connection member 539 include at least one of a via, a via hole, and a through hole.

The reflective member 511 is disposed around the cavity 512 on the support member 510, and may reflect the ultraviolet wavelength region having the greatest intensity among the wavelengths emitted from the light emitting device 100.

The reflective member 511 may be a resin based printed circuit board (PCB), silicon based on silicon (silicon) or silicon carbide (silicon carbide (SiC)), ceramic based on AlN (aluminum nitride; AlN), or polyphthalamide. It may be formed of at least one of a resin series such as (polyphthalamide: PPA) and a liquid crystal polymer (Liquid Crystal Polymer), but is not limited thereto. The support member 510 and the reflective member 511 may include a ceramic-based material, and the ceramic-based material may have a higher heat dissipation efficiency than the resin material.

The light emitting device 100 may be disposed on the second frame 537 or on the support member 510 and electrically connected to the first frame 535 and the second frame 537. do. The light emitting device 100 may be connected to the first frame 535 by a wire. The light emitting device 100 may emit an ultraviolet wavelength.

The light transmissive film 515 is disposed on the cavity 512 and emits light emitted from the light emitting device 100. The light transmissive film 515 may include a glass material, a ceramic material, or a light transmissive resin material. In addition, an optical lens or a phosphor layer may be further disposed on the cavity 512, but 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 having one or more light emitting devices or light emitting device packages, and may include an ultraviolet lamp.

12 is a block diagram illustrating a driving device of a light emitting device disclosed above, and FIG. 13 is a view showing an example of a driving circuit of a light emitting device according to an exemplary embodiment of the present invention.

12 and 13, the light emitting device driving apparatus may include a temperature measuring unit 214, a control unit 211, a current supply unit 140, a voltage detector 213, and a light emitting device 200. The light emitting device 200 may include a light emitting part 201 having a plurality of light emitting cells LS1, LS2, LS3 and LSn and a conductive member 203 supporting the light emitting part 201. The light emitting device 200 may be the light emitting device disclosed in FIGS. 1 to 10 or may include the light emitting device package illustrated in FIG. 11. The conductive member 203 may be a conductive substrate or a lead frame or pad portion. The conductive member 203 may include a lead having an anode and a cathode electrode. The conductive member 203 may include a lead mounted on a circuit board. The light emitting device 200 may be disposed on a circuit board and electrically connected to the light emitting device 200.

Since the plurality of light emitting cells LS1, LS2, LS3, and LSn are connected in series, the light emitting device 200 may have a capacitance value smaller than that of one light emitting cell. That is, the capacitance value of the light emitting device 200 may be reduced in inverse proportion to the number of light emitting cells. The capacitance can include parasitic capacitance.

Each of the light emitting cells 111, 112, 113, and 114 including the light emitting structures may act as a resistance and a capacitance in a circuit. When each of the light emitting cells 111, 112, 113, and 114 acts as a capacitance, a circuit of the plurality of light emitting cells 111, 112, 113, and 114 connected in series may be provided as a circuit in which the capacitances are connected in series. In this case, the sum of the plurality of capacitances in the light emitting device 100 may be inversely proportional to the number of connection of the light emitting cells 111, 112, 113, and 114. Referring to FIG. 13, for example, in one light emitting cell LS1, LS2,..., LSn, the value of capacitance C _D1 is 1 / C _D1 , and the sum of capacitances of n light emitting cells is 1 / C _D1 +. 1 / C _D2 +... + 1 / C _Dn It can be calculated as In the light emitting device 100, as the number of light emitting cells connected in series increases, the total capacitance value of the light emitting device decreases in inverse proportion. Since the value of the total capacitance is reduced in the light emitting device 100, the response characteristic of the pulse width modulated signal may be improved. That is, the time constant value may be reduced in proportion to the value of the capacitance.

The temperature measuring unit 214 measures the temperature generated from the light emitting device 200 and provides it to the control unit 211. When the light emitting device 200 emits light in the ultraviolet region having the greatest intensity among the wavelengths of the emitted light, heat generation is higher because the wall plug efficiency (WPE) is lower than that of the blue LED. Such heat generation may cause a shortening of the life of the ultraviolet light emitting device. The embodiment of the present invention can lower the heat generation and increase the current injection through the pulse driving of a plurality of light emitting cells connected in series in the light emitting device.

The voltage detector 213 may detect forward voltages of the light emitting device 200 driven by current pulses. The voltage detector 213 provides the detected voltages to the controller 211.

The controller 211 receives the information on the temperature of the light emitting device 200, the current value of the current pulses, and the detected voltages to control the driving of the light emitting device 200. The temperature, current, and voltage values are stored in the memory 211A as a look-up table (LUT). For example, the controller 211 stores in the memory 10 a table of the temperatures of the light emitting device 200, current values of current pulses, and detected voltages as a look-up table in the memory 211A. Then, the stored values are loaded to control the light emitting device 200.

The controller 211 controls the current supply unit 212 to output the pulse information according to the temperature information of the light emitting device 200 and the time constant value.

When the detection temperature is less than or equal to the first reference temperature, the controller 211 may reduce the pulse width and increase the input current. When the detection temperature is greater than the second reference temperature, the controller 211 may increase the pulse width to reduce the input current. When the input current is increased, the exothermic temperature of the light emitting device may be increased, and when the input current is decreased or turned-open, the exothermic temperature of the light emitting device may be decreased.

The light emitting device 100 may turn on or turn off a plurality of light emitting cells LS1, LS2, LS3, and LSn simultaneously. The light emitting device 100 may control the plurality of light emitting cells LS1, LS2, LS3, and LSn by increasing or decreasing a driving current with a pulse signal.

The injection of current into the light emitting device 100 can increase and decrease the duty of the pulse signal, and the value of the time constant when the width of the pulse signal is decreased is due to the decrease of the capacitance. It can improve the response characteristic of. FIG. 16 is a graph illustrating charging and discharging of capacitance according to time constants according to an embodiment of the present invention. As shown in FIG. 16, it can be seen that as the time constant value decreases, the charge and discharge graph rapidly increases or decreases.

14 and 15, the duty cycle (D) is the ratio of the pulse width to the pulse period, for example t _p / T, where t _p is the pulse width and T is the pulse period. In FIG. 15, when the duty cycle is 1, the light emitting device may be driven at a rated current of 100 mA. In the case of a duty cycle of 0.5, the light emitting device may be driven at a pulse width of about 1 ms at 200 mA, so that twice the current may be injected. can. In addition, if the duty cycle is less than 0.005 (one pulse every 20ms), it can be driven with 100µs pulse width at up to 2.2A. This narrows the pulse width so that it can be driven at high currents above 1A. Here, the duty cycle may be defined as a duty ratio, and a ratio of a pulse width and a period may be represented as a per center. In Figure 14 I _F is the amplification level.

Therefore, the narrower the pulse width in the duty cycle, the higher the pulse current can be driven, and the degradation of the pulse response characteristic can be prevented by the time constant value. In this case, when the pulse width is decreased, a minimum pulse width corresponding to the time constant value may be provided. Accordingly, the efficiency of converting the light emitting device into the WPE, that is, the optical power can be increased.

17 is a flowchart illustrating a method of driving a light emitting device according to an embodiment of the present invention.

Referring to FIG. 17, when a light emitting device in which a plurality of light emitting cells are connected in series is provided (301), the controller supplies an input current having a pulse width of a duty cycle to the light emitting device through a current supply unit and drives it (302). ). The light emitting device is driven and emits an ultraviolet wavelength having the largest intensity among the wavelengths of emitted light, for example, a wavelength of 200 nm to 280 nm. In the light emitting device, since each of the plurality of light emitting cells emits the wavelength of 200 nm to 280 nm, the light intensity may be increased. In addition, since the capacitances of the respective light emitting cells of the light emitting device are connected in series with each other, the value of the total capacitance can be reduced.

As the light emitting device is driven, the temperature and voltage generated from the light emitting device are fed back. When the heating temperature is lower than the first reference temperature according to the driving of the light emitting device, the pulse width is decreased to increase the driving current. When the temperature is above the second reference temperature, the pulse width is increased or the driving current is blocked. do. In operation 305, it is checked whether the driving is normal based on the voltage fed back from the light emitting device.

The controller varies the pulse width according to the temperature and voltage detected from the light emitting device (307). In this case, the controller controls the current supply unit to be driven with a pulse width matched to the temperature and the feedback voltage with reference to a lookup table. In addition, it can be driven to the minimum pulse width by the capacitance according to the connection of the light emitting cells.

In the light emitting device, a plurality of light emitting cells may be connected in series, and two or more light emitting cells may be connected in parallel with each other.

The embodiment of the present invention can increase the area of the connection electrode for connecting a plurality of light emitting cells emitting ultraviolet light or a wavelength of 280nm or less in series or in parallel, thereby improving current spreading.

According to an embodiment of the present invention, a plurality of light emitting cells of a light emitting device may be connected in series, thereby reducing overall capacitance of the light emitting device and improving pulse response characteristics.

The light emitting device according to the embodiment of the present invention can lower the heat generation of the light emitting device and increase the input current through pulse driving of the plurality of light emitting cells, thereby improving the WPE. In addition, it is possible to increase the sterilization power by using a light emitting device having a plurality of light emitting cells that emit ultraviolet wavelengths. In addition, it is possible to improve the reliability of the ultraviolet light emitting device and the package having the same.

Features, structures, effects, and the like 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, the features, structures, effects, and the like illustrated in each embodiment may be combined or modified with respect to other embodiments by those skilled in the art to which the embodiments belong. Therefore, it should be interpreted that the contents related to such a combination and modification are included in the scope of the present invention.

In addition, the above description has been made with reference to the embodiment, which is merely an example, and is not intended to limit the present invention. It will be appreciated that various modifications and applications are possible. For example, each component specifically shown in the embodiment can be modified. And differences relating to these modifications and applications will have to be construed as being included in the scope of the invention defined in the appended claims.

11: first conductivity type semiconductor layer
12: active layer
13: second conductivity type semiconductor layer
30,40,50: insulation layer
60: second electrode
61: contact layer
62: reflective layer
c1: first contact electrode
h1: first recess
r1: external recess
81: conductive substrate
83: first electrode
85,86,87: connecting electrode
100: light emitting element
111,112,113,114: light emitting cells

Claims (11)

Conductive substrates;
A plurality of light emitting cells disposed on the conductive substrate and including a first conductive semiconductor layer, an active layer, and a second conductive semiconductor layer and spaced apart from each other; And
And a first insulating layer disposed between the plurality of light emitting cells and the conductive substrate.
The plurality of light emitting cells are connected in series,
In each of the plurality of light emitting cells, a wavelength of light having the greatest intensity among the wavelengths of emitted light is an ultraviolet wavelength region.
The first insulating layer includes a first insulating portion disposed between the plurality of light emitting cells,
The first insulating part includes a first protrusion protruding from the conductive substrate toward a top surface of the plurality of light emitting cells;
The upper surface of the first protrusion is disposed higher than the upper surface of the plurality of active layers and lower than the upper surface of the first conductive semiconductor layer. The method of claim 1, further comprising a plurality of first electrodes disposed between the plurality of light emitting cells and the conductive substrate,
The first electrode includes a second protrusion that overlaps the first insulation in a vertical direction.
And the second protrusion is disposed higher than a lower surface of the light emitting cell or a lower surface of the second conductive semiconductor layer. The method of claim 2,
A first recess disposed in each of the plurality of light emitting cells,
The first recess penetrates from a lower surface of the second conductive semiconductor layer to a lower portion of the first conductive semiconductor layer.
The first electrode extends into the first recess and is electrically connected to the first conductive semiconductor layer. The method of claim 3,
The plurality of light emitting cells includes first, second and third light emitting cells spaced apart from each other,
The first to third light emitting cells are electrically connected to a second electrode disposed below,
A second electrode connected to the first light emitting cell is connected to a first electrode connected to the second light emitting cell,
And a second electrode connected to the second light emitting cell is connected to a first electrode connected to the third light emitting cell. The method of claim 4, wherein
The second light emitting cell is disposed between the first and third light emitting cells,
The first protrusion part is disposed on at least two side surfaces of the second light emitting cell. The method of claim 4, wherein
The second light emitting cell is disposed between the first and third light emitting cells,
The first protrusion part is disposed in an area in which the second light emitting cell and the first light emitting cell face each other, and an area in which the second light emitting cell and the third light emitting cell face each other. The method according to any one of claims 3 to 6,
The first insulating layer includes a second insulating portion disposed in the first recess,
An upper surface width of the first insulating part is wider than a gap between the light emitting cells.
An outer side of each light emitting cell includes an outer recess having an inclined side surface,
And a depth of an outer recess of each of the light emitting cells is equal to a depth of the first recess. The semiconductor device of claim 7, wherein the first electrode includes a connection portion connected to the first conductive semiconductor layer in the first recess.
The length of the connection portion is greater than the distance between the first recess of each of the light emitting cells,
The length of the first recess has a long length in one direction,
The longitudinal direction of the first recess is disposed in the same direction in each of the light emitting cells,
The longitudinal direction of the first recess is disposed in a direction orthogonal to each other with respect to adjacent light emitting cells. The light emitting device according to any one of claims 3 to 6, wherein the upper surfaces of the plurality of light emitting cells include an uneven portion and a reflecting portion disposed in an area between the plurality of light emitting cells. Conductive substrates;
A plurality of light emitting cells disposed on the conductive substrate and including a first conductive semiconductor layer, an active layer, and a second conductive semiconductor layer and spaced apart from each other; And
And a first insulating layer disposed between the plurality of light emitting cells and the conductive substrate.
The first insulating layer includes a first insulating portion disposed between the plurality of light emitting cells,
The first insulating part includes a first protrusion protruding from the conductive substrate toward a top surface of the plurality of light emitting cells;
An upper surface of the first protrusion may include a light emitting device disposed above the upper surface of the plurality of active layers and lower than the upper surface of the first conductive semiconductor layer.
The light emitting device is provided with the plurality of light emitting cells connected in series,
Driven by a drive current adjusted to a pulse width of a preset duty cycle;
Emitting an ultraviolet wavelength having the greatest intensity among the wavelengths of light emitted from each of the light emitting cells by the driving current;
And varying the pulse width according to the heating temperature and the fed back voltage according to the driving. The method of claim 10, wherein the pulse width is reduced to a maximum pulse width corresponding to a time constant value by a sum of capacitance values of the plurality of light emitting cells.

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