KR102303460B1 - Light emitting device and light emitting device package including the same - Google Patents

Abstract

The light emitting device of the embodiment and the light emitting device package including the same include: a substrate; a plurality of light emitting cells spaced apart from each other on a substrate and including a first conductivity type semiconductor layer, an active layer, and a second conductivity type semiconductor layer; a first electrode and a second electrode respectively disposed on the first conductivity-type semiconductor layer and the second conductivity-type semiconductor layer; a connection electrode connecting neighboring light emitting cells among the plurality of light emitting cells; and a reflective layer disposed on the substrate and spaced apart from each other among the plurality of light emitting cells. Including , high luminous efficiency can be achieved by enabling light extraction by reflection of light even on a substrate in an area where no light emitting cells are disposed.

Description

A light emitting device and a light emitting device package including the same

The embodiment relates to a light emitting device and a light emitting device package including the same.

Group III-V compound semiconductors, such as GaN and AlGaN, are widely used in optoelectronics and electronic devices due to their many advantages, such as wide and easily tunable band gap energy.

In particular, light emitting devices such as light emitting diodes or laser diodes using group III-V or group II-VI compound semiconductor materials of semiconductors have developed thin film growth technology and device materials such as red, green, blue, and ultraviolet light. Various colors can be realized, and efficient white light can be realized by using fluorescent materials or combining colors. It has the advantage of environmental friendliness.

Accordingly, a light emitting diode backlight that replaces a Cold Cathode Fluorescence Lamp (CCFL) constituting a transmission module of an optical communication means, a backlight of a Liquid Crystal Display (LCD) display device, and a white light emission that can replace a fluorescent lamp or incandescent light bulb Applications are expanding to diode lighting devices, automobile headlights and traffic lights.

Light-emitting devices (LEDs) are replacing existing light sources because they have excellent eco-friendliness, long lifespan, low power consumption characteristics, and the like. A key competitive element of these LED devices is the realization of high luminance by high-efficiency and high-output chips and packaging technology.

In order to realize high brightness, it is important to increase light extraction efficiency, and to improve light extraction efficiency, flip-chip structure, surface texturing, and uneven sapphire substrate (PSS: Patterned Sapphire Substrate) , photonic crystal technology, and various methods using an anti-reflection layer structure are being studied.

The embodiment provides a light emitting device having improved light extraction efficiency by adding a reflective layer between a plurality of light emitting cells, and a light emitting device package including the same.

Examples include substrates; a plurality of light emitting cells spaced apart from each other on the substrate and including a first conductivity type semiconductor layer, an active layer, and a second conductivity type semiconductor layer; first and second electrodes respectively disposed on the first conductivity-type semiconductor layer and the second conductivity-type semiconductor layer; a connection electrode connecting neighboring light emitting cells among the plurality of light emitting cells; and a reflective layer disposed on the substrate and spaced apart from each other among the plurality of light emitting cells adjacent to each other. It provides a light emitting device comprising a.

The reflective layer may be further disposed in an edge region of the substrate.

The reflective layer may be disposed in contact with the substrate.

At least a portion of the connection electrode may be disposed on the reflective layer.

and a first insulating layer disposed on the plurality of light emitting cells and having a first open region and a second open region respectively formed on the first conductivity-type semiconductor layer and the second conductivity-type semiconductor layer.

The first electrode may be electrically connected to the first conductivity-type semiconductor layer in the first open region, and the second electrode may be electrically connected to the second conductivity-type semiconductor layer in the second open region.

It may further include a second insulating layer disposed on the reflective layer, wherein a first surface of the second insulating layer faces the connection electrode and a second surface facing the first surface faces the reflective layer. have.

The connection electrode may connect the first electrode of one of the neighboring light emitting cells and the second electrode of the other of the neighboring light emitting cells.

The reflective layer may be formed of a material having a refractive index greater than 2.0.

The reflective layer may include any one selected from the group consisting _{of TiO 2} , Ta ₂ O _{5 and NiO.}

The reflective layer may _{include TiO 2} , and the reflective layer may have a thickness of 75 nm to 105 nm or 260 nm to 290 nm.

The reflective layer may include Ta ₂ O ₅ , and the reflective layer may have a thickness of 85 nm to 115 nm or 270 nm to 300 nm.

The reflective layer may include NiO, and the reflective layer may have a thickness of 80 nm to 110 nm or 265 nm to 295 nm.

Another embodiment is a lead frame; the light emitting device of any one of the above-described embodiments disposed on the lead frame; a molding part disposed to surround the light emitting device; and a phosphor included in the molding part and excited by light emitted from the light emitting device; It provides a light emitting device package comprising a.

The light emitting device may emit blue light, and the light emitting device may have an emission center wavelength of 440 nm to 460 nm.

The phosphor includes a plurality of phosphors having emission wavelengths in different wavelength ranges, and the plurality of phosphors includes a first phosphor having a central emission wavelength of 480 nm to 550 nm and a second phosphor having an emission central wavelength of 600 nm to 700 nm. It may include at least one.

In the light emitting device and the light emitting device package including the same according to the embodiment, by arranging a reflective layer having high reflectivity in a limited wavelength region in a spaced apart space between a plurality of light emitting cells, it is possible to reflect light even on a substrate in an area where the light emitting cells are not disposed. It is possible to extract light by means of a high luminous efficiency can be exhibited.

1 is a view showing a cross-section of a light emitting device of an embodiment,
2 is a diagram showing the relationship between wavelength and optical thickness;
3A to 3B are views showing optical characteristics in a reflective layer according to an embodiment;
4 is a view showing the optical characteristics of the reflective layer according to an embodiment according to the wavelength,
5 is a plan view of a light emitting device according to an embodiment;
6 to 7 are cross-sectional views of a light emitting device according to an embodiment,
8 is a view showing a light emitting device package according to an embodiment;
9 is a diagram illustrating an example of light extraction in a light emitting device package according to an embodiment.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, embodiments of the present invention that can specifically realize the above objects will be described with reference to the accompanying drawings.

In the description of the embodiment according to the present invention, in the case where it is described as being formed in "on or under" of each element, above (above) or below (on) or under) includes both elements in which two elements are in direct contact with each other or one or more other elements are disposed between the two elements indirectly. In addition, when expressed as “up (up) or down (on or under)”, the meaning of not only the upward direction but also the downward direction based on one element may be included.

Also, as used hereinafter, relational terms such as “first” and “second”, “upper/upper/above” and “lower/lower/below” refer to any physical or logical relationship or order between such entities or elements. may be used only to distinguish one entity or element from another, without necessarily requiring or implying that

In the drawings, the thickness or size of each layer is exaggerated, omitted, or schematically illustrated for convenience and clarity of description. Also, the size of each component does not fully reflect the actual size.

1 is a cross-sectional view of a light emitting device according to an embodiment.

The light emitting device 200A according to an embodiment includes a substrate 110 , a plurality of light emitting cells 100a and 100b disposed on the substrate, and a first conductivity type semiconductor layer 122 and a second conductivity type semiconductor layer of the plurality of light emitting cells. Between the first electrode 142 and the second electrode 146 respectively disposed on the 126 , the connection electrode 148 connecting the neighboring light emitting cells among the plurality of light emitting cells, and the neighboring light emitting cells among the plurality of light emitting cells may include a reflective layer 170 disposed on a space spaced apart from each other.

The substrate 110 included in the light emitting device 200A according to an embodiment may be formed of a material suitable for semiconductor material growth, a carrier wafer, or the like. In addition, the substrate 110 may be formed of a material having excellent thermal conductivity, and may be a conductive substrate or an insulating substrate.

For example, the substrate 110 may be a material including at least one _{of sapphire (Al 2} 0 ₃ ), GaN, SiC, ZnO, Si, GaP, InP, Ga ₂ 0 _{3 , and GaAs.} As shown in FIG. 1 , a concave-convex pattern P may be formed on the upper surface of the substrate 110 . That is, the substrate 110 may be a patterned sapphire substrate (PSS) having an uneven pattern. As such, when the upper surface of the substrate 110 has the concave-convex pattern, the light extraction efficiency of the light emitting device may be improved.

In addition, although not shown in FIG. 1 , the buffer layer is disposed between the substrate 110 and the light emitting structure 120 and may be formed using a compound semiconductor of a group III-V element. The buffer layer may serve to reduce a difference in lattice constant between the substrate 110 and the light emitting structure 120 .

In the embodiment of the light emitting device 200A shown in FIG. 1 , a plurality of light emitting cells 100a and 100b may be disposed on the substrate 110 . In an embodiment of the light emitting device, a plurality of light emitting cells may be electrically connected in series, but the embodiment is not limited thereto.

Meanwhile, in the cross-sectional view of FIG. 1, only two light emitting cells are shown for convenience of explanation, but the embodiment is not limited thereto. The plurality of light emitting cells to be used may be disposed adjacent to each other in the row and column directions on the substrate, or may be arranged in various forms.

Each of the plurality of light emitting cells 100a and 100b may include a light emitting structure 120 .

The light emitting structure 120 of FIG. 1 may include a first conductivity type semiconductor layer 122 , an active layer 124 on the first conductivity type semiconductor layer, and a second conductivity type semiconductor layer 126 disposed on the active layer. .

The first conductivity type semiconductor layer 122 may be implemented with a compound semiconductor such as group III-V or group II-VI, and may be doped with a first conductivity type dopant. The first conductivity type semiconductor layer 122 is _{a semiconductor material having a composition formula of Al x} In _y Ga _(1-xy) N (0≤x≤1, 0≤y≤1, 0≤x+y≤1), AlGaN , GaN, InAlGaN, AlGaAs, GaP, may be formed of any one or more of GaAs, GaAsP, AlGaInP.

When the first conductivity-type semiconductor layer 122 is an n-type semiconductor layer, the first conductivity-type dopant may include an n-type dopant such as Si, Ge, Sn, Se, Te, or the like. The first conductivity type semiconductor layer 122 may be formed as a single layer or a multilayer, but is not limited thereto.

An active layer 124 may be disposed on the first conductivity type semiconductor layer 122 .

The active layer 124 is disposed between the first conductivity type semiconductor layer 122 and the second conductivity type semiconductor layer 126 , and includes a single well structure, a multiple well structure, a single quantum well structure, and a multiple quantum well structure. It may include any one of a multi-quantum well (MQW) structure, a quantum dot structure, or a quantum wire structure.

The active layer 124 is formed of a well layer and a barrier layer, for example, AlGaN/AlGaN, InGaN/GaN, InGaN/InGaN, AlGaN/GaN, InAlGaN/GaN, GaAs (InGaAs) using a III-V group element compound semiconductor material. /AlGaAs, GaP (InGaP) / may be formed in any one or more pair (Pair) structure (Pair) structure, but is not limited thereto. The well layer may be formed of a material having an energy band gap smaller than that of the barrier layer.

The second conductivity type semiconductor layer 126 may be formed of a semiconductor compound on the surface of the active layer 124 . The second conductivity type semiconductor layer 126 may be implemented with a group III-V group or group II-VI compound semiconductor, and may be doped with a second conductivity type dopant. The second conductivity type semiconductor layer 126 is, for example, _{a semiconductor material having a composition formula of In x} Al _y Ga _{1 -x- y} N (0≤x≤1, 0≤y≤1, 0≤x+y≤1) , AlGaN, GaN AlInN, AlGaAs, GaP, GaAs, GaAsP, may be formed of any one or more of AlGaInP, for example, the second conductivity type semiconductor layer 126 may be made of Al _x Ga _(1-x) N have.

When the second conductivity-type semiconductor layer 126 is a p-type semiconductor layer, the second conductivity-type dopant may be a p-type dopant such as Mg, Zn, Ca, Sr, or Ba. The second conductivity type semiconductor layer 126 may be formed as a single layer or a multilayer, but is not limited thereto.

A conductive layer 130 may be further disposed on the second conductivity type semiconductor layer 126 .

The conductive layer 130 may improve electrical characteristics of the second conductivity-type semiconductor layer 126 and may improve electrical contact with the second electrode 146 . The conductive layer 130 may be formed to have a plurality of layers or patterns, and the conductive layer 130 may be formed as a transparent electrode layer having transparency.

The conductive layer 130 is, for example, ITO (Indium Tin Oxide), IZO (Indium Zinc Oxide), IZTO (Indium Zinc Tin Oxide), IAZO (Indium Aluminum Zinc Oxide), IGZO (Indium Gallium Zinc Oxide), IGTO ( Indium Gallium Tin Oxide), AZO (Aluminum Zinc Oxide), ATO (Antimony Tin Oxide), GZO (Gallium Zinc Oxide), IZON (IZO Nitride), AGZO (Al-Ga ZnO), IGZO (In-Ga ZnO), ZnO (Zinc Oxide), IrOx (Iridium Oxide), RuOx (Ruthenium Oxide), NiO (Nickel Oxide), RuOx/ITO, Ni/IrOx/Au (Gold) may be formed including at least one of, but limited to these materials doesn't happen

Meanwhile, in an embodiment, the first conductivity-type semiconductor layer 122 included in the light emitting structure 120 may be an n-type semiconductor layer, and the second conductivity-type semiconductor layer 126 may be a p-type semiconductor layer. Accordingly, the light emitting structure 120 may include at least one of an n-p junction, a p-n junction, an n-p-n junction, and a p-n-p junction structure.

A first electrode 142 may be disposed on the first conductivity-type semiconductor layer 122 of the light emitting structure 120 , and a second electrode 146 may be disposed on the second conductivity-type semiconductor layer 126 . In this case, the first electrode ( The 142 and the second electrode 146 may be electrically connected to the first conductivity type semiconductor layer 122 and the second conductivity type semiconductor layer 126 , respectively.

The first electrode 142 and the second electrode 146 are formed of a conductive material such as indium (In), cobalt (Co), silicon (Si), germanium (Ge), gold (Au), palladium (Pd), Platinum (Pt), ruthenium (Ru), rhenium (Re), magnesium (Mg), zinc (Zn), hafnium (Hf), tantalum (Ta), rhodium (Rh), iridium (Ir), tungsten (W), A metal selected from titanium (Ti), silver (Ag), chromium (Cr), molybdenum (Mo), niobium (Nb), aluminum (Al), nickel (Ni), copper (Cu) and titanium tungsten alloy (WTi) Alternatively, it may be formed as a single layer or a multi-layer using an alloy, but the materials constituting the first electrode 142 and the second electrode 146 are not limited to the illustrated materials.

Also, in FIG. 1 , the light emitting device 200A according to the exemplary embodiment may include a connection electrode 148 for connecting neighboring light emitting cells among a plurality of light emitting cells.

The connection electrode 148 may connect the first electrode 142 of one of the neighboring light emitting cells and the second electrode 146 of the other of the neighboring light emitting cells.

For example, in the embodiment of FIG. 1 , the first electrode 142 of one light emitting cell 100a among the neighboring light emitting cells and the second electrode 146 of the other light emitting cell 100b are connected to the connection electrode ( 148) can be electrically connected.

For the connection electrode 148 , a light-transmitting conductive material and a metal material may be selectively used.

For example, the connection electrode 148 may include 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), ATO (antimony tin oxide), GZO (gallium zinc oxide), IZON (IZO Nitride), AGZO (Al-Ga ZnO), IGZO (In-Ga ZnO), ZnO , IrOx, RuOx, NiO, RuOx/ITO, Ni/IrOx/Au, or Ni/IrOx/Au/ITO, Ag, Ni, Cr, Ti, Al, Rh, Pd, Ir, Sn, In, Ru, Mg, It may be formed including at least one of Zn, Pt, Au, and Hf.

The connection electrode 148 may be disposed on the reflective layer 170 or the insulating layer 150 - 1 to be described later. For example, at least a portion of the connection electrode 148 may be disposed on the reflective layer 170 , and at least a portion of the connection electrode 148 may be disposed on the insulating layer 150 - 1 .

When the connection electrode 148 is formed to include Al (Aluminum) or Ag (Silver), the connection electrode may serve as a reflective layer in the light emitting device.

Meanwhile, the connection electrode 148 may be integrally formed with the first electrode 142 and the second electrode 146 connected to both sides, respectively.

That is, when the light emitting device 200A of an embodiment is used as a light emitting device for high voltage, the connection electrode 148 electrically connects the plurality of light emitting cells so that the light emitting device 200A operates. can In addition, by including a material having a reflective function in the connection electrode 148 , the light emitted from the light emitting device is reflected by the connection electrode 148 to be directed upwards of the light emitting device, thereby improving luminous efficiency.

In addition, in the light emitting device 200A according to an exemplary embodiment, a reflective layer 170 may be disposed in a space between the plurality of light emitting cells 100a and 100b.

The reflective layer 170 is disposed on the substrate 110 , and one surface of the reflective layer may be formed in contact with the substrate 110 . For example, when the concave-convex pattern P is formed on the substrate 110 as in the embodiment shown in FIG. 1 , the reflective layer 170 may fill the concavo-convex portion on the substrate and be disposed in contact with the substrate.

Also, referring to FIG. 1 , the reflective layer 170 may also be disposed on an edge region of the substrate 110 . That is, the reflective layer 170 may be disposed not only in a space between adjacent light emitting cells in the plurality of light emitting cells, but also in other regions on the substrate where the light emitting cells are not disposed and exposed.

The reflective layer 170 may include a material having a high refractive index. For example, the reflective layer 170 may include a material having a refractive index greater than 2.0.

Specifically, the reflective layer 170 may _{include any one selected from the group consisting of TiO 2} (Titanium Dioxide), Ta ₂ O ₅ (Tantalum pentoxide), and NiO (Nickel oxide).

The refractive index of the material included in the reflective layer may be 2.45 for _{TiO 2 , 2.15 for Ta 2} O ₅ , and 2.3 for NiO at a wavelength of 450 nm, respectively.

In the case of such a high refractive index material, the amount of change in optical thickness with respect to wavelength is large. Therefore, in the case of a reflective layer formed including a high refractive index material, the width of change in transmittance or reflectance depending on the wavelength region of light is relatively small. It may appear larger than the case where the material is included.

2 is a diagram illustrating a relationship between a wavelength of light and an optical thickness.

Referring to the graph of FIG. 2 , it can be seen that the optical thickness tends to decrease as the wavelength of light increases.

That is, it can be seen that in order to exhibit the same optical characteristics, for example, the same reflectivity, the optical thickness should be changed according to the wavelength of the supplied light.

On the other hand, the relationship between the optical thickness and the physical thickness can be expressed by the following equation.

Here, T _optical is the optical thickness, n is the refractive index value of the material used, d is the physical thickness, and λ corresponds to the wavelength of the supplied light.

That is, referring to the relationship of Equation 1, in the reflective layer having the same thickness d, the higher the refractive index n, the greater the change in the optical thickness. In addition, the higher the refractive index, the greater the change in the optical thickness according to the change in the wavelength (λ).

On the other hand, since the reflectance (%) of the reflective layer _{changes depending on the optical thickness (T optical} ), as a result, the higher the refractive index (n), the greater the change in the optical thickness according to the wavelength (λ) region of the light. The range of change in optical properties of the reflective layer, such as reflectivity, may be large.

3A to 3B are diagrams illustrating optical characteristics of a reflective layer included in a light emitting device according to an exemplary embodiment.

Figure 3a is a graph showing the transmittance (Transmittance, %) according to the optical thickness (Optical Thickness) of the reflective layer, Figure 3b is a graph showing the relationship between the reflectance (Reflectance, %) according to the optical thickness of the reflective layer.

For example, the graph for the optical properties of FIGS. 3A to 3B shows the optical properties when the _{reflective layer made of TiO 2} is disposed on the ITO layer, and at this time, the refractive index value of the ITO layer is 2.0, and the reflective layer is supplied The wavelength of light may be 450 nm.

Referring to Figures 3a to 3b, on the ITO layer TiO ₂ When the layer is formed, it can be seen that the transmittance and reflectivity of the reflective layer are repeated with periodicity depending on the optical thickness.

That is, the transmittance is maximum at the same optical thickness and the reflectivity may have a corresponding minimum value, and the transmittance and reflectivity may be changed in response to a change in the optical thickness with periodicity in the form of a sine wave.

For example, referring to the graphs of FIGS. 3A to 3B , the transmittance shows a high value of 90% or more in the range of the optical thickness of 0.4 to 0.6, and correspondingly, the reflectance in the reflective layer when the optical thickness is 0.4 to 0.6 It can be seen that is less than 5%. In addition, since the transmittance or reflectance value has a sinusoidal periodicity, for example, even when the optical thickness of the reflective layer is 0.9 to 1.1, the transmittance is maximum and the reflectance is 5% or less.

Therefore, in order to best transmit light of a wavelength of 450 nm, the optical thickness of the reflective layer should be 0.4 to 0.6 or 0.9 to 1.1.

When the physical thickness of the reflective layer corresponding to the optical thickness of 0.4 to 0.6 or 0.9 to 1.1 at which the transmittance is maximum at 450 nm in the example of FIG. 3A is obtained using Equation 1 above, the thickness (d) of the reflective layer is 75 nm to 105 nm or 260 nm to 290 nm.

On the other hand, when light having a wavelength of 480 nm to 700 nm is supplied to the reflective layer having a maximum transmittance at 450 nm, the optical thickness may be different even if the light has the same physical thickness. The light having a wavelength of 700 nm may have a relatively high reflectivity compared to light having a wavelength of 450 nm.

For example, by disposing the reflective layer 170 between the substrate 110 and the connection electrode 148 in the light emitting device of an embodiment, the transmittance for blue light near a wavelength of 450 nm is high, and a relatively long wavelength of 480 nm to 700 nm With respect to green light or red light, it has a higher reflectivity than blue light, so that the light of green light or red light can be selectively reflected.

Therefore, in the light emitting device of one embodiment, by including the high refractive index material in the reflective layer 170, it is possible to have different reflectivity for each wavelength region of light at a specific thickness. It can function as a reflective layer.

That is, in the light emitting device shown in FIG. 1 , the reflective layer 170 may be a selective reflective layer that exhibits different reflectivity according to the wavelength of incident light.

The thickness of the reflective layer 170 may vary depending on a material constituting the reflective layer. For example, the thickness of the reflective layer 170 may vary according to a refractive index value of a material forming the reflective layer.

Specifically, as the refractive index value of the material forming the reflective layer increases, the thickness of the reflective layer having the same optical characteristics may tend to decrease.

For example, as described above, the reflective layer 170 having a maximum transmittance for light of 450 nm and a relatively high reflectivity for light in a wavelength range of 480 nm to 700 nm is made of a TiO ₂ (refractive index: 2.45) layer. The thickness of may be 75 nm to 105 nm or 260 nm to 290 nm. In addition, when the reflective layer 170 is formed of a NiO (refractive index: 2.3) layer, the reflective layer thickness is 80 nm to 110 nm or 265 nm to 295 nm, and _{when the reflective layer is formed of a Ta 2} O ₅ (refractive index: 2.15) layer, the reflective layer thickness is 85 nm to 115 nm or 270 nm to 300 nm.

Meanwhile, in the embodiment of FIG. 1 , the thickness of the reflective layer 170 formed on the substrate 110 may be several to several tens of times the height of the concave-convex pattern P of the substrate. When the thickness of the reflective layer 170 from the highest point of the concave-convex pattern P formed on the upper surface of the substrate is t1, and the thickness of the reflective layer from the lowest point of the concave-convex pattern P is t2, the reflective layer 170 is The thickness may be an average value of the t1 and t2 thicknesses.

For example, when the thickness of the reflective layer 170 is d, d=(t1+t2)/2. In this case, the thickness d of the reflective layer corresponds to the physical thickness of the reflective layer.

FIG. 4 shows a comparison of reflectance (Reflectance, %) according to a wavelength (Wavelength, nm) of light in a case in which a reflective layer is included on the substrate and the substrate.

In FIG. 4 , a comparative example may be a reflectance value in a sapphire substrate, and an example may be a reflectance value in a case in which a reflective layer having a high refractive index is applied on the sapphire substrate. In this case, the reflective layer may be a _{TiO 2 layer.}

4, in the comparative example, a uniform reflectivity of about 6% in the entire wavelength region of 400 nm to 800 nm is exhibited, and in comparison with this, in the embodiment, a relatively low reflectivity of 10% or less is shown in the wavelength region near 450 nm, but It can be seen that the reflectivity in the reflective layer increases toward a long wavelength of 480 nm or more, and in particular, it can be seen that a reflectivity of 20% or more is exhibited at a long wavelength of 600 nm to 700 nm.

Accordingly, as in the embodiment shown in FIG. 1, a reflective layer is further included on the substrate, and by forming the reflective layer including a high refractive index material, it has the effect of selectively reflecting relatively high reflectivity to long-wavelength light. can

Referring back to FIG. 1 , an embodiment of the light emitting device 200A may include a first insulating layer 150 - 1 disposed on a plurality of light emitting cells.

The first insulating layer 150 - 1 may be disposed to surround the side surface as well as the upper surface of the light emitting structure 120 .

In the light emitting device according to an embodiment, the first insulating layer 150 - 1 is disposed on the plurality of light emitting cells, the first open region formed on the first conductivity type semiconductor layer 122 and the second conductivity type semiconductor layer 126 . ) may include a second open region formed on the .

Meanwhile, the first electrode 142 may be disposed in the first open area of the first insulating layer 150 - 1 , and the second electrode 146 may be disposed in the second open area. That is, in the first open region of the first insulating layer, the first conductivity-type semiconductor layer 122 and the first electrode 142 are electrically connected, and in the second open region, the second conductivity-type semiconductor layer 126 and the first electrode 142 are electrically connected. The two electrodes 146 may be electrically connected.

The first insulating layer 150 - 1 may be formed of a material such as _{SiO 2} , Si ₃ N _{4 , or polyimide.}

In addition, the first insulating layer 150 - 1 may be formed of a material having a high reflectance in order to increase the efficiency of light emitted from the light emitting structure 120 , and may have, for example, a DBR structure.

The first insulating layer 150 - 1 is disposed on the plurality of light emitting cells to prevent direct contact between the connecting electrode 148 and the light emitting cell, thereby preventing an electrical short by the connecting electrode 148 .

In addition, the first insulating layer 150 - 1 is disposed on the light emitting structure 120 exposed between the first electrode 142 and the second electrode 146 in one light emitting cell. ) and can prevent an electrical short circuit by the first electrode 142 and the second electrode 146 .

5 may be a plan view of a light emitting device according to an embodiment.

In the embodiment shown in FIG. 5 , the light emitting device may include a plurality of light emitting cells 100a to 100f, and neighboring light emitting cells among the plurality of light emitting cells 100a to 100f are connected to each other by the connection electrode 148 . can be electrically connected. Specifically, the plurality of light emitting cells 100a to 100f may be electrically connected in series.

For example, in FIG. 5 , the first electrode 142 of the first light emitting cell 100a, which is one of the plurality of light emitting cells, and the second electrode 146 of the neighboring second light emitting cell 100b are connected to the connection electrode ( 148), and in the case of a third light emitting cell 100c adjacent to the first light emitting cell 100a, the second electrode 146 of the first light emitting cell 100a and the third light emitting cell 100c) The first electrode 142 of may be electrically connected by the connection electrode 148 .

Meanwhile, referring to FIG. 5 , a reflective layer 170 may be disposed in a space spaced apart between the plurality of light emitting cells 100a to 100f and in an edge region of the substrate.

That is, by disposing the reflective layer 170 in a region on the substrate where the plurality of light emitting cells are not disposed, light emitted from the light emitting cells is reflected from the reflective layer 170 without being absorbed back to the substrate and extracted to the outside of the light emitting device. Accordingly, it is possible to have an effect of improving the light efficiency of the light emitting device according to an embodiment.

Hereinafter, in the description of the light emitting device embodiment of FIGS. 6 to 7 , the content overlapping with the description of the light emitting device embodiment of FIG. 1 will not be described again, and differences will be mainly described.

6 is a cross-sectional view of a light emitting device according to an embodiment.

In FIG. 6 , the light emitting device 200B according to an embodiment includes a substrate 110 , a plurality of light emitting cells, a connection electrode 148 connecting neighboring light emitting cells among the plurality of light emitting cells, and a space between the plurality of light emitting cells, and A reflective layer 170 disposed on the substrate at the edge of the substrate may be included.

In addition, in the embodiment of the light emitting device 200B shown in FIG. 6 , it includes a first insulating layer 150 - 1 disposed on a plurality of light emitting cells, and a reflective layer ( It may further include a second insulating layer 150 - 2 disposed on the 170 .

That is, in the embodiment of FIG. 6 , the first surface of the second insulating layer 150 - 2 faces the connection electrode 148 and is disposed, and the second surface facing the first surface faces the reflective layer 170 . can be placed.

Accordingly, the second insulating layer 150 - 2 including a reflective material or having a DBR structure is additionally formed on the reflective layer 170 , so that light reflected from the surface of the reflective layer 170 and directed upwards of the light emitting device is reduced. Since it is not absorbed by the second insulating layer and may be extracted to the outside, the ratio of light emitted to the outside of the light emitting device may be increased to improve light efficiency.

7 is a cross-sectional view of another embodiment of a light emitting device.

The light emitting device 200C of the embodiment shown in FIG. 7 includes a substrate 110 , a plurality of light emitting cells spaced apart from each other on the substrate, a connection electrode 148 for electrically connecting neighboring light emitting cells, and a plurality of light emitting cells. The reflective layer 170 may be disposed in a region on the substrate on which the cell is not disposed.

In addition, in the embodiment of FIG. 7 , in the case of the reflective layer 170 disposed on the substrate in a space spaced apart between neighboring light emitting cells, the first surface is in contact with the substrate, and the second surface facing the first surface is connected to the connection electrode and may be placed in contact.

That is, compared to the light emitting devices 200A and 200B of the exemplary embodiment shown in FIG. 1 or 6 , the light emitting device 200C of the embodiment of FIG. 7 may not include an insulating layer.

In the embodiment of FIG. 7 , the reflective layer 170 may be made of an insulating material, and the reflective layer 170 is disposed in a space between the connection electrode 148 and the light emitting structure 120 or between the connection electrode 148 and the substrate 110 . ) is formed to protect the light emitting structure 120 and prevent an electrical short circuit without additionally disposing an insulating layer.

In the case of the light emitting devices 100A, 100B, and 100C of the embodiments described above in FIGS. 1 and 6 to 7 , the reflective layer 170 is disposed on the region on the substrate 110 on which the light emitting cell is not disposed, and the reflective layer 170 is By forming it to include a high refractive index material, the reflectivity can be varied according to the wavelength of the light incident on the reflective layer 170 , so that it can have an effect of selectively reflecting light according to a wavelength region.

8 is a diagram illustrating an embodiment of a light emitting device package including the light emitting devices 100A, 100B, and 100C of the above-described embodiment.

The light emitting device package 300 of one embodiment is formed including lead frames 242 and 246, the light emitting device 200 of the above-described embodiment disposed on the lead frame, and the molding part 260 disposed to surround the light emitting device. can be

In addition, the molding part 260 may include the phosphor 270 excited by the light emitted from the light emitting device 200 .

The light emitting device package 300 according to the embodiment shown in FIG. 8 may further include a package body 230 having a cavity, and the package body 230 has a lead frame for electrical connection with the light emitting device 200 . (242, 246) can be arranged fixedly. In addition, the light emitting device 200 may be included in the cavity fixed on the lead frame.

The package body 230 may be formed of a silicon material, a synthetic resin material, or a metal material, and may be formed of a ceramic material having excellent thermal conductivity.

The upper portion of the package body 230 is open and may have a cavity composed of a side surface and a bottom surface. The cavity may be formed in a cup shape, a concave container shape, or the like, and the side surface of the cavity may be formed to be perpendicular or inclined with respect to the bottom surface, and the size and shape thereof may vary. The shape of the cavity viewed from above may be a circular shape, a polygonal shape, an elliptical shape, or the like, and may have a curved edge shape, but is not limited thereto.

The light emitting device 200 may be disposed in the cavity of the package body 230 , may be disposed on the package body 230 , or may be disposed on the first lead frame 242 or the second lead frame 246 .

The first lead frame 242 and the second lead frame 246 may be formed of a conductive material such as copper and, for example, may be plated with gold (Au).

The first lead frame 242 and the second lead frame 246 are electrically isolated from each other, and may supply a current to the light emitting device 200 . In addition, the first lead frame 242 and the second lead frame 246 reflect light generated from the light emitting device 200 to increase light efficiency, and heat generated from the light emitting device 200 to the outside. It can also be ejected.

The light emitting device 200 may be electrically connected to the first or second lead frames 242. 246 through a wire 248 . The wire 248 may be made of a conductive material.

In the embodiment of the light emitting device package 300 of FIG. 8 , a molding part 260 may be disposed to surround the light emitting device 200 and the like.

In the embodiment shown in FIG. 8 , the upper surface of the molding part 260 is shown to be formed on the same line as the upper surface of the side surface of the cavity, but the embodiment is not limited thereto. It may be formed high or formed lower than the cavity side height.

In addition, the molding portion 260 is formed higher than the sidewall of the cavity of the package body to be formed in a dome type, and may be arranged in a different shape to adjust the light emission angle of the light emitting device package 200 . The molding unit 260 surrounds and protects the light emitting device 200 and may act as a lens for changing the path of light emitted from the light emitting device 200 .

The molding unit 260 may include a resin layer, and the resin layer may include a resin selected from the group consisting of a mixture including any one of a silicone-based resin, an epoxy-based resin, and an acrylic resin, or a group thereof.

The molding part 260 may include a phosphor 270 .

The phosphor 270 may be excited by the light emitted from the light emitting device 200 to emit wavelength-converted light.

In the light emitting device package 300 of the embodiment, the light emitting device 200 may emit blue light that excites the phosphor 270 . Meanwhile, the emission center wavelength of light emitted from the light emitting device 200 may be 440 nm to 460 nm.

The phosphor 270 included in the molding part 260 may include a plurality of phosphors having emission wavelengths in different wavelength ranges.

The plurality of phosphors 270 may include at least one of a first phosphor 270a having a central emission wavelength of 480 nm to 550 nm and a second phosphor 270b having an emission central wavelength of 600 nm to 700 nm.

The first phosphor 270a may be a phosphor emitting yellow or green light.

For example, the yellow phosphor is _{^{X 2 SiO 4: Eu 2 +}} ( wherein, X is Ca, Sr, one Ba of at _{least), Sr 3 SiO 5: Eu} 2 + , or _{Y 3 Al 5 O1 2: Ce} 3 + a may be included, the green phosphor is _{Ba 3 Si 6 O 12 N 2} : Eu 2+, β-SiAlON: Eu 2 +, Ca - ?? - SiAlON: Yb, CaSi 2 O 2 N 2: Eu 2 + _3, or Lu Al ₅ O ₁₂ :Ce ³⁺ may include.

The second phosphor 270b may be a phosphor emitting red light.

For example, the red phosphor _{Y 2 Si 5 N 8: Eu} 2 + ( where, Y is Ca, Sr, Ba of one at ^{_{least), CaAlSiN 3: Eu 2 +}} , SrCaSi 5 N 8: Eu 2 + , or K ₂ MF ₆ :Mn ^{4 +} (where M is at least one of Si, Ge, and Ti) and the like may be included.

On the other hand, the type of the phosphor included in the light emitting device package of an embodiment is not limited to the disclosed type, and a phosphor material emitting light in a green or yellow wavelength region or another type of phosphor material emitting light in a red wavelength region is implemented. Examples may be included.

9 is a view showing in more detail a portion A in the embodiment of the light emitting device package of FIG. 8 .

9 is a schematic diagram illustrating a path of light emitted from the light emitting device in the case of the light emitting device package including the light emitting device of the above-described embodiment.

A solid arrow R1 indicates a path along which light emitted from the light emitting structure 120 travels, and the light emitted from the light emitting structure 120 is directed toward the upper portion of the light emitting cell or toward the substrate 110 under the light emitting cell. can be headed

Light directed upwards of the light emitting cell may be supplied to the phosphor 270 to excite the phosphor. In addition, the light directed toward the substrate 110 may be reflected from the concave-convex pattern formed on the surface of the substrate, and the direction of the light may be changed so as to return to the upper portion of the light emitting cell.

Meanwhile, the light emitted to the upper portion of the light emitting cell may excite the phosphor included in the molding part disposed to surround the light emitting device, so that the phosphor emits green light or red light.

Some of the light emitted from the phosphor indicated by the dotted arrow R2 may be directed downward of the light emitting device, and in this case, the reflective layer 170 included in the light emitting device of the embodiment reflects the green light or red light emitted from the phosphor to the light emitting device. can be directed upwards.

In this case, the reflective layer 170 may be a selective reflective layer that transmits light in a blue wavelength region and reflects light in a green or red wavelength region.

Accordingly, the blue light emitted from the light emitting structure 120 of the light emitting cell is emitted to the outside of the light emitting device package from the upper direction of the light emitting cell, and in the case of the blue light directed toward the substrate 110 , the blue light is transmitted through the reflective layer 170 , and thus the blue light is transmitted to the reflective layer. Even when it is incident, it may be reflected from the unevenness of the surface of the substrate or may be emitted to the outside of the light emitting device package through the reflective layer.

In comparison, the green or red light emitted from the phosphor excited by the blue light supplied from the light emitting device is emitted to the outside of the light emitting device package in the upper direction of the light emitting device, or the green or red light directed toward the light emitting device is emitted from the reflective layer 170 ) may be reflected from the light emitting device, and the direction may be changed to be emitted toward the upper direction of the light emitting device.

That is, in the case of the light emitting device package of one embodiment, the reflective layer 170 is disposed in a space spaced apart between a plurality of light emitting cells, and the reflective layer 170 is formed of a high refractive index material having a large change in reflectance depending on the wavelength of light. Blue light generated in the light emitting cell is easily transmitted through the reflective layer to be emitted to the outside, and green or red light is reflected from the reflective layer 170 to prevent it from re-entering the light emitting cell, thereby exhibiting improved luminous efficiency and improved luminance. have.

A plurality of light emitting device packages according to an embodiment may be arranged on a substrate, and optical members such as a light guide plate, a prism sheet, and a diffusion sheet may be disposed on a light path of the light emitting device package. Such a light emitting device package, a substrate, and an optical member may function as a backlight unit.

In addition, a display device, an indicator device, and a lighting device including the light emitting device package according to an embodiment may be implemented.

Here, the display device includes a bottom cover, a reflecting plate disposed on the bottom cover, a light emitting module emitting light, a light guide plate disposed in front of the reflecting plate and guiding light emitted from the light emitting module in front of the light guide plate An optical sheet comprising prism sheets disposed thereon, a display panel disposed in front of the optical sheet, an image signal output circuit connected to the display panel and supplying an image signal to the display panel, and a color filter disposed in front of the display panel. may include Here, the bottom cover, the reflector, the light emitting module, the light guide plate, and the optical sheet may form a backlight unit.

In addition, the lighting device includes a light source module including a substrate and a light emitting device package according to an embodiment, a heat sink for dissipating heat of the light source module, and a power supply unit that processes or converts an electrical signal provided from the outside and provides it to the light source module may include For example, the lighting device may include a lamp, a head lamp, or a street lamp.

The head lamp includes a light emitting module including light emitting device packages disposed on a substrate, a reflector that reflects light emitted from the light emitting module in a predetermined direction, for example, forward, and a lens that refracts light reflected by the reflector forward. , and a shade that blocks or reflects a portion of light reflected by the reflector and directed to the lens to form a light distribution pattern desired by the designer.

In addition, in the case of a display device or a lighting device including a light emitting device package according to an embodiment, a light emitting device having a reflective layer exhibiting a selective reflection effect is included, thereby increasing the transmittance of blue light generated from the light emitting device, and green light and red light emitted from the phosphor. For the luminance and light efficiency can be improved by increasing the reflectance.

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

100a, 100b: light emitting cell 110: substrate
120: light emitting structure 142: first electrode
146: second electrode 148: connection electrode
170: reflective layer 200, 200A, 200B, 200C: light emitting element
270: phosphor 300: light emitting device package

Claims (17)

Board;
a plurality of light emitting cells spaced apart from each other on the substrate and including a first conductivity type semiconductor layer, an active layer, and a second conductivity type semiconductor layer;
first and second electrodes respectively disposed on the first conductivity-type semiconductor layer and the second conductivity-type semiconductor layer;
a connection electrode connecting neighboring light emitting cells among the plurality of light emitting cells; and
a reflective layer disposed on the substrate and disposed in a spaced space between adjacent light emitting cells among the plurality of light emitting cells; including,
The connection electrode connects the first electrode of one of the neighboring light emitting cells and the second electrode of the other of the neighboring light emitting cells,
The reflective layer includes any one selected from the group consisting _{of TiO 2} , Ta ₂ O _{5 and NiO,}
The reflective layer contains TiO ₂ and has a thickness of 75 nm to 105 nm or 260 nm to 290 nm,
The reflective layer includes Ta ₂ O ₅ and has a thickness of 85 nm to 115 nm or 270 nm to 300 nm,
The reflective layer includes NiO and has a thickness of 80 nm to 110 nm or 265 nm to 295 nm. According to claim 1, wherein the reflective layer is further disposed on the edge region of the substrate,
The reflective layer is disposed in contact with the substrate,
At least a portion of the connection electrode is a light emitting device disposed on the reflective layer. delete delete According to claim 1, wherein the light emitting device
a first insulating layer disposed on the plurality of light emitting cells and having a first open region and a second open region respectively formed on the first conductivity-type semiconductor layer and the second conductivity-type semiconductor layer; and
Further comprising a second insulating layer disposed on the reflective layer,
The first electrode is electrically connected to the first conductivity-type semiconductor layer in the first open region, and the second electrode is electrically connected to the second conductivity-type semiconductor layer in the second open region,
A light emitting device in which a first surface of the second insulating layer faces the connection electrode and a second surface that faces the first surface faces the reflective layer. delete delete delete delete delete delete delete delete lead frame;
A light emitting device according to any one of claims 1, 2 and 5 disposed on the lead frame;
a molding part disposed to surround the light emitting device; and
a phosphor included in the molding part and excited by light emitted from the light emitting device; including,
The light emitting device has a light emission center wavelength of 440 nm to 460 nm,
The phosphor includes a plurality of phosphors having emission wavelengths in different wavelength ranges,
The plurality of phosphors includes at least one of a first phosphor having a central emission wavelength of 480 nm to 550 nm and a second phosphor having a central emission wavelength of 600 nm to 700 nm. delete delete delete

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