Nitride-based long-wavelength light-emitting diode

Abstract

A red-light-emitting device according to one embodiment comprises: a first conductive semiconductor layer; an active area including a barrier layer and a well layer; a strain control layer disposed between the first conductive semiconductor layer and the active area; a superlattice layer disposed between the strain control layer and the active area; a second conductive semiconductor layer disposed on the active area; and an electron blocking layer disposed between the active area and the second conductive semiconductor layer, wherein the first conductive semiconductor layer and the well layer are represented by chemical formula 1, and an index value (P5) representing the band gap of the well layer and an index value (P1) representing the band gap of the first conductive semiconductor layer satisfy mathematical relation 1: (Chemical formula 1) AxByCzD(1-x-y-z) (Here, A is one element selected from Al, In and Ga, B is one element selected from Al, In and Ga, C is one element selected from Al, In and Ga, D is nitrogen, A, B and C are elements different from each other, x+y+z=0.5, and 0≤x, y, z≤0.5); and (mathematical relation 1) (αx+βy+γz)P5 - (αx+βy+γz)P1 < 0 (where α, β and γ represent the band gaps of AD, BD and CD, respectively).

Description

Nitride-based long-wavelength light-emitting diodes

[0001] The present disclosure relates to light emitting diodes, and more particularly, to nitride-based light emitting diodes that emit light with a longer wavelength than green light, for example, red light, and light emitting devices and applications having the same.

[0002] Compound semiconductors are used as light sources in displays, traffic lights, lighting, and optical communication devices. Nitride semiconductors are primarily used in light-emitting diodes (LEDs) and laser diodes, which emit ultraviolet, blue, or green light.

[0003] Light-emitting diodes (LEDs) made of InGaN-based nitride semiconductors, which emit blue and green light, are widely used in lighting and display applications. InGaN-based nitride semiconductors are particularly attracting attention as blue and green light sources for large-area micro LED displays and head-mounted displays (HMDs).

[0004] Lighting devices and displays require red light, along with blue and green light. Red light has a longer wavelength than green, is sensitive to temperature, and exhibits color shifts depending on the viewing angle.

[0005] Embodiments of the present disclosure provide a nitride-based light-emitting diode, for example, a nitride-based red light-emitting diode, that emits light with a wavelength longer than that of green light.

[0006] Embodiments of the present disclosure provide a light emitting diode capable of easily changing color temperature across yellow and red regions.

[0007] Embodiments of the present disclosure provide nitride-based red light-emitting diodes having a relatively small decrease in external quantum efficiency with increasing current density compared to blue and green light-emitting diodes.

[0008] Embodiments of the present disclosure provide various applications utilizing nitride-based light emitting diodes that emit light with a longer wavelength than green light, for example, red light.

[0009] A light emitting diode according to one embodiment of the present disclosure comprises: a first conductive semiconductor layer; an active region including a barrier layer and a well layer; a strain control layer disposed between the first conductive semiconductor layer and the active region; a superlattice layer disposed between the strain control layer and the active region; a second conductive semiconductor layer disposed on the active region; and an electron blocking layer disposed between the active region and the second conductive semiconductor layer, and emits light having a spectrum having a main peak and at least one secondary peak.

[0010] The intensity of the auxiliary peak may be less than 10% of the intensity of the main peak.

[0011] The area formed by the spectrum around the auxiliary peak may be less than 10% of the area formed by the spectrum around the main peak.

[0012] The wavelength of the above main peak may be longer than 580 nm, and the wavelength of the above auxiliary peak may be shorter than 500 nm.

[0013] The at least one auxiliary peak may include an auxiliary peak having a peak wavelength within a range of 400 nm to 430 nm.

[0014] The above main peak may shift toward shorter wavelengths as the current increases.

[0015] The above light-emitting diode can emit light with higher color purity as the current increases.

[0016] The above superlattice layer may include a lower superlattice layer and an upper superlattice layer, and the lower superlattice layer and the upper superlattice layer may be formed of InGaN / GaN, and the In content of the upper superlattice layer may be greater than the In content of the upper superlattice layer.

[0017] The InGaN layer within the lower superlattice layer may be thicker than the InGaN layer within the upper superlattice layer.

[0018] The above electron blocking layer may include a lower layer in contact with the active region, an upper layer in contact with the second conductive semiconductor layer, and an intermediate layer disposed between the lower layer and the upper layer, and the lower layer, the intermediate layer, and the upper layer may be nitride-based semiconductor layers having different compositions.

[0019] The lower layer may be an AlN layer, the middle layer may be an InAlGaN layer, and the upper layer may be an AlGaN grading layer.

[0020] An application according to one embodiment of the present disclosure includes the light emitting diode described above as a light source.

[0021] The above application may be a lighting device, and the lighting device may further include a substrate having wiring, and the light emitting diode may be disposed on the substrate.

[0022] The above application may be a display device.

[0023] The above display device may be a head mounted display device.

[0024] The above light emitting diodes can be arranged in pixels to implement an image.

[0025] The head mounted display device may include a sensing device, and the light emitting diode may be used as a light source of the sensing device.

[0026] The above application may be a vehicle including a tail light, and the light emitting diode may be used as a light source of the tail light.

[0027] The above application may be a skin treatment device.

[0028] The above skin treatment device can change the depth of the skin to be treated by changing the current applied to the light-emitting diode.

[0029] According to one embodiment of the present disclosure, a nitride-based light-emitting diode comprises: a first conductive semiconductor layer; an active region including a barrier layer and a well layer; a strain control layer disposed between the first conductive semiconductor layer and the active region; a superlattice layer disposed between the strain control layer and the active region; a second conductive semiconductor layer disposed on the active region; and an electron blocking layer disposed between the active region and the second conductive semiconductor layer, wherein the active region is configured to emit red light and has an emission intensity of 4 A / cm. 2 20A / cm 2 It has a maximum external quantum efficiency within the current density range of 10 A / cm 2 20A / cm 2 The external quantum efficiency within the current density range is 90% or more of the maximum external quantum efficiency.

[0030] The standardized external quantum efficiency graph of the above nitride light emitting diode is 20 A / cm 2 The current density can have a negative slope at the first point (P1).

[0031] The above superlattice layer may include a lower superlattice layer and an upper superlattice layer, and the lower superlattice layer and the upper superlattice layer may be formed of InGaN / GaN, and the In content of the upper superlattice layer may be greater than the In content of the upper superlattice layer.

[0032] The above electron blocking layer may include a lower layer in contact with the active region, an upper layer in contact with the second conductive semiconductor layer, and an intermediate layer disposed between the lower layer and the upper layer, and the lower layer, the intermediate layer, and the upper layer may be nitride-based semiconductor layers having different compositions.

[0033] The upper layer may be a grading layer in which the Al content decreases as it moves away from the active region.

[0034] The lower layer may be an AlN layer, the middle layer may be an InAlGaN layer, and the upper layer may be an AlGaN grading layer.

[0035] A light-emitting device according to one embodiment of the present disclosure includes the above-described nitride-based light-emitting diode.

[0036] The above light emitting device may further include a nitride blue light emitting diode, and has an emission efficiency of 10 A / cm 2 20A / cm 2 Within the current density range, the normalized external quantum efficiency of the nitride-based light-emitting diode may have a value greater than the normalized external quantum efficiency of the nitride-based blue light-emitting diode.

[0037] The above light emitting device may further include a nitride-based green light emitting diode, and has an emission rate of 10 A / cm 2 20A / cm 2 Within the current density range, the normalized external quantum efficiency of the nitride-based light-emitting diode may have a value greater than the normalized external quantum efficiency of the nitride-based green light-emitting diode.

[0038] The standardized external quantum efficiency graph of the above nitride light emitting diode is 20 A / cm 2 The current density can have a negative slope at the first point (P1).

[0039] The absolute value of the above negative slope is 20A / cm 2The absolute value of the slope of the normalized external quantum efficiency graphs of the nitride-based blue and green light-emitting diodes at the current density may be smaller.

[0040] The current density exhibiting the maximum external quantum efficiency of the above nitride-based light-emitting diode may be higher than the current density exhibiting the maximum external quantum efficiency of the above nitride-based blue and green light-emitting diodes.

[0041] The external quantum efficiency graph according to the current density of the above nitride-based light-emitting diode can intersect with the external quantum efficiency graphs according to the current density of the above nitride-based blue and green light-emitting diodes at the second point (P2) and the third point (P3), respectively, and the current density of the second point (P2) and the third point (P3) is 10 A / cm 2 It can be smaller.

[0042] The standardized external quantum efficiency graph of the above nitride light emitting diode may have a positive slope at the second point (P2).

[0043] The normalized external quantum efficiency graph of the above nitride-based blue light-emitting diode may have a negative slope at the second point (P2).

[0044] The above positive slope may be greater than the absolute value of the above negative slope.

[0045] The standardized external quantum efficiency graph of the above nitride light emitting diode may have a positive slope at the third point (P3).

[0046] The normalized external quantum efficiency graph of the above nitride-based green light-emitting diode may have a negative slope at the third point (P3).

[0047] Furthermore, the positive slope may be greater than the absolute value of the negative slope.

[0048] 20A / cm 2Within the current density range below, the minimum radius of curvature of the normalized external quantum efficiency graph of the nitride-based light-emitting diode may be greater than the minimum radius of curvature of the normalized external quantum efficiency graphs of the nitride-based blue and green light-emitting diodes.

[0049] According to one embodiment of the present disclosure, a light-emitting diode is a light-emitting diode that emits red light, comprising: a first conductive semiconductor layer; an active region including a barrier layer and a well layer; a strain control layer disposed between the first conductive semiconductor layer and the active region; a superlattice layer disposed between the strain control layer and the active region; a second conductive semiconductor layer disposed on the active region; and an electron blocking layer disposed between the active region and the second conductive semiconductor layer, wherein the composition of each layer is expressed by the following chemical formula 1, wherein an index value (P5) representing a band gap of the well layer and an index value (P1) representing a band gap of the first conductive semiconductor layer satisfy the following mathematical formula 1:

[0050] (Chemical formula 1) A x B y C z D (1-x-y-z) (wherein, A is one element selected from Al, In, and Ga, B is one element selected from Al, In, and Ga, C is one element selected from Al, In, and Ga, D is nitrogen, A, B, and C are different elements, x+y+z=0.5, and 0≤x, y, z≤0.5); and

[0051] (Mathematical formula 1) (αx+βy+γz) P5 - (αx+βy+γz) P1 < 0 (where α, β, and γ represent the band gaps of AD, BD, and CD, respectively).

[0052] The above superlattice layer may have a structure in which a first layer and a second layer are alternately laminated, and the first layer contains more In than the second layer, and an index value (P5) representing a band gap of the well layer and an index value (P2) representing a band gap of the first layer of the superlattice layer may satisfy the following mathematical expression 2:

[0053] (Mathematical formula 2) (αx+βy+γz) P5 - (αx+βy+γz) P2 < 0.

[0054] The index value (P5) representing the band gap of the above well layer and the index value (P3) representing the band gap of the second layer of the above superlattice layer can satisfy the following mathematical expression 3:

[0055] (Equation 3) (αx+βy+γz) P5 - (αx+βy+γz) P3 < 0.

[0056] The index value (P5) representing the band gap of the above well layer and the index value (P4) representing the band gap of the above barrier layer can satisfy the following mathematical expression 4:

[0057] (Equation 4) (αx+βy+γz) P5 - (αx+βy+γz) P4 < 0.

[0058] The above well layer can be in contact with two barrier layers, and the above well layer and the two barrier layers can each satisfy the above mathematical expression 4.

[0059] The index value (P5) representing the band gap of the above well layer and the index value (P6) representing the band gap of the above electron block layer can satisfy the following mathematical expression 5:

[0060] (Equation 5) (αx+βy+γz) P5 - (αx+βy+γz) P6 < 0.

[0061] The index value (P5) representing the band gap of the above well layer and the index value (P7) representing the band gap of the second conductive semiconductor layer can satisfy the following mathematical expression 6:

[0062] (Equation 6) (αx+βy+γz) P5 - (αx+βy+γz) P7 < 0.

[0063] The index value (P4) representing the band gap of the above barrier layer and the index value (P1) representing the band gap of the first conductive semiconductor layer can satisfy the following mathematical expression 7:

[0064] (Equation 7) (αx+βy+γz) P4 - (αx+βy+γz) P1 ≥ 0.

[0065] The index value (P4) representing the band gap of the above barrier layer may be greater than the index value (P1) representing the band gap of the first conductive semiconductor layer.

[0066] The index value (P4) representing the band gap of the above barrier layer and the index value (P3) representing the band gap of the first layer of the above superlattice layer can satisfy the following mathematical expression 8:

[0067] (Equation 8) (αx+βy+γz) P4 - (αx+βy+γz) P3 ≥ 0.

[0068] The index value (P4) representing the band gap of the above barrier layer and the index value (P6) representing the band gap of the above electron block layer can satisfy the following mathematical expression 9:

[0069] (Equation 9) (αx+βy+γz) P4 - (αx+βy+γz) P6 < 0.

[0070] The index value (P4) representing the band gap of the above barrier layer and the index value (P7) representing the band gap of the second conductive semiconductor layer can satisfy the following mathematical expression 10:

[0071] (Equation 10) (αx+βy+γz) P4- (αx+βy+γz) P7 ≥ 0.

[0072] The index value (P4) representing the band gap of the above barrier layer may be greater than the index value (P7) representing the band gap of the second conductive semiconductor layer.

[0073] The above superlattice layer has a structure in which a first layer and a second layer are alternately laminated, the first layer contains more In than the second layer, and an index value (P3) representing a band gap of the second layer of the superlattice layer and an index value (P1) representing a band gap of the first conductive semiconductor layer can satisfy the following mathematical expression 11:

[0074] (Equation 11) (αx+βy+γz) P3 - (αx+βy+γz) P1 ≤ 0.

[0075] The index value (P3) representing the band gap of the second layer of the above superlattice layer and the index value (P7) representing the band gap of the second conductive semiconductor layer can satisfy the following mathematical expression 12:

[0076] (Equation 12) (αx+βy+γz) P3 - (αx+βy+γz) P7 ≤ 0.

[0077] The index value (P3) representing the band gap of the second layer of the above superlattice layer may be smaller than the index value (P7) representing the band gap of the second conductive semiconductor layer.

[0078] The light emitting diode may further include a lower superlattice layer interposed between the superlattice layer and the strain control layer.

[0079] The above electronic block layer may include a gradient composition layer.

[0080] The light emitting diode can emit red light having a peak wavelength within a range of 600 nm to 720 nm.

[0081] At least one of the above barrier layers may include a reference band gap layer and a protruding band gap layer, and an index value (P8) representing a band gap of the protruding band gap layer and an index value (P4) representing a band gap of the reference band gap layer may satisfy the following mathematical expression 13:

[0082] (Equation 13) (αx+βy+γz) P8 - (αx+βy+γz) P4 > 0.

[0083] The index value (P8) representing the band gap of the above-mentioned protruding band gap layer and the index value (P6) representing the band gap of the above-mentioned electron block layer can satisfy the following mathematical expression 14:

[0084] (Equation 14) (αx+βy+γz) P8 - (αx+βy+γz) P6 > 0.

[0085] The above protruding band gap layer is disposed on barrier layers other than the last barrier layer of the active region.

[0086] The above protruding bandgap layer may be an AlN layer.

[0087] FIG. 1 is a schematic cross-sectional view illustrating a red light-emitting diode according to one embodiment of the present disclosure.

[0088] Figure 2 is an enlarged cross-sectional view of the lower superlattice layer of Figure 1.

[0089] Figure 3 is an enlarged cross-sectional view of the upper superlattice layer of Figure 1.

[0090] Fig. 4 is an enlarged cross-sectional view of the active layer of Fig. 1.

[0091] Fig. 5 is an enlarged cross-sectional view of the electronic block layer of Fig. 1.

[0092] Fig. 6 is an enlarged cross-sectional view of the second conductive semiconductor layer of Fig. 1.

[0093] FIG. 7 is a graph showing the spectrum of light emitted from a light-emitting diode according to one embodiment of the present disclosure.

[0094] FIG. 8A is a graph showing the spectrum of light emitted from a light emitting diode according to one embodiment of the present disclosure.

[0095] Figure 8B is an enlarged graph of a portion of Figure 8A.

[0096] Figure 9 shows the color coordinates of a light emitting diode according to one embodiment of the present disclosure.

[0097] FIG. 10 is a schematic cross-sectional view illustrating a lighting device according to one embodiment of the present disclosure.

[0098] FIG. 11 is a schematic cross-sectional view illustrating a lighting device according to another embodiment of the present disclosure.

[0099] FIG. 12 is a schematic plan view illustrating a head mounted display according to one embodiment of the present disclosure.

[0100] FIG. 13 is a schematic rear view illustrating a vehicle equipped with a light-emitting diode according to one embodiment of the present disclosure.

[0101] Figure 14A is a graph illustrating the external quantum efficiency of light-emitting diodes according to current density.

[0102] Figure 14B is a graph showing an enlarged portion of Figure 14A.

[0103] FIG. 15 is a schematic plan view illustrating a light-emitting module according to one embodiment of the present disclosure.

[0104] FIG. 16 is a schematic plan view illustrating a display device according to one embodiment of the present disclosure.

[0105] FIG. 17 is a schematic cross-sectional view illustrating a light emitting diode according to one embodiment of the present disclosure.

[0106] FIG. 18 is a schematic diagram for explaining the band gap of each layer of a light-emitting diode according to one embodiment of the present disclosure.

[0107] Figure 19 is an enlarged cross-sectional view of the superlattice layer of Figure 18.

[0108] FIG. 20 is a band diagram illustrating a light emitting diode according to another embodiment of the present disclosure.

[0109] FIG. 21 is an enlarged cross-sectional view of an active area of ​​a light-emitting diode according to another embodiment of the present disclosure.

[0110] FIG. 22 is a schematic cross-sectional view illustrating a light-emitting device according to one embodiment of the present disclosure.

[0111] In the following description, for purposes of explanation, numerous specific details are set forth to provide a thorough understanding of various embodiments or implementations of the present disclosure. As used herein, the terms "embodiment" and "implementation" are interchangeable to refer to non-limiting examples of devices or methods that utilize one or more of the inventive concepts disclosed herein. However, it will be apparent that various embodiments may be practiced without utilizing these specific details or using one or more equivalent arrangements. In other instances, well-known structures and devices are shown in block diagram form to avoid unnecessarily obscuring the various embodiments. Furthermore, while the various embodiments may vary from one another, they are not necessarily exclusive. For example, specific features, configurations, and characteristics of an embodiment may be utilized or implemented in other embodiments without departing from the scope of the inventive concepts.

[0112] Unless otherwise specified, the illustrated embodiments should be understood to provide exemplary features of varying details of some ways in which the concepts of the present invention may be practically implemented. Therefore, unless otherwise specified, the features, components, modules, layers, membranes, panels, regions, and / or aspects (hereinafter, individually or collectively referred to as "elements") of the various embodiments may be differently combined, separated, interchanged, and / or rearranged without departing from the scope of the concepts of the present invention.

[0113] The use of cross-hatching and / or shading in the accompanying drawings is provided to clarify boundaries between adjacent elements. As such, the presence or absence of cross-hatching or shading, unless expressly stated, does not imply or indicate any preference or requirement for any particular material, material properties, dimensions, proportions, commonality between the illustrated elements, and / or any other features, properties, or characteristics of the elements. Furthermore, in the accompanying drawings, the dimensions and relative sizes of elements may be exaggerated for clarity and / or illustrative purposes. When embodiments are implemented differently, certain process sequences may be performed differently from the described sequence. For example, two consecutively described processes may be performed substantially simultaneously or in a reverse order from the described sequence. Furthermore, like reference numerals designate like elements.

[0114] When an element, such as a layer, is referred to as being "on," "connected to," or "joined to" another element or layer, the element may be directly on, connected to, or joined to the other element or layer, or there may be intervening elements or layers present. However, when an element or layer is referred to as being "directly on," "directly connected to," or "directly joined to" another element or layer, there are no intervening elements or layers present. For this purpose, the term "connected" may refer to physical, electrical, and / or fluidic connections, with or without intervening elements. Furthermore, the DR1-axis, DR2-axis, and DR3-axis are not limited to the three axes of a Cartesian coordinate system, such as the x, y, and z-axes, and may be interpreted in a broader sense. For example, the DR1-axis, DR2-axis, and DR3-axis may be perpendicular to one another, or may represent different directions that are not perpendicular to one another. For purposes of this disclosure, “one or more of X, Y or Z” and “one or more selected from the group consisting of X, Y or Z” may be interpreted as only X, only Y, only Z or any combination of two or more of X, Y and Z, such as, for example, XYZ, XYY, YZ and ZZ. The term “and / or” as used herein includes any and all combinations of one or more of the associated listed items.

[0115] Although the terms "first," "second," and the like may be used herein to describe various types of elements, these elements should not be limited by these terms. These terms are used to distinguish one element from another. Therefore, the first element discussed below may be referred to as the second element without departing from the teachings of the present disclosure.

[0116] Spatially relative terms such as "beneath," "beneath," "directly beneath," "lower," "above," "upper," "above," "higher than," "side" (as in, for example, a "side wall"), and the like may be used for descriptive purposes and thereby to describe the relationship of one element to other element(s) as depicted in the drawings. Spatially relative terms are intended to encompass different orientations of the device in use, operation, and / or manufacture in addition to the orientations depicted in the drawings. For example, if the device in the drawings were turned over, an element described as "beneath" or "beneath" another element or feature would then be oriented "above" the other element or feature. Therefore, the exemplary term "beneath" can encompass both orientations above and below. Furthermore, the device can be oriented differently (e.g., rotated 90° or oriented in other orientations), and thus the spatially relative descriptors used herein can also be interpreted accordingly.

[0117] The terminology used herein is for the purpose of describing particular embodiments and is not limiting. The singular forms "a," "an," and "the" as used herein also include the plural forms unless the context clearly dictates otherwise. Furthermore, the terms "comprises," "comprising," "includes," and / or "comprising" as used herein specify the presence of stated features, integers, steps, operations, elements, components, and / or groups thereof, but do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and / or groups thereof. Furthermore, the terms "substantially," "about," and other similar terms as used herein are used as terms of approximation rather than degrees, and as such, are used to describe inherent deviations from measured, calculated, and / or provided values ​​that would be recognized by one of ordinary skill in the art.

[0118] Various embodiments are described below with reference to cross-sectional and / or exploded illustrations, which are schematic illustrations of idealized embodiments and / or intermediate structures. As such, variations from the shapes of the illustrated drawings may be expected, for example, as a result of manufacturing techniques and / or tolerances. Therefore, the embodiments disclosed herein should not necessarily be construed as limited to the shapes of specific illustrated regions, but should be construed to include, for example, deviations in shape resulting from manufacturing. In this way, the regions depicted in the drawings may be schematic in nature, and the shapes of these regions may not reflect the actual shapes of regions of the device, and as such, are not necessarily intended to have a limiting meaning.

[0119] As is conventional in the art, some embodiments may be illustrated and described in the accompanying drawings in terms of functional blocks, units, and / or modules. Those skilled in the art will appreciate that these blocks, units, and / or modules are physically implemented by electronic (or optical) circuits such as logic circuits, discrete components, microprocessors, wiring circuits, memory elements, and wiring connections formed using semiconductor-based or other manufacturing techniques. When the blocks, units, and / or modules are implemented by microprocessors or other similar hardware, they may be programmed and controlled using software (e.g., microcode) to perform the various functions discussed herein, and optionally may be driven by firmware and / or software. Furthermore, each block, unit, and / or module may be implemented by dedicated hardware, or by a combination of dedicated hardware for performing some functions and processors (e.g., one or more programmed processors and associated circuitry) for performing other functions. Additionally, the blocks, units, and / or modules of some embodiments may be physically separated into two or more interacting and individual blocks, units, and / or modules without departing from the scope of the present invention. Additionally, the blocks, units, and / or modules of some embodiments may be physically combined into more complex blocks, units, and / or modules without departing from the scope of the present invention.

[0120] Unless otherwise defined, all terms (including technical or scientific terms) used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this disclosure pertains. Terms defined in commonly used dictionaries, such as terms defined in commonly used dictionaries, should be interpreted to have a meaning consistent with their meaning in the context of the relevant technology, and should not be interpreted in an idealistic or overly formal sense unless explicitly defined herein.

[0121] FIG. 1 is a schematic cross-sectional view illustrating a light emitting diode (100) according to one embodiment of the present disclosure.

[0122] Referring to FIG. 1, a light emitting diode (100) may include a substrate (21), a buffer layer (23), an undoped layer (25), a first conductive semiconductor layer (27), a strain control layer (29), a lower superlattice layer (31), an upper superlattice layer (33), an active region (35), an electron block layer (37), a second conductive semiconductor layer (39), a transparent electrode layer (41), a first electrode (43a), and a second electrode (43b).

[0123] The substrate (21) may be a growth substrate for growing a gallium nitride-based semiconductor layer, such as a sapphire substrate, a silicon substrate, a SiC substrate, a spinel substrate, a Ga2O3 substrate, etc. In one embodiment, the substrate (21) may be a patterned sapphire substrate. The substrate (21) may also be removed from the light emitting diode (100).

[0124] The buffer layer (23) may be formed as a low-temperature buffer layer, for example, an AlGaN layer, for example, as a nucleus layer for growing a gallium nitride-based semiconductor layer on a heterogeneous substrate. The undoped layer (25) may be formed as a high-temperature buffer layer, for example, and may include a gallium nitride-based semiconductor layer, for example, a GaN layer.

[0125] The first conductive semiconductor layer (27) may be a semiconductor layer containing an n-type impurity, for example, Si. The first conductive semiconductor layer (27) may be a contact layer on which a first electrode (43a) is formed. For example, the first conductive semiconductor layer (27) may be formed of GaN.

[0126] The strain control layer (29) is arranged between the first conductive semiconductor layer (27) and the active region (35). The active region (35) contains a high content of In to generate relatively long-wavelength light by recombination of electrons and holes. Accordingly, the lattice constant of the active region (35) is larger than the lattice constant of the first conductive semiconductor layer (27), and thus, strain occurs in the active region (35). The strain control layer (29) is formed to control the strain generated in the active region (35).

[0127] The strain control layer (29) may be formed as a single layer or multiple layers, and may have a thickness of, for example, about 200 nm to 300 nm. The strain control layer (29) may include a V-pit generation layer for generating V-pits. For example, the strain control layer (29) may be formed as a nitride layer having the same composition as the first conductive semiconductor layer (27), but may be formed at a temperature lower than the growth temperature of the first conductive semiconductor layer (27), for example, about 700 to 900° C. In particular, the strain control layer (29) may be grown at a relatively fast rate using trimethylgallium (TMGa) as a Ga source, and by growing the strain control layer (29) relatively quickly at a relatively low temperature, the density of actual dislocations may be lowered and V-pits may be generated.

[0128] The lower superlattice layer (31) can be formed by stacking InGaN / GaN in 3 to 4 cycles. As illustrated in FIG. 2, the thickness of the InGaN layer (31a) in the lower superlattice layer (31) can be smaller than the GaN layer (31b). For example, the thickness of the InGaN layer (31a) can be about 2.5 nm, and the thickness of the GaN layer (31b) can be about 7.5 nm. The total thickness of the lower superlattice layer (31) can be, for example, in the range of 30 nm to 40 nm, but is not limited thereto. Meanwhile, with respect to the total composition of In, Ga, and N, the In composition ratio of InGaN can be in the range of 0.01 to 0.025, and the Ga composition ratio can be in the range of 0.475 to 0.49.

[0129] The upper superlattice layer (33) may be formed of InGaN / GaN, and may be formed by stacking more periods, for example, 5 to 6 periods, than the lower superlattice layer (31). As shown in FIG. 3, the thickness of the InGaN layer (33a) in the upper superlattice layer (33) may be smaller than the GaN layer (33b). In addition, the thickness of the InGaN layer (33a) in the upper superlattice layer (33) may be smaller than the thickness of the InGaN layer (31a) in the lower superlattice layer (31). For example, the thickness of the InGaN layer (33a) in the upper superlattice layer (33) may be about 2.0 nm, and the thickness of the GaN layer (33b) may be about 8.0 nm. The total thickness of the upper superlattice layer (33) may be greater than the total thickness of the lower superlattice layer (31), and may be, for example, in the range of about 50 nm to about 60 nm, but is not limited thereto.

[0130] The In composition ratio of the InGaN in the upper superlattice layer (33) may be greater than the In composition ratio of the InGaN in the lower superlattice layer (31). For example, the In composition ratio of the InGaN in the upper superlattice layer (33) may be within the range of 0.025 to 0.05 for the total composition of In, Ga, and N. Meanwhile, the Ga composition ratio of the InGaN in the upper superlattice layer (33) may be within the range of 0.45 to 0.475 for the total composition of In, Ga, and N.

[0131] The lower superlattice layer (31) and the upper superlattice layer (33) can be grown at a relatively slow rate using triethylgallium (TEGa) as a Ga source. V-pits are created by the strain control layer (29) grown relatively quickly at a low temperature, and the size of the V-pits increases by the lower superlattice layer (31) and the upper superlattice layer (33). In particular, by growing the lower and upper superlattice layers (31, 33) using a TEGa source, V-pits with a relatively uniform density and size can be formed over the entire wafer area. The size and uniformity of the V-pits can be variously controlled by controlling the growth conditions and thickness of the strain control layer (29) and the growth conditions and thickness of the lower and upper superlattice layers (31, 33).

[0132] By forming the lower superlattice layer (31) and the upper superlattice layer (33) as InGaN / GaN superlattice layers with similar structures, lattice changes can be reduced, thereby reducing defects within the active region (35). In addition, by increasing the In content of the upper superlattice layer (33) compared to the lower superlattice layer (31), the In content of the well layer (35b) within the active region (35) can be increased.

[0133] The V-pits formed by the strain control layer (29) help to relieve strain and introduce more indium into the active region (35) formed thereon. Accordingly, a quantum well structure containing a higher indium content can be included in the active region (35) of the light-emitting diode (100), and thus, long-wavelength visible light such as yellow light and red light can be easily realized, and luminous efficiency can be improved.

[0134] Referring to FIGS. 1 and 4, an active region (35) is disposed on an upper superlattice layer (33). The active region (35) may include a barrier layer (35a) and a well layer (35b). The active region (35) may have a single quantum well structure including a single well layer (35b) or a multi-quantum well structure including a plurality of well layers (35b). The number of well layers (35b) may be, for example, in the range of 1 to 10.

[0135] The barrier layer (35a) may include a GaN layer, and the well layer (35b) may include an InGaN layer. The well layer (35b) includes a higher content of In than the barrier layer (35a) to generate long-wavelength light. The composition ratio of In in the well layer (35b) may be 0.15 or more and 0.2 or less with respect to the entire composition in the well layer (35b). In a further embodiment, the active region (35) may include at least one well layer in which the composition ratio of In with respect to the entire composition is smaller than that of the well layer (35b) described above and larger than the composition ratio of In in the InGaN in the upper superlattice layer (33), for example, the composition ratio of In with respect to the entire composition is 0.05 or more and less than 0.15, and the well layer with the smaller In composition ratio may be arranged closer to the upper superlattice layer (33) than the well layer with the relatively larger In composition ratio.

[0136] The barrier layer (35a) and the well layer (35b) may also be formed within the V-pit. The well layer (35b) formed within the V-pit may contain less In than the well layer formed on the flat surface surrounding the V-pit. Accordingly, short-wavelength light may be generated using the well layer formed within the V-pit.

[0137] An electron blocking layer (37) is disposed on the active region (35). The electron blocking layer (37) is formed along the surface of the active region (35). The electron blocking layer (37) may include a plurality of layers (37a, 37b, 37c), as illustrated in FIG. 5. The lowermost layer (37a) may be in contact with the last barrier layer (35a) of the active region (35), the uppermost layer (37c) may be in contact with the second conductivity type semiconductor layer (39), and the intermediate layer (37b) may be disposed between the lowermost layer (37a) and the uppermost layer (37c). For example, the lowermost layer (37a) may be formed to have a thickness of about 2 nm to 3 nm, the intermediate layer (37b) to have a thickness of about 10 nm to 15 nm, and the uppermost layer (37c) to have a thickness of about 12 nm to 20 nm.

[0138] The intermediate layer (37b) may contain a higher concentration of p-type impurities than the lowermost layer (37a) and the uppermost layer (37c). For example, the intermediate layer (37b) may contain about 1×10 20 / cm 3 3×10 20 / cm 3 It may contain Mg doped at a high concentration.

[0139] Each layer within the electronic block layer (37) may include Al. The lowest layer (37a) may be, for example, an AlN layer. In addition, the uppermost layer (37c) may be a grading layer in which the composition ratio of Al decreases as it moves away from the active region (35). For example, the uppermost layer (37c) may be an AlGaN grading layer. In addition, the Al composition ratio of the intermediate layer (37b) may be lower than the Al composition ratio of the lowest layer (37a), and may be lower than the maximum Al composition ratio and greater than the minimum Al composition ratio within the uppermost layer (37c), which is a grading layer. For example, the intermediate layer (37b) may be an InAlGaN layer.

[0140] The second conductive semiconductor layer (39) may be disposed on the electron blocking layer (37). The second conductive semiconductor layer (39) may fill the V-pits, but the present disclosure is not limited thereto. For example, the second conductive semiconductor layer (39) may be formed along the V-pits, and thus, grooves corresponding to the V-pits may remain on the surface of the second conductive semiconductor layer (39).

[0141] The second conductive semiconductor layer (39) may be a nitride semiconductor layer doped with a p-type impurity, for example, Mg. The second conductive semiconductor layer (39) may include, for example, a GaN layer. The second conductive semiconductor layer (39) may be a contact layer on which an ohmic electrode is formed. As illustrated in FIG. 6, the second conductive semiconductor layer (39) may include layers (39a, 39b, 39c) having different doping concentrations of a p-type impurity, such as Mg. The first layer (39a) may be in contact with the electron blocking layer (37), and an ohmic contact may be formed in the third layer (39c). The second layer (39b) may be disposed between the first layer (39a) and the third layer (39c). The first layer (39a), the second layer (39b), and the third layer (39c) may have different doping concentrations. For example, the second layer (39b) may have a higher doping concentration than the first layer (39a), and the third layer (39c) may have a higher doping concentration than the second layer (39b). The doping concentration of the p-type impurity of the third layer (39c) may be higher than the doping concentration of the intermediate layer (37b) of the electron blocking layer (37), for example, 5×10 20 / cm 3 Inside 9×10 20 / cm 3 It can be within the range.

[0142] The second layer (39b) may be thicker than the first layer (39a) and the third layer (39c). For example, the first layer (39a) and the third layer (39c) may have a thickness within a range of about 100 nm to about 200 nm, and the second layer (39b) may have a thickness within a range of about 200 nm to about 300 nm. Each of the layers (39a, 39b, 39c) of the second conductive semiconductor layer (39) may be formed of, for example, a GaN layer.

[0143] A transparent electrode layer (41) may be disposed on the second conductive semiconductor layer (39). The transparent electrode layer (41) may make an ohmic contact with the third layer (39c). The transparent electrode layer (41) may be formed of a conductive oxide, such as indium tin oxide (ITO) or indium zinc oxide (IZO).

[0144] The first electrode (43a) may be disposed on the first conductive semiconductor layer (27). The first electrode (43a) may make an ohmic contact with the first conductive semiconductor layer (27). For example, the first electrode (43a) may be formed of, for example, Cr / Pt / Au.

[0145] The second electrode (43b) may be formed on the transparent electrode layer (41). The second electrode (43b) may be formed of various metal layers, and may also be formed of the same material as the first electrode (43a). The first electrode (43a) and the second electrode (43b) may be formed together from the same material in the same process.

[0146] In this embodiment, the transparent electrode layer (41) is illustrated and described as being in ohmic contact with the second conductive semiconductor layer (39), but the present disclosure is not necessarily limited thereto, and instead of the transparent electrode layer (41), a metal layer may be in ohmic contact with the second conductive semiconductor layer (39).

[0147] According to embodiments of the present disclosure, a nitride-based light-emitting diode that emits light with a wavelength longer than that of green light is provided. For example, a nitride-based red light-emitting diode may be provided. The nitride-based red light-emitting diode may be used in lighting devices and display devices together with nitride-based blue and green light-emitting diodes. The nitride-based light-emitting diode according to embodiments of the present disclosure can maintain luminous efficiency even in a small size, and further, has low temperature sensitivity, making it suitable for use in micro LED displays.

[0148] FIG. 7 is a graph showing the spectrum of light emitted from a light-emitting diode according to one embodiment of the present disclosure.

[0149] Referring to Fig. 7, light emitted from a light-emitting diode may have at least two peaks (P1, P2, P3). The first peak (P1) is a main peak and has a higher intensity than other peaks. The first peak (P1) is located in a wavelength range longer than about 580 nm, and the second peak (P2) and the third peak (P3) are located in a wavelength range shorter than about 500 nm. The second peak (P2) and the third peak (P3) may be located in a wavelength range longer than about 400 nm. The first peak (P1) may be a main peak and primarily determine the color temperature of light emitted from the light-emitting diode, and the second peak (P2) and the third peak (P3), which are located in a wavelength range shorter than the wavelength of the first peak (P1), are auxiliary peaks that have a higher Melanopic synthesis reactivity than the first peak (P1), thereby suppressing melatonin secretion and increasing the user's physical activity.

[0150] The first peak (P1) may be light emitted from the well layer (35b) of the active region (35). In particular, the first peak (P1) may be formed by light emitted from the well layer (35b) formed in the flat region. Meanwhile, the second peak (P2) and the third peak (P3) may be formed by light emitted from the well layer (35b) formed within the V-pit. When the size of the V-pit is varied, or when the thickness of the well layer formed within the V-pit is different, auxiliary peaks of various peaks may be formed.

[0151] The intensities of the second and third peaks (P2, P3) may be less than 10% of the intensity of the first peak (P1). In addition, the area formed by the spectra around the second and third peaks (P2, P3) may be less than 10% of the area formed by the spectra around the first peak (P1). By making the intensity of the first peak (P1) relatively greater than the intensities of the other peaks (P2, P3), a light-emitting diode that emits long-wavelength visible light with high color purity can be provided.

[0152] FIG. 8A is a graph showing a spectrum of light emitted from a light-emitting diode according to one embodiment of the present disclosure, and FIG. 8B is an enlarged graph of a portion of FIG. 8A.

[0153] Referring to FIGS. 8A and 8B, the light emitting diode according to the present embodiment exhibits an emission spectrum having two peaks. The main peak is located in a wavelength range longer than about 580 nm, and the secondary peak may be located in a wavelength range shorter than about 430 nm, or further, in a wavelength range shorter than about 420 nm. Meanwhile, the secondary peak may be located in a wavelength range longer than about 400 nm. The main peak may primarily determine the color temperature, and the secondary peak located in a wavelength range shorter than the wavelength of the main peak may have a higher melanophore synthesis reactivity than the main peak, thereby suppressing melatonin secretion and increasing the user's physical activity.

[0154] The main peak may be light emitted from the well layer (35b) of the active region (35). In particular, the main peak may be formed by light emitted from the well layer (35b) formed in the flat region. Meanwhile, the secondary peak may be formed by light emitted from the well layer (35b) formed within the V-pit. When the size of the V-pit is uniform and the thickness of the well layer formed within the V-pit is constant, a single secondary peak may be formed, as shown in FIG. 8B.

[0155] The intensity of the secondary peak may be less than 10% of the intensity of the main peak. Furthermore, the area formed by the spectrum around the secondary peak may be less than 10% of the area formed by the spectrum around the main peak. By making the intensity of the main peak relatively greater than that of the secondary peak, a light-emitting diode that emits long-wavelength visible light with high color purity can be provided.

[0156] Meanwhile, the intensity of the main peak and the secondary peak can be increased by increasing the current applied to the light-emitting diode. Figures 8A and 8B show the spectra of light emitted by applying 0.2 mA, 1 mA, and 5 mA to the same light-emitting diode. As the current increases, the intensity of the main peak and the secondary peak increases, and the wavelength of the main peak shifts toward shorter wavelengths. However, the wavelength of the secondary peak can be seen to generally maintain the same wavelength. Furthermore, as the current increases in the spectrum of the main peak, the ratio of the height to the full width at half maximum also increases. Therefore, the color purity of the light emitted from the light-emitting diode can be improved as the current increases.

[0157] Figure 9 shows the color coordinates of a light emitting diode according to one embodiment of the present disclosure.

[0158] Referring to Fig. 9, as the current applied to the light-emitting diode increases, the color coordinates of the light emitted from the light-emitting diode move in the direction indicated by the arrow. For example, the light-emitting diode can emit red light around 598 nm to yellow light around 584 nm as the current increases. The CIE X coordinate can decrease as the current applied to the light-emitting diode increases. In addition, the CIE Y coordinate can increase as the current applied to the light-emitting diode increases. That is, the CIE coordinate can move to the upper left as the current applied to the diode increases. Furthermore, it can be seen that as the current increases, the color purity of the light emitted from the light-emitting diode is further improved.

[0159] The light-emitting diode according to the present embodiment can be used in various applications such as lighting devices, display devices, and vehicle light source devices.

[0160] FIG. 10 is a schematic cross-sectional view illustrating a lighting device according to one embodiment of the present disclosure.

[0161] Referring to FIG. 10, the lighting device (1000a) includes a main body (110), a cover (120), and a light-emitting module (130).

[0162] The light-emitting module (130) may be mounted on the main body (110). Various components, such as components and wiring, for driving the light-emitting module (130) may be arranged inside the main body (110). In addition, the main body (110) may include a heat dissipation unit and a socket connected to an external power source.

[0163] The cover portion (120) may be formed of a material that transmits light. The cover portion (120) may be formed to cover the light-emitting module (130) by being combined with the main body portion (110).

[0164] The light-emitting module (130) may include a substrate (131) and a light-emitting diode (100). The substrate (131) may include wiring electrically connected to the light-emitting diode (100). The substrate (131) may be a printed circuit board, but is not limited thereto. The substrate (131) may be any material as long as it provides an electrical path for driving the light-emitting diode (100).

[0165] One or more light-emitting diodes (100) may be mounted on a substrate (131). The light-emitting diode (100) is the same as the light-emitting diode (100) described with reference to FIG. 1, and thus a detailed description thereof will be omitted. The light-emitting diode (100) may receive driving power through wiring of an electrically connected substrate (131) to emit light. The substrate (131) may include a driving circuit or a driving element for driving the light-emitting diode (100), and may also include both a driving circuit and a driving element.

[0166] As illustrated in FIG. 9, the light emitting diode (100) can emit light whose color coordinates move from the red side to the yellow side as the current increases. In other words, the color coordinates can move to the upper left as the current increases. Therefore, the lighting device (1000a) can change the color of the light emitted over a range from red light to yellow light by controlling the current applied to the light emitting diode (100). Such a lighting device (1000a) can be suitably used in applications that emit light whose color changes, such as Christmas trees. In addition, when a light emitting diode (100) having a first peak (P1) and a second peak (P2) which is an auxiliary peak having a shorter wavelength range is applied, the first peak (P1) determines the color temperature, and the second peak is located in a region where the melanin synthesis reactivity is higher than the first peak (P1), thereby suppressing melatonin secretion, thereby implementing a light emitting device having an auxiliary effect of increasing the user's physical activity. Additionally, when the intensity of the second peak (P2) is less than 10% of the intensity of the first peak (P1), the secondary peak does not affect the color purity, so a light-emitting device having high color purity can be implemented.

[0167] FIG. 11 is a schematic cross-sectional view illustrating a lighting device according to another embodiment of the present disclosure.

[0168] Referring to FIG. 11, a lighting device (1000b) according to the present embodiment is generally similar to the lighting device (1000a) described with reference to FIG. 10, but differs in that it further includes a light-emitting diode (101) that emits blue light and a light-emitting diode (103) that emits green light.

[0169] White light can be realized by driving a blue light emitting diode (101) and a green light emitting diode (103) together with a light emitting diode (100) that emits yellow or red light. In addition, the color of light emitted from the light emitting diode (100) can be changed by controlling the current applied to the light emitting diode (100), and thus the color temperature of light emitted from the lighting device (1000b) can be changed.

[0170] Although the light bulb-shaped lighting device is illustrated in FIGS. 10 and 11, the lighting devices of the present disclosure are not limited to light bulb-shaped lighting devices and may be implemented as lighting devices of various shapes.

[0171] FIG. 12 is a schematic plan view illustrating a head-mounted display (HMD) device according to one embodiment of the present disclosure. Augmented reality (AR), virtual reality (VR), mixed reality (MR), and the like can be experienced through the head-mounted display device.

[0172] Referring to FIG. 12, a head mounted display device (2000) may include a main body (210), a protective cushion (230), a display panel (250), an eyepiece (270), and a sensing device (290).

[0173] The display panel (250) may include arrayed micro LEDs, and blue, green, and red LEDs may be arranged in pixel units to implement colors. The light emitting diodes (100) of the present disclosure may be arranged as red LEDs on the display panel (250). Since the light emitting diodes (100) are nitride-based light emitting diodes, the red LEDs along with the blue and green LEDs may all be configured as nitride-based light emitting diodes. Therefore, even when small micro LEDs are arranged as light emitting diodes, the efficiency of the light emitting diodes can be prevented from decreasing, and the light angular distributions of the blue, green, and red light emitting diodes can be maintained similarly, thereby reducing color changes depending on the viewing angle. Furthermore, a display with low temperature sensitivity can be provided.

[0174] Meanwhile, the sensing device (290) includes a light source that irradiates light toward a target and a sensor that senses light reflected from the target. The light emitting diode (100) described above can be used as a light source that irradiates light toward a target in the sensing device (290). In particular, in a head mounted display device (2000), the sensing light source can be used for face recognition and body recognition. For example, the light emitting diode (100) of the present disclosure emits relatively short-wavelength light at high intensity under a relatively high current, and emits relatively long-wavelength light at low intensity under a relatively low current. Therefore, the light emitting diode (100) can be used as a light source for face recognition to detect whether the head mounted display device (2000) is worn under a relatively high current, and on the other hand, after the head mounted display device (2000) is worn on a human body, it can be used as a light source for body recognition under a relatively low current.

[0175] Accordingly, one type of light-emitting diode (100) of the present disclosure can be used as a light source for face recognition and body recognition, thereby simplifying the structure of the sensing device.

[0176] FIG. 13 is a schematic perspective view illustrating a vehicle (3000) equipped with a light-emitting diode according to one embodiment of the present disclosure.

[0177] Referring to FIG. 13, a vehicle (3000) includes a main body (310) and a tail light (330) mounted on the main body. The tail light (330) can emit red light and yellow light. The light emitting diode (100) according to the present embodiment can emit red light or yellow light by changing the current. Therefore, by arranging the light emitting diodes (100) of the present disclosure in the tail light (330), red light or yellow light can be emitted using the same light emitting diodes (100). For example, when the vehicle is braking, the light emitting diode can be driven under a low current to emit deep red light, while for direction indication, the light emitting diode can be driven under a high current to emit yellow light. In addition, the current applied to the light emitting diode can be changed to emit light of various colors to indicate the tail light or the vehicle is reversing.

[0178] Although various applications using the light-emitting diode (100) of the present disclosure have been described above, the applications of the light-emitting diode (100) of the present disclosure are not limited to those described above. The light-emitting diode (100) can be used in large-scale micro LED displays, and can also be used as a light source in a skin treatment device for skin treatment. In particular, since the wavelength of the emitted light can be changed by changing the current, the same light-emitting diode (100) can be used to treat skin at various depths, from the epidermis to the dermis. Accordingly, the skin treatment device according to the present disclosure can change the depth of the skin to be treated by changing the current. For example, the epidermis can be treated at a high current, and the dermis can be treated at a low current.

[0179] The external quantum efficiency characteristics exhibited by the light emitting diode (100) of the present disclosure are described with reference to FIGS. 14A and 14B.

[0180] Fig. 14A is a graph illustrating the normalized external quantum efficiency of light-emitting diodes according to current density, and Fig. 14B is an enlarged graph of a portion of Fig. 14A.

[0181] Referring to FIGS. 14A and 14B, the indicator line R indicates an external quantum efficiency graph of a red light-emitting diode (100) manufactured according to an embodiment of the present disclosure, the indicator line G indicates an external quantum efficiency graph of a green light-emitting diode, and the indicator line B indicates an external quantum efficiency graph of a blue light-emitting diode. The green light-emitting diode and the blue light-emitting diode may be light-emitting diodes used together with the red light-emitting diode (100) in a light-emitting device, and may also be typical nitride-based green and blue light-emitting diodes. For example, the green and blue light-emitting diodes may be light-emitting diodes used together with the red light-emitting diode in a micro LED display device.

[0182] The red light emitting diode (100) according to this embodiment is 4A / cm 2 20A / cm 2 It has a maximum external quantum efficiency within the current density range of 10 A / cm 2 20A / cm 2 It exhibits an external quantum efficiency of more than 90% of the maximum external quantum efficiency within the current density range. Thus, the maximum quantum efficiency of the light-emitting device is 4 A / cm 2 20A / cm 2 When positioned in the area of ​​, it is possible to achieve high efficiency even in cases where small light-emitting diodes are used, such as micro displays, or in low-current driving devices of 1uA to 10mA or less. In addition, when a light-emitting device is used in a range where the external quantum efficiency is 90% or more of the maximum external quantum efficiency, the thermal efficiency of the electrical light-emitting device can be improved.

[0183] In the graph of Figure 14A, the vertical dotted line indicates a current density of 20 A / cm 2 The standardized external quantum efficiency of the red light-emitting diode (100) is 10 A / cm 2 20A / cm 2 It has a higher value than the standardized external quantum efficiency of blue or green light-emitting diodes within the current density range. This can improve the light uniformity of the light-emitting module and compensate for the relatively low red luminous efficacy, thereby realizing a light-emitting module with high color purity.

[0184] Meanwhile, the standardized external quantum efficiency graph (R) of the red light-emitting diode (100) is 20 A / cm 2At the first point (P1), the normalized external quantum efficiency graphs (B, G) of the blue and green light-emitting diodes also have negative slopes (b1, g1) at the first point (P1). At the first point (P1), the absolute value of the slope (r1) of the normalized external quantum efficiency graph of the red light-emitting diode (100) is smaller than the absolute value of the slopes (b1, g1) of the normalized external quantum efficiency graphs (B, G) of the blue and green light-emitting diodes. Through this, 20 A / cm 2 In the red light emitting diode (100), the red light emitting diode is more stable to current changes than the green or blue light emitting diode.

[0185] The current density at which the red light-emitting diode (100) has the maximum external quantum efficiency is higher than the current densities at which the blue light-emitting diode and the green light-emitting diode have the maximum external quantum efficiency. In addition, the current density at which the green light-emitting diode has the maximum external quantum efficiency is higher than the current density at which the blue light-emitting diode has the maximum external quantum efficiency. When the light-emitting diodes are driven at a current density at which the red light-emitting diode (100) has the maximum external quantum efficiency, the reliability of the red light-emitting diode can be improved.

[0186] The normalized external quantum efficiency graph (R) of the red light-emitting diode (100) intersects with the normalized external quantum efficiency graphs (B, G) of the blue light-emitting diode and the green light-emitting diode at a second point (P2) and a third point (P3), respectively. The second point (P2) may be located at a lower current density than the third point (P3). More preferably, the intersection of the green light-emitting diode and the red light-emitting diode, which have relatively low light quantities, intersect at a higher current density than the intersection of the blue light-emitting diode and the red light-emitting diode, so that the green light-emitting diode and the red light-emitting diode can be driven in a relatively high external quantum efficiency region, thereby improving the reliability of the green and red light-emitting diodes and increasing the light uniformity of the light-emitting module.

[0187] The second point (P2) and the third point (P3) are 10A / cm 2 It is a smaller current density. In one embodiment, the driving current density of the light emitting diodes is greater than the current density at the third point (P3) and is 20 A / cm 2 It can be smaller. In this case, under the driving current density, the normalized external quantum efficiency of the red light-emitting diode (100) is higher than the normalized external quantum efficiency of the blue and green light-emitting diodes. Since the rate of change near the maximum quantum efficiency is small, it is 10 A / cm 2 20A / cm 2 By driving between them, stability can be improved according to current changes or sizes.

[0188] Meanwhile, the standardized external quantum efficiency graph (R) of the red light-emitting diode (100) has a positive slope (r2) at the second point (P2). In contrast, the standardized external quantum efficiency graph (B) of the blue light-emitting diode has a negative slope (b2) at the second point (P2). The slope (r2) may be greater than the absolute value of the slope (b2). In addition, the standardized external quantum efficiency graph of the red light-emitting diode (100) has a positive slope (r3) at the third point (P3). In contrast, the standardized external quantum efficiency graph (G) of the green light-emitting diode has a negative slope (g2) at the third point (P3). The slope (r3) may be greater than the slope (g2).

[0189] As shown in Fig. 14A, graphs (R, G, B) show a tendency to increase rapidly as the current density increases and then gradually decrease after passing the maximum quantum efficiency. Graphs (R, G, B) have a section where the current density increases rapidly and then gradually increases and then decreases, and they have a minimum radius of curvature in this section, which is 20 A / cm. 2 Smaller. The minimum radii of curvature of graphs (R, G, B) are different. In one embodiment, as illustrated in FIG. 14A, the minimum radii of curvature of graph (R) are larger than the minimum radii of curvature of graph (B) and graph (G), and the larger the radii of curvature, the smaller the rate of change in current density, allowing for stable operation in small sizes or at low currents.

[0190] FIG. 15 is a schematic plan view illustrating a light-emitting module (200a) according to one embodiment of the present disclosure.

[0191] Referring to FIG. 15, the light-emitting module (200a) includes a substrate (110a), a first light-emitting diode (120a) disposed on one surface of the substrate (110a) and generating light having a first peak wavelength, a second light-emitting diode (130a) disposed on one surface of the substrate (110a) and generating light having a second peak wavelength, and a third light-emitting diode (140a) disposed on one surface of the substrate (110a) and generating light having a third peak wavelength.

[0192] The above substrate (110a) is a substrate on which a plurality of light-emitting diodes (120a, 130a, 140a) are mounted on the upper surface, and is not limited to a specific type as long as it can support light-emitting diodes, such as a circuit board, a lead frame, a flexible substrate, a transparent substrate, etc.

[0193] The first to third light-emitting diodes (120a, 130a, 140a) may emit different peak wavelengths, or may be a plurality of light-emitting diodes (120a, 130a, 140a) having a difference in peak wavelengths within a range of 5 nm. At least one of the first to third light-emitting diodes (120a, 130a, 140a) may be a nitride-based light-emitting diode that emits red light. In one embodiment, the first to third light-emitting diodes (120a, 130a, 140a) may all be nitride-based light-emitting diodes that emit red light, and the difference in peak wavelengths of light emitted from these light-emitting diodes may be within 5 nm, enabling uniform color implementation. In another embodiment, the first to third light-emitting diodes (120a, 130a, 140a) may include nitride-based light-emitting diodes that emit red light, green light, and blue light, and the difference in peak wavelengths of light emitted from the diodes may be 10 nm or more, and if the difference in peak wavelengths is 10 nm or more, a wide color gamut may be achieved. Although illustrated as first to third, the number is not limited thereto.

[0194] The above substrate (110a) has an insulating layer and wiring for electrical connection with the first to third light-emitting diodes (120a, 130a, 140a), and may include circuits for supplying and driving an electrical source such as current or voltage to the first to third light-emitting diodes (120a, 130a, 140a).

[0195] On the upper surface of the substrate (110a), pads for mounting first to third light-emitting diodes (120a, 130a, 140a) may be formed, and on the lower surface of the substrate (110a), pads for mounting on another substrate (e.g., a display substrate, a circuit board) may also be formed. The substrate (110a) may be formed in a single-layer or multi-layer structure, and may be formed in various thicknesses as needed. It may have a thickness thicker than the first to third light-emitting diodes (120a, 130a, 140a), and may protect the light-emitting diodes from external impact.

[0196] A plurality of light emitting diodes (120a, 130a, 140a) may be arranged horizontally spaced apart from each other on the substrate (110a). However, this is not limited to the first to third light emitting diodes (120a, 130a, 140a) and may be arranged vertically stacked to arrange multiple light emitting diodes in a narrow space.

[0197] A cover layer may be formed on the plurality of light-emitting diodes (120a, 130a, 140a). The cover layer may cover the plurality of light-emitting diodes (120a, 130a, 140a), and may additionally include various fillers, light-absorbing materials such as carbon black, light-reflecting materials, etc. to increase light extraction efficiency. The cover layer may function as a type of buffer layer and may cover not only the light-emitting diodes but also the upper surface of the substrate (110a).

[0198] The above cover layer can encapsulate a plurality of light-emitting diodes (120a, 130a, 140a), and can also function as a refractive layer that refracts light emitted therefrom and adjusts the projection angle.

[0199] The above cover layer may be composed of a single layer or multiple layers, and may be a light-transmitting transparent molding for transmitting light emitted from a light-emitting diode (120a, 130a, 140a).

[0200] The cover layer may be formed of a resin including one or more of silicone, epoxy, PMMA (Polymethyl methacrylate), and PS (Polystyrene) series. In addition, the cover layer may be formed of a fluororesin to improve the light extraction efficiency emitted from a plurality of light-emitting diodes (120a, 130a, 140a).

[0201] Meanwhile, the cover layer may further include a light diffusing material capable of diffusing light emitted from a plurality of light emitting diodes (120a, 130a, 140a). For example, the light diffusing material may include one or more of TiO2, BaO, SiO2, and MgO, Y2O3 capable of scattering light, and this may be distributed inside the cover layer.

[0202] Additionally, the cover layer may further include a wavelength conversion material capable of converting the wavelength of light emitted from the plurality of light-emitting diodes (120a, 130a, 140a). For example, the wavelength conversion material may include a fluorescent material capable of emitting one or more of red light, blue light, and green light, and may be distributed within the cover layer.

[0203] The light-emitting module (200a) according to the present embodiment may be a light-emitting device in itself, or may be used in various light-emitting devices such as other lighting devices or display devices. A display device (4000) including the light-emitting module (200a) will be described below.

[0204] FIG. 16 is a schematic plan view illustrating a display device (4000) according to one embodiment of the present disclosure.

[0205] Referring to FIG. 16, a display device (4000) may include a plurality of light-emitting modules (200a). Each light-emitting module (200a) may include nitride-based blue, green, and red light-emitting diodes. The light-emitting module (200a) may constitute at least one pixel. The light-emitting module (200a) may be arranged on a circuit board and may be operated to implement an image by receiving power through wiring on the circuit board.

[0206] FIG. 17 is a schematic cross-sectional view for explaining a light-emitting diode (100b) according to one embodiment of the present disclosure, and FIG. 18 is a schematic drawing for explaining the band gap of each layer of the light-emitting diode according to one embodiment of the present disclosure.

[0207] Referring to FIG. 17, the light emitting diode (100b) may include a substrate (21), a buffer layer (23), an undoped layer (25), a first conductive semiconductor layer (27), a strain control layer (29), a superlattice layer (33), an active region (35), an electron blocking layer (37), a second conductive semiconductor layer (39), a transparent electrode layer (41), a first electrode (43a), and a second electrode (43b). Since the substrate (21), the buffer layer (23), the first conductive semiconductor layer (27), the strain control layer (29), the superlattice layer (33), the active region (35), the electron blocking layer (37), the second conductive semiconductor layer (39), the transparent electrode layer (41), the first electrode (43a), and the second electrode (43b) are similar to those described in the previous embodiment, a detailed description thereof is omitted herein to avoid duplication.

[0208] In this embodiment, the first conductive semiconductor layer (27) can be expressed by the following chemical formula 1:

[0209] (Chemical Formula 1) AxByCzD(1-xyz), where A may be one element selected from Al, In, and Ga, B may be one element selected from Al, In, and Ga, C may be one element selected from Al, In, and Ga, and D may be nitrogen, A, B, and C are different elements, x+y+z=0.5, and 0≤x, y, z≤0.5.

[0210] However, the first challenge type semiconductor layer (27) may include Ga and N.

[0211] Meanwhile, the index (P) representing the band gap of the nitride semiconductor layer expressed by Chemical Formula 1 in this specification can be expressed as (αx+βy+γz), where α, β, and γ represent the band gaps of AD, BD, and CD, respectively. For example, when AD, BD, and CD are AlN, GaN, and InN, respectively, α, β, and γ can be 0.62, 3.4, and 6.2, respectively.

[0212] The superlattice layer (33) may be formed of InGaN / GaN or InGaN / InGaN, and may be formed by stacking in 2 to 6 cycles, for example. As illustrated in FIG. 19, the thickness of the first layer (33a) having a high In content within the superlattice layer (33) may be smaller than the thickness of the second layer (33b) having a relatively low In content. For example, the thickness of the first layer (33a) within the superlattice layer (33) may be about 2.0 nm, and the thickness of the second layer (33b) may be about 8.0 nm. The total thickness of the superlattice layer (33) may be, for example, in the range of about 50 nm to about 60 nm, but is not limited thereto.

[0213] For the overall composition of In, Ga, and N, the In composition ratio of the first layer (33a) of the superlattice layer (33) may be within the range of 0.025 to 0.05. Meanwhile, for the overall composition of In, Ga, and N, the Ga composition ratio within the first layer (33a) may be within the range of 0.45 to 0.475.

[0214] The superlattice layer (33) can be grown at a relatively slow rate using triethylgallium (TEGa) as a Ga source. V-pits are created by the strain control layer (29) grown relatively quickly at a low temperature, and the size of the V-pits increases by the superlattice layer (33). In particular, by growing the superlattice layer (33) using a TEGa source, V-pits with a relatively uniform density and size can be formed over the entire wafer area.

[0215] By forming the superlattice layer (33) as an InGaN / GaN or InGaN / InGaN superlattice layer, lattice changes can be reduced, thereby reducing defects in the active region (35).

[0216] An active region (35) is arranged on a superlattice layer (33). The active region (35) may include a barrier layer (35a) and a well layer (35b), as illustrated in FIG. 4. The active region (35) may have a single quantum well structure including a single well layer (35b) or a multi-quantum well structure including multiple well layers (35b). The number of well layers (35b) may be, for example, in the range of 1 to 10.

[0217] The compositions of the barrier layer (35a) and the well layer (35b) can be expressed by the chemical formula 1 described above, i.e., AxByCzD(1-xyz). However, the well layer (35b) contains a higher content of In than the barrier layer (35a) in order to emit red light. The composition ratio of In in the well layer (35b) may be 0.15 or more and 0.2 or less with respect to the entire composition in the well layer (35b).

[0218] An electron blocking layer (37) is disposed on the active region (35). The electron blocking layer (37) is formed along the surface of the active region (35). The electron blocking layer (37) may include a plurality of layers (37a, 37b, 37c), as illustrated in FIG. 5. The lowermost layer (37a) may be in contact with the last barrier layer (35a) of the active region (35), the uppermost layer (37c) may be in contact with the second conductivity type semiconductor layer (39), and the intermediate layer (37b) may be disposed between the lowermost layer (37a) and the uppermost layer (37c). For example, the lowermost layer (37a) may be formed to have a thickness of about 2 nm to 3 nm, the intermediate layer (37b) to have a thickness of about 10 nm to 15 nm, and the uppermost layer (37c) to have a thickness of about 12 nm to 20 nm.

[0219] The intermediate layer (37b) may contain a higher concentration of p-type impurities than the lowermost layer (37a) and the uppermost layer (37c). For example, the intermediate layer (37b) may contain about 1×10 20 / cm 3 3×10 20 / cm 3 It may contain Mg doped at a high concentration.

[0220] The composition formula of each layer in the electron block layer (37) can be expressed by the chemical formula 1 described above. However, each layer in the electron block layer (37) may include Al. The lowest layer (37a) may be, for example, an AlN layer. In addition, the uppermost layer (37c) may be a grading layer in which the composition ratio of Al decreases as it moves away from the active region (35). For example, the uppermost layer (37c) may be an AlGaN grading layer. In addition, the Al composition ratio of the intermediate layer (37b) may be lower than the Al composition ratio of the lowest layer (37a), and may be lower than the maximum Al composition ratio and greater than the minimum Al composition ratio in the uppermost layer (37c), which is the grading layer. For example, the intermediate layer (37b) may be an InAlGaN layer.

[0221] The second challenge type semiconductor layer (39) can be placed on the electron block layer (37).

[0222] Each layer (39a, 39b, 39c) of the second conductive semiconductor layer (39) can be expressed by chemical formula 1 similarly to the first conductive semiconductor layer (27).

[0223] (Chemical formula 1) A x B y C z D (1-x-y-z) , where A may be one element selected from Al, In, and Ga, B may be one element selected from Al, In, and Ga, C may be one element selected from Al, In, and Ga, and D may be nitrogen, and A, B, and C are different elements, and x+y+z=0.5, and 0≤x, y, z≤0.5.

[0224] However, at least one of the first layer (39a) to the third layer (39c) must contain Ga. The first layer (39a) to the third layer (39c) may be formed with the same composition.

[0225] Referring to Fig. 18, the index (P) representing the band gap of each layer can be calculated as (αx+βy+γz). The index representing the band gap of the first conductive semiconductor layer (27) or the strain control layer (29) can be represented as P1, the indices of the first and second layers in the superlattice layer (33) can be represented as P2, P3, the index of the barrier layer (35a) can be represented as P4, the index of the well layer (35b) can be represented as P5, the index of the electron locking layer (37) can be represented as P6, and the index of the second conductive semiconductor layer (39) can be represented as P7. In order to distinguish the calculation formula for calculating each index value, (αx+βy+γz) P can be written as (αx+βy+γz). For example, the calculation formula for P1 is (αx+βy+γz). P1 , the calculation formula for P2 is (αx+βy+γz) P2 can be expressed as

[0226] In the embodiments of the present disclosure, the index value P5 of at least one well layer (35b) is smaller than the index value P1 of the first conductive semiconductor layer (27) or the strain control layer (39), and satisfies the following mathematical expression 1.

[0227] (Mathematical formula 1) (αx+βy+γz) P5 - (αx+βy+γz) P1 < 0.

[0228] The value obtained by subtracting the indicator value P1 from the indicator value P5 may be negative. Alternatively, the absolute value of the value obtained by subtracting the indicator value P1 from the indicator value P5 may be greater than or equal to 0.6.

[0229] In addition, in the embodiments of the present disclosure, the index value P5 of the well layer (35b) is smaller than the index value P2 of at least one first layer (33a) in the superlattice layer (33), and satisfies the following mathematical expression 2.

[0230] (Mathematical formula 2) (αx+βy+γz) P5 - (αx+βy+γz) P2 < 0.

[0231] The value obtained by subtracting the index value P2 from the index value P5 may be negative. Alternatively, the absolute value of the value obtained by subtracting the index value P2 from the index value P5 may be greater than or equal to 0.5. Accordingly, light generated in the well layer (35b) can be prevented from being absorbed by the first layer (33a).

[0232] In addition, in the embodiments of the present disclosure, the index value P5 of the well layer (35b) is smaller than the index value P3 of at least one second layer (33b) in the superlattice layer (33), and satisfies the following mathematical expression 3.

[0233] (Equation 3) (αx+βy+γz) P5 - (αx+βy+γz) P3 < 0.

[0234] The value obtained by subtracting the index value P3 from the index value P5 may be negative. Alternatively, the absolute value of the value obtained by subtracting the index value P3 from the index value P5 may be greater than or equal to 0.6. The absolute value of the value obtained by subtracting the index value P2 from the index value P5 may be less than the absolute value of the value obtained by subtracting the index value P3 from the index value P5. Therefore, the electrons supplied to the light-emitting element can smoothly move to the well layer (35b).

[0235] In addition, in the embodiments of the present disclosure, the index value P5 of the well layer (35b) is smaller than the index value P4 of the barrier layer (35a) in contact with the well layer (35b), and satisfies the following mathematical expression 4.

[0236] (Equation 4) (αx+βy+γz) P5 - (αx+βy+γz) P4 < 0.

[0237] The value obtained by subtracting the index value P4 from the index value P5 may be negative. Alternatively, the absolute value of the value obtained by subtracting the index value P4 from the index value P5 may be greater than or equal to 0.9. The value obtained by subtracting the index value P5 from the index value P4 may be less than the value obtained by subtracting the index value P2 from the index value P3. Therefore, the probability that electrons supplied to the light-emitting element are trapped in the well layer (35b) may be increased.

[0238] Two barrier layers (35a) can be in contact with each well layer (35b), and in this case, the well layer (35b) and the two barrier layers (35a) can each satisfy mathematical expression 4. Accordingly, the active region (35) can emit red light.

[0239] In the embodiments of the present disclosure, the index value P5 of the well layer (35b) is smaller than the index value P6 of the electron block layer (37) and satisfies the following mathematical expression 5.

[0240] (Equation 5) (αx+βy+γz) P5 - (αx+βy+γz) P6 < 0.

[0241] The value obtained by subtracting the index value P6 from the index value P5 may be negative. Alternatively, the absolute value of the value obtained by subtracting the index value P6 from the index value P5 may be greater than or equal to 1.4. The value obtained by subtracting the index value P5 from the index value P6 may be greater than the value obtained by subtracting the index value P5 from the index value P4. Therefore, electrons may be prevented from moving to the second conductive semiconductor layer (39).

[0242] When the electronic block layer (37) includes a composition gradient layer, P6 can be calculated as a layer having the maximum band gap of the composition gradient layer.

[0243] In the embodiments of the present disclosure, the index value P5 of the well layer (35b) is smaller than the index value P7 of the second conductive semiconductor layer (39) and satisfies the following mathematical expression 6.

[0244] (Equation 6) (αx+βy+γz) P5 - (αx+βy+γz) P7 < 0.

[0245] The value obtained by subtracting the index value P7 from the index value P5 may be negative. Alternatively, the absolute value of the value obtained by subtracting the index value P7 from the index value P5 may be greater than or equal to 0.6. The value obtained by subtracting the index value P7 from the index value P6 may be greater than the value obtained by subtracting the index value P4 from the index value P6. Therefore, light generated in the well layer (35b) can be prevented from being absorbed in the second conductive semiconductor layer (39).

[0246] Meanwhile, in the embodiments of the present disclosure, the index value P4 of the barrier layer (35a) is greater than or equal to the index value P1 of the first conductive semiconductor layer (27) or the strain control layer (29), and satisfies the following mathematical expression 7.

[0247] (Equation 7) (αx+βy+γz) P4 - (αx+βy+γz) P1 ≥ 0.

[0248] The value obtained by subtracting the indicator value P1 from the indicator value P4 may be positive. Alternatively, the value obtained by subtracting the indicator value P1 from the indicator value P4 may be greater than 0.15.

[0249] The index value P4 of the barrier layer (35a) may be greater than the index value P1 of the first conductive semiconductor layer (27) or the strain control layer (29).

[0250] In addition, in the embodiments of the present disclosure, the index value P4 of the barrier layer (35a) is not smaller than the index value P3 of the second layer (33b) in the superlattice layer (33), and satisfies the following mathematical expression 8.

[0251] (Equation 8) (αx+βy+γz) P4 - (αx+βy+γz) P3 ≥ 0.

[0252] The index value P4 of the barrier layer (35a) may be greater than the index value P3 of the second layer (33b). The value obtained by subtracting the index value P3 from the index value P4 may be a positive number. The value obtained by subtracting the index value P3 from the index value P4 may be greater than 0.2. Therefore, the index value of the layer acting as a barrier may be increased as it gets closer to the second conductive semiconductor layer (39), thereby improving the flow of electrons and holes.

[0253] In the embodiments of the present disclosure, the index value P4 of the barrier layer (35a) is smaller than the index value P6 of the electron block layer (37), and satisfies the following mathematical expression 9.

[0254] (Equation 9) (αx+βy+γz) P4 - (αx+βy+γz) P6 < 0.

[0255] The value obtained by subtracting the indicator value P6 from the indicator value P4 may be negative. Alternatively, the absolute value of the value obtained by subtracting the indicator value P6 from the indicator value P4 may be greater than or equal to 0.4.

[0256] In the embodiments of the present disclosure, the index value P4 of the barrier layer (35a) is greater than or equal to the index value P7 of the second conductive semiconductor layer (39), and satisfies the following mathematical expression 10.

[0257] (Equation 10) (αx+βy+γz) P4 - (αx+βy+γz) P7 ≥ 0.

[0258] The value obtained by subtracting the indicator value P7 from the indicator value P4 may be positive. Alternatively, the value obtained by subtracting the indicator value P7 from the indicator value P4 may be greater than or equal to 0.1.

[0259] The index value P4 of the barrier layer (35a) may be greater than the index value P7 of the second conductive semiconductor layer (39).

[0260] The index value P3 of at least one second layer (33b) of the superlattice layer (33) is less than or equal to the index value P1 of the first conductive semiconductor layer (27) or the strain control layer (29), and satisfies the following mathematical expression 11.

[0261] (Equation 11) (αx+βy+γz) P3 - (αx+βy+γz) P1 ≤ 0.

[0262] The value obtained by subtracting the indicator value P1 from the indicator value P3 may be negative. Alternatively, the absolute value of the value obtained by subtracting the indicator value P1 from the indicator value P3 may be greater than or equal to 0.01.

[0263] The index value P3 of at least one second layer (33b) of the superlattice layer (33) may be smaller than the index value P1 of the first conductive semiconductor layer (27) or the strain control layer (29).

[0264] The index value P3 of at least one second layer (33b) of the superlattice layer (33) is less than or equal to the index value P7 of the second conductive semiconductor layer (39), and satisfies the following mathematical expression 12.

[0265] (Equation 12) (αx+βy+γz) P3 - (αx+βy+γz) P7 ≤ 0.

[0266] The value obtained by subtracting the indicator value P7 from the indicator value P3 may be negative. Alternatively, the absolute value of the value obtained by subtracting the indicator value P7 from the indicator value P3 may be greater than or equal to 0.01.

[0267] The index value P3 of at least one second layer (33b) of the superlattice layer (33) may be smaller than the index value P7 of the second conductive semiconductor layer (39).

[0268] The light emitting diode (100b) of the present disclosure may further include a lower superlattice layer (31) as described with reference to FIGS. 1 and 2, and a detailed description thereof is omitted.

[0269] FIG. 20 is a band diagram for explaining a light-emitting diode according to another embodiment of the present disclosure, and FIG. 21 is a cross-sectional view showing an enlarged view of an active region (35') of a light-emitting diode according to another embodiment of the present disclosure.

[0270] Referring to FIGS. 20 and 21, the light-emitting diode according to the present embodiment is similar to the light-emitting diode described with reference to FIG. 17, but differs in that the barrier layer (35a') of the active region (35') includes a protruding bandgap layer (35c) together with a reference bandgap layer (35a). The reference bandgap layer (35a) has an index value (P4) representing the bandgap of the barrier layer (35a) described in the preceding embodiments, and the protruding bandgap layer (35c) has a bandgap wider than the reference bandgap. The bandgap of the protruding bandgap layer (35c) is wider than the bandgap of the electron blocking layer (37).

[0271] The protruding band gap layer (35c) may be arranged as an intermediate layer between the reference band gap layers (35a) within the barrier layer (35a') as illustrated in FIGS. 20 and 21, but the present disclosure is not limited thereto. The protruding band gap layer (35c) may be formed as a starting layer of the barrier layer (35a') or a terminating layer of the barrier layer (35a') so as to be in contact with the well layer (35b). The protruding band gap layer (35c) may be formed within all the barrier layers within the active region (35'). In one embodiment, the last barrier layer (35a) in contact with the electron blocking layer (37) may not include the protruding band gap layer (35c).

[0272] The index value P8 representing the band gap of the protruding band gap layer (35c) is greater than the index value P4 of the reference barrier layer (35a), and satisfies the following mathematical expression 13.

[0273] (Equation 13) (αx+βy+γz) P8 - (αx+βy+γz) P4 > 0.

[0274] The index value P8 representing the band gap of the protruding band gap layer (35c) is greater than the index value P6 representing the band gap of the electron block layer (37), and satisfies the following mathematical expression 14.

[0275] (Equation 14) (αx+βy+γz) P8 - (αx+βy+γz) P6 > 0.

[0276] In one embodiment, the protruding bandgap layer (35c) may be an AlN layer.

[0277] FIG. 22 is a schematic cross-sectional view illustrating a light-emitting device according to one embodiment of the present disclosure.

[0278] Referring to FIG. 22, the light-emitting device includes a substrate (210a), a first light-emitting diode (220a) disposed on one surface of the substrate (210a) and emitting light having a first peak wavelength, a second light-emitting diode (230a) disposed on one surface of the substrate (210a) and emitting light having a second peak wavelength, and a third light-emitting diode (240a) disposed on one surface of the substrate (210a) and emitting light having a third peak wavelength.

[0279] The above substrate (210a) is a substrate on which a plurality of light-emitting diodes (220a, 230a, 240a) are mounted on the upper surface, and is not limited to a specific type as long as it can support light-emitting diodes, such as a circuit board, a lead frame, a flexible substrate, a transparent substrate, etc.

[0280] The first to third light-emitting diodes (220a, 230a, 240a) may emit different peak wavelengths, or may be a plurality of light-emitting diodes (220a, 230a, 240a) having a difference in peak wavelengths within a range of 5 nm. At least one of the first to third light-emitting diodes (220a, 230a, 240a) may be a nitride-based light-emitting diode that emits red light. In one embodiment, the first to third light-emitting diodes (220a, 230a, 240a) may all be nitride-based light-emitting diodes that emit red light, and the difference in peak wavelengths of light emitted from these light-emitting diodes may be within 5 nm. In another embodiment, the first to third light-emitting diodes (220a, 230a, 240a) may include nitride-based light-emitting diodes that emit red light, green light, and blue light. In the city, they are numbered 1 to 3, but the number is not limited to this.

[0281] The above substrate (210a) has an insulating layer and wiring for electrical connection with the first to third light-emitting diodes (220a, 230a, 240a), and may include circuits for supplying and driving an electrical source such as current or voltage to the first to third light-emitting diodes (220a, 230a, 240a).

[0282] On the upper surface of the substrate (210a), pads for mounting first to third light-emitting diodes (220a, 230a, 240a) may be formed, and on the lower surface of the substrate (210a), pads for mounting on another substrate (not shown, for example, a display substrate or a circuit board) may be formed. The substrate (210a) may be formed in a single-layer or multi-layer structure, and may be formed in various thicknesses as needed.

[0283] A plurality of light emitting diodes (220a, 230a, 240a) may be arranged horizontally spaced apart from each other on the substrate (210a). However, this is not limited to the first to third light emitting diodes (220a, 230a, 240a) and may be arranged vertically stacked.

[0284] A cover layer (250a) may be formed on the plurality of light-emitting diodes (220a, 230a, 240a). The cover layer (250a) may cover the plurality of light-emitting diodes (220a, 230a, 240a), and may additionally include various fillers, light-absorbing materials such as carbon black, light-reflecting materials, etc. to increase light extraction efficiency. The cover layer (250a) may function as a type of buffer layer and may cover not only the light-emitting diodes but also the upper surface of the substrate (210a).

[0285] The above cover layer (250a) can encapsulate a plurality of light-emitting diodes (220a, 230a, 240a) and can also function as a refractive layer that refracts light emitted therefrom.

[0286] The above cover layer (250a) may be composed of a single layer or multiple layers, and may be a transparent molding having light transmission properties for transmitting light emitted from a light-emitting diode (220a, 230a, 240a).

[0287] For example, the cover layer (250a) may be formed of a resin including one or more of silicone, epoxy, PMMA (Polymethyl methacrylate), and PS (Polystyrene) series. In addition, the cover layer (250a) may be formed of a fluororesin to improve the light extraction efficiency emitted from a plurality of light-emitting diodes (220a, 230a, 240a).

[0288] Meanwhile, the cover layer (250a) may further include a light diffusing material capable of diffusing light emitted from a plurality of light emitting diodes (220a, 230a, 240a). For example, the light diffusing material may include one or more of TiO2, BaO, SiO2, and MgO, Y2O3 capable of scattering light, and this may be distributed within the cover layer (250a).

[0289] Additionally, the cover layer (250a) may further include a wavelength conversion material capable of converting the wavelength of light emitted from a plurality of light-emitting diodes (220a, 230a, 240a). For example, the wavelength conversion material may include a fluorescent material capable of emitting one or more of red light, blue light, and green light, and may be distributed within the cover layer.

[0290] While specific embodiments and aspects of the present disclosure have been illustrated and described, various changes and modifications may be made without departing from the spirit and scope of the present disclosure. Furthermore, while various aspects have been described herein, these aspects need not be used in combination. Accordingly, the following claims are intended to encompass all modifications and variations within the scope of the present disclosure.

Claims

1. In a light-emitting diode that emits red light, First challenge type semiconductor layer; An active region comprising a barrier layer and a well layer; A strain control layer disposed between the first challenge type semiconductor layer and the active region; A superlattice layer disposed between the strain control layer and the active region; A second conductive semiconductor layer disposed on the active region; and Including an electron blocking layer disposed between the active region and the second conductive semiconductor layer, The composition of each layer is expressed by the following chemical formula 1, and the index value (P5) representing the band gap of the well layer and the index value (P1) representing the band gap of the first conductive semiconductor layer are light-emitting diodes satisfying the following mathematical formula 1: (Chemical Formula 1) AxByCzD(1-xyz) (wherein, A is one element selected from Al, In, and Ga, B is one element selected from Al, In, and Ga, C is one element selected from Al, In, and Ga, D is nitrogen, A, B, and C are different elements, x+y+z=0.5, and 0≤x, y, z≤0.5); and (Mathematical expression 1) (αx+βy+γz) P5 - (αx+βy+γz) P1 < 0 (where α, β, and γ represent the band gaps of AD, BD, and CD, respectively).

2. In claim 1, the superlattice layer has a structure in which the first layer and the second layer are alternately laminated, the first layer contains more In than the second layer, and an index value (P5) representing the band gap of the well layer and an index value (P2) representing the band gap of the first layer of the superlattice layer satisfy the following mathematical expression 2: (Mathematical expression 2) (αx+βy+γz) P5 - (αx+βy+γz) P2 < 0.

3. In claim 2, the indicator value (P5) representing the band gap of the well layer and the indicator value (P3) representing the band gap of the second layer of the superlattice layer satisfy the following mathematical expression 3: (Mathematical expression 3) (αx+βy+γz) P5 - (αx+βy+γz) P3 < 0.

4. In claim 1, the indicator value (P5) representing the band gap of the well layer and the indicator value (P4) representing the band gap of the barrier layer are light-emitting diodes satisfying the following mathematical expression 4: (Mathematical expression 4) (αx+βy+γz) P5 - (αx+βy+γz) P4 < 0.

5. In claim 4, the light emitting diode wherein the well layer is in contact with two barrier layers, and the well layer and the two barrier layers each satisfy the mathematical expression 4.

6. In claim 1, the indicator value (P5) representing the band gap of the well layer and the indicator value (P6) representing the band gap of the electron block layer are light-emitting diodes satisfying the following mathematical expression 5: (Mathematical expression 5) (αx+βy+γz) P5 - (αx+βy+γz) P6 < 0.

7. In claim 1, the indicator value (P5) representing the band gap of the well layer and the indicator value (P7) representing the band gap of the second conductive semiconductor layer are light-emitting diodes satisfying the following mathematical expression 6: (Mathematical expression 6) (αx+βy+γz) P5 - (αx+βy+γz) P7 < 0.

8. In claim 1, the indicator value (P4) representing the band gap of the barrier layer and the indicator value (P1) representing the band gap of the first conductive semiconductor layer are light-emitting diodes satisfying the following mathematical expression 7: (Mathematical formula 7) (αx+βy+γz) P4 - (αx+βy+γz) P1 ≥ 0.

9. In claim 8, a light emitting diode in which an index value (P4) representing a band gap of the barrier layer is greater than an index value (P1) representing a band gap of the first conductive semiconductor layer.

10. In claim 1, the indicator value (P4) representing the band gap of the barrier layer and the indicator value (P3) representing the band gap of the first layer of the superlattice layer satisfy the following mathematical expression 8: (Mathematical expression 8) (αx+βy+γz) P4 - (αx+βy+γz) P3 ≥ 0.

11. In claim 1, the indicator value (P4) representing the band gap of the barrier layer and the indicator value (P6) representing the band gap of the electron block layer are light-emitting diodes satisfying the following mathematical expression 9: (Mathematical formula 9) (αx+βy+γz) P4 - (αx+βy+γz) P6 < 0.

12. In claim 1, the indicator value (P4) representing the band gap of the barrier layer and the indicator value (P7) representing the band gap of the second conductive semiconductor layer are light-emitting diodes satisfying the following mathematical expression 10: (Mathematical expression 10) (αx+βy+γz) P4 - (αx+βy+γz) P7 ≥ 0.

13. In claim 12, a light emitting diode in which an index value (P4) representing a band gap of the barrier layer is greater than an index value (P7) representing a band gap of the second conductive semiconductor layer.

14. In claim 1, the superlattice layer has a structure in which the first layer and the second layer are alternately laminated, the first layer contains more In than the second layer, and an index value (P3) representing the band gap of the second layer of the superlattice layer and an index value (P1) representing the band gap of the first conductive semiconductor layer satisfy the following mathematical expression 11: (Mathematical expression 11) (αx+βy+γz) P3 - (αx+βy+γz) P1 ≤ 0.

15. In claim 14, the index value (P3) representing the band gap of the second layer of the superlattice layer and the index value (P7) representing the band gap of the second conductive semiconductor layer are light-emitting diodes satisfying the following mathematical expression 12: (Mathematical expression 12) (αx+βy+γz) P3 - (αx+βy+γz) P7 ≤ 0.

16. In claim 15, a light-emitting diode in which an index value (P3) representing a band gap of the second layer of the superlattice layer is smaller than an index value (P7) representing a band gap of the second conductive semiconductor layer (39).

17. In claim 1, at least one of the barrier layers comprises a reference band gap layer and a protruding band gap layer, The indicator value (P8) representing the band gap of the above-mentioned protruding band gap layer and the indicator value (P4) representing the band gap of the above-mentioned reference band gap layer are light-emitting diodes satisfying the following mathematical expression 13: (Mathematical expression 13) (αx+βy+γz) P8 - (αx+βy+γz) P4 > 0.

18. In claim 17, The index value (P8) representing the band gap of the above-mentioned protruding band gap layer and the index value (P6) representing the band gap of the above-mentioned electron block layer are light-emitting diodes satisfying the following mathematical expression 14: (Mathematical expression 14) (αx+βy+γz) P8 - (αx+βy+γz) P6 > 0.

19. A light emitting diode according to claim 18, wherein the protruding band gap layer is disposed in barrier layers other than the last barrier layer of the active region.

20. A light emitting diode according to claim 18, wherein the protruding band gap layer is an AlN layer.

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