CN115663080A

CN115663080A - Light emitting diode

Info

Publication number: CN115663080A
Application number: CN202211424122.4A
Authority: CN
Inventors: 张景琼; 樊本杰; 杨鸿志; 邓顺达
Original assignee: Kaistar Lighting Xiamen Co Ltd
Current assignee: Kaistar Lighting Xiamen Co Ltd
Priority date: 2020-05-22
Filing date: 2020-05-22
Publication date: 2023-01-31
Also published as: CN111613702A; CN111613702B

Abstract

The application discloses a light emitting diode. The light emitting diode includes an epitaxial light emitting structure to generate a light beam having a broadband blue light spectrum, and the epitaxial light emitting structure includes a P-type semiconductor layer, an N-type semiconductor layer, and a light emitting stack. The light emitting laminated layer is located between the P and N type semiconductor layers and provided with m well layers and m +1 barrier layers which are alternately stacked, wherein the m well layers comprise at least five first to fifth well layers with different forbidden band widths respectively so as to generate five sub-beams with five wavelengths respectively. Wherein at least one of the 1 st to x well layers close to the N-type semiconductor layer is a fifth well layer, x and m are natural numbers, and x and m satisfy the following relation that x is not more than (m/3). Therefore, the influence of the change of the operating current density on the waveform of the white light spectrum of the mixed light beam generated by the light-emitting module can be reduced, and the white light spectrum of the mixed light beam has better stability relative to the change of the operating current.

Description

Light emitting diode

The application is a divisional application of Chinese patent application No. 2020104423693, the application date is 2020-05-22, and the name is light emitting diode and light emitting module.

Technical Field

The present invention relates to a light emitting diode, and more particularly, to a light emitting diode for generating a broadband blue light spectrum.

Background

In the prior art, a narrow-peak blue Light Emitting Diode (LED) is usually used to excite a phosphor to generate white light, which is used as an illumination light source or a display light source. In the white light spectrum generated by the above method, the blue light is presented by a high-intensity peak, and therefore, the waveform of the white light spectrum generated by the blue light emitting diode in the blue light wave band still has an optimized space.

In addition, when the current for driving the blue light emitting diode to emit light changes, the waveform of the white light spectrum generated by the blue light emitting diode in cooperation with the fluorescent powder in the blue light wave band changes too much, which may cause each index of the color rendering index to change and possibly not meet the application standard. That is, the stability of the waveform of the blue light band with respect to the operating current of the white light spectrum generated by the conventional blue light emitting diode still needs to be improved.

Disclosure of Invention

The present application provides a light emitting diode to optimize a waveform of a white light spectrum in a blue light band, and to improve stability of the waveform of the light emitting diode in the blue light band with respect to an operating current.

In order to solve the above technical problem, one of the technical solutions provided in the present application is to provide a light emitting diode including an epitaxial light emitting structure to generate a light beam having a broadband blue light spectrum, wherein the epitaxial light emitting structure includes a P-type semiconductor layer, an N-type semiconductor layer, and a light emitting stack. The light emitting laminated layer is located between the P-type semiconductor layer and the N-type semiconductor layer and is provided with m well layers and m +1 barrier layers which are alternately stacked, wherein the m well layers comprise at least five first well layers, second well layers, third well layers, fourth well layers and fifth well layers which respectively have different forbidden band widths so as to respectively generate a first sub-beam with a first wavelength, a second sub-beam with a second wavelength, a third sub-beam with a third wavelength, a fourth sub-beam with a fourth wavelength and a fifth sub-beam with a fifth wavelength, the fifth wavelength is the longest, the first wavelength is the shortest, at least one of the x well layers which are 1-x and are close to the N-type semiconductor layer is the fifth well layer, x and m are natural numbers, and x and m satisfy the following relation that x is less than or equal to (m/3).

In summary, one of the advantages of the present application is that, in the light emitting diode provided in the embodiment of the present application, by "the light emitting stack of the epitaxial light emitting structure has m well layers and m +1 barrier layers that are alternately stacked, wherein the m well layers include at least five first to fifth well layers respectively having different forbidden bandwidths, so as to generate the first to fifth sub-beams having different wavelengths" and at least one of the "1 st to x th well layers close to the N-type semiconductor layer is the fifth well layer, wherein x and m are both natural numbers, and x and m satisfy the following relation, x ≦ m/3", the influence of the variation of the operating current density on the waveform of the white light spectrum of the mixed light beam generated by the light emitting module can be reduced. That is to say, the white light spectrum generated by the light emitting module of the embodiment of the present application has better stability in the waveform of the blue light band relative to the change of the operating current.

For a better understanding of the nature and technical content of the present application, reference should be made to the following detailed description and accompanying drawings which are provided for purposes of illustration and description and are not intended to limit the present application.

Drawings

Fig. 1 is a schematic cross-sectional view of a light emitting module according to an embodiment of the present disclosure.

Fig. 2 is a schematic diagram of an led according to an embodiment of the present disclosure.

Fig. 3 is a schematic diagram of a forbidden band structure of a light emitting stack according to a first embodiment of the present application.

Fig. 4 shows a spectrum of broadband blue light of the led according to the embodiment of the present application.

Fig. 5 is a schematic diagram of a forbidden band structure of a light emitting stack according to a second embodiment of the present application.

Fig. 6 is a schematic diagram of a forbidden band structure of a light emitting stack according to a third embodiment of the present application.

Fig. 7 is a schematic diagram of a forbidden band structure of a light emitting stack according to a fourth embodiment of the present application.

Fig. 8 is a schematic diagram of a bandgap structure of a light emitting stack according to a fifth embodiment of the present application.

Fig. 9 is a schematic white light spectrum of the mixed light beam and the standard light source generated by the light emitting module of the embodiment of the present application under different current densities.

Fig. 10 is a schematic white light spectrum of the mixed light beam and the standard light source generated by the light emitting module of the embodiment of the present application under different current densities.

Fig. 11 is a schematic diagram illustrating a spectrum deviation index of a mixed light beam generated by a light emitting module according to an embodiment of the present disclosure under different current densities.

Fig. 12 is a schematic diagram illustrating a deviation index of a spectrum of a mixed light beam generated by a light emitting module according to an embodiment of the present disclosure under different current densities.

Fig. 13 is a schematic white light spectrum of the mixed light beam and the standard light source generated by the light emitting module of the embodiment of the present application under different current densities.

Fig. 14 is a white light spectrum diagram of the standard light source and the mixed light beam generated by the light emitting module of the embodiment of the present application under different current densities.

Fig. 15 is a schematic diagram illustrating a deviation index of a spectrum of a mixed light beam generated by a light emitting module according to an embodiment of the present disclosure under different current densities.

Fig. 16 is a schematic diagram illustrating a deviation index of a spectrum of a mixed light beam generated by a light emitting module according to an embodiment of the present disclosure under different current densities.

Fig. 17 is a color rendering index variation curve of the mixed light beam generated by the light emitting module according to the embodiment of the present disclosure under different current densities.

Fig. 18 is a color rendering index variation curve of the mixed light beam generated by the light emitting module according to the embodiment of the present disclosure under different current densities.

Fig. 19 is a color rendering index variation curve of the mixed light beam generated by the light emitting module according to the embodiment of the disclosure under different current densities.

Fig. 20 is a color rendering index variation curve of the mixed light beam generated by the light emitting module of the embodiment of the present application under different current densities.

Fig. 21 is a color rendering index variation curve of a mixed light beam generated by the light emitting module according to the embodiment of the disclosure under different current densities.

Fig. 22 is a color rendering index variation curve of the mixed light beam generated by the light emitting module according to the embodiment of the present disclosure under different current densities.

Fig. 23 is a color rendering index variation curve of the mixed light beam generated by the light emitting module according to the embodiment of the disclosure under different current densities.

Fig. 24 is a color rendering index variation curve of the mixed light beam generated by the light emitting module according to the embodiment of the present disclosure under different current densities.

Detailed Description

The following description is provided for the embodiments of the "light emitting module and light emitting diode" disclosed in the present application by specific examples, and those skilled in the art can understand the advantages and effects of the present application from the disclosure of the present application. The present application is capable of other and different embodiments and its several details are capable of modifications and variations in various respects, all without departing from the present application. The drawings in the present application are for illustrative purposes only and are not intended to be drawn to scale. The following embodiments will further explain the related art of the present application in detail, but the disclosure is not intended to limit the scope of the present application.

Referring to fig. 1, fig. 1 is a schematic cross-sectional view of a light emitting module according to an embodiment of the present disclosure. In the embodiment of the present application, the light emitting module Z1 is used for generating a white light. As shown in fig. 1, the light emitting module Z1 includes a substrate Z10, a reflective element Z11, a light emitting diode Z12 and a wavelength conversion layer Z13.

A die bonding region is defined on the substrate Z10. In one embodiment, the material of the substrate Z10 may be selected from materials having high thermal conductivity, high reflectivity for visible light beams, and low light transmittance, such as: metal or ceramic. In other embodiments, the substrate Z10 may also include a high thermal conductivity substrate and a reflective layer coated on the high thermal conductivity substrate. The present application does not limit the material of the substrate Z10 to a single material or a composite material.

The reflective element Z11 and the light emitting diode Z12 are disposed on the substrate Z10 together, and are used for reflecting and guiding the light beam generated by the light emitting diode Z12 to a specific direction. The reflection assembly Z11 is arranged around the die bonding area and defines an accommodating space.

The light emitting diode Z12 is disposed in the die bonding region of the substrate Z10, is located in the accommodating space defined by the reflective component Z11, and can be used to generate a light beam having a broadband blue spectrum. The full width at half maximum (FWHM) of the spectral waveform of the light beam is at least greater than 30nm.

In the embodiment, the light emitting module Z1 includes one light emitting diode Z12, but in another embodiment, the light emitting module Z1 may include a plurality of light emitting diodes Z12, and the plurality of light emitting diodes Z12 respectively generate a plurality of blue light beams having different peak wavelengths. A plurality of blue light beams having different peak wavelengths are mixed to form the aforementioned broadband blue light.

The wavelength conversion layer Z13 fills the space defined by the reflective component Z11 and covers the light emitting diode Z12. The broad-band blue light generated by the light emitting diode Z12 passes through the wavelength conversion layer Z13, and a mixed beam (white light) can be generated.

In one embodiment, the wavelength conversion layer Z13 at least includes green phosphor and red phosphor. The material of the green phosphor may be lutetium aluminum garnet (LuAG) or gallium-containing yttrium aluminum garnet (GaYAG) phosphor, and the material of the red phosphor may be aluminum silicon nitride, such as: calcium-aluminium-silicon-nitride (CASN) or silicon-nitride (Sr 2Si5N 8) or sulfurSelenium compound (Ca 2 SeS) or potassium fluosilicate (K) containing tetravalent manganese ion ₂ SiF ₆ :Mn ⁴⁺ KSF). In another embodiment, the wavelength conversion layer Z13 may further include a yellow phosphor, but the present application is not limited thereto. The material of the yellow phosphor is, for example, yttrium Aluminum Garnet (YAG).

It should be noted that the excitation efficiency of the green phosphor is different for the light beams of different wavelength bands. According to the material difference of the green phosphor, the green phosphor has the best excitation efficiency in a specific wave band. As described above, in the present embodiment, the light emitting diode Z12 can generate a light beam having a broad-band blue light spectrum. The following further describes the detailed structure of the light emitting diode according to an embodiment of the present application.

Referring to fig. 2 to 3, fig. 2 is a schematic view of a light emitting diode according to an embodiment of the present disclosure. Fig. 3 is a schematic diagram of a forbidden band structure of a light emitting stack according to a first embodiment of the present application.

The light emitting diode Z12 of the embodiment of the present application includes a substrate 1, a buffer layer 2, an epitaxial light emitting structure 3, a first electrode 4, and a second electrode 5. The material of the substrate 1 may be sapphire, silicon carbide, gallium nitride, or silicon or other materials suitable for crystal growth. In the present embodiment, the material of the substrate 1 is sapphire. The buffer layer 2 is formed on the substrate 1 through an epitaxial process and has a lattice constant matched to the material of the substrate 1 and the material of the epitaxial light emitting structure 3. In an embodiment, the material of the buffer layer 2 may be aluminum nitride or gallium nitride.

Referring to fig. 2, the epitaxial light emitting structure 3 is disposed on the buffer layer 2 and has an N-type semiconductor layer 30, a P-type semiconductor layer 31, and a light emitting stack 32. In the present embodiment, the N-type semiconductor layer 30 is disposed on the buffer layer 2, and the light emitting stack 32 and the P-type semiconductor layer 31 are sequentially disposed on the N-type semiconductor layer 30.

In addition, the width of the light emitting stack 32 and the width of the P-type semiconductor layer 31 are both smaller than the width of the N-type semiconductor layer 30, and a portion of the N-type semiconductor layer 30 is exposed. In other words, the light emitting stack and the P-type semiconductor layer 31 together form a mesa. However, the embodiment shown in FIG. 2 is not intended to limit the present application. In other embodiments, the positions of the N-type semiconductor layer 30 and the P-type semiconductor layer 31 may be interchanged.

The first electrode 4 and the second electrode 5 are electrically connected to the N-type semiconductor layer 30 and the P-type semiconductor layer 31, respectively, for electrically connecting to an external control circuit. In the present embodiment, the first electrode 4 is disposed on the N-type semiconductor layer 30, and the second electrode 5 is disposed on the P-type semiconductor layer 31 (i.e., the mesa portion).

Further, the N-type semiconductor layer 30 and the P-type semiconductor layer 31 are an electron supply layer and a hole supply layer, respectively, for supplying electrons and holes, respectively. In one embodiment, the material of the N-type semiconductor layer 30 is silicon-doped gallium nitride. The P-type semiconductor layer 31 is made of magnesium-doped gallium nitride or magnesium-doped aluminum gallium nitride.

The light emitting stack 32 is located between the N-type semiconductor layer 30 and the P-type semiconductor layer 31, and has a first side 32a connected to the N-type semiconductor layer 30 and a second side 32b connected to the P-type semiconductor layer 31. The light emitting stack 32 may be used to produce a light beam having a broad band blue spectrum. Specifically, by applying a bias voltage to the first electrode 4 and the second electrode 5 by an external control circuit, a current passing through the N-type semiconductor layer 30, the light emitting stack 32, and the P-type semiconductor layer 31 is generated, and the light emitting stack 32 is excited to generate a light beam having a specific wavelength band.

In the present embodiment, the waveform of the broadband blue light spectrum generated by the light emitting stack 32 has a wide full width at half maximum (FWHM) and has at least three peak turning points. In one embodiment, the full width at half maximum of the spectral waveform of the light beam is not less than 30nm. In addition, in the broadband blue light spectrum, the difference value between two wavelength values respectively corresponding to any two nearest peak turning points does not exceed 18nm. The structure of the light emitting stack 32 to produce the broad band blue spectrum is further described below.

Referring to fig. 3, the light emitting stack 32 has a multiple quantum well structure. That is, the light emitting stack 32 includes a plurality of barrier layers 320 and a plurality of well layers 321 alternately stacked. The bandgap of each barrier layer 320 is greater than that of any of the well layers 321, so that the light emitting stack 32 has a multiple quantum well structure. In the embodiment of the present application, the light emitting stack 32 includes m well layers 321 and m +1 barrier layers 320, where m is a natural number. That is, each well layer 321 is connected to two barrier layers 320, and the N-type semiconductor layer 30 and the P-type semiconductor layer 31 are respectively connected to one barrier layer 320.

In this embodiment, the plurality of well layers 321 do not have to have the same forbidden bandwidth, but may have different forbidden bandwidths to generate a plurality of sub-beams having different wavelengths. The plurality of sub-beams are superimposed on one another to form a beam having a broad-band blue spectrum.

As shown in fig. 3, the m well layers 321 include at least five layers each having a different energy gap Eg ₁ ～Eg ₅ The well layers 321a to 321e can make the waveform of the broadband blue light spectrum generated by the light emitting stack 32 have a wide full width at half maximum (FWHM) and have a plurality of peak turning points.

Specifically, the plurality of well layers 321 may include a first well layer 321a, a second well layer 321b, a third well layer 321c, a fourth well layer 321d, and a fifth well layer 321e, and the first to fifth well layers 321a to 321e have different band gaps, respectively, to generate a first sub-beam having a first wavelength, a second sub-beam having a second wavelength, a third sub-beam having a third wavelength, a fourth sub-beam having a fourth wavelength, and a fifth sub-beam having a fifth wavelength, respectively.

The first to fifth well layers 321a to 321e have different band gaps Eg, respectively ₁ ～Eg ₅ However, the first to fifth well layers 321a to 321e are used to generate light beams having wavelengths in the blue wavelength band, but the light beams generated by the first to fifth well layers 321a to 321e have different peak wavelengths, respectively.

Further, the barrier layer 320 is a gallium nitride (GaN) layer, and the well layer 321 is an indium gallium nitride (In) _x Ga _1-x N) layers. Since the indium concentration in the well layers 321 affects the band gap of the well layers 321, the band gap can be adjusted by controlling the indium concentration in each well layer, and thus the wavelength of the sub-beam can be controlled. Referring to table 1 below, the relationship between the indium concentration (%) in the well layer 321 and the wavelength of the sub-beam is shown by theoretical calculation.

TABLE 1

Referring to table 1, it can be seen that the higher the indium concentration in the well layer 321, the longer the wavelength of the sub-beam generated by the well layer 321. As shown in fig. 3, in the present embodiment, the band gap Eg of the first well layer 321a ₁ Maximum, and the band gap Eg of the fifth well layer 321e ₅ And minimum. Accordingly, the first indium concentration of the first well layer 321a is the smallest, and the fifth indium concentration of the fifth well layer 321e is the highest.

In addition, the second well layer 321b has a bandgap Eg ₂ Greater than the forbidden band width Eg of the third well layer 321c ₃ And the band gap Eg3 of the third well layer 321c is greater than the band gap Eg4 of the fourth well layer 321d. That is, in this embodiment, the first to fifth well layers 321a to 321e have the band gap Eg thereof ₁ ～Eg ₅ The magnitude relationship of (1) is Eg ₁ >Eg ₂ >Eg ₃ >Eg ₄ >Eg ₅ . Accordingly, the second indium concentration of the second well layer 321b may be less than the third indium concentration of the third well layer 321c, and the third indium concentration may be less than the fourth indium concentration of the fourth well layer 321d.

The forbidden bandwidth of the well layer 321 will be inversely proportional to the wavelength of the generated light beam. That is, the larger the forbidden bandwidth of the well layer 321, the smaller the wavelength of the sub-beam generated by the well layer 321. Accordingly, the first wavelength is shortest and the fifth wavelength is longest. In addition, the second wavelength is less than the third wavelength, and the third wavelength is less than the fourth wavelength.

In this embodiment, the first wavelength is in the range of less than or equal to 435nm, preferably 425nm to 435nm. The second wavelength ranges from 430nm to 450nm, preferably from 435nm to 445nm. The third wavelength ranges from 442nm to 465nm, preferably 450nm to 460nm. The fourth wavelength ranges from 455nm to 475nm, preferably from 455nm to 465nm. The fifth wavelength is in the range of 470nm or more, preferably 470nm to 485nm.

The well layers 321 may have different forbidden bandwidths according to the desired blue spectral shape, so as to adjust the difference range between any two of the first to fifth wavelengths (e.g., the first and second wavelengths, the first and third wavelengths, or the second and third wavelengths).

Referring to FIG. 3, the conduction band 321E of the first well layer 321a ₁ Form a first barrier height Δ E with a conduction band 320E of the barrier layer 320 ₁ . Conduction band 321E of second well layer 321b ₂ Form a second barrier height Δ E with the conduction band 320E of the barrier layer 320 ₂ . Conduction band 321E of third well layer 321c ₃ Form a third barrier height Δ E with the conduction band 320E of the barrier layer 320 ₃ . Conduction band 321E of fourth well layer 321d ₄ Form a fourth barrier height Δ E with the conduction band 320E of the barrier layer 320 ₄ And a conduction band 321E of the fifth well layer 321E ₅ Forms a fifth barrier height Δ E with the conduction band 320E of the barrier layer 320 ₅ . First to fifth barrier heights Δ E ₁ ～ΔE ₅ The magnitude relationship of (a) is as follows ₁ <ΔE ₂ <ΔE ₃ <ΔE ₄ <ΔE ₅ 。

In addition, the intensity of the sub-beams generated by the well layers 321 affects the waveform of the final broad-band blue light spectrum. However, the light intensity of the first to fifth sub-beams is related to the forbidden bandwidth, the number and the position of the first to fifth well layers 321a to 321e and the thickness of the barrier layer 320 connected thereto. The larger the forbidden band width of the well layer 321 (e.g., the conduction band 321E of the first well layer 321 a) ₁ ) A barrier height (e.g., a first barrier height Δ E) formed with respect to a conduction band 320E of the barrier layer 320 ₁ ) The smaller and less prone to confining electrons. Therefore, in the well layer 321 with a large forbidden band width, the probability of recombination of electrons and holes is relatively low, and the light intensity of the generated sub-beam is also low. Conversely, the smaller the band gap of the well layer 321, the more easily electrons are confined.

In addition, since the mobility of electrons is faster than that of holes, electrons are more easily recombined with holes in the well layer 321 near the P-type semiconductor layer 31. That is, the closer to the well layer 321 of the P-type semiconductor layer 31, the higher the light intensity of the sub-beam generated. On the other hand, the thicker the two barrier layers 320 connected to each well layer 321, particularly the thicker the barrier layer 320 closer to the P-type semiconductor layer 31, is, the easier it is to confine electrons, and the higher the light intensity of the sub-beams of the well layer 321 is.

Therefore, in order to make the waveform of the broadband blue light spectrum of the light beam generated by the light emitting stack 32 have a larger half-height bandwidth and a plurality of peak turning points, the positions and the numbers of the first to fifth well layers 321a to 321e and the thickness of the barrier layer 320 connected thereto can be adjusted according to the foregoing principles.

Specifically, in the present embodiment, the number of first well layers 321a (having the widest forbidden bandwidth Eg 1) may be greater than the number of third well layers 321c, the number of fourth well layers 321d, and the number of fifth well layers 321e, and the number of second well layers 321b may also be greater than the number of third well layers 321c, the number of fourth well layers 321d, and the number of fifth well layers 321e.

For example, the light emitting stack 32 of the present embodiment includes four first well layers 321a, three second well layers 321b, at least one third well layer 321c, at least one fourth well layer 321d, and at least one fifth well layer 321e.

Since the band gap of the fifth well layer 321e is the smallest, electrons are easier to confine and the fifth sub-beam is generated than the first to fourth well layers 321a to 321d. Therefore, if the fifth well layer 321e is located too close to the P-type semiconductor layer 31, the intensity of the fifth sub-beam may be caused to be too strong. Accordingly, in the embodiment of the present application, the fifth well layer 321e is located closer to the N-type semiconductor layer 30 and farther from the P-type semiconductor layer 31.

In detail, in the m-well layer 321 of the embodiment of the present application, at least one of the 1 st to x-th well layers 321 adjacent to the N-type semiconductor layer 30 is a fifth well layer 321e, where x is a natural number, and x, m satisfy the following relationship of x ≦ m/3. In a preferred embodiment, x is ≦ (m/4).

For example, if the light emitting stack 32 includes 11 well layers 321 (i.e., m = 11), at least one of the 3 well layers 321 of the 1 st to 3 rd adjacent to the N-type semiconductor layer 30 is a fifth well layer 321e. That is, the fifth well layer 321e may be the well layer 321 that is 1 st adjacent, 2 nd adjacent, or 3 rd adjacent to the N-type semiconductor layer 30.

In the embodiment shown in fig. 3, the well layer 321 closer to the N-type semiconductor layer 30 in the 2 nd is a fifth well layer 321e. However, in other embodiments, the fifth well layer 321e may be the well layer 321 that is 3 rd adjacent to the N-type semiconductor layer 30.

On the other hand, since the first well layer 321a has a large forbidden band width, electrons are less likely to be confined in the first well layer 321a than in the second to fifth well layers 321b to 321e. Therefore, in order to increase the intensity of the first sub-beam and make the blue spectral waveform of the light beam generated by the light emitting stack 32 have a wider half-height bandwidth, in the m-well layer 321 of the embodiment of the present application, at least the 1 st to y-well layers 321 close to the P-type semiconductor layer 31 are the first well layer 321a, where y is a natural number, and y, m satisfy the following relation that y is greater than or equal to (m/4).

For example, the light emitting stack 32 includes 11 well layers 321 (i.e., m = 11), and at least 3 well layers 321 (i.e., y = 3) adjacent to the P-type semiconductor layer 31 from 1 st to 3 rd are all the first well layers 321a. In the embodiment shown in fig. 3, the 1 st to 4 th front 4-layer well layers 321 closest to the P-type semiconductor layer 31 (second side 32 b) are all the first well layers 321a.

In addition, the well layer 321 near the N-type semiconductor layer 30 of the 1 st may be one of the first to fifth well layers 321a to 321e. In the embodiment shown in fig. 3, the well layer 321 proximate to the N-type semiconductor layer 30 of the 1 st is a third well layer 321c. The well layer 321 near the N-type semiconductor layer 30 of the 3 rd is a fourth well layer 321d, and the well layer 321 near the N-type semiconductor layer 30 of the 4 th is a third well layer 321c. In other words, one of the two third well layers 321c, one of the third well layers 321c is closest to the N-type semiconductor layer 30, and the other third well layer 321c is closer to the P-type semiconductor layer 31 than the fourth well layer 321d. In addition, the other three-layer well layer 321 located between the 4 th adjacent N-type semiconductor layer 30 and the 4 th adjacent P-type semiconductor layer 31 is the second well layer 321b.

With reference to fig. 3, the thickness of each barrier layer 320 is greater than the thickness of any one of the well layers 321. In addition, the thickness of the barrier layer 320 and the thickness of the well layer 321 affect the spectral waveform of the broadband blue light finally generated by the light emitting stack 32.

Note that the thickness of the conventional barrier layer is about 2 to 3.5 times the thickness of the well layer. Specifically, the thickness of the conventional barrier layer ranges from 8.5nm to 10.5 nm. However, when the operating current is varied, the spectral shape is easily changed.

Accordingly, in the embodiment of the present application, the ratio between the thickness of the barrier layer 320 and the thickness of the well layer 321 ranges from 2.5 to 5 times, preferably from 3 to 4 times. Thus, compared with the prior art, the method and the device can reduce the influence of the operating current change on the spectrum waveform. Preferably, the thickness of the barrier layer 320 is in the range of 8.5nm to 15nm, and preferably in the range of 9.5nm to 15nm. In addition, the thickness of the well layer 321 ranges from 2.5nm to 4.5nm.

In the embodiment of fig. 3, the multilayer barrier layer 320 includes at least two first barrier layers 320a and second barrier layers 320b having different thicknesses, respectively, and the thickness of the first barrier layer 320a is less than or equal to the thickness of the second barrier layer 320b. In an embodiment, the thickness of the second barrier layer 320b is 1 to 1.5 times the thickness of the first barrier layer 320a.

In addition, in this embodiment, two barrier layers 320 connected to opposite sides of the fifth well layer 321e are both the second barrier layer 320b, and the other barrier layers 320 are both the first barrier layers 320a. That is, the two barrier layers 320 (second barrier layers 320 b) connected to the fifth well layer 321e are thick. Thus, in the fifth well layer 321e, the probability of electron and hole recombination can be increased, thereby increasing the intensity of the fifth sub-beam.

Referring to fig. 4, fig. 4 shows a plurality of broadband blue light spectrums of the led according to the embodiment of the present application. It should be noted that the light emitting diodes of samples 1 to 3 are also the light emitting diode Z12 of the first embodiment. However, even under the same conditions of the same equipment, the thickness of the well layers 321 and the thickness of the barrier layers 320 in the samples 1 to 3 are different from each other due to the error in the equipment and the manufacturing. Although the error is within the allowable range, the spectral waveforms generated by the leds of samples 1 to 3 are still different. However, the spectral waveforms generated by the leds of samples 1 to 3 can meet the requirements of the product of the present application.

As shown in fig. 4, the spectrum waveform generated by each of the samples 1 to 3 has a plurality of peak turning points, and each of the peak turning points corresponds to a wavelength value and an intensity value. Since samples 1 to 3 in fig. 4 are all spectral waveforms generated by the light emitting diode of the same embodiment, the spectral waveform of sample 1 will be described as an example. As shown in fig. 4, the spectrum waveform of the sample 1 has first to fifth peak turning points P11 to P15 corresponding to the first to fifth wavelength values and the first to fifth intensity values, respectively.

It is noted that the difference between the two wavelength values (e.g., the first and second wavelength values, the second and third wavelength values, the third and fourth wavelength values, or the fourth and fifth wavelength values) corresponding to any two nearest peak turning points (e.g., the first and second peak turning points P11, P12, the second and third peak turning points P12, P13, the third and fourth peak turning points P13, P14, or the fourth and fifth peak turning points P14, P15) is no more than 18nm.

According to the experimental measurement result, the stability of the spectrum waveform relative to the operating current can be increased by making the difference between the two wavelength values respectively corresponding to any two nearest peak turning points not exceed 18nm. That is, when the operating current of the led Z12 is changed, the change of the spectral waveform generated by the led Z12 can be limited within a specific range. In a preferred embodiment, the difference between the two wavelength values corresponding to any two nearest peak turning points is not more than 15nm.

Since the spectral waveform of the light beam generated by the light emitting stack 32 is formed by the superposition of the first to fifth sub-light beams, the first wavelength value in the spectral waveform is not necessarily the same as the first wavelength of the first sub-light beam, but the first wavelength value and the first wavelength correspond to the same wavelength range, i.e. not more than 435nm. Similarly, the second wavelength value is not necessarily the same as the second wavelength of the second sub-beam, but corresponds to the same wavelength range, which is between 430nm and 450nm; the third wavelength value is not necessarily the same as the third wavelength of the third sub-beam, but both correspond to the same wavelength range, and are between 442nm and 465nm. The fourth wavelength value and the fourth wavelength of the fourth sub-beam both correspond to the same wavelength range from 455nm to 475nm, and the fifth wavelength value and the fifth wavelength of the fifth sub-beam both correspond to the same wavelength range greater than or equal to 470nm.

Accordingly, by controlling the forbidden band widths of the first to fifth well layers 321a to 321e in the light emitting stack 32, the difference between two wavelength values corresponding to two nearest peak turning points in the spectrum waveform can be controlled.

Referring to fig. 4, from the spectral waveform changes of the samples 1 to 3, it can be seen that the first intensity value corresponding to the first peak turning point P11 and the third to fifth intensity values corresponding to the third to fifth peak turning points P13 to P15 actually increase or decrease relative to the second intensity value of the second peak turning point P12.

If the second intensity value is 100%, the first intensity value may be 20% to 80%, the third intensity value may be 40% to 140%, the fourth intensity value may be 20% to 120%, and the fifth intensity value may be 10% to 80%. That is, the ratio of the first intensity value to the second intensity value ranges from 0.2 to 0.8, the ratio of the third intensity value to the second intensity value ranges from 0.4 to 1.4, the ratio of the fourth intensity value to the second intensity value ranges from 0.2 to 1.2, and the ratio of the fifth intensity value to the second intensity value ranges from 0.1 to 0.8.

Referring to fig. 5, fig. 5 is a schematic diagram of a forbidden band structure of a light emitting stack according to a second embodiment of the present application. By using the light-emitting laminated layer of the embodiment, a light beam with a broadband blue light spectrum can be generated, the half-height wave width of the spectrum waveform is not less than 30nm, and the spectrum waveform has a plurality of peak turning points. The difference value between two wavelength values respectively corresponding to any two nearest peak turning points is not more than 18nm.

The same elements in this embodiment as those in the first embodiment have the same reference numerals, and the description of the same parts is omitted. In the light emitting stack of the present embodiment, the fourth well layer 321d is located closer to the P-type semiconductor layer 31 (the second side 32 b) than one of the third well layers 321c is.

In detail, in this embodiment, the well layer 321 closer to the N-type semiconductor layer 30 (the first side 32 a) at the 3 rd position is the third well layer 321c, and the well layer 321 closer to the N-type semiconductor layer 30 (the first side 32 a) at the 4 th position is the fourth well layer 321d. Since the fourth well layer 321d is located closer to the P-type semiconductor layer 31, the intensity of the fourth sub-beam may be stronger.

Accordingly, in order to avoid an excessively high intensity of the fourth sub-beam, the thickness of the barrier layer 320 connected to the fourth well layer 321d cannot be too thick. That is, at least one of the two barrier layers 320 connected to both sides of the fourth well layer 321d is the first barrier layer 320a. Further, the barrier layer 320 connected to the fourth well layer 321d and closer to the N-type semiconductor layer 30 (the first side 32 a), that is, the barrier layer 320 located between the third well layer 321c and the fourth well layer 321d, is the first barrier layer 320a having a smaller thickness. In this embodiment, the two barrier layers 320 connected to both sides of the fourth well layer 321d are both the first barrier layer 320a.

However, the thicknesses of the two barrier layers 320 connected to both sides of the fourth well layer 321d are not necessarily the same. In one embodiment, the thickness of the barrier layer 320 connected to the fourth well layer 321d and closer to the N-type semiconductor layer 30 (the first side 32 a) is smaller than the thickness of the other barrier layer 320 closer to the P-type semiconductor layer 31 (the second side 32 b).

Referring to fig. 6, fig. 6 is a schematic diagram of a forbidden band structure of a light emitting stack according to a third embodiment of the present application. The light-emitting laminated layer of the embodiment can also generate light beams with broadband blue light spectrums, the half-height wave width of the spectrum waveform is not less than 30nm, and the light-emitting laminated layer is provided with at least three wave crest turning points. The difference value between two wavelength values respectively corresponding to any two nearest peak turning points is not more than 18nm.

The same elements in this embodiment as those in the first embodiment have the same reference numerals, and the description of the same parts is omitted. In the light emitting stack of this embodiment, the number of second well layers 321b is larger than the number of first well layers 321a.

In detail, in the m-well layer 321 of the embodiment of the present application, at least the 1 st to y-well layers 321 close to the P-type semiconductor layer 31 are all the first well layers 321a, where y is a natural number, and y, m satisfy the following relationship of y ≧ m/4.

For example, the light emitting stack 32 shown in fig. 6 includes 11 well layers 321 (i.e., m = 11), and the 3 well layers 321 (i.e., y = 3) that are 1 st to 3 rd adjacent to the P-type semiconductor layer 31 are all the first well layers 321a. In addition, the well layer 321 between the 4 th adjacent N-type semiconductor layer 30 (first side 32 a) and the 3 rd adjacent P-type semiconductor layer 31 (second side 32 b) is both the second well layer 321b. Accordingly, in the present embodiment, the light emitting stack 32 includes three first well layers 321a and four second well layers 321b.

Referring to fig. 7, fig. 7 is a schematic diagram of a forbidden band structure of a light emitting stack according to a fourth embodiment of the present application. The light-emitting laminated layer of the embodiment can also generate light beams with broadband blue light spectrums, the half-height wave width of the spectrum waveform is not less than 30nm, and the light-emitting laminated layer is provided with at least three wave crest turning points. The difference value between two wavelength values respectively corresponding to any two nearest peak turning points is not more than 18nm.

The same elements in this embodiment as those in the first embodiment have the same reference numerals, and the description of the same parts is omitted. In the light emitting stack of the present embodiment, the 1 st to x-th well layers 321 close to the N-type semiconductor layer 30 (the first side 32 a) include two fifth well layers 321e. As mentioned above, x and m satisfy the following relationship of x ≦ (m/3). In a preferred embodiment, x is ≦ (m/4).

For example, if the light emitting stack 32 includes 11 well layers 321 (i.e., m = 11), two of the 3 well layers 321 of the 1 st to 3 rd adjacent to the N-type semiconductor layer 30 are fifth well layers 321e. In this embodiment, the well layers 321 near the 1 st and 2 nd N-type semiconductor layers 30 are all fifth well layers 321e.

Since two fifth well layers 321e are included in the x well layers 321 closer to the N-type semiconductor layer 30 (the first side 32 a) from 1 st to x, the intensity of the fifth sub-beam may increase. In order to avoid the spectral waveform from being changed due to the excessively high intensity of the fifth sub-beam, the thickness of the barrier layer 320 connected between the two fifth well layers 321e does not need to be particularly increased in this embodiment. That is, in the present embodiment, the plurality of barrier layers 320 may have the same thickness. In a preferred embodiment, the thickness of the two barrier layers 320 (assumed as T1) connected to each of the fifth well layers 321e is about 0.5 to 1 times the thickness of the barrier layer 320 (assumed as T2) connected to any one of the first to fourth well layers 321 a-321 d. That is, the relationship between T1 and T2 is T1 ≈ (0.5-1) × T2.

Referring to fig. 8, fig. 8 is a schematic diagram of a forbidden band structure of a light emitting stack according to a fifth embodiment of the present application. With the light emitting stack of the present embodiment, a light beam having a broad band blue light spectrum can be generated as well. The same elements in this embodiment as those in the fourth embodiment have the same reference numerals, and the description of the same parts is omitted.

In the light emitting stack of the present embodiment, the well layers 321 near the 1 st and 2 nd N-type semiconductor layers 30 are all fifth well layers 321e, and the barrier layers 320 connected to the two fifth well layers 321e are all thicker second barrier layers 320b. The barrier layers 320 connected to the first to fourth well layers 321a to 321d may be the first barrier layer 320a having a small thickness.

However, in the present embodiment, the spectral waveform of the light beam generated by the light emitting stack is adjusted by increasing the number of well layers 321. In detail, the light emitting stack 32 of the embodiment of the present application includes 13 well layers 321 (i.e., m = 13). In this embodiment, both the well layers 321 near the N-type semiconductor layer 30 of 1 st and 2 nd are fifth well layers 321e.

In order to avoid the intensity of the fifth sub-beam from being too high to change the spectral waveform, in this embodiment, the number of the second well layers 321b and the third well layers 321c is increased. In detail, compared to the fourth embodiment, the light emitting stack 32 of the present embodiment includes 4 second well layers 321b and 2 third well layers 321c.

Please refer to fig. 9 to 10. Fig. 9 and 10 are schematic white light spectrums of the standard light source and the mixed light beam generated by the light emitting module of the embodiment of the present application under different current densities. It should be noted that the color temperature of the mixed light beam generated by the light emitting module in the embodiment of the present application is greater than or equal to 5000K, so that the standard light source is a simulated daylight light source (D50 light source) with a color temperature of 5000K.

As shown in fig. 1, the light beam generated by the light emitting diode Z12 passes through the wavelength conversion layer Z13, and a mixed light beam having a white light spectrum can be generated. FIG. 9 shows the light-emitting modules respectively operated at a current density of 80mA/mm ² 、100mA/mm ² And 120mA/mm ² The white light spectrum of the mixed light beam is measured. FIG. 10 shows the light-emitting modules respectively operated at a current density of 140mA/mm ² 、160mA/mm ² And 200mA/mm ² The white light spectrum of the mixed light beam is measured. In addition, the chip size of the light emitting diode of the light emitting module is 26 × 30mil ² 。

As can be seen from FIGS. 9 and 10, even at different operating current densities (80 to 200 mA/mm) ² ) Next, the waveform of the white light spectrum of the mixed light beam generated by the light emitting module Z1 in the blue light band (wavelength range 440nm to 500 nm) in the embodiment of the present application conforms to the spectrum waveform of the standard light source, and the variation range is small.

Fig. 11 and 12 are schematic diagrams illustrating spectral deviation indexes of mixed light beams generated by the light emitting module according to the embodiment of the present disclosure under different current densities. The spectral deviation index is a measure of the spectral deviation of the mixed light beam corresponding to any wavelength (lambda) _x ) Light intensity (I) of _x ) The spectrum minus the standard light source corresponds to this wavelength (λ) _x ) Reference light intensity (I) _s ) Then, the spectrum of the standard light source is divided by the wavelength (λ) _x ) Is measured with respect to the reference light intensity (I) _s ). That is, corresponding to any wavelength (λ) _x ) Spectral deviation index (C) of _x ) With light intensity (I) _x ) And a reference light intensity (I) _s ) The relationship between them is: c _x ＝(I _x -I _s )/I _s . FIG. 11 shows the operation current density of the light emitting module at 80mA/mm ² 、100mA/mm ² And 120mA/mm ² Under the condition (2), the measured spectrum deviation index of the mixed light beam, and FIG. 12 shows that the light emitting modules are respectively operated at the current density of 140mA/mm ² 、160mA/mm ² And 200mA/mm ² Under the condition (1), the spectral deviation indexes of the mixed light beam measured corresponding to different wavelengths are determined.

It should be noted that the operating current density was from 80mA/mm ² Increased to 200mA/mm ² The white light spectra obtained under the conditions of (1) are normalized (normalized) with a standard light source by Y =100 (Y is the Y of the tristimulus values XYZ in colorimetry). Each normalized white light spectrum is then compared to the spectrum of the standard light source to calculate a spectral deviation indicator corresponding to each wavelength.

Referring to FIG. 11, when the operating current density is 80mA/mm ² When the white light spectrum is in the wavelength range of 450nm to 500nm, the spectrum deviation index of the white light spectrum relative to the standard light source spectrum is changed from-0.1 to 0.2. Referring to FIG. 12, when the operating current density is 200mA/mm ² When the white light spectrum is in the wavelength range of 450nm to 500nm, the spectrum deviation index of the white light spectrum relative to the standard light source spectrum is changed from-0.15 to 0.3.

In addition, the operating current density was 80mA/mm ² To 200mA/mm ² Any two (after normalization) white light spectra resulting from the ranges of (a) do not differ by more than 0.3 between the two spectral deviation indicators corresponding to any one wavelength between the wavelength ranges of 450-500 nm. For example, at an operating current density of 80mA/mm ² And 200mA/mm ² The resulting two (normalized) white light spectra, in the wavelength range 450-500nm, correspond to any wavelength (. Lamda.) _x ) Two spectral deviation indicators (assumed to be C) relative to the standard illuminant spectrum _80x And C _200x ) The difference between them does not exceed 0.3.

Please refer to fig. 13 to 14. Fig. 13 and 14 are schematic white light spectrums of the standard light source and the mixed light beam generated by the light emitting module of the embodiment of the present application under different current densities. FIG. 13 shows the operation current density of the light emitting modules at 160mA/mm ² 、200mA/mm ² And 240mA/mm ² The white light spectrum of the mixed light beam is measured. FIG. 14 shows the operation current density of 280mA/mm for the light emitting module ² And 300mA/mm ² The white light spectrum of the mixed light beam is measured. The chip size of the LED of the light-emitting module is 26 × 30mil ² 。

As can be seen from FIGS. 13 and 14, the current density (160-300 mA/mm) was varied at different operation ² ) Next, the waveform of the white light spectrum of the mixed light beam generated by the light emitting module Z1 in the blue light band (wavelength range 440nm to 500 nm) also conforms to the spectrum waveform of the standard light source, and the variation range is small.

Fig. 15 and 16 are schematic diagrams illustrating spectral deviation indexes of mixed light beams generated by the light emitting module according to the embodiment of the present disclosure under different current densities. As previously mentioned, the spectral deviation index (C) _x ) Means that the spectrum of the mixed light beam corresponds to any wavelength (lambda) _x ) Light intensity (I) of _x ) The spectrum minus the standard light source corresponds to this wavelength (λ) _x ) Reference light intensity (I) _s ) Then, the spectrum of the standard light source is divided by the wavelength (λ) _x ) Is measured with respect to the reference light intensity (I) _s ). That is, corresponding to any wavelength (λ) _x ) Spectral deviation index (C) of _x ) With light intensity (I) _x ) And a reference light intensity (I) _s ) The relationship between them is: c _x ＝(I _x -I _s )/I _s 。

Similarly, the operating current density was 160mA/mm ² To 300mA/mm ² The resulting multiple white light spectra of range (c) are normalized (normalized) to a standard light source with Y =100 (Y being the Y of the tristimulus values XYZ in colorimetry). And calculating a spectrum deviation index corresponding to each wavelength by using the spectrum of the white light after normalization relative to the spectrum of the standard light source. FIG. 15 shows the light-emitting modules respectively operated at a current density of 160mA/mm ² 、200mA/mm ² And 240mA/mm ² Under the condition (1), the measured spectrum deviation index of the mixed light beam, and FIG. 16 shows that the light emitting modules are respectively operated at a current density of 280mA/mm ² And 300mA/mm ² Under the condition (1), the spectral deviation index of the mixed light beam is measured.

Referring to FIG. 15, when the operating current density is 160mA/mm ² When the white light spectrum is in the wavelength range of 450nm to 500nm, the spectrum deviation index of the white light spectrum relative to the standard light source spectrum is changed from-0.08 to 0.2. Referring to FIG. 16, when the operating current density is 300mA/mm ² When the white light spectrum is in the wavelength range of 450nm to 500nm, the spectrum deviation index of the white light spectrum relative to the standard light source spectrum is changed from-0.12 to 0.22.

In addition, the operating current density was 160mA/mm ² To 300mA/mm ² Any two (after normalization) white light spectra resulting from the ranges of (b) are such that the difference between the two spectral deviation indicators corresponding to either wavelength relative to the standard light source spectrum is no more than 0.2 between the wavelength ranges of 450-500 nm.

For example, the operating current density is 160mA/mm relative to the spectrum of a standard light source ² The resulting (normalized) white light spectrum and the operating current density of 300mA/mm under the conditions of (2) ² Under the conditions of (b) obtaining another (normalized) white light spectrum corresponding to two spectral deviation indicators (assumed to be C) at any wavelength between the wavelength range 450-500nm _160x And C _300x ) The difference between them does not exceed 0.2.

Overall, the operating current density applied to the LED was 80mA/mm ² To 300mA/mm ² Any two white light spectrums (after normalization) obtained by the range of (1) have the maximum difference of the spectrum deviation indexes corresponding to the same wavelength of no more than 0.42 relative to the standard light source spectrum in the wavelength range of 450nm to 500 nm.

For example, at an operating current density of 80mA/mm relative to the spectrum of a standard light source ² The resulting (normalized) white light spectrum at an operating current density of 300mA/mm ² Under the conditions of (b) obtaining another (normalized) white light spectrum in the wavelength range 450-500nm, corresponding to two spectral deviation indicators (assumed to be C) for any wavelength _80x And C _300x ) The difference between them does not exceed 0.42.

Fig. 17 to 20 show color rendering index variation curves of the mixed light beam generated by the light emitting module of the embodiment of the present application under different current densities. In detail, FIGS. 17 to 20 show the light emitting module of the embodiment of the present application at an operating current density of 80mA/mm ² 、100mA/mm ² 、120mA/mm ² 、140mA/mm ² 、160mA/mm ² And 200mA/mm ² The average Color Rendering Index (CRI) of the mixed light beam and the variation curves of the component Color Rendering indices R1 to R15 were measured. The chip size of the LED of the light-emitting module is 26 × 30mil ² 。

When the operating current density is 80mA/mm ² To 200mA/mm ² The average Color Rendering Index (CRI) of the mixed beam, as well as the individual component color rendering indices R1 through R15, are all greater than 90 when varied. In addition, referring to Table 2 below, it is shown that the current density at the operation is 80mA/mm ² 、100mA/mm ² 、120mA/mm ² 、140mA/mm ² 、160mA/mm ² And 200mA/mm ² Under the conditions of (1), the average Color Rendering Index (CRI) of the mixed beam and the values of the constituent Color Rendering indices R1 to R15 were measured.

TABLE 2

As shown in Table 2, the operating current density was 80mA/mm ² To 200mA/mm ² When varied, the average Color Rendering Index (CRI) varies by no more than 3, preferably less than 2.5. In addition, the amount of change in the other component color rendering indices R1 to R15 is not more than 7, preferably not more than 5.

Fig. 21 to 24 are graphs showing color rendering index variation curves of mixed light beams generated by the light emitting module according to the embodiment of the present disclosure under different current densities. In detail, fig. 21 to 24 show the light emitting module of the embodiment of the present application at an operating current density of 160mA/mm ² 、200mA/mm ² 、240mA/mm ² 、280mA/mm ² And 300mA/mm ² The average Color Rendering Index (CRI) of the mixed light beam and the variation curves of the component Color Rendering indices R1 to R15 were measured. The chip size of the LED of the light-emitting module is 26 × 30mil ² 。

When the operating current density is 160mA/mm ² To 300mA/mm ² When it is changedThe average Color Rendering Index (CRI) of the mixed beam and the individual component color rendering indices R1 to R15 are all greater than 90. In addition, referring to Table 3 below, it is shown that the current density at the operation is 160mA/mm ² 、200mA/mm ² 、240mA/mm ² 、280mA/mm ² And 300mA/mm ² The average Color Rendering Index (CRI) of the mixed beam and the values of the constituent Color Rendering indices R1 to R15 were measured.

TABLE 3

As shown in Table 3, the operating current density was adjusted from 160mA/mm ² To 300mA/mm ² The variation of the average Color Rendering Index (CRI) is not more than 3, preferably not more than 2.5. In addition, the other compositional color rendering indices R1 to R15 do not vary more than 10, preferably not more than 7.

Based on the above, the white light spectrum of the mixed light beam generated by the light emitting module Z1 provided in the embodiment of the present application under different operating current densities has better stability in the waveform of the blue light band relative to the operating current. Besides, the operating current density is controlled by 80mA/mm ² To 300mA/mm ² The variation of the average color rendering index of the mixed light beam and the variation of the color rendering index of each composition are not more than 10, preferably not more than 7.

In addition, the light output cold-heat ratio of the light emitting diode Z12 provided by the embodiment of the present application under different operating current densities can also be improved. In the present embodiment, the current densities at the operation are 120mA/mm, respectively ² To 300mA/mm ² Under the condition (2), the light output cooling-heating ratios of the light emitting diode Z12 were 91% and 89.5%, respectively. The light output cold-heat ratio refers to a ratio of the light-emitting diode (photogenerated particle) 25976 when the light-emitting diode (Z12) is high (about 85 ℃). That is, when the operating current density is changed, the cooling-heating ratio of the light emitting diode Z12 of the embodiment of the present application is less affected by the change in the operating current density.

To sum up, one of the advantages of the present application lies in that, in the light emitting module Z1 and the light emitting diode Z12 provided in the present application, a light beam having a broad-band blue light spectrum is generated by the "epitaxial light emitting structure, wherein, a half-height wave width of a waveform of the broad-band blue light spectrum is not less than 30nm, and has a plurality of peak turning points, and a difference between two wavelength values respectively corresponding to any two nearest peak turning points does not exceed 18nm", so that an influence of a variation in operating current density on a waveform of a white light spectrum of a mixed light beam generated by the light emitting module Z1 can be reduced. That is to say, the white spectrum generated by the light emitting module Z1 of the present application has a better stability of the waveform in the blue band with respect to the variation of the operating current.

As mentioned above, the operating current density is from 80mA/mm ² To 300mA/mm ² The variation of the average color rendering index of the mixed light beam and the variation of the color rendering index of each component are not more than 7, so that the application standard required by the industry can be met.

In addition, in the light emitting diode Z12 provided by the present application, the light emitting stack 32 of the epitaxial light emitting structure 3 has m well layers 321 and m +1 barrier layers 320 which are alternately stacked, wherein the m well layers 321 include at least five first to fifth well layers 321a to 321e respectively having different forbidden bandwidths so as to generate first to fifth sub-beams having different wavelengths, respectively, and at least one of the x well layers adjacent to the N-type semiconductor layer from 1 to x is a fifth well layer, wherein x and m are natural numbers, and x and m satisfy the following relation that x ≦ m/3 may generate a beam having a broad-band blue light spectrum.

In addition, the light output cold-heat ratio of the light emitting diode Z12 provided by the present application under different operating current densities can also be improved.

The disclosure is only a preferred embodiment of the present application and is not intended to limit the scope of the claims of the present application, so that all technical equivalents and modifications made by the disclosure of the present application and the drawings are included in the scope of the claims of the present application.

Claims

1. A light emitting diode comprising an epitaxial light emitting structure to generate a light beam having a broad band blue spectrum, the epitaxial light emitting structure comprising:

a P-type semiconductor layer;

an N-type semiconductor layer; and

a light emitting stack layer between the P-type semiconductor layer and the N-type semiconductor layer and having m well layers and m +1 barrier layers stacked alternately, wherein the m well layers include at least five first well layers, second well layers, third well layers, fourth well layers, and fifth well layers having different band gap widths, respectively, to generate a first sub-beam having a first wavelength, a second sub-beam having a second wavelength, a third sub-beam having a third wavelength, a fourth sub-beam having a fourth wavelength, and a fifth sub-beam having a fifth wavelength, respectively, the fifth wavelength being longest, the first wavelength being shortest, the third wavelength being smaller than the fourth wavelength, and the second wavelength being smaller than the third wavelength,

wherein at least one of x well layers adjacent to the N-type semiconductor layer from 1 st to x is the fifth well layer, wherein x and m are natural numbers, and x and m satisfy the following relationship of x ≦ (m/3).

2. A light emitting diode comprising an epitaxial light emitting structure to generate a light beam having a broad band blue spectrum, the epitaxial light emitting structure comprising:

a P-type semiconductor layer;

an N-type semiconductor layer; and

a light emitting stack between the P-type semiconductor layer and the N-type semiconductor layer and having m well layers and m +1 barrier layers alternately stacked, wherein the m well layers include at least five first, second, third, fourth, and fifth well layers having different indium concentrations, respectively, the fifth well layer having a highest indium concentration and the first well layer having a smallest indium concentration,

3. The light-emitting diode according to claim 1 or 2, wherein at least y well layers from 1 st to y adjacent to the P-type semiconductor layer are the first well layer, wherein y is a natural number, and y and m satisfy the relationship of y ≧ (m/4).

4. The light-emitting diode of claim 3, wherein at least one of the third well layers is closer to the P-type semiconductor layer than at least one of the fourth well layers is.

5. The light-emitting diode according to claim 4, wherein a plurality of the well layers between at least one of the third well layer and the y-th P-type semiconductor layer are all the second well layer.

6. The light-emitting diode according to claim 1 or 2, wherein the plurality of barrier layers includes at least two kinds of first barrier layers and second barrier layers each having a different thickness, the thickness of the first barrier layer is smaller than that of the second barrier layer, and both of the barrier layers connected to opposite sides of the fifth well layer are the second barrier layers.

7. The LED of claim 6, wherein at least one of the fourth well layers is closer to the P-type semiconductor layer than at least one of the third well layers.

8. The light-emitting diode according to claim 7, wherein the barrier layer connected to at least one of the fourth well layers and closer to the N-type semiconductor layer is the first barrier layer.

9. The light-emitting diode according to claim 1 or 2, wherein the plurality of barrier layers includes at least two kinds of first barrier layers and second barrier layers each having a different thickness, the thickness of the first barrier layer is smaller than that of the second barrier layer, the other of the x well layers from 1 th to x th adjacent to the N-type semiconductor layer further includes the fifth well layer, and the barrier layer connected between the two fifth well layers is the first barrier layer.

10. The led of claim 1 or 2, wherein the half-height bandwidth of the broad-band blue-light spectrum waveform is not less than 30nm, and has a plurality of peak turning points, and the difference between two wavelength values corresponding to any two nearest peak turning points is not more than 18nm.

11. The light emitting diode of claim 10, wherein the peak inflection points comprise a first peak inflection point corresponding to a first wavelength and a first intensity value, a second peak inflection point corresponding to a second wavelength and a second intensity value, a third peak inflection point corresponding to a third wavelength and a third intensity value, a fourth peak inflection point corresponding to a fourth wavelength and a fourth intensity value, and a fifth peak inflection point corresponding to a fifth wavelength and a fifth intensity value, wherein the first wavelength is the smallest, the fifth wavelength is the longest, the second wavelength is less than the third wavelength, and the third wavelength is less than the fourth wavelength.

12. The illumination module of claim 11, wherein the first wavelength value is no more than 435nm, the second wavelength value is 430nm to 450nm, the third wavelength value is 442nm to 465nm, the fourth wavelength value is 455nm to 475nm, and the fifth wavelength value is greater than or equal to 470nm.

13. The lighting module of claim 11, wherein the ratio of the first intensity value to the second intensity value ranges from 0.2 to 0.8, the ratio of the third intensity value to the second intensity value ranges from 0.4 to 1.4, the ratio of the fourth intensity value to the second intensity value ranges from 0.2 to 1.2, and the ratio of the fifth intensity value to the second intensity value ranges from 0.1 to 0.8.