Light emitting diode and light emitting device

Abstract

The invention provides a light-emitting diode, which at least comprises a semiconductor lamination layer comprising a first semiconductor layer, an active layer and a second semiconductor layer which are stacked in sequence; the active layer comprises multiple periods of multi-quantum well structures, and each period of multi-quantum well structure comprises a well layer and a barrier layer which are stacked in sequence; the radiation wavelength of the light-emitting diode ranges from 605 nm to 730 nm, the number of cycles of the multi-quantum well structure of the active layer ranges from 5 pairs to 25 pairs, and the thickness of the barrier layer is smaller than or equal to # imgabs0 #. According to the technical scheme, the structure of the active layer is optimized for wave bands with different wavelengths, and particularly, by adjusting the number of cycles of the multi-quantum well structure or the thickness of the barrier layer, the light-emitting efficiency of the light-emitting diode is improved. And the Al component in the barrier layer is accurately controlled, so that the problem that the longer the low-temperature wavelength of the LED is, the poorer the voltage stability is can be solved, the voltage of a component under the low-temperature condition is stable and controllable, and finally the purpose of improving the brightness of emergent light and the performance of a product is achieved.

Description

Technical Field

[0001] The present application relates to the field of semiconductor manufacturing technology, and in particular to a light emitting diode and a light emitting device. Background Art

[0002] Light Emitting Diode (LED) has the advantages of high luminous intensity, high efficiency, small size and long service life, and is considered to be one of the most promising light sources. In recent years, LED has been widely used in daily life, such as lighting, signal display, backlight, car lights and large-screen display. At the same time, these applications have also put forward higher requirements on the brightness and luminous efficiency of LED.

[0003] In response to the growing demand for high-performance automotive LEDs, the HC (Hot Cold Factor) of LED chips has become a key indicator for measuring their market competitiveness and applicability. The HC level is directly related to the performance and stability of LEDs under extreme temperature conditions, and is an important consideration for many automakers when choosing LED light sources.

[0004] In order to improve the HC performance of LED chips, the technical means commonly used in the industry include increasing the number of multiple quantum wells (MQW) or increasing the thickness of the barrier layer. These improvements have been proven in practical applications to effectively reduce the carrier overflow phenomenon and improve the HC level. However, the above scheme also has a disadvantage, that is, the chip voltage will increase significantly in a low temperature environment, and the voltage difference between low temperature and room temperature is too large, even exceeding a specific threshold, which cannot meet the reliable operation of LED devices under extreme climate conditions.

[0005] Therefore, it is necessary to provide an improved technical solution to address the deficiencies in the above-mentioned prior art. Summary of the invention

[0006] In view of the defects and shortcomings in the above-mentioned prior art, the purpose of the present application is to provide a light-emitting diode and a light-emitting device, which can effectively control and reduce the voltage increase in a low-temperature environment while obtaining good HC performance, thereby achieving an optimal balance between HC performance and low-temperature voltage characteristics.

[0007] According to one aspect of the present application, a light emitting diode is provided, comprising at least:

[0008] A semiconductor stack having a first surface and a second surface opposite to each other, and comprising a first semiconductor layer, an active layer, and a second semiconductor layer stacked in sequence from the first surface to the second surface;

[0009] The active layer includes a multi-quantum well structure of multiple periods, and each period of the multi-quantum well structure includes a well layer and a barrier layer stacked in sequence;

[0010] The radiation wavelength of the light emitting diode is between 605nm and 730nm, the period number of the multi-quantum well structure of the active layer is between 5 pairs and 25 pairs, and the thickness of the barrier layer is less than or equal to

[0011] According to one aspect of the present application, there is also provided a light emitting diode, comprising at least:

[0012] A semiconductor stack having a first surface and a second surface opposite to each other, and comprising a first semiconductor layer, an active layer, and a second semiconductor layer stacked in sequence from the first surface to the second surface;

[0013] The active layer includes a multi-quantum well structure of multiple periods, and each period of the multi-quantum well structure includes a well layer and a barrier layer stacked in sequence;

[0014] In a characteristic band, the maximum number of periods of the active layer decreases with increasing wavelength, and the wavelength of the characteristic band is between 605nm and 730nm.

[0015] According to one aspect of the present application, there is also provided a light emitting diode, comprising at least:

[0016] A semiconductor stack having a first surface and a second surface opposite to each other, and comprising a first semiconductor layer, an active layer, and a second semiconductor layer stacked in sequence from the first surface to the second surface;

[0017] The active layer includes a multi-quantum well structure of multiple periods, and each period of the multi-quantum well structure includes a well layer and a barrier layer stacked in sequence;

[0018] In a characteristic waveband, the thickness of the barrier layer decreases with increasing wavelength, and the wavelength of the characteristic waveband is between 605nm and 730nm.

[0019] According to one aspect of the present application, a light-emitting device is also provided, which includes a light source, which is a light-emitting diode as described in any one of the above technical solutions.

[0020] Compared with the prior art, the light emitting diode and the light emitting device provided by the present application have at least the following beneficial effects:

[0021] The technical solution of the present application optimizes the structure of the active layer according to the wavelength changes in different bands, especially by adjusting the number of periods of the multi-quantum well structure or the thickness of the barrier layer: within the band of 605nm to 730nm, the number of periods of the multi-quantum well structure of the active layer is between 5 pairs and 25 pairs, and the thickness of the barrier layer is less than or equal to In order to improve the problem that the voltage stability becomes worse as the wavelength becomes longer, the voltage difference between the light-emitting diode at low temperature and at room temperature is stable and controllable.

[0022] In addition, the light-emitting device provided in the present application includes the light-emitting diode provided by the above technical solution. Therefore, the light-emitting device also has the above good technical effects, and effectively improves the HC performance and low-temperature voltage stability of the device. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, the following is a brief introduction to the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work. The positional relationships described in the drawings in the following description are based on the directions in which the components are drawn in the diagrams, unless otherwise specified.

[0024] For the purpose of convenience or clarity, the thickness and size of each layer shown in the drawings can be exaggerated, omitted or roughly drawn. In addition, the size of the light emitting device does not completely reflect the actual size.

[0025] Figure 1 Shown is a schematic diagram of the cross-sectional structure of a semiconductor stack provided by the present application;

[0026] Figure 2 Shown is a schematic diagram of the cross-sectional structure of the active layer provided by the present application;

[0027] Figure 3 Shown is a schematic cross-sectional structure diagram of a light emitting diode provided by the present application;

[0028] Figure 4 Shown is a schematic cross-sectional structure diagram of another light emitting diode provided by the present application;

[0029] Figure 5 Shown is a schematic structural diagram of the light-emitting device provided in the present application.

[0030] List of reference numerals:

[0031] 100 Growth substrate

[0032] 101 Buffer Layer

[0033] 102 Etching stop layer

[0034] 103 First Ohmic Contact Layer

[0035] 104 First current spreading layer

[0036] 105 First Covering Layer

[0037] 106 First spacer layer

[0038] 107 Active layer

[0039] 108 Second compartment

[0040] 109 Second Covering Layer

[0041] 110 Second current spreading layer

[0042] 111 Second Ohmic Contact Layer

[0043] 200 substrates

[0044] 201 Bonding layer

[0045] 202 Reflection layer

[0046] 203 first electrode

[0047] 204 second electrode

[0048] 300 Lighting Device

[0049] 310 Circuit board

[0050] 320 Luminous light source DETAILED DESCRIPTION

[0051] Hot / Cold performance characterizes the relationship between the brightness of the LED and the operating temperature. The better the Hot / Cold performance, the better the performance of the LED at extreme temperatures. HC can be understood as the thermal attenuation value. For example, the ratio of the brightness of the LED at 85 degrees to the brightness at 25 degrees is used as the HC parameter of the above temperature conditions. LEDs are used in various scenarios. As car lights, the ambient temperature used outdoors is even lower than minus 40 degrees. In extremely low temperature environments, the chip voltage will increase significantly, which may cause excessive power consumption or even dead lights. At present, the market has increasing requirements for the brightness attenuation of LED products at high and low temperatures. Existing technologies can no longer meet the requirements for the reliable operation of LED devices under extreme climate conditions.

[0052] Based on the above background technology, the present application optimizes the design of the LED epitaxial structure and provides a light-emitting diode, which at least includes:

[0053] A semiconductor stack having a first surface and a second surface opposite to each other, and comprising a first semiconductor layer, an active layer, and a second semiconductor layer stacked in sequence from the first surface to the second surface;

[0054] The active layer includes a multi-quantum well structure of multiple periods, and each period of the multi-quantum well structure includes a well layer and a barrier layer stacked in sequence;

[0055] The radiation wavelength of the light emitting diode is between 605nm and 730nm, the period number of the multi-quantum well structure of the active layer is between 5 pairs and 25 pairs, and the thickness of the barrier layer is less than or equal to In a specific band, by adjusting the number of periods of the multi-quantum well structure and the thickness of the barrier layer, the number of periods of the multi-quantum well structure and the thickness of the barrier layer are reduced as the wavelength increases within the band. Without significantly reducing the HC performance, the voltage increase in a low-temperature environment is effectively controlled and reduced, thereby achieving the best balance between the HC performance and the low-temperature voltage characteristics.

[0056] In some embodiments, the barrier layer comprises an Al component, and the content of the Al component is between 30% and 100%. The content of the Al component is adjusted to increase the energy band offset of the barrier layer or reduce interlayer lattice defects.

[0057] In some embodiments, the active layer has a multi-quantum well structure with a period number ranging from 7 pairs to 22 pairs, and the barrier layer has a thickness ranging from

[0058] In some embodiments, the content of the Al component is between 55% and 75%.

[0059] In some embodiments, the radiation wavelength of the light emitting diode is less than or equal to 625 nm;

[0060] The number of periods of the multi-quantum well structure of the active layer is between 8 pairs and 25 pairs, and the thickness of the barrier layer is between

[0061] In some implementations, the Al component content of the barrier layer is between 50% and 100%.

[0062] In some embodiments, the radiation wavelength of the light emitting diode is between 615nm and 625nm; the number of periods of the multi-quantum well structure of the active layer is between 15 pairs and 22 pairs, and the thickness of the barrier layer is between

[0063] In some implementations, the Al component content of the barrier layer is between 65% and 75%.

[0064] In some embodiments, the radiation wavelength of the light emitting diode is greater than or equal to 625 nm, the number of periods of the multi-quantum well structure of the active layer is between 5 pairs and 15 pairs, and the thickness of the barrier layer is between

[0065] In some implementations, the Al component content of the barrier layer is between 30% and 80%.

[0066] In some embodiments, the radiation wavelength of the light emitting diode is between 625nm and 635nm; the number of periods of the multi-quantum well structure of the active layer is between 7 pairs and 12 pairs, and the thickness of the barrier layer is between Further optimize the low temperature voltage performance of long-wave LEDs.

[0067] In some implementations, the Al component content of the barrier layer is between 55% and 65%.

[0068] In some embodiments, the light emitting diode further includes a first electrode and a second electrode, which are electrically connected to the first semiconductor layer and the second semiconductor layer respectively.

[0069] A light emitting diode, comprising at least:

[0070] A semiconductor stack having a first surface and a second surface opposite to each other, and comprising a first semiconductor layer, an active layer, and a second semiconductor layer stacked in sequence from the first surface to the second surface;

[0071] The active layer includes a multi-quantum well structure of multiple periods, and each period of the multi-quantum well structure includes a well layer and a barrier layer stacked in sequence;

[0072] In a characteristic band, the maximum number of periods of the active layer decreases with the increase of wavelength, and the wavelength of the characteristic band is between 605nm and 730nm. In a specific band, by adjusting the number of periods of the multi-quantum well structure, the number of periods of the multi-quantum well structure is reduced with the increase of wavelength within the band, and the voltage increase in a low temperature environment is effectively controlled and reduced without significantly reducing the HC performance, so as to achieve the best balance between the HC performance and the low-temperature voltage characteristics.

[0073] In some embodiments, the maximum number of periods of the active layer varies non-equidistantly, and as the wavelength of radiation increases, the difference in the maximum number of periods of the active layer gradually increases. For shorter wavelength bands, a multi-quantum well structure of a certain period can ensure the stability of the HC performance of the product. As the wavelength increases, the maximum number of periods of the active layer decreases more, thereby improving the problem of low-temperature voltage increase.

[0074] In some implementations, within the characteristic band, the thickness of each barrier layer in the active layer is the same or different. The thickness of the barrier layer is optimized and adjusted according to actual needs to meet the performance requirements of different products.

[0075] A light emitting diode, comprising at least:

[0076] A semiconductor stack having a first surface and a second surface opposite to each other, and comprising a first semiconductor layer, an active layer, and a second semiconductor layer stacked in sequence from the first surface to the second surface;

[0077] The active layer includes a multi-quantum well structure of multiple periods, and each period of the multi-quantum well structure includes a well layer and a barrier layer stacked in sequence;

[0078] In a characteristic band, the thickness of the barrier layer decreases with the increase of wavelength, and the wavelength of the characteristic band is between 605nm and 730nm. By adjusting the thickness of the barrier layer of the multi-quantum well structure, the thickness of each barrier layer is reduced with the increase of wavelength within the band, so as to ensure that the voltage increase in a low temperature environment is effectively controlled and reduced without significantly reducing the HC performance, and achieve the best balance between the HC performance and the low temperature voltage characteristics.

[0079] In some embodiments, the characteristic band includes a first band and a second band in order from low to high wavelength, and the critical wavelength values ​​of the first band and the second band are in the band of 620nm to 630nm; wherein,

[0080] The maximum period difference of the active layer in the second band is greater than the maximum period difference in the first band. For bands with longer wavelengths, the period number of the multi-quantum well structure of the active layer and / or the thickness of the barrier layer are further reduced to balance HC performance with production cost and low temperature voltage level.

[0081] In some embodiments, the wavelength of the first wavelength band is less than or equal to 625 nm;

[0082] In the first band, the number of periods of the multi-quantum well structure of the active layer is between 8 pairs and 25 pairs, and the thickness of the barrier layer is between The Al component content of the barrier layer is between 50% and 100%.

[0083] In some embodiments, the wavelength of the second waveband is greater than or equal to 625 nm.

[0084] In the second band, the number of periods of the multi-quantum well structure of the active layer is between 5 pairs and 15 pairs, and the thickness of the barrier layer is between The Al component content of the barrier layer is between 30% and 80%.

[0085] In some embodiments, the thickness of each well layer in the active layer is between

[0086] In some embodiments, the barrier layer material is Al x1 Ga y1 In 1-x1-y1 P, the material of the well layer is Al x2 Ga y2 In 1-x2-y2 P, where 0≤x2<x1≤1, x1≥0.3, and 0≤y1<y2≤1, is applicable to the red light LED provided by the technical solution of the present application, and realizes precise control of the LED light emission wavelength.

[0087] The present application also includes a light-emitting device, which includes a light source. The light source is a light-emitting diode provided by the above technical solution. The light-emitting device also has good HC performance and low-temperature voltage performance.

[0088] In some embodiments, under working conditions below -40 degrees, the difference between the voltage of the light emitting device and the voltage under room temperature working conditions is less than or equal to 10%, or less than or equal to 0.2 V. The light emitting device can maintain voltage stability at extremely low temperatures, meeting the requirements for reliable operation of the device under extreme climate conditions.

[0089] The following specific embodiments illustrate the implementation of the present application, and those familiar with the technology can easily understand other advantages and effects of the present application from the content disclosed in this specification. The present application can also be implemented or applied through other different specific implementations, and the details in this specification can also be modified or changed in various ways based on different viewpoints and applications without departing from the spirit of the present application. It should be noted that the following embodiments and features in the embodiments can be combined with each other without conflict.

[0090] The composition and dopant of each layer included in the light-emitting diode of the present application can be analyzed by any suitable method, such as secondary ion mass spectrometer (SIMS). The thickness of each layer included in the light-emitting diode of the present application can be analyzed by any suitable method, such as transmission electron microscopy (TEM) or scanning electron microscopy (SEM), for example, to match the depth position of each layer on the SIMS map.

[0091] Embodiment 1:

[0092] See also Figure 1 and Figure 2, this embodiment provides an epitaxial structure of a light emitting diode.

[0093] Figure 1 A schematic diagram of the light-emitting diode epitaxial structure provided in this embodiment is shown, and the epitaxial structure at least includes a growth substrate 100 and a semiconductor stack located above the growth substrate 100, and the semiconductor stack has a first surface and a second surface relative to each other, and from the first surface to the second surface, includes a first semiconductor layer, an active layer 107, and a second semiconductor layer stacked in sequence.

[0094] Continue to see Figure 1 , the growth substrate 100 includes but is not limited to GaAs, and other materials may also be used, such as GaP, InP, etc. In this embodiment, a GaAs growth substrate 100 is taken as an example. In an optional implementation, a buffer layer 101, an etching stop layer 102 and a first ohmic contact layer 103 are sequentially arranged between the growth substrate 100 and the first current spreading layer 104; wherein, since the lattice quality of the buffer layer 101 is relatively good compared to the lattice quality of the growth substrate 100, growing the buffer layer 101 on the growth substrate 100 is beneficial to eliminating the influence of the lattice defects of the growth substrate 100 on the semiconductor stack; the etching stop layer 102 is used as a stop layer for chemical etching in the later step. In an optional implementation, the etching stop layer 102 is an n-type etching stop layer, and the material is n-GaInP. In order to facilitate the subsequent removal of the growth substrate 100, its thickness is controlled within 500nm or within 200nm. In an optional embodiment, the first ohmic contact layer 103 is made of GaAs material, with a thickness ranging from 10 to 100 nm and a doping concentration ranging from 1 to 10E+18 / cm 3 , preferably 2E18 / cm 3 , to achieve better ohmic contact results.

[0095] Continue to see Figure 1 , the semiconductor stack has a first surface and a second surface relative to each other, and includes a first semiconductor layer, an active layer 107, and a second semiconductor layer stacked in sequence from the first surface to the second surface. The first semiconductor layer and the second semiconductor layer can be provided with electrons or holes by n-type doping or p-type doping, respectively. The n-type semiconductor layer can be doped with n-type dopants such as Si, Ge, or Sn, and the p-type semiconductor layer can be doped with p-type dopants such as Mg, Zn, Ca, Sr, C, or Ba. When the first semiconductor layer is an n-type semiconductor, the second semiconductor layer is a p-type semiconductor layer; when the first semiconductor layer is a p-type semiconductor layer, the second semiconductor layer is an n-type semiconductor layer. The first semiconductor layer, the active layer 107, and the second semiconductor layer can be made of materials such as aluminum gallium indium nitride, gallium nitride, aluminum gallium nitride, aluminum indium phosphide, aluminum gallium indium phosphide, gallium arsenide, or aluminum gallium arsenic. This embodiment is described in detail by taking the first semiconductor layer as an n-type semiconductor layer as an example.

[0096] Each layer of the semiconductor stack can be formed on the growth substrate 100 by physical vapor deposition (PVD), chemical vapor deposition (CVD), epitaxial growth (Epitaxy Growth Technology) and atomic beam deposition (ALD). The semiconductor stack is a semiconductor material that can provide conventional radiation such as ultraviolet, blue, green, yellow, red, infrared light, etc. By adjusting the composition ratio of the semiconductor material in the active layer 107, it is expected to radiate light of the target wavelength so that the light-emitting band is between 200nm and 950nm. For example, a gallium nitride-based semiconductor stack doped with elements such as aluminum and indium mainly provides radiation in the band of 200nm to 550nm; or an aluminum gallium indium phosphorus-based or aluminum gallium arsenic-based semiconductor stack mainly provides radiation in the band of 550nm to 950nm. The light-emitting diode provided in this embodiment is a red light LED, and the light-emitting wavelength is between 600nm and 650nm.

[0097] Continue to see Figure 1 The first semiconductor layer includes a first covering layer 105, such as aluminum gallium indium phosphide, which provides electrons for the active layer 107. In order to improve the uniformity of current expansion, the first semiconductor layer may also include a first current expansion layer 104, such as aluminum gallium indium phosphide, with a thickness of 2500nm to 4000nm. In order to prevent the dopant of the first covering layer 105 from diffusing into the active layer 107 and affecting the crystal quality of the active layer 107, a first spacer layer 106 may also be provided between the first covering layer 105 and the active layer 107. It can be understood that the first semiconductor layer may also be configured with other layers in addition to the above layers, and some layers may also be omitted.

[0098] See also Figure 1 and Figure 2 The active layer 107 provides a light radiation area for electron and hole recombination, including a multi-quantum well structure of multiple periods, each of which includes a well layer and a barrier layer stacked in sequence, wherein the barrier layer has a larger band gap than the well layer. In this embodiment, the material of the barrier layer is Al x1 Ga y1 In 1-x1-y1 P, the material of the well layer is Al x2 Ga y2 In 1-x2-y2P, where 0≤x2<x1≤1, 0≤y1<y2≤1, is applicable to the red light LED provided by the technical solution of the present application, and realizes precise control of the LED emission wavelength, so that the active layer 107 can radiate red light with a wavelength of 550nm to 750nm. In an optional embodiment, the material of the well layer is GaInP to improve the aging stability of the components. With the increase of the Al component in the barrier layer, the bandgap width will increase, causing the emission wavelength to move toward the short-wave direction, but the excessive Al component causes more defects and stresses inside the material, thereby reducing the life and reliability of the device. Furthermore, the Al component content of the barrier layer is between 30% and 100%, that is, 0.3≤x1≤1, so as to achieve a balance of the various different performances of the above-mentioned device.

[0099] In a characteristic band, the maximum number of periods of the active layer 107 decreases with the increase of wavelength. The wavelength of the characteristic band is between 605nm and 730nm. By adjusting the number of periods of the multi-quantum well structure, the number of periods of the multi-quantum well structure is reduced with the increase of wavelength within the above-mentioned band, for example, from the existing 25 pairs or more to 15 pairs or even less pairs. In the case that HC does not decrease significantly, the voltage increase in a low temperature environment is effectively controlled and reduced, and the best balance between HC performance and low-temperature voltage characteristics is achieved. It can be understood that as the temperature changes, the mobility of the carriers also changes. Under extremely low temperature conditions, the mobility of the carriers is significantly reduced. If the number of periods of the multi-quantum well structure is maintained unchanged, more carriers may be captured or recombined in the non-radiative center during the transmission process, thereby reducing the number of carriers reaching the effective light-emitting area. In order to maintain the same light-emitting intensity, it is necessary to increase the voltage to drive more carriers to migrate. In the above-mentioned characteristic band, the longer the wavelength, the smaller the required band gap width, and the energy required for recombination is relatively lower, so its voltage change is more affected by temperature. As the wavelength increases, the number of cycles of the multi-quantum well structure is reduced, which can effectively control the voltage fluctuation of components in a low-temperature environment. Furthermore, the wavelength of this characteristic band is between 615nm and 635nm.

[0100] In an optional embodiment, the maximum number of periods of the active layer 107 varies non-equidistantly, and as the wavelength of radiation increases, the difference in the maximum number of periods of the active layer 107 gradually increases. For example, for the bands of 600nm to 615nm and 615nm to 625nm, the maximum number of periods of the active layer 107 only needs to be reduced by 2 pairs or less in sequence, while for the bands above 625nm, the maximum number of periods of the active layer 107 needs to be reduced by 5 pairs or more to meet the requirements of low-temperature voltage stability. For bands with shorter wavelengths, a multi-quantum well structure of a certain period can ensure the stability of the product HC performance, but as the wavelength increases, the maximum number of periods of the active layer 107 is reduced more to improve the problem of low-temperature voltage increase. Furthermore, the thickness of each barrier layer in the active layer 107 is the same or different, and the thickness of the barrier layer is optimized and adjusted according to actual needs to meet the performance requirements of different products. In an optional implementation, the thickness of each barrier layer in the active layer 107 is the same, which is conducive to improving the consistency and reliability of LED manufacturing; the thickness of the barrier layer can also be set to be different in one or several layers to adjust the band structure and state density in the quantum well, further optimize the luminescence performance, and meet the needs of different products. The more the number of periods of the active layer 107 is within the above-defined range, the better the HC performance of the light-emitting diode. Appropriately reducing the number of periods of the active layer 107 can not only balance the problem of low-temperature voltage stability, but also save production costs. According to the actual performance requirements of products in different bands, a suitable active layer structure is selected.

[0101] In an optional embodiment, the characteristic band includes a first band and a second band in order from low to high wavelength, and the critical wavelength value of the first band and the second band is in the band of 620nm to 630nm; wherein, the maximum period number difference of the active layer 107 in the second band is greater than the maximum period number difference in the first band. For bands with longer wavelengths, the period number of the multi-quantum well structure of the active layer 107 is further reduced to balance the HC performance with the production cost and low-temperature voltage level. Furthermore, the critical wavelength value is 625nm, that is, for light-emitting diodes with wavelengths above 625nm, the maximum period number of the active layer 107 decreases more with increasing wavelength, so as to effectively improve the problem of increased low-temperature voltage; for light-emitting diodes with wavelengths below 625nm, the maximum period number of the active layer 107 does not need to be excessively reduced with increasing wavelength to balance the problem of HC performance with increased low-temperature voltage. In an optional embodiment, the thickness of the well layer is between The thickness of the barrier layer also decreases with increasing wavelength. For light-emitting diodes of each wavelength band, the thickness of each barrier layer may be the same or different.

[0102] In an optional embodiment, the wavelength of the first wavelength band is less than or equal to 625 nm. In the first wavelength band, the number of periods of the multi-quantum well structure of the active layer 107 is between 8 pairs and 25 pairs, and the thickness of the barrier layer is less than or equal to The thickness of the well layer is between Furthermore, the number of periods of the multi-quantum well structure is between 15 pairs and 22 pairs, and the thickness of the barrier layer is between The thickness of the well layer is For light-emitting diodes with shorter emission wavelengths within the characteristic band, the reduction in operating temperature has little effect on the reduction in their carrier mobility, and the voltage increase is also relatively small. Appropriately reducing the number of periods of the multi-quantum well structure can balance the HC performance and low-temperature voltage issues. At the same time, the thickness of the barrier layer can be controlled, for example, the thickness of the barrier layer can be thinned accordingly, to further optimize product performance.

[0103] Specifically, the first band also includes a first sub-band and a second sub-band, and the critical wavelength value of the first sub-band and the second sub-band is about 615nm. In this embodiment, the critical wavelength value of 615nm is taken as an example, and the wavelength of the first sub-band is between 600nm and 615nm; the wavelength of the second sub-band is between 615nm and 625nm. For the light-emitting diode of the first sub-band, the number of periods of the multi-quantum well structure of its active layer 107 is between 8 pairs and 25 pairs, and the thickness of the barrier layer is between Furthermore, the number of periods of the active layer 107 is between 18 pairs and 20 pairs, for example, 18 pairs, 19 pairs or 20 pairs, and the thickness of the barrier layer is between For the light emitting diode of the second sub-band, the period number of the multi-quantum well structure of the active layer 107 is between 8 pairs and 20 pairs, and the thickness of the barrier layer is between Furthermore, the number of periods of the active layer 107 is between 16 pairs and 20 pairs, for example, 16 pairs or 18 pairs, and the thickness of the barrier layer is between For a light-emitting diode emitting light in the first band, a balance between HC performance and low-temperature voltage performance can be basically achieved simply by adjusting the number of periods of its multi-quantum well structure, and the thickness of the barrier layer can remain unchanged.

[0104] In an optional embodiment, the wavelength of the second band is greater than or equal to 625 nm. In the second band, the number of periods of the multi-quantum well structure of the active layer 107 is between 5 pairs and 15 pairs, and the thickness of the barrier layer is between The thickness of the well layer is between Furthermore, the number of periods of the multi-quantum well structure is between 7 pairs and 12 pairs, and the thickness of the barrier layer is between The thickness of the well layer is For LEDs with longer emission wavelengths in the characteristic band, the reduction in operating temperature has a more obvious effect on the reduction of their carrier mobility, and the voltage increase is also relatively large. The difference between the voltage in the operating environment of -40 degrees and the voltage at room temperature is even higher than 10%. The number of periods of the multi-quantum well structure is reduced to no more than 15 pairs, or no more than 12 pairs, in order to balance the HC performance and low-temperature voltage issues. At the same time, the thickness of the barrier layer is controlled and the thickness of the barrier layer is also greatly reduced to ensure that a sufficient number of carriers recombine in the well layer, ensure product brightness, and further optimize product performance.

[0105] As an example, for light-emitting diodes with wavelengths of 600 nm, 615 nm, 625 nm and 635 nm, the number of periods of their multi-quantum well structures can be set to 21 pairs, 20 pairs, 18 pairs and 10 pairs respectively.

[0106] Continue to see Figure 1 , the second semiconductor layer is above the active layer 107, and the second semiconductor layer includes a second covering layer 109, such as aluminum gallium indium phosphide, which provides holes for the active layer 107. In order to improve the uniformity of current expansion, the second semiconductor layer may also include a second current expansion layer 110 with a thickness of 2500nm to 4000nm. In order to prevent the dopants in the second covering layer 109 from diffusing into the active layer 107 and affecting the crystal quality of the active layer 107, a second spacer layer 108 may be further provided between the second covering layer 109 and the active layer 107 in this embodiment. The second semiconductor layer may also be configured with other layers in addition to the above layers, and in addition, some layers may be omitted.

[0107] Embodiment 2:

[0108] See also Figure 1 and Figure 2 , this embodiment also provides an epitaxial structure of a light-emitting diode. The same or similar points as those in the first embodiment are not repeated in this embodiment. The difference from the first embodiment is that: the active layer includes a multi-quantum well structure with multiple periods, and each period of the multi-quantum well structure includes a well layer and a barrier layer stacked in sequence; wherein the barrier layer has a larger band gap than the well layer, and within a characteristic band, the thickness of the barrier layer decreases with increasing wavelength, and the wavelength of the characteristic band is between 600nm and 650nm. By adjusting the thickness of the barrier layer, the barrier layer is thinned as the wavelength increases within the above-mentioned band, for example, from or thicker down to Or thinner, it can effectively control and reduce the voltage increase in low temperature environment while maintaining no significant decrease in HC, achieve the best balance between HC performance and low temperature voltage characteristics, and meet product application requirements. Furthermore, the wavelength of this characteristic band is between 615nm and 635nm.

[0109] It is understandable that as the temperature changes, the mobility of the carriers also changes. Under extremely low temperature conditions, the mobility of the carriers is significantly reduced. If the thickness of the barrier layer is maintained unchanged, more carriers may not be able to transition, thereby reducing the number of carriers reaching the effective light-emitting area. In order to maintain the same luminous intensity, it is necessary to increase the voltage to drive more carriers to migrate. In the characteristic band, the longer the wavelength, the smaller the required band gap width, and the energy required for recombination is relatively lower, so its voltage change is more affected by temperature. Thinning the thickness of the barrier layer as the wavelength increases can effectively control the voltage fluctuation of components in a low-temperature environment. Furthermore, the maximum number of periods of the active layer 107 also shows a decreasing trend as the wavelength increases, that is, the number of periods of the multi-quantum well structure and the thickness of the barrier layer decrease simultaneously as the wavelength increases, jointly optimizing the performance of components.

[0110] In an optional embodiment, the characteristic band includes a first band and a second band in order from low to high wavelength, and the critical wavelength value of the first band and the second band is within the band of 620nm to 630nm; wherein the difference in the thickness of the barrier layer corresponding to the second band is greater than the difference in the thickness of the barrier layer in the first band. For bands with longer wavelengths, the thickness of the barrier layer is further reduced to balance the HC performance and production costs. Further, the critical wavelength value is 625nm, that is, for light-emitting diodes with wavelengths above 625nm, the thickness of the barrier layer decreases more with increasing wavelength, so as to effectively improve the problem of low-temperature voltage increase and reduce production costs at the same time; for light-emitting diodes with wavelengths below 625nm, the thickness of the barrier layer does not need to be excessively reduced as the wavelength increases to balance the problem of HC performance and low-temperature voltage increase. Further, the thickness of the well layer in the active layer 107 is between

[0111] In an optional embodiment, the wavelength of the first waveband is less than or equal to 625 nm. In the first waveband, the thickness of the barrier layer is less than or equal to For example or The thickness of the well layer is between For example or Furthermore, the thickness of the barrier layer is between The thickness of the well layer is For light-emitting diodes with shorter emission wavelengths within the characteristic band, the reduction in operating temperature has little effect on the reduction in their carrier mobility, and the voltage increase is also relatively small. The appropriate thickness of the barrier layer can balance the HC performance and low-temperature voltage issues. At the same time, the number of periods of the active layer can be controlled to further optimize product performance.

[0112] In an optional embodiment, the wavelength of the second waveband is greater than or equal to 625 nm. In the second waveband, the thickness of the barrier layer is less than or equal to For example or The thickness of the well layer is between For example or Furthermore, the thickness of the barrier layer is between The thickness of the well layer is For LEDs with longer emission wavelengths in the characteristic band, the reduction in operating temperature has a more obvious effect on the reduction of their carrier mobility, and the voltage increase is relatively large. In actual use, the difference between the operating voltage in a -40 degree environment and the voltage at room temperature is even higher than 10%, or the actual difference is higher than 0.2V. The thickness of the barrier layer is reduced as much as possible to even Next, in order to balance the HC performance and the problem of increased low-temperature voltage, at the same time, the number of periods of the active layer is controlled, and the number of periods of the active layer is also greatly reduced. The two together ensure that a sufficient number of carriers recombine in the well layer, ensure product brightness, and further optimize product performance.

[0113] As an example, for light-emitting diodes with wavelengths of 605nm, 615nm, 625nm, and 635nm, the thickness of the barrier layer can be set to and

[0114] Embodiment three:

[0115] This embodiment provides a light emitting diode, comprising at least:

[0116] A semiconductor stack having a first surface and a second surface opposite to each other, and comprising a first semiconductor layer, an active layer 107, and a second semiconductor layer stacked in sequence from the first surface to the second surface; the active layer 107 comprises a multi-quantum well structure of multiple periods, and each period of the multi-quantum well structure comprises a well layer and a barrier layer stacked in sequence; the radiation wavelength of the light-emitting diode is between 600nm and 730nm, the number of periods of the multi-quantum well structure of the active layer 107 is between 5 pairs and 25 pairs, and the thickness of the barrier layer is less than or equal to The barrier layer contains an Al component, and the content of the Al component is between 30% and 100%. Furthermore, the number of periods of the multi-quantum well structure of the active layer 107 is between 7 pairs and 22 pairs, and the thickness of the barrier layer is between The content of Al component is between 55% and 75%, and the radiation wavelength of the light emitting diode is between 625nm and 635nm. The light emitting diode is a better design solution for balancing HC performance and low temperature voltage stability, and effectively solves the problem of too high voltage difference between low temperature and room temperature devices in this band.

[0117] In an optional embodiment, the radiation wavelength of the light emitting diode is between 615nm and 625nm; the number of periods of the multi-quantum well structure of the active layer 107 is between 15 pairs and 22 pairs, and the thickness of the barrier layer is between Furthermore, the Al content of the barrier layer is between 65% and 75%. For products with a light emission band of 615nm to 625nm, the multi-quantum well structure provided by the above technical solution can better balance the HC performance and low temperature voltage issues. The thickness of the barrier layer is set to The Al component content of the barrier layer is between 65% and 75% to further optimize product performance and wavelength stability.

[0118] In an optional embodiment, the radiation wavelength of the light emitting diode is between 625nm and 635nm; the number of periods of the multi-quantum well structure of the active layer 107 is between 7 pairs and 12 pairs, and the thickness of the barrier layer is between Furthermore, the Al content of the barrier layer is between 55% and 65%. For products with a light emission band of 625nm to 635nm, the multi-quantum well structure provided by the above technical solution can better balance the HC performance and low temperature voltage issues. The thickness of the barrier layer is set to Further optimize product performance and wavelength stability.

[0119] Embodiment 4:

[0120] See also Figure 3 This embodiment provides a light emitting diode. The light emitting diode provided in this embodiment adopts Figure 1 The epitaxial structure shown further includes a first electrode 203 and a second electrode 204, which are electrically connected to the first semiconductor layer and the second semiconductor layer respectively.

[0121] The light-emitting diode includes a substrate 200, and a semiconductor stack is bonded to the substrate 200 through a bonding layer 201. The semiconductor stack includes a second ohmic contact layer 111, a second current spreading layer 110, a second covering layer 109, a second spacer layer 108, an active layer 107, a first spacer layer 106, a first covering layer 105, a first current spreading layer 104 and a first ohmic contact layer 103 stacked in sequence on the substrate 200.

[0122] In an optional embodiment, the substrate 200 is a conductive substrate, which may be a silicon, silicon carbide or metal substrate, and the metal substrate is preferably a copper, tungsten or molybdenum substrate. In order to support the semiconductor stack with sufficient mechanical strength, the thickness of the substrate 200 is preferably 50 μm or more. In addition, in order to facilitate mechanical processing of the substrate 200 after bonding to the semiconductor stack, the thickness of the substrate 200 is preferably not more than 300 μm. In this embodiment, the substrate 200 is preferably a silicon substrate.

[0123] A first electrode 203 is disposed on the first ohmic contact layer 103, and an ohmic contact is formed between the first electrode 203 and the first ohmic contact layer 103 to realize current flow. A reflective layer 202 may be disposed between the semiconductor stack and the substrate 200, and the reflective layer 202 includes an ohmic contact metal layer and a dielectric material layer, which cooperate to form an ohmic contact with the first ohmic contact layer 103 on the one hand, and to reflect the light beam emitted by the active layer 107 to the light emitting surface of the first current spreading layer 104 or the side wall of the semiconductor stack for light emission.

[0124] The light emitting diode further comprises a second electrode 204, which is located on the back side of the substrate 200, or the second electrode 204 is located on the substrate 200, on the same side as the semiconductor stack. The first electrode 203 and the second electrode 204 comprise transparent conductive materials and / or metal materials. The transparent conductive material comprises a transparent conductive layer, such as ITO or IZO; the metal material comprises at least one of GeAuNi, AuGe, AuZn, Au, Al, Pt, and Ti.

[0125] Embodiment five:

[0126] See also Figure 4 This embodiment provides a light emitting diode. The light emitting diode provided in this embodiment adopts Figure 1 The epitaxial structure shown further includes a first electrode 203 and a second electrode 204, which are electrically connected to the first semiconductor layer and the second semiconductor layer respectively. The same or similar aspects of this embodiment and the third embodiment are not repeated in this embodiment. The difference from the third embodiment is:

[0127] The light-emitting diode includes a substrate 200, and a semiconductor stack is bonded to the substrate 200 through a bonding layer 201. The semiconductor stack includes a first ohmic contact layer 103, a first current spreading layer 104, a first covering layer 105, a first spacer layer 106, an active layer 107, a second spacer layer 108, a second covering layer 109, a second current spreading layer 110 and a second ohmic contact layer 111 which are sequentially stacked on the substrate 200.

[0128] In an optional embodiment, the substrate 200 is a conductive substrate, and preferably the substrate 200 is a copper substrate.

[0129] A second electrode 204 is disposed on the second ohmic contact layer 111, and an ohmic contact is formed between the second electrode 204 and the second ohmic contact layer 111 to achieve current flow. The light-emitting diode further includes a first electrode 203, which is located on the back side of the substrate 200, or the first electrode 203 is disposed on the substrate 200 and on the same side as the semiconductor epitaxial stack.

[0130] Embodiment six:

[0131] See also Figure 5 , this embodiment provides a light-emitting device 300, including a circuit substrate 310 and a plurality of light-emitting light sources 320 arranged in an array, a driving circuit is provided in the circuit substrate 310, the light-emitting light source 320 is electrically connected to the driving circuit so as to be controlled to light up or extinguish by the driving circuit, and the light-emitting light source 320 is any one of the light-emitting diodes in the first to fourth embodiments. The light-emitting device 300 can be a vehicle lamp, such as a brake light, a turn signal or an atmosphere light, or can be other lighting devices, such as a projector, a stage light or a display screen. The light-emitting device provided in this embodiment has good voltage stability in a low-temperature environment. In the working condition of -20 degrees or even below -40 degrees, the difference between the voltage of the light-emitting device 300 and the voltage under room temperature working condition is less than or equal to 10%, and the actual voltage difference between the two is not higher than 0.2V after testing. The light-emitting device 300 and the light-emitting diodes provided in other embodiments of the present application can effectively balance HC performance and low-temperature voltage stability to obtain good light output brightness and product quality.

[0132] In summary, the light emitting diode and the light emitting device provided by the present application effectively overcome various shortcomings in the prior art and have high industrial utilization value.

[0133] The above embodiments are merely illustrative of the principles and effects of the present application and are not intended to limit the present application. Anyone familiar with the technology may modify or change the above embodiments without violating the spirit and scope of the present application. Therefore, all equivalent modifications or changes made by a person of ordinary skill in the art without departing from the spirit and technical ideas disclosed in the present application shall still be covered by the claims of the present application.

Claims

1. A light emitting diode, characterized in that: At least: A semiconductor stack having a first surface and a second surface opposite to each other, and comprising a first semiconductor layer, an active layer, and a second semiconductor layer stacked in sequence from the first surface to the second surface; The active layer includes a multi-quantum well structure of multiple periods, and each period of the multi-quantum well structure includes a well layer and a barrier layer stacked in sequence; The radiation wavelength of the light emitting diode is between 605nm and 730nm, the period number of the multi-quantum well structure of the active layer is between 5 pairs and 25 pairs, and the thickness of the barrier layer is between 2. The light emitting diode according to claim 1, characterized in that: The barrier layer contains an Al component, and the content of the Al component is between 30% and 100%.

3. The light emitting diode according to claim 2, characterized in that: The active layer has a multi-quantum well structure with a period number ranging from 7 pairs to 22 pairs, and the barrier layer has a thickness ranging from 4. The light emitting diode according to claim 3, characterized in that: The content of the Al component is between 55% and 75%.

5. The light emitting diode according to claim 1, characterized in that: The radiation wavelength of the light emitting diode is less than or equal to 625nm; The number of periods of the multi-quantum well structure of the active layer is between 8 pairs and 25 pairs, and the thickness of the barrier layer is between 6. The light emitting diode according to claim 5, characterized in that: The Al component content of the barrier layer is between 50% and 100%.

7. The light emitting diode according to claim 5, characterized in that: The radiation wavelength of the light emitting diode is between 615nm and 625nm; In the first band, the number of periods of the multi-quantum well structure of the active layer is between 15 pairs and 22 pairs, and the thickness of the barrier layer is between 8. The light emitting diode according to claim 7, characterized in that: The Al component content of the barrier layer is between 65% and 75%.

9. The light emitting diode according to claim 1, characterized in that: The radiation wavelength of the light emitting diode is greater than or equal to 625nm, The active layer has a multi-quantum well structure with a period number of between 5 pairs and 15 pairs, and the barrier layer has a thickness of between 10. The light emitting diode according to claim 9, characterized in that: The Al component content of the barrier layer is between 30% and 80%.

11. The light emitting diode according to claim 9, characterized in that: The radiation wavelength of the light emitting diode is between 625nm and 635nm; The active layer has a multi-quantum well structure with a period number of between 7 pairs and 12 pairs, and the barrier layer has a thickness between 12. The light emitting diode according to claim 11, characterized in that: The Al component content of the barrier layer is between 55% and 65%.

13. The light emitting diode according to any one of claims 1 to 12, characterized in that: The light emitting diode further includes a first electrode and a second electrode, which are electrically connected to the first semiconductor layer and the second semiconductor layer respectively.

14. A light emitting diode, characterized in that: At least: A semiconductor stack having a first surface and a second surface opposite to each other, and comprising a first semiconductor layer, an active layer, and a second semiconductor layer stacked in sequence from the first surface to the second surface; The active layer includes a multi-quantum well structure of multiple periods, and each period of the multi-quantum well structure includes a well layer and a barrier layer stacked in sequence; In a characteristic band, the maximum number of periods of the active layer decreases with increasing wavelength, and the wavelength of the characteristic band is between 605nm and 730nm.

15. The light emitting diode according to claim 14, characterized in that: The maximum number of periods of the active layer varies non-arithmetically, and as the radiation wavelength increases, the difference in the maximum number of periods of the active layer gradually increases.

16. The light emitting diode according to claim 14, characterized in that: Within the characteristic band, the thickness of each barrier layer in the active layer is the same or different.

17. A light emitting diode, characterized in that: At least: A semiconductor stack having a first surface and a second surface opposite to each other, and comprising a first semiconductor layer, an active layer, and a second semiconductor layer stacked in sequence from the first surface to the second surface; The active layer includes a multi-quantum well structure of multiple periods, and each period of the multi-quantum well structure includes a well layer and a barrier layer stacked in sequence; In a characteristic waveband, the thickness of the barrier layer decreases with increasing wavelength, and the wavelength of the characteristic waveband is between 605nm and 730nm.

18. The light emitting diode according to claim 14 or 17, characterized in that: The characteristic bands include a first band and a second band in order from low to high wavelengths, and the critical wavelength values ​​of the first band and the second band are located in the band of 620nm to 630nm; wherein, The maximum period number difference of the active layer in the second band is greater than the maximum period number difference in the first band.

19. The light emitting diode according to claim 18, characterized in that: The wavelength of the first waveband is less than or equal to 625 nm; In the first band, the number of periods of the multi-quantum well structure of the active layer is between 8 pairs and 25 pairs, and the thickness of the barrier layer is between The Al component content of the barrier layer is between 50% and 100%.

20. The light emitting diode according to claim 18, characterized in that The wavelength of the second waveband is greater than or equal to 625nm; In the second band, the number of periods of the multi-quantum well structure of the active layer is between 5 pairs and 15 pairs, and the thickness of the barrier layer is between The Al content of the barrier layer is between 30% and 80%. between.

21. The light emitting diode according to claim 14 or 17, characterized in that: The thickness of each well layer in the active layer is between 22. The light emitting diode according to claim 14 or 17, characterized in that: The barrier layer material is Al x1 Ga y1 In 1-x1-y1 P, the material of the well layer is Al x2 Ga y2 In 1-x2-y2 P, where 0≤x2<x1≤1, x1≥0.3, 0≤y1<y2≤1.

23. A light emitting device, characterized in that: The light emitting device comprises: a light source, and the light source is a light emitting diode as described in any one of claims 1 to 22.

24. The light emitting device according to claim 23, characterized in that: In the working condition of -40 degrees or below, the difference between the voltage of the light emitting device and the voltage under the room temperature working condition is less than or equal to 10%, or less than or equal to 0.2V.

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