Quantum cascade light-emitting structure and preparation method thereof

Abstract

The invention provides a quantum cascade light-emitting structure and a preparation method thereof. The quantum cascade light-emitting structure comprises an active layer; the active layer comprises a first active layer group to an Mth active layer group which are stacked in the first direction, any mth active layer group is of a superlattice structure and comprises a plurality of mth active layer units stacked in the first direction, and any mth active layer unit comprises mth potential barrier layers and mth potential well layers which are alternately stacked in the first direction; the equivalent material of any mth barrier layer is In < x > Al < 1-x > As, and the equivalent material of any mth potential well layer is In < y > Ga < 1-y > As; m is an integer greater than or equal to 1, and m is an integer greater than or equal to 1 and less than or equal to M; x of at least two barrier layers in each active layer unit in at least one active layer group is different; and / or the y of the at least two potential well layers in each active layer unit in the at least one active layer group is different.

Description

Technical Field

[0001] The present invention relates to the field of semiconductor technology, and particularly to a quantum cascade light emitting structure and a preparation method thereof. Background Art

[0002] The quantum cascade laser is a new type of semiconductor laser and an important achievement of semiconductor energy band engineering. Its working band extends from the mid-infrared to the terahertz band. The quantum cascade laser based on the InGaAs / InAlAs / InP material system shows unique advantages in the mid-infrared and long-wave infrared bands. Due to the characteristics of small volume, light weight and low power consumption of the quantum cascade laser, the directional infrared countermeasure system based on the quantum cascade laser can be applied to more complex application environments. In particular, its application in protecting aircraft and other aircraft as airborne equipment has attracted much attention. In addition to applications in the security field, the quantum cascade laser has shown its potential importance in fields such as gas detection and free space optical communication. The working wavelengths of mid-infrared and long-wave infrared quantum cascade lasers basically cover the wavelength range of 4μm - 12μm, which is not only suitable for the detection of various trace gases, but also a highly anticipated light source in the field of free space optical communication. Whether it is for trace gas detection applications or free space optical communication applications, multi-wavelength quantum cascade lasers are one of the very important development directions. Summary of the Invention

[0003] Therefore, the technical problem to be solved by the present invention is how to obtain a larger wavelength tuning range and reduce the process difficulty, so as to provide a quantum cascade light emitting structure and a preparation method thereof.

[0004] The present application provides a quantum cascade light emitting structure, including: an active layer; wherein, the active layer includes a first active layer group to an Mth active layer group stacked along a first direction, any mth active layer group has a superlattice structure and includes a plurality of mth active layer units stacked along the first direction, and any mth active layer unit includes an mth barrier layer and an mth well layer stacked alternately along the first direction; the equivalent material of any mth barrier layer is In x Al 1-x As, and the equivalent material of any mth well layer is In y Ga 1-yAs; M is an integer greater than or equal to 1, and m is an integer greater than or equal to 1 and less than or equal to M; wherein, the x values of at least two barrier layers in each active layer unit in at least one active layer group are different; and / or, the y values of at least two well layers in each active layer unit in at least one active layer group are different; wherein, any m-th well layer includes a first type of m-th sub-well layer and a second type of m-th sub-well layer alternately stacked along a first direction, the second type of m-th sub-well layer is located between adjacent first type of m-th sub-well layers, and the material of the first type of m-th sub-well layer is In y1 Ga 1-y1 As, and the material of the second type of m-th sub-well layer is InAs; any m-th barrier layer includes a first type of m-th sub-barrier layer and a second type of m-th sub-barrier layer alternately stacked along the first direction, the second type of m-th sub-barrier layer is located between adjacent first type of m-th sub-barrier layers; the material of the first type of m-th sub-barrier layer is In x1 Al 1-x1 As, and the material of the second type of m-th sub-barrier layer is AlAs.

[0005] Optionally, for different m1-th active layer groups and m2-th active layer groups, the x values of at least one m-th barrier layer in the m1-th active layer group and the x values of each m-th barrier layer in the m2-th active layer group are different, and the y values of at least one m-th well layer in the m1-th active layer group and the y values of each m-th well layer in the m2-th active layer group are different; M is an integer greater than or equal to 2, m1 is an integer greater than or equal to 1 and less than or equal to M, m2 is an integer greater than or equal to 1 and less than or equal to M, and m1 is not equal to m2.

[0006] Optionally, for different m1-th active layer groups and m2-th active layer groups, the thicknesses along the first direction of at least one m-th barrier layer in the m1-th active layer group and the thicknesses along the first direction of each m-th barrier layer in the m2-th active layer group are different, and the thicknesses along the first direction of at least one m-th well layer in the m1-th active layer group and the thicknesses along the first direction of each m-th well layer in the m2-th active layer group are different; M is an integer greater than or equal to 2, m1 is an integer greater than or equal to 1 and less than or equal to M, m2 is an integer greater than or equal to 1 and less than or equal to M, and m1 is not equal to m2.

[0007] Optionally, 0.53 ≤ y < 1, 0 < x ≤ 0.52.

[0008] Optionally, the thickness of any m-th barrier layer is 0.1 nm to 100 nm; the thickness of any m-th well layer is 0.1 nm to 100 nm.

[0009] Optionally, the thickness of each first type of m-th sub-well layer is greater than 0.5 monolayers, and the thickness of each second type of m-th sub-well layer is greater than 0.5 monolayers.

[0010] Optionally, the thickness of the m-th sub-barrier layer of the first type in each layer is greater than 0.5 monolayers, and the thickness of the m-th sub-barrier layer of the second type in each layer is greater than 0.5 monolayers.

[0011] The present application also provides a method for preparing a quantum cascade light-emitting structure, including: forming an active layer; wherein, forming the active layer includes: forming a first active layer group to an M-th active layer group stacked along a first direction, any m-th active layer group having a superlattice structure and including a plurality of m-th active layer units stacked along the first direction, any m-th active layer unit including an m-th barrier layer and an m-th well layer stacked alternately along the first direction; the equivalent material of any m-th barrier layer is In x Al 1-x As, the equivalent material of any m-th well layer is In y Ga 1-y As; M is an integer greater than or equal to 1, and m is an integer greater than or equal to 1 and less than or equal to M; wherein, at least two barrier layers in each active layer unit in at least one active layer group have different x values; and / or, at least two well layers in each active layer unit in at least one active layer group have different y values; wherein, forming any m-th well layer includes: forming a first type of m-th sub-well layer and a second type of m-th sub-well layer stacked alternately along the first direction, the second type of m-th sub-well layer being located between adjacent first type of m-th sub-well layers, the material of the first type of m-th sub-well layer being In y1 Ga 1-y1 As, the material of the second type of m-th sub-well layer being InAs; wherein, forming any m-th barrier layer includes: forming a first type of m-th sub-barrier layer and a second type of m-th sub-barrier layer stacked alternately along the first direction, the second type of m-th sub-barrier layer being located between adjacent first type of m-th sub-barrier layers; the material of the first type of m-th sub-barrier layer being In x1 Al 1-x1 As, the material of the second type of m-th sub-barrier layer being AlAs.

[0012] Optionally, forming a first type of m-th sub-well layer and a second type of m-th sub-well layer stacked alternately along the first direction includes: obtaining the designed thickness of the m-th well layer as p monolayers; obtaining the total designed thickness of the first basic epitaxial layer as p*y monolayers, and obtaining the total designed thickness of the second basic epitaxial layer as p*(1 - y) monolayers; the material of the first basic epitaxial layer being InAs, and the material of the second basic epitaxial layer being GaAs; obtaining the designed growth rate of the first basic epitaxial layer as r 1 monolayers / s, and obtaining the designed growth rate of the second basic epitaxial layer as r 2individual monolayer / s; Obtain the total designed growth time t of the first basic epitaxial layer according to the designed growth rate of the first basic epitaxial layer and the total designed thickness of the first basic epitaxial layer 1 =(p*y / r 1 )s; Obtain the total designed growth time t of the second basic epitaxial layer according to the designed growth rate of the second basic epitaxial layer and the total designed thickness of the second basic epitaxial layer 2 =(p*(1 - y) / r 2 )s, where t 1 is greater than t 2 ; Divide the second basic epitaxial layer into the first to the nth 1 second sub - basic epitaxial layers; n 1 is an integer greater than or equal to 2; During the continuous growth of the first basic epitaxial layer within the growth time t 3 , the first to the nth 3 second sub - basic epitaxial layers are grown at intervals within the growth time t 1 , t 3 =t 1 , and the growth time of each second sub - basic epitaxial layer is t 2 / n 1 ; The interval time t s between the growth of adjacent second sub - basic epitaxial layers=(t 3 -t 2 ) / (n 1 -1); Within t 2 / n 1 , the second sub - basic epitaxial layer and the first basic epitaxial layer react to form the mth sub - potential well layer of the first type; Within the interval time t s , the first basic epitaxial layer forms the mth sub - potential well layer of the second type.

[0013] Optionally, the value range of p is 1 to 400.

[0014] Optionally, t s *r 1 is greater than 0.5 individual monolayer; (r 1 +r 2 )*t 2 / n 1 is greater than 0.5 individual monolayer; n 1 .

[0015] Optionally, a first type of m-th sub-barrier layer and a second type of m-th sub-barrier layer are formed by alternately stacking along a first direction, including: obtaining a designed thickness of the m-th barrier layer as q monolayers; obtaining a total designed thickness of the third basic epitaxial layer as q*x monolayers, and obtaining a total designed thickness of the fourth basic epitaxial layer as q*(1 - x) monolayers; the material of the third basic epitaxial layer is InAs, and the material of the fourth basic epitaxial layer is AlAs; obtaining a designed growth rate of the third basic epitaxial layer as r 3 monolayers / s, and obtaining a designed growth rate of the fourth basic epitaxial layer as r 4 monolayers / s; obtaining a total designed growth time t 4 =(q*x / r 3 ) s for the third basic epitaxial layer according to the designed growth rate and the total designed thickness of the third basic epitaxial layer; obtaining a total designed growth time t 5 =(q*(1 - x) / r 4 ) s for the fourth basic epitaxial layer according to the designed growth rate and the total designed thickness of the fourth basic epitaxial layer, where t 5 is greater than t 4 ; dividing the third basic epitaxial layer into the first to the n 2 th third sub-basic epitaxial layers; n 2 is an integer greater than or equal to 2; during the continuous growth of the fourth basic epitaxial layer within the growth time t 6 , the first to the n 6 th third sub-basic epitaxial layers are grown at intervals within the growth time t 2 , t 6 =t 5 , and the growth time of each third sub-basic epitaxial layer is t 4 / n 2 ; the interval time t s ’ =(t 6 -t 4 ) / (n 2 -1) for growing adjacent third sub-basic epitaxial layers; within t 4 / n 2 , the third sub-basic epitaxial layer and the fourth basic epitaxial layer react to form a first type of m-th sub-barrier layer; within the interval time t s ’ , the fourth basic epitaxial layer forms a second type of m-th sub-barrier layer.

[0016] Optionally, the value range of q is 1 to 400.

[0017] Optionally, t s ’ *r4 Greater than 0.5 monolayers; (r 3 +r 4 )*t 4 / n 2 Greater than 0.5 monolayers; n 2 2r 4 *(t 5 -t 4 )+1。

[0018] Optionally, the y of the a-th m-th potential well layer in each m-th active layer unit in the m-th active layer group is different from the y in the b-th m-th potential well layer, where a is an integer greater than or equal to 1, b is an integer greater than or equal to 1, and a is not equal to b; during the formation of the a-th m-th potential well layer, the As source furnace, the first In source furnace, and the first Ga source furnace in the reaction chamber are used; during the formation of the b-th m-th potential well layer, the As source furnace, the first In source furnace, and the first Ga source furnace in the reaction chamber are used.

[0019] Optionally, the x of the a-th m-th potential barrier layer in any one m-th active layer unit in the m-th active layer group is different from the x in the b-th m-th potential barrier layer, where a is an integer greater than or equal to 1, b is an integer greater than or equal to 1, and a is not equal to b; during the formation of the a-th m-th potential barrier layer, the As source furnace, the second In source furnace, and the first Al source furnace in the reaction chamber are used; during the formation of the b-th m-th potential barrier layer, the As source furnace, the second In source furnace, and the first Al source furnace in the reaction chamber are used.

[0020] The technical solution of the present invention has the following beneficial effects: The quantum cascade light-emitting structure provided by the technical solution of the present invention has at least two potential barrier layers with different x values in each active layer unit of at least one active layer group; and / or, at least two potential well layers with different y values in each active layer unit of at least one active layer group. By designing the values of x and y to adjust the lasing wavelength of any m-th active layer group, the lasing wavelength of any m-th active layer group can be selected within a large wavelength range. The optional range of the lasing wavelength of any m-th active layer group is expanded. And any m-th potential well layer includes a first type of m-th sub-potential well layer and a second type of m-th sub-potential well layer alternately stacked along the first direction, and the first type of m-th sub-potential well layer and the second type of m-th sub-potential well layer are alternately stacked to be equivalent to the m-th potential well layer, and any m-th potential barrier layer includes a first type of m-th sub-potential barrier layer and a second type of m-th sub-potential barrier layer alternately stacked along the first direction, and the first type of m-th sub-potential barrier layer and the second type of m-th sub-potential barrier layer are alternately stacked to be equivalent to the m-th potential barrier layer. In this way, the difficulty of the preparation process is reduced. Description of the Drawings

[0021] To more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the following will briefly introduce the drawings required for the description of the specific embodiments or the prior art. Obviously, the drawings in the following description are some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can also be obtained based on these drawings.

[0022] Figure 1 Structural diagram of a quantum cascade light-emitting structure according to an embodiment of the present application; Figure 2 Timing diagram for forming the m-th sub-well layer of the first type and the m-th sub-well layer of the second type in an embodiment of the present application; Figure 3 Forming the m-th sub-barrier layer of the first type and the m-th sub-barrier layer of the second type in an embodiment of the present application. Specific embodiments

[0023] It has been found through research that in the related art, for the active regions of high-performance mid-wave infrared and long-wave infrared quantum cascade lasers, a strain compensation design is adopted, using a multi-period In y Ga 1-y As / In x Al 1-x As multi-quantum well structure as the active region structure of the quantum cascade laser. Each period contains dozens of In y Ga 1-y As / In x Al 1-x As alternating layers, where the tensile stress and compressive stress between adjacent layers partially cancel each other out, and the overall strain of a single-period In y Ga 1-y As / In x Al 1-x As superlattice structure is generally less than 200 arcsec. By designing the In composition y of In y Ga 1-y As, the In composition x of In x Al 1-x As, and the thickness of each layer within a single period, the active region structure of a quantum cascade laser with a certain wavelength can be obtained. Although adjusting the thickness of each layer within a single period can adjust the designed lasing wavelength of the quantum cascade laser within a certain range, it is difficult to obtain a change in the designed lasing wavelength within a large wavelength range.

[0024] On this basis, the present application provides a quantum cascade light-emitting structure and a preparation method thereof, which can obtain a large wavelength adjustment range.

[0025] The technical solution of the present invention will be described clearly and completely below in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0026] In the description of the present invention, it should be noted that the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer", etc., indicating the orientation or positional relationship, are based on the orientation or positional relationship shown in the drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as limiting the present invention. In addition, the terms "first", "second", and "third" are used for descriptive purposes only, and cannot be understood as indicating or implying relative importance.

[0027] In addition, the technical features involved in the different embodiments of the present invention described below can be combined with each other as long as they do not conflict with each other.

[0028] An embodiment of the present invention provides a quantum cascade light emitting structure, referring to Figure 1 , including: an active layer 130 .

[0029] refer to Figure 1 The quantum cascade light emitting structure further includes: a first confinement layer 110; a first waveguide layer 120 located on one side of the first confinement layer 110 along the first direction; wherein the active layer 130 is located on the side of the first waveguide layer 120 away from the first confinement layer 110 along the first direction. The quantum cascade light emitting structure further includes: a second waveguide layer 140 located on the side of the active layer 130 away from the first waveguide layer 120 along the first direction; and a second confinement layer 150 located on the side of the second waveguide layer 140 away from the active layer 130 along the first direction.

[0030] The quantum cascade light emitting structure may further include: a substrate layer 100 located on a side of the first confinement layer 110 away from the first waveguide layer 120 .

[0031] The active layer includes a first active layer group to an Mth active layer group stacked along a first direction, any mth active layer group presents a superlattice structure and includes a plurality of mth active layer units stacked along the first direction, and any mth active layer unit includes an mth barrier layer and an mth potential well layer alternately stacked along the first direction; and the equivalent material of any mth barrier layer is In x Al 1-x As, the equivalent material of any mth potential well layer is In y Ga 1-yAs; M is an integer greater than or equal to 1, and m is an integer greater than or equal to 1 and less than or equal to M; wherein, x of at least two barrier layers in each active layer unit of at least one active layer group is different; and / or, y of at least two well layers in each active layer unit of at least one active layer group is different.

[0032] Wherein, any m-th well layer includes a first-type m-th sub-well layer and a second-type m-th sub-well layer alternately stacked along a first direction, the second-type m-th sub-well layer is located between adjacent first-type m-th sub-well layers, and the material of the first-type m-th sub-well layer is In y1 Ga 1-y1 As, and the material of the second-type m-th sub-well layer is InAs; any m-th barrier layer includes a first-type m-th sub-barrier layer and a second-type m-th sub-barrier layer alternately stacked along the first direction, the second-type m-th sub-barrier layer is located between adjacent first-type m-th sub-barrier layers; the material of the first-type m-th sub-barrier layer is In x1 Al 1-x1 As, and the material of the second-type m-th sub-barrier layer is AlAs.

[0033] In this embodiment, x of at least two barrier layers in each active layer unit of at least one active layer group is different; and / or, y of at least two well layers in each active layer unit of at least one active layer group is different. By designing the values of x and y to adjust the lasing wavelength of any m-th active layer group, the lasing wavelength of any m-th active layer group can be selected within a large wavelength range. The selectable range of the lasing wavelength of any m-th active layer group is expanded. The flexibility of the quantum cascade light-emitting structure design is extended. The first-type m-th sub-well layer and the second-type m-th sub-well layer are alternately stacked to be equivalent to the m-th well layer, and the first-type m-th sub-barrier layer and the second-type m-th sub-barrier layer are alternately stacked to be equivalent to the m-th barrier layer. In this way, the difficulty of the preparation process is reduced.

[0034] In this embodiment, any m-th active layer group has a superlattice structure and includes a plurality of m-th active layer units stacked along a first direction. In any m-th active layer group, the m-th active layer units are repeatedly arranged in plurality along the first direction, so that any m-th active layer group has a superlattice structure. In any m-th active layer unit, the m-th active layer unit includes a plurality of m-th barrier layers and a plurality of m-th well layers, and the m-th barrier layer and the m-th well layer are alternately stacked along the first direction.

[0035] In one embodiment, in any m-th active layer unit, the thicknesses of multiple m-th barrier layers are the same, and the thicknesses of multiple m-th well layers are the same. By designing that at least two m-th barrier layers have different x values and / or at least two m-th well layers have different y values in any m-th active layer unit, any m-th active layer group emits light of a certain wavelength. Specifically, it can be that in any m-th active layer unit, all m-th barrier layers have different x values and / or all m-th well layers have different y values. It can also be that in any m-th active layer unit, a partial number of m-th barrier layers have different x values. It can also be that in any m-th active layer unit, a partial number of m-th well layers have different y values.

[0036] In one embodiment, in any m-th active layer unit, at least two m-th barrier layers have different thicknesses, and at least two m-th well layers have different thicknesses. By designing that at least two m-th barrier layers have different x values and / or at least two m-th well layers have different y values, at least two m-th barrier layers have different thicknesses, and at least two m-th well layers have different thicknesses in any m-th active layer unit, any m-th active layer group emits light of a certain wavelength. By designing any m-th active layer group in terms of thickness and composition, the optional range of the lasing wavelength of any m-th active layer group is further expanded. Specifically, it can be that in any m-th active layer unit, a partial number of m-th barrier layers have different thicknesses, and a partial number of m-th well layers have different thicknesses. It can also be that in any m-th active layer unit, a partial number of m-th barrier layers have different thicknesses, and all m-th well layers have different thicknesses. Specifically, it can be that in any m-th active layer unit, all m-th barrier layers have different x values and / or all m-th well layers have different y values. It can also be that in any m-th active layer unit, a partial number of m-th barrier layers have different x values. It can also be that in any m-th active layer unit, a partial number of m-th well layers have different y values.

[0037] In one embodiment, the active layer includes a first active layer group to an M-th active layer group stacked in a first direction. When M is greater than or equal to 2, different active layer groups emit different wavelengths. Correspondingly, the quantum cascade light-emitting structure is a multi-wavelength quantum cascade light-emitting structure.

[0038] In one embodiment, for different m1-th active layer groups and m2-th active layer groups, x in at least one m-th barrier layer in the m1-th active layer group is different from x in each m-th barrier layer in the m2-th active layer group, and y in at least one m-th well layer in the m1-th active layer group is different from y in each m-th well layer in the m2-th active layer group; M is an integer greater than or equal to 2, m1 is an integer greater than or equal to 1 and less than or equal to M, and m2 is an integer greater than or equal to 1 and less than or equal to M. m1 is not equal to m2. It can be that, for different m1-th active layer groups and m2-th active layer groups, x in a partial number of m-th barrier layers in the m1-th active layer group is different from x in each m-th barrier layer in the m2-th active layer group, or x in all the m-th barrier layers in the m1-th active layer group is different from x in each m-th barrier layer in the m2-th active layer group. It can be that, for different m1-th active layer groups and m2-th active layer groups, y in a partial number of m-th well layers in the m1-th active layer group is different from y in each m-th well layer in the m2-th active layer group, or y in all the m-th well layers in the m1-th active layer group is different from y in each m-th well layer in the m2-th active layer group.

[0039] In one embodiment, for different m1-th active layer groups and m2-th active layer groups, the thicknesses along a first direction of at least one m-th barrier layer in the m1-th active layer group are different from the thicknesses along the first direction of each m-th barrier layer in the m2-th active layer group, and the thicknesses along the first direction of at least one m-th well layer in the m1-th active layer group are different from the thicknesses along the first direction of each m-th well layer in the m2-th active layer group; M is an integer greater than or equal to 2, m1 is an integer greater than or equal to 1 and less than or equal to M, m2 is an integer greater than or equal to 1 and less than or equal to M, and m1 is not equal to m2. It can be that, for different m1-th active layer groups and m2-th active layer groups, the thicknesses along the first direction of a partial number of m-th barrier layers in the m1-th active layer group are different from the thicknesses along the first direction of each m-th barrier layer in the m2-th active layer group, or the thicknesses along the first direction of all the m-th barrier layers in the m1-th active layer group are different from the thicknesses along the first direction of each m-th barrier layer in the m2-th active layer group. It can be that, for different m1-th active layer groups and m2-th active layer groups, the thicknesses along the first direction of a partial number of m-th well layers in the m1-th active layer group are different from the thicknesses along the first direction of each m-th well layer in the m2-th active layer group, or the thicknesses along the first direction of all the m-th well layers in the m1-th active layer group are different from the thicknesses along the first direction of each m-th well layer in the m2-th active layer group.

[0040] In one embodiment, 0 < y < 1 and 0 < x < 1.

[0041] In one embodiment, 0.53 ≤ y < 1 and 0 < x ≤ 0.52. In other embodiments, the values of y and the values of x can also be other numerical values.

[0042] In one embodiment, the thickness of any m-th barrier layer is 0.1 nm to 100 nm, such as 0.1 nm, 0.5 nm, 1 nm, 10 nm, 20 nm, 30 nm, 40 nm, 50 nm, 60 nm, 70 nm, 80 nm, 90 nm or 100 nm. Preferably, the thickness of any m-th barrier layer is 0.1 nm to 10 nm; the thickness of any m-th well layer is 0.1 nm to 100 nm, such as 0.1 nm, 0.5 nm, 1 nm, 10 nm, 20 nm, 30 nm, 40 nm, 50 nm, 60 nm, 70 nm, 80 nm, 90 nm or 100 nm. Preferably, the thickness of any m-th well layer is 0.1 nm to 10 nm.

[0043] In one embodiment, any m-th well layer includes a first type of m-th sub-well layer and a second type of m-th sub-well layer that are alternately stacked in a first direction. The second type of m-th sub-well layer is located between adjacent first type of m-th sub-well layers. The first type of m-th sub-well layer is a ternary layer, and the second type of m-th sub-well layer is a binary layer; the material of the first type of m-th sub-well layer is In y1 Ga 1-y1 As, and the material of the second type of m-th sub-well layer is InAs.

[0044] In one embodiment, the thickness of each first type of m-th sub-well layer is greater than 0.5 monolayers. It should be noted that the monolayer here refers to one layer of atoms of the first type of m-th sub-well layer in the first direction. The thickness of each second type of m-th sub-well layer is greater than 0.5 monolayers. It should be noted that the monolayer here refers to one layer of atoms of the second type of m-th sub-well layer in the first direction.

[0045] The material of the first type of m-th sub-well layer is In y1 Ga 1-y1 As, and the material of the second type of m-th sub-well layer is InAs. The total thickness of multiple first type of m-th sub-well layers in any m-th well layer is L 1 monolayers. The monolayer here refers to one layer of atoms of the first type of m-th sub-well layer in the first direction. The total thickness of multiple second type of m-th sub-well layers in any m-th well layer is L 2 monolayers. The monolayer here refers to one layer of atoms of the second type of m-th sub-well layer in the first direction. The equivalent material of the m-th well layer is In y Ga 1-y As, and the thickness of the m-th well layer is L monolayers. The monolayer here refers to one layer of atoms of the equivalent material of the m-th well layer in the first direction. Then there is y 1 *L1 +L 2 =y*L;(1–y 1 )*L 1 =(1 - y)*L。

[0046] In one embodiment, any m-th barrier layer includes a first type of m-th sub-barrier layer and a second type of m-th sub-barrier layer that are alternately stacked along a first direction, and the second type of m-th sub-barrier layer is located between adjacent first type of m-th sub-barrier layers; the first type of m-th sub-barrier layer is a ternary layer, and the second type of m-th sub-barrier layer is a binary layer; the material of the first type of m-th sub-barrier layer is In x1 Al 1-x1 As, and the material of the second type of m-th sub-barrier layer is AlAs.

[0047] In one embodiment, the thickness of each first type of m-th sub-barrier layer is greater than 0.5 monolayers. It should be noted that the monolayer here refers to one layer of atoms of the first type of m-th sub-barrier layer in the first direction. The thickness of each second type of m-th sub-barrier layer is greater than 0.5 monolayers. It should be noted that the monolayer here refers to one layer of atoms of the second type of m-th sub-barrier layer in the first direction.

[0048] The material of the first type of m-th sub-barrier layer is In x1 Al 1-x1 As, and the material of the second type of m-th sub-barrier layer is AlAs. The total thickness of multiple first type of m-th sub-barrier layers in any m-th barrier layer is K 1 monolayers, where the monolayer here refers to one layer of atoms of the first type of m-th sub-barrier layer in the first direction. The total thickness of multiple second type of m-th sub-barrier layers in any m-th barrier layer is K 2 monolayers, where the monolayer here refers to one layer of atoms of the second type of m-th sub-barrier layer in the first direction. The equivalent material of the m-th barrier layer is In x Al 1-x As, and the thickness of the m-th barrier layer is K monolayers, where the monolayer here refers to one layer of atoms of the equivalent material of the m-th barrier layer in the first direction. Then there is (1 - x 1 )*K 1 +K 2 = (1 - x)*K; x 1 *K 1 = x*K.

[0049] On the other hand, the present application also provides a method for preparing a quantum cascade light-emitting structure, including: forming an active layer; wherein, forming the active layer includes: forming a first active layer group to an Mth active layer group stacked along a first direction, any mth active layer group having a superlattice structure and including a plurality of mth active layer units stacked along the first direction, any mth active layer unit including an mth barrier layer and an mth well layer stacked alternately along the first direction; the equivalent material of any mth barrier layer is In x Al 1- x As, and the equivalent material of any mth well layer is In y Ga 1-y As; M is an integer greater than or equal to 1, and m is an integer greater than or equal to 1 and less than or equal to M; wherein, the x of at least two barrier layers in each active layer unit in at least one active layer group is different; and / or, the y of at least two well layers in each active layer unit in at least one active layer group is different; Wherein, forming any mth well layer includes: forming a first type of mth sub-well layer and a second type of mth sub-well layer stacked alternately along the first direction, the second type of mth sub-well layer being located between adjacent first type of mth sub-well layers, and the material of the first type of mth sub-well layer being In y1 Ga 1-y1 As, and the material of the second type of mth sub-well layer being InAs; Wherein, forming any mth barrier layer includes: forming a first type of mth sub-barrier layer and a second type of mth sub-barrier layer stacked alternately along the first direction, the second type of mth sub-barrier layer being located between adjacent first type of mth sub-barrier layers; the material of the first type of mth sub-barrier layer being In x1 Al 1-x1 As, and the material of the second type of mth sub-barrier layer being AlAs.

[0050] In this embodiment, the method for preparing the quantum cascade light-emitting structure further includes: forming a first confinement layer on one side of the substrate layer along the first direction; forming a first waveguide layer on the side of the first confinement layer facing away from the substrate layer; wherein, forming the active layer includes: forming the active layer on the side of the first waveguide layer facing away from the first confinement layer. The method for preparing the quantum cascade light-emitting structure further includes: forming a second waveguide layer on the side of the active layer facing away from the first waveguide layer; forming a second confinement layer on the side of the second waveguide layer facing away from the active layer.

[0051] In this embodiment, any m-th active layer group has a superlattice structure and includes a plurality of m-th active layer units stacked along a first direction. In any m-th active layer group, the m-th active layer units are repeatedly arranged in plurality along the first direction, so that any m-th active layer group has a superlattice structure. In any m-th active layer unit, the m-th active layer unit includes a plurality of m-th barrier layers and a plurality of m-th well layers, and the m-th barrier layers and the m-th well layers are alternately stacked along the first direction.

[0052] In one embodiment, in any m-th active layer unit, the plurality of m-th barrier layers have the same thickness, and the plurality of m-th well layers have the same thickness.

[0053] In one embodiment, in any m-th active layer unit, at least two of the m-th barrier layers have different thicknesses, and at least two of the m-th well layers have different thicknesses.

[0054] In one embodiment, the active layer includes a first active layer group to an M-th active layer group stacked along the first direction. When M is greater than or equal to 2, different active layer groups emit different wavelengths. Correspondingly, the quantum cascade light emitting structure is a multi-wavelength quantum cascade light emitting structure.

[0055] In one embodiment, for different m1-th active layer groups and m2-th active layer groups, x in at least one m-th barrier layer in the m1-th active layer group is different from x in each m-th barrier layer in the m2-th active layer group, and y in at least one m-th well layer in the m1-th active layer group is different from y in each m-th well layer in the m2-th active layer group; M is greater than or equal to 2, m1 is an integer greater than or equal to 1 and less than or equal to M, and m2 is an integer greater than or equal to 1 and less than or equal to M. m1 is not equal to m2.

[0056] In one embodiment, for different m1-th active layer groups and m2-th active layer groups, the thicknesses along the first direction of at least one m-th barrier layer in the m1-th active layer group are different from the thicknesses along the first direction of each m-th barrier layer in the m2-th active layer group, and the thicknesses along the first direction of at least one m-th well layer in the m1-th active layer group are different from the thicknesses along the first direction of each m-th well layer in the m2-th active layer group; M is greater than or equal to 2, m1 is an integer greater than or equal to 1 and less than or equal to M, m2 is an integer greater than or equal to 1 and less than or equal to M, and m1 is not equal to m2.

[0057] In one embodiment, forming any m-th well layer includes: forming a first type of m-th sub-well layer and a second type of m-th sub-well layer alternately stacked along the first direction, the second type of m-th sub-well layer being located between adjacent first type of m-th sub-well layers, the first type of m-th sub-well layer being a ternary layer, and the second type of m-th sub-well layer being a binary layer; the material of the first type of m-th sub-well layer is In y1 Ga 1-y1As, the material of the m-th sub-potential well layer of the second type is InAs.

[0058] In one embodiment, forming the m-th sub-potential well layer of the first type and the m-th sub-potential well layer of the second type that are alternately stacked along the first direction includes: obtaining that the designed thickness of the m-th potential well layer is p single atomic layers, where the single atomic layer refers to one layer of atoms of the equivalent material of the m-th potential well layer in the first direction; obtaining that the total designed thickness of the first basic epitaxial layer is p*y single atomic layers, where the single atomic layer refers to one layer of atoms of the first basic epitaxial layer in the first direction; obtaining that the total designed thickness of the second basic epitaxial layer is p*(1 - y) single atomic layers, where the single atomic layer refers to one layer of atoms of the second basic epitaxial layer in the first direction; the material of the first basic epitaxial layer is InAs, and the material of the second basic epitaxial layer is GaAs; obtaining that the designed growth rate of the first basic epitaxial layer is r 1 single atomic layers / s, where the single atomic layer refers to one layer of atoms of the first basic epitaxial layer in the first direction; obtaining that the designed growth rate of the second basic epitaxial layer is r 2 single atomic layers / s, where the single atomic layer refers to one layer of atoms of the second basic epitaxial layer in the first direction; obtaining the total designed growth time t 1 =(p*y / r 1 ) s; obtaining the total designed growth time t 2 =(p*(1 - y) / r 2 ) s, where t 1 is greater than t 2 ; dividing the second basic epitaxial layer into the first to the n 1 th second sub-basic epitaxial layers; n 1 is an integer greater than or equal to 2; during the continuous growth of the first basic epitaxial layer within the growth time t 3 , within the growth time t 3 , the first to the n 1 th second sub-basic epitaxial layers are grown at intervals, t 3 =t 1 , and the growth time of each second sub-basic epitaxial layer is t 2 / n 1 ; the interval time t s =(t 3 -t 2 ) / (n 1 -1); within t 2 / n 1The second sub-basic epitaxial layer and the first basic epitaxial layer react to form the m-th sub-potential well layer of the first type; at the interval time t s The first basic epitaxial layer forms the m-th sub-potential well layer of the second type.

[0059] The starting time of the growth of the first portion of the second sub-basic epitaxial layer is the same as the starting time of the growth of the first basic epitaxial layer, and the ending time of the growth of the n-th 1 portion of the second sub-basic epitaxial layer is the same as the ending time of the growth of the first basic epitaxial layer. This avoids excessive lattice mismatch at the interface between the m-th sub-potential well layer of the first type and the m-th barrier layer, and reduces the possibility of local relaxation.

[0060] In one embodiment, the value range of p is 1 to 400, such as 1, 10, 20, 30, 50, 80, 100, 200, 300 or 400. Preferably, the value range of p is 1 to 30.

[0061] In one embodiment, t s *r 1 is greater than 0.5 monolayers. Here, the monolayer refers to one layer of atoms of the m-th sub-potential well layer of the second type in the first direction; (r 1 +r 2 )*t 2 / n 1 is greater than 0.5 monolayers. Here, the monolayer refers to one layer of atoms of the m-th sub-potential well layer of the first type in the first direction; n 1 .

[0062] n 1 =(t 3 -t 2 ) / t s +1.

[0063] Wherein, y 1 =r 1 / (r 1 +r 2 ). The thickness of each m-th sub-potential well layer of the first type is (r 1 +r 2 )*t 2 / n 1 . The thickness of each m-th sub-potential well layer of the second type is t s *r 1 .

[0064] In this embodiment, the x values of at least two barrier layers in each active layer unit of at least one active layer group are different; and / or, the y values of at least two well layers in each active layer unit of at least one active layer group are different. Any m-th well layer includes: a first type of m-th sub-well layer and a second type of m-th sub-well layer alternately stacked in a first direction, the second type of m-th sub-well layer is located between adjacent first type of m-th sub-well layers, the first type of m-th sub-well layer is a ternary layer, and the second type of m-th sub-well layer is a binary layer; the material of the first type of m-th sub-well layer is In y1 Ga 1-y1 As, and the material of the second type of m-th sub-well layer is InAs. Correspondingly, during the continuous growth of the first basic epitaxial layer within the growth time t 3 inside, the first to n 3 th second sub-basic epitaxial layers are grown at intervals within the growth time t 1 to form the first type of m-th sub-well layer and the second type of m-th sub-well layer.

[0065] In at least two potential well layers in each active layer unit of at least one active layer group is different in the y direction. For example, in the m-th active layer group, the y value of the a-th m-th potential well layer in each m-th active layer unit is different from the y value of the b-th m-th potential well layer. Here, a is an integer greater than or equal to 1, b is an integer greater than or equal to 1, and a is not equal to b. During the formation of the a-th m-th potential well layer, an As source furnace, a first In source furnace, and a first Ga source furnace in the reaction chamber are used. In atoms emitted by the first In source furnace react with As atoms emitted by the As source furnace to form a first basic epitaxial layer, and Ga atoms emitted by the first Ga source furnace react with As atoms emitted by the As source furnace to form a second sub-basic epitaxial layer. The thickness of the first type of m-th sub-potential well layer is controlled by the growth time of the second sub-basic epitaxial layer, and the thickness of the second type of m-th sub-potential well layer is controlled by setting the interval time between adjacent second sub-basic epitaxial layers. In this way, multiple layers of the first type of m-th sub-potential well layer and multiple layers of the second sub-basic epitaxial layer are equivalent to the a-th m-th potential well layer. During the formation of the b-th m-th potential well layer, an As source furnace, a first In source furnace, and a first Ga source furnace in the reaction chamber are used. In atoms emitted by the first In source furnace react with As atoms emitted by the As source furnace to form a first basic epitaxial layer, and Ga atoms emitted by the first Ga source furnace react with As atoms emitted by the As source furnace to form a second sub-basic epitaxial layer. The thickness of the first type of m-th sub-potential well layer is controlled by the growth time of the second sub-basic epitaxial layer, and the thickness of the second type of m-th sub-potential well layer is controlled by setting the interval time between adjacent second sub-basic epitaxial layers. In this way, multiple layers of the first type of m-th sub-potential well layer and multiple layers of the second sub-basic epitaxial layer are equivalent to the b-th m-th potential well layer. The In composition in the a-th m-th potential well layer and the b-th m-th potential well layer is different, but the a-th m-th potential well layer and the b-th m-th potential well layer can share the As source furnace, the first In source furnace, and the first Ga source furnace, reducing the requirement for the number of source furnaces. In the case where the number of source furnaces is limited, the wavelength range of the multi-wavelength quantum cascade light-emitting structure that can be grown is increased.

[0066] In this embodiment, during the formation of the m-th potential well layer, the temperature of the As source furnace remains unchanged, the temperature of the first In source furnace remains unchanged, the temperature of the first Ga source furnace remains unchanged, the power of the As source furnace remains unchanged, the power of the first In source furnace remains unchanged, and the power of the first Ga source furnace remains unchanged to ensure the stability of the growth process. The equipment used for forming the m-th potential well layer is a molecular beam epitaxy equipment, and the process used for forming the m-th potential well layer is a molecular beam epitaxy process.

[0067] In the related art, the growth of In y Ga 1-yThe As source furnace, Ga source furnace, and In source furnace adopted emit As atoms, Ga atoms, and In atoms respectively within the same period of time. If the value of y changes, it is necessary to change the temperature of the Ga source furnace and / or In source furnace to change the beam currents of Ga atoms emitted by the Ga source furnace and In atoms emitted by the In source furnace. However, to change the temperature of the Ga source furnace and / or In source furnace, one way is to use different Ga source furnaces with different temperatures and different In source furnaces with different temperatures. However, this increases the number of source furnaces used. Another way is to adjust the temperature of the same Ga source furnace and the temperature of the same In source furnace. However, adjusting the temperature takes a certain amount of time and it is difficult to ensure the stability of the growth process.

[0068] In one embodiment, forming any m-th barrier layer includes: forming a first type of m-th sub-barrier layer and a second type of m-th sub-barrier layer that are alternately stacked along a first direction, and the second type of m-th sub-barrier layer is located between adjacent first type of m-th sub-barrier layers; the first type of m-th sub-barrier layer is a ternary layer, and the second type of m-th sub-barrier layer is a binary layer; the material of the first type of m-th sub-barrier layer is In x1 Al 1-x1 As, and the material of the second type of m-th sub-barrier layer is AlAs.

[0069] In one embodiment, forming a first type of m-th sub-barrier layer and a second type of m-th sub-barrier layer that are alternately stacked along a first direction includes: obtaining that the designed thickness of the m-th barrier layer is q monolayers of atoms, where the monolayer of atoms refers to one layer of atoms of the equivalent material of the m-th barrier layer in the first direction; obtaining that the total designed thickness of the third basic epitaxial layer is q*x monolayers of atoms, where the monolayer of atoms refers to one layer of atoms of the third basic epitaxial layer in the first direction; obtaining that the total designed thickness of the fourth basic epitaxial layer is q*(1 - x) monolayers of atoms, where the monolayer of atoms refers to one layer of atoms of the fourth basic epitaxial layer in the first direction; the material of the third basic epitaxial layer is InAs, and the material of the fourth basic epitaxial layer is AlAs; obtaining that the designed growth rate of the third basic epitaxial layer is r 3 monolayers of atoms / s, where the monolayer of atoms refers to one layer of atoms of the third basic epitaxial layer in the first direction; obtaining that the designed growth rate of the fourth basic epitaxial layer is r 4 monolayers of atoms / s, where the monolayer of atoms refers to one layer of atoms of the fourth basic epitaxial layer in the first direction; obtaining the total designed growth time t of the third basic epitaxial layer according to the designed growth rate of the third basic epitaxial layer and the total designed thickness of the third basic epitaxial layer 4 =(q*x / r 3)s; Obtain the total designed growth time t of the fourth basic epitaxial layer according to the designed growth rate of the fourth basic epitaxial layer and the total designed thickness of the fourth basic epitaxial layer 5 =(q * (1 - x) / r 4 )s, where t 5 is greater than t 4 ; Divide the third basic epitaxial layer into the first to the nth 2 portions of the third sub-basic epitaxial layer; n 2 is an integer greater than or equal to 2; During the continuous growth of the fourth basic epitaxial layer within the growth time t 6 , the first to the nth 6 portions of the third sub-basic epitaxial layer are grown at intervals within the growth time t 2 , t 6 =t 5 , and the growth time of each portion of the third sub-basic epitaxial layer is t 4 / n 2 ; The interval time t s ’ =(t 6 -t 4 ) / (n 2 -1); Within t 4 / n 2 , the third sub-basic epitaxial layer and the fourth basic epitaxial layer react to form the mth sub-barrier layer of the first type; During the interval time t s ’ the fourth basic epitaxial layer forms the mth sub-barrier layer of the second type.

[0070] The starting moment of the growth of the first portion of the third sub-basic epitaxial layer is the same as the starting moment of the growth of the fourth basic epitaxial layer, and the ending moment of the growth of the nth 2 portion of the third sub-basic epitaxial layer is the same as the ending moment of the growth of the fourth basic epitaxial layer. This avoids excessive lattice mismatch at the interface between the mth sub-barrier layer of the first type and the mth potential well layer, reducing the possibility of local relaxation. The existence of the mth sub-barrier layer of the second type is beneficial to raising the barrier of the mth barrier layer and suppressing the thermal escape of electrons.

[0071] In one embodiment, the value range of q is 1 to 400, such as 1, 10, 20, 30, 50, 80, 100, 200, 300, or 400. Preferably, the value range of q is 1 to 30.

[0072] In one embodiment, t s ’ *r 4 is greater than 0.5 monolayers. Here, the monolayer refers to a layer of atoms of the mth sub-barrier layer of the second type in the first direction; (r3 +r 4 )*t 4 / n 2 Greater than 0.5 monolayers, where the monolayer refers to a layer of atoms in the first direction of the m-th sub-barrier layer of the first type; n 2 2r 4 *(t 5 -t 4 ) + 1.

[0073] n 2 =(t 6 -t 4 ) / t s ’ + 1.

[0074] Wherein, x1 = r 3 / (r 3 + r 4 ). The thickness of each m-th sub-barrier layer of the first type is (r 3 + r 4 )*t 4 / n 2 . The thickness of each m-th sub-barrier layer of the second type is t s ’ *r 4 .

[0075] In this embodiment, the x of at least two barrier layers in each active layer unit of at least one active layer group is different; and / or, the y of at least two well layers in each active layer unit of at least one active layer group is different. Any m-th barrier layer includes: the m-th sub-barrier layer of the first type and the m-th sub-barrier layer of the second type alternately stacked along the first direction, the m-th sub-barrier layer of the second type is located between adjacent m-th sub-barrier layers of the first type, the material of the m-th sub-barrier layer of the first type is In x1 Al 1-x1 As, and the material of the m-th sub-barrier layer of the second type is AlAs. Correspondingly, during the continuous growth of the fourth basic epitaxial layer within the growth time t 6 , the first to n 6 th third sub-basic epitaxial layers are grown at intervals within the growth time t 2 , thereby forming the m-th sub-barrier layer of the first type and the m-th sub-barrier layer of the second type.

[0076] In at least one active layer group, the x values of at least two barrier layers in any one active layer unit are different. For example, in the m-th active layer group, the x value of the a-th m-th barrier layer in any one m-th active layer unit is different from the x value of the b-th m-th barrier layer. Here, a is an integer greater than or equal to 1, b is an integer greater than or equal to 1, and a is not equal to b. During the formation of the a-th m-th barrier layer, an As source furnace, a second In source furnace, and a first Al source furnace in the reaction chamber are used. In atoms emitted by the second In source furnace react with As atoms emitted by the As source furnace to form a third sub-basic epitaxial layer, and Al atoms emitted by the first Al source furnace react with As atoms emitted by the As source furnace to form a fourth basic epitaxial layer. The thickness of the first type of m-th sub-barrier layer is controlled by the growth time of the third sub-basic epitaxial layer, and the thickness of the second type of m-th sub-barrier layer is controlled by setting the interval time between adjacent third sub-basic epitaxial layers. In this way, multiple layers of the first type of m-th sub-barrier layer and multiple layers of the m-th sub-barrier layer are equivalent to the a-th m-th barrier layer. During the formation of the b-th m-th barrier layer, an As source furnace, a second In source furnace, and a first Al source furnace in the reaction chamber are used. In atoms emitted by the second In source furnace react with As atoms emitted by the As source furnace to form a third sub-basic epitaxial layer, and Al atoms emitted by the first Al source furnace react with As atoms emitted by the As source furnace to form a fourth basic epitaxial layer. The thickness of the first type of m-th sub-barrier layer is controlled by the growth time of the third sub-basic epitaxial layer, and the thickness of the second type of m-th sub-barrier layer is controlled by setting the interval time between adjacent third sub-basic epitaxial layers. In this way, multiple layers of the first type of m-th sub-barrier layer and multiple layers of the m-th sub-barrier layer are equivalent to the b-th m-th barrier layer. The In compositions in the a-th m-th barrier layer and the b-th m-th barrier layer are different, but the a-th m-th barrier layer and the b-th m-th barrier layer can share the As source furnace, the second In source furnace, and the first Al source furnace, reducing the requirement for the number of source furnaces. When the number of source furnaces is limited, the wavelength range of the multi-wavelength quantum cascade light-emitting structure that can be grown is increased.

[0077] In this embodiment, during the formation of the m-th barrier layer, the temperature of the As source furnace remains unchanged, the temperature of the second In source furnace remains unchanged, and the temperature of the first Al source furnace remains unchanged. The power of the As source furnace remains unchanged, the power of the second In source furnace remains unchanged, and the power of the first Al source furnace remains unchanged to ensure the stability of the growth process. The equipment used for forming the m-th barrier layer is a molecular beam epitaxy equipment, and the process used for forming the m-th barrier layer is a molecular beam epitaxy process.

[0078] Any m-th barrier layer and any m-th quantum well layer can share the same As source furnace during the growth process. This reduces the requirement for the number of source furnaces.

[0079] In one embodiment, the first In source furnace and the second In source furnace can be the same In source furnace, or: the first In source furnace and the second In source furnace are different In source furnaces.

[0080] In related technologies, when growing In x Al 1-x As, the As source furnace, Al source furnace, and In source furnace used emit As atoms, Al atoms, and In atoms respectively within the same time. If the value of x changes, it is necessary to change the temperature of the Al source furnace and / or In source furnace to change the beam currents of Al atoms emitted by the Al source furnace and In atoms emitted by the In source furnace. However, one way to change the temperature of the Al source furnace and / or In source furnace is to use different Al source furnaces with different temperatures and different In source furnaces with different temperatures. However, this increases the number of source furnaces used. Another way is to adjust the temperature of the same Al source furnace and the temperature of the same In source furnace. However, adjusting the temperature takes a certain amount of time, making it difficult to ensure the stability of the growth process.

[0081] In this embodiment, the preparation method of the quantum cascade light emitting structure has low verification requirements, can handle the growth of different quantum cascade light emitting structures through simple verification, reduces the verification cost, improves the verification efficiency, and has great industrial application value.

[0082] For the preparation method of the quantum cascade light emitting structure, it only requires pre-verifying the growth rates of the first basic epitaxial layer, the second substrate epitaxial layer, the third basic epitaxial layer, and the fourth basic epitaxial layer, and then it can grow the first active layer group to the Mth active layer group that can emit different wavelengths, without the need to verify the first active layer group to the Mth active layer group that emits different wavelengths separately, which improves the actual epitaxial production efficiency and reduces the cost. In addition, the preparation method of the quantum cascade light emitting structure of the present invention has a wide application range.

[0083] The materials of both the first basic epitaxial layer and the third basic epitaxial layer are InAs, and the designed growth rates of the first basic epitaxial layer and the third basic epitaxial layer are the same. Or, the designed growth rates of the first basic epitaxial layer and the third basic epitaxial layer are different.

[0084] In a specific embodiment, by way of example, an mth active layer unit includes an mth barrier layer and an mth well layer alternately stacked along the first direction. The equivalent material of the mth barrier layer is In 0.36 Al 0.64 As, and the equivalent material of the mth well layer is In 0.57 Ga 0.3As, the designed thickness of the m-th potential well layer is p monolayers of single atoms, which is 29 Å, approximately 9.83 monolayers of single atoms. The designed thickness of the m-th potential barrier layer is q monolayers of single atoms, which is 29 Å, approximately 10.10 monolayers of single atoms.

[0085] When the equivalent material of the m-th potential well layer is In 0.57 Ga 0.3 As, the total designed thickness of the first basic epitaxial layer is p*y monolayers of single atoms = 5.6 monolayers of single atoms, and the total designed thickness of the second basic epitaxial layer is p*(1 - y) monolayers of single atoms = 4.23 monolayers of single atoms. The designed growth rate of the first basic epitaxial layer is 0.5 monolayers of single atoms / s, and the designed growth rate of the second basic epitaxial layer is 0.5 monolayers of single atoms / s. The total designed growth time of the first basic epitaxial layer is t 1 =(p*y / r 1 ) s = 11.21 s, and the total designed growth time of the second basic epitaxial layer is t 2 =(p*(1 - y) / r 2 ) s = 8.45 s. t 1 is greater than t 2 . Let n 1 = 3, and the second basic epitaxial layer is divided into the first second sub-basic epitaxial layer, the second second sub-basic epitaxial layer, and the third second sub-basic epitaxial layer. t s =(t 3 - t 2 ) / (n 1 - 1) = 1.38 s. At the interval time t s , the m-th sub-potential well layer of the second type is formed. The thickness of each m-th sub-potential well layer of the second type is t s *r 1 = 0.69 monolayers of single atoms, and t s *r 1 is greater than 0.5 monolayers of single atoms. At t 2 / n 1 , the second sub-basic epitaxial layer and the first basic epitaxial layer react to form the m-th sub-potential well layer of the first type. t 2 / n 1 = 2.82 s. The thickness of each m-th sub-potential well layer of the first type is (r 1 + r 2 )*t 2 / n 1 = 2.82 monolayers of single atoms, and (r 1 + r 2 )*t 2 / n 1 is greater than 0.5 monolayers of single atoms.

[0086] When the equivalent material of the m-th potential barrier layer is In 0.36 Al0.64 As, the total designed thickness of the third basic epitaxial layer is q * x monolayers = 3.64 monolayers, the total designed thickness of the fourth basic epitaxial layer is q * (1 - x) monolayers = 6.46 monolayers, the designed growth rate of the third basic epitaxial layer is 0.5 monolayers / s, the designed growth rate of the fourth basic epitaxial layer is 0.5 monolayers / s, and the total designed growth time of the third basic epitaxial layer is t 4 =(q * x / r 3 ) s = 7.27 s, and the total designed growth time of the fourth basic epitaxial layer is t 5 =(q * (1 - x) / r 4 ) s = 12.93 s. t 5 is greater than t 4 . Let n 2 = 4, and divide the third basic epitaxial layer into the first sub-third basic epitaxial layer, the second sub-third basic epitaxial layer, the third sub-third basic epitaxial layer, and the fourth sub-third basic epitaxial layer. t s ’ =(t 6 - t 4 ) / (n 2 - 1) = 1.41 s. At the interval time t s ’ a second-type m-th sub-barrier layer is formed, and the thickness t s ’ * r 4 of each second-type m-th sub-barrier layer is 0.94 monolayers, and t s ’ * r 4 is greater than 0.5 monolayers. At t 4 / n 2 the third sub-basic epitaxial layer and the fourth basic epitaxial layer react to form a first-type m-th sub-barrier layer, t 4 / n 2 = 1.82 s, and the thickness of each first-type m-th sub-barrier layer is (r 3 + r 4 ) * t 4 / n 2 = 1.82 monolayers, and (r 3 + r 4 ) * t 4 / n 2 is greater than 0.5 monolayers.

[0087] Obviously, the above embodiments are merely examples for clear illustration and not limitations on the implementation manners. For those of ordinary skill in the art, other different forms of changes or modifications can be made based on the above description. It is not necessary and impossible to enumerate all the implementation manners here. And the obvious changes or modifications derived therefrom still fall within the protection scope of the present invention.

Claims

1. A quantum cascade luminescence structure, characterized in that: include: Active layer; The active layer includes a first active layer group to an Mth active layer group stacked along a first direction, any mth active layer group presents a superlattice structure and includes a plurality of mth active layer units stacked along the first direction, and any mth active layer unit includes an mth barrier layer and an mth potential well layer alternately stacked along the first direction; and the equivalent material of any mth barrier layer is In x Al 1-x As, the equivalent material of any mth potential well layer is In y Ga 1-y As; M is an integer greater than or equal to 1, and m is an integer greater than or equal to 1 and less than or equal to M; Wherein, x of at least two potential barrier layers in each active layer unit in at least one active layer group is different; and / or y of at least two potential well layers in each active layer unit in at least one active layer group is different; Wherein, any m-th potential well layer comprises a first type m-th potential well layer and a second type m-th potential well layer alternately stacked along a first direction, the second type m-th potential well layer is located between adjacent first type m-th potential well layers, and the material of the first type m-th potential well layer is In y1 Ga 1-y1 As, the material of the mth potential well layer of the second type is InAs; any mth barrier layer includes the mth sub-barrier layer of the first type and the mth sub-barrier layer of the second type alternately stacked along the first direction, and the mth sub-barrier layer of the second type is located between adjacent mth sub-barrier layers of the first type; the material of the mth sub-barrier layer of the first type is InAs x1 Al 1-x1 As, the material of the second type m-th sub-barrier layer is AlAs.

2. The quantum cascade light emitting structure according to claim 1, characterized in that: For different m1-th active layer groups and m2-th active layer groups, x in at least one m-th barrier layer in the m1-th active layer group and each m-th barrier layer in the m2-th active layer group are different, y in at least one m-th potential well layer in the m1-th active layer group and each m-th potential well layer in the m2-th active layer group are different; M is an integer greater than or equal to 2, m1 is an integer greater than or equal to 1 and less than or equal to M, m2 is an integer greater than or equal to 1 and less than or equal to M, and m1 is not equal to m2.

3. The quantum cascade light emitting structure according to claim 1, characterized in that: For different m1-th active layer groups and m2-th active layer groups, the thicknesses of at least one m-th barrier layer in the m1-th active layer group and each m-th barrier layer in the m2-th active layer group along the first direction are different, and the thicknesses of at least one m-th potential well layer in the m1-th active layer group and each m-th potential well layer in the m2-th active layer group along the first direction are different; M is an integer greater than or equal to 2, m1 is an integer greater than or equal to 1 and less than or equal to M, m2 is an integer greater than or equal to 1 and less than or equal to M, and m1 is not equal to m2.

4. The quantum cascade light emitting structure according to claim 1, characterized in that: 0.53≤y<1,0<x≤0.

52.

5. The quantum cascade light emitting structure according to claim 1, characterized in that: The thickness of any m-th barrier layer is 0.1 nm to 100 nm; the thickness of any m-th potential well layer is 0.1 nm to 100 nm.

6. The quantum cascade light emitting structure according to claim 1, characterized in that: The thickness of the m-th potential well layer of the first type in each layer is greater than 0.5 monoatomic layer, and the thickness of the m-th potential well layer of the second type in each layer is greater than 0.5 monoatomic layer.

7. The quantum cascade light emitting structure according to claim 1, characterized in that: The thickness of the mth sub-barrier layer of the first type in each layer is greater than 0.5 monoatomic layer, and the thickness of the mth sub-barrier layer of the second type in each layer is greater than 0.5 monoatomic layer.

8. A method for preparing a quantum cascade light-emitting structure, characterized in that: include: forming an active layer; Wherein, forming the active layer comprises: forming a first active layer group to an Mth active layer group stacked along a first direction, any mth active layer group presents a superlattice structure and comprises a plurality of mth active layer units stacked along the first direction, any mth active layer unit comprises an mth barrier layer and an mth potential well layer alternately stacked along the first direction; and the equivalent material of any mth barrier layer is In x Al 1-x As, the equivalent material of any mth potential well layer is In y Ga 1-y As; M is an integer greater than or equal to 1, and m is an integer greater than or equal to 1 and less than or equal to M; Wherein, x of at least two potential barrier layers in each active layer unit in at least one active layer group is different; and / or y of at least two potential well layers in each active layer unit in at least one active layer group is different; Wherein, forming any m-th potential well layer comprises: forming a first type m-th potential well layer and a second type m-th potential well layer alternately stacked along a first direction, wherein the second type m-th potential well layer is located between adjacent first type m-th potential well layers, and the material of the first type m-th potential well layer is In y1 Ga 1-y1 As, the material of the m-th potential well layer of the second type is InAs; Wherein, forming any m-th barrier layer comprises: forming a first type m-th sub-barrier layer and a second type m-th sub-barrier layer alternately stacked along a first direction, wherein the second type m-th sub-barrier layer is located between adjacent first type m-th sub-barrier layers; the material of the first type m-th sub-barrier layer is In x1 Al 1-x1 As, the material of the second type m-th sub-barrier layer is AlAs.

9. The method for preparing a quantum cascade light-emitting structure according to claim 8, characterized in that: Forming a first type m-th potential well layer and a second type m-th potential well layer alternately stacked along a first direction, comprising: Obtaining a designed thickness of the mth potential well layer as p monoatomic layers; The total design thickness of the first basic epitaxial layer is obtained to be p*y monoatomic layers, and the total design thickness of the second basic epitaxial layer is obtained to be p*(1-y) monoatomic layers; the material of the first basic epitaxial layer is InAs, and the material of the second basic epitaxial layer is GaAs; The designed growth rate of the first basic epitaxial layer is obtained as r1 monoatomic layers / s, and the designed growth rate of the second basic epitaxial layer is obtained as r2 monoatomic layers / s; Obtain the total designed growth time t1=(p*y / r1)s of the first basic epitaxial layer according to the designed growth rate of the first basic epitaxial layer and the total designed thickness of the first basic epitaxial layer; Obtaining a total designed growth time t2=(p*(1-y) / r2)s of the second basic epitaxial layer according to the designed growth rate of the second basic epitaxial layer and the total designed thickness of the second basic epitaxial layer, wherein t1 is greater than t2; The second basic epitaxial layer is divided into a first second sub-basic epitaxial layer to an n1th second sub-basic epitaxial layer; n1 is an integer greater than or equal to 2; In the process of continuously growing the first basic epitaxial layer within the growth time t3, the first second sub-basic epitaxial layer to the n1th second sub-basic epitaxial layer are grown at intervals within the growth time t3, t3=t1, and the growth time of each second sub-basic epitaxial layer is t2 / n1; the interval time t2 is used to grow adjacent second sub-basic epitaxial layers. s =(t3-t2) / (n1-1); within t2 / n1, the second sub-basic epitaxial layer and the first basic epitaxial layer react to form the mth sub-potential well layer of the first type; at the interval time t s The first basic epitaxial layer forms the mth sub-well layer of the second type.

10. The method for preparing a quantum cascade light-emitting structure according to claim 9, characterized in that: The value range of p is 1~400.

11. The method for preparing a quantum cascade light-emitting structure according to claim 9, characterized in that: t s *r1 is greater than 0.5 monoatomic layer; (r1+r2)*t2 / n1 is greater than 0.5 monoatomic layer; n1 .

12. The method for preparing a quantum cascade light-emitting structure according to claim 8, characterized in that: Forming a first type m-th sub-barrier layer and a second type m-th sub-barrier layer alternately stacked along a first direction, comprising: The designed thickness of the mth barrier layer is obtained as q monoatomic layers; The total design thickness of the third basic epitaxial layer is q*x monoatomic layers, and the total design thickness of the fourth basic epitaxial layer is q*(1-x) monoatomic layers; the material of the third basic epitaxial layer is InAs, and the material of the fourth basic epitaxial layer is AlAs; The designed growth rate of the third basic epitaxial layer is obtained as r3 monoatomic layers / s, and the designed growth rate of the fourth basic epitaxial layer is obtained as r4 monoatomic layers / s; According to the designed growth rate of the third basic epitaxial layer and the total designed thickness of the third basic epitaxial layer, the total designed growth time t4 = (q * x / r3) s of the third basic epitaxial layer is obtained; Obtaining a total designed growth time t5=(q*(1-x) / r4)s of the fourth basic epitaxial layer according to a designed growth rate of the fourth basic epitaxial layer and a total designed thickness of the fourth basic epitaxial layer, wherein t5 is greater than t4; The third basic epitaxial layer is divided into a first third sub-basic epitaxial layer to an n2th third sub-basic epitaxial layer; n2 is an integer greater than or equal to 2; In the process of continuously growing the fourth basic epitaxial layer within the growth time t6, the first third sub-basic epitaxial layer to the n2th third sub-basic epitaxial layer are grown at intervals within the growth time t6, t6=t5, and the growth time of each third sub-basic epitaxial layer is t4 / n2; the interval time for growing adjacent third sub-basic epitaxial layers is t s ’ =(t6-t4) / (n2-1); within t4 / n2, the third basic epitaxial layer and the fourth basic epitaxial layer react to form the mth sub-barrier layer of the first type; at the interval time t s ’ The fourth base epitaxial layer forms an m-th sub-barrier layer of the second type.

13. The method for preparing a quantum cascade light-emitting structure according to claim 12, characterized in that: The value range of q is 1~400.

14. The method for preparing a quantum cascade light-emitting structure according to claim 12, characterized in that: t s ’ *r4 is greater than 0.5 monoatomic layer; (r3+r4)*t4 / n2 is greater than 0.5 monoatomic layer; n2 2R4*(T5-T4)+1.

15. The method for preparing a quantum cascade light-emitting structure according to claim 8, characterized in that: y of the ath mth potential well layer in each mth active layer unit in the mth active layer group is different from y in the bth mth potential well layer, a is an integer greater than or equal to 1, b is an integer greater than or equal to 1, and a is not equal to b; in the process of forming the ath mth potential well layer, an As source furnace, a first In source furnace, and a first Ga source furnace in a reaction chamber are used; In the process of forming the bth mth potential well layer, an As source furnace, a first In source furnace and a first Ga source furnace in the reaction chamber are used.

16. The method for preparing a quantum cascade light-emitting structure according to claim 8, characterized in that: x of the a-th m-th barrier layer in any m-th active layer unit in the m-th active layer group is different from x in the b-th m-th barrier layer, a is an integer greater than or equal to 1, b is an integer greater than or equal to 1, and a is not equal to b; in the process of forming the a-th m-th barrier layer, an As source furnace, a second In source furnace, and a first Al source furnace in the reaction chamber are used; In the process of forming the bth and mth barrier layers, an As source furnace, a second In source furnace and a first Al source furnace in the reaction chamber are used.

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