Inter-band cascade laser epitaxial structure and inter-band cascade laser

Abstract

The invention provides an inter-band cascade laser epitaxial structure. The inter-band cascade laser epitaxial structure comprises a substrate, a buffer layer, a lower limiting layer, a lower waveguide layer, an active cascade region, an upper waveguide layer, an upper limiting layer and a contact layer, wherein the lower limiting layer is used for limiting laser leakage in a first direction, and the upper limiting layer is used for limiting laser leakage in a second direction; the band gap width of the lower waveguide layer is between the lower limiting layer and the active cascade region, the band gap width of the lower waveguide layer is greater than the band gap width of the active cascade region, and the refractive index of the lower waveguide layer is greater than the refractive index of the lower limiting layer; and the active cascade region comprises one or more periods of injection composite laminated layers, and each injection composite laminated layer comprises an electron injection region, a hole injection region and an electron-hole recombination region arranged between the electron injection region and the hole injection region. Compared with a traditional W-type quantum well, the laser epitaxial structure provided by the invention has the advantages that the interaction between electrons and holes is stronger, and the optical gain is higher.

Description

Technical Field

[0001] The present disclosure relates to the technical field of semiconductor lasers, and in particular to an inter-band cascade laser epitaxial structure and an inter-band cascade laser. Background Art

[0002] The mid-infrared spectral region has abundant gas characteristic absorption peaks, so lasers working in this band have great application value in gas detection, industrial processing, and scientific research. At the same time, as an important atmospheric transparent window, this type of device also has great application value in infrared countermeasures and wireless communication.

[0003] Interband cascade laser (ICL) is an important device for achieving 3-5 micron laser band. Because the electrons and holes in the radiation recombination zone of this laser are confined in different material layers, it can break through the limitation of the material band gap on the device operating wavelength, thereby achieving the expansion of the operating wavelength. However, this type II quantum well structure leads to the weakening of electron-hole interaction and the reduction of optical gain, which hinders the further reduction of the device threshold current. Summary of the invention

[0004] 1. Technical issues to be resolved

[0005] In view of the existing technical problems, the present disclosure provides an inter-band cascade laser epitaxial structure for at least partially solving the above technical problems.

[0006] (II) Technical solution

[0007] The present disclosure provides an inter-band cascade laser epitaxial structure, comprising: a substrate, a buffer layer, a lower confinement layer, a lower waveguide layer, an active cascade region, an upper waveguide layer, an upper confinement layer and a contact layer stacked in sequence; wherein the lower confinement layer is used to limit the leakage of laser light in a first direction, and the upper confinement layer is used to limit the leakage of laser light in a second direction; the bandgap width of the lower waveguide layer is between the lower confinement layer and the active cascade region, the bandgap width of the lower waveguide layer is greater than the bandgap width of the active cascade region, and the refractive index of the lower waveguide layer is greater than the refractive index of the lower confinement layer; the bandgap width of the upper waveguide layer is between the upper confinement layer and the active cascade region, the bandgap width of the upper waveguide layer is greater than the bandgap width of the active cascade region, and the refractive index of the upper waveguide layer is greater than the refractive index of the upper confinement layer; and the active cascade region comprises one or more periods of injection composite stacks, the injection composite stacks comprise an electron injection region, a hole injection region, and an electron-hole recombination region arranged between the electron injection region and the hole injection region, and electrons and holes recombine in the electron-hole recombination region to emit light.

[0008] Optionally, the electron-hole recombination zone includes: an electron-hole recombination stack and at least one electron transport stack; wherein the electron-hole recombination stack is used to recombine electrons and holes, and the electron-hole recombination stack includes an indium arsenide layer, an indium gallium antimony layer and an indium arsenic layer stacked in sequence; the electron transport stack is used to concentrate electrons to the interface between the indium gallium antimony layer and the indium arsenic layer; the electron transport stack is arranged on at least one side of the electron-hole recombination stack.

[0009] Optionally, the electron transport stack includes: indium arsenide layers and aluminum antimony layers stacked on each other; wherein the multiple indium arsenide layers are not in contact with each other.

[0010] Optionally, the thickness of each layer in the electron-hole recombination zone and the composition of the InGaSb layer are determined according to the operating wavelength of the interband cascade laser; and the thickness control law of the InAs layer is opposite to that of the AlAnTi layer, and the thickness control law of the InAs layer is the same as that of the InGaSb layer.

[0011] Optionally, the electron injection zone includes: one or more periods of electron transport stacks; wherein the thickness of each indium arsenide layer in the electron injection zone gradually decreases along the direction pointing to the electron-hole recombination zone; and / or the hole injection zone includes: one or more periods of hole transport stacks; wherein the hole transport stacks include gallium antimony layers and aluminum antimony layers superimposed on each other.

[0012] Optionally, the indium arsenide layer in the electron injection region is doped with N-type silicon.

[0013] Optionally, an aluminum antimony layer is provided between the hole injection zone and the electron-hole recombination zone.

[0014] Optionally, the substrate is lattice matched with the material of at least one of the buffer layer, the lower confinement layer, the lower waveguide layer, the active cascade region, the upper waveguide layer, the upper confinement layer, and the contact layer; wherein the material of the substrate is indium arsenic or gallium antimony; the lower confinement layer is a superlattice in which an indium arsenic layer and an aluminum antimony layer are superimposed on each other, or an aluminum gallium arsenic antimony bulk material, or an aluminum indium arsenic antimony bulk material; the material of the lower waveguide layer is indium arsenic or gallium antimony, or an aluminum gallium arsenic antimony bulk material, or an aluminum indium arsenic antimony bulk material; the material of the upper waveguide layer is indium arsenic or gallium antimony, or an aluminum gallium arsenic antimony bulk material, or an aluminum indium arsenic antimony bulk material; and the upper confinement layer is a superlattice in which an indium arsenic layer and an aluminum antimony layer are superimposed on each other, or an aluminum gallium arsenic antimony bulk material, or an aluminum indium arsenic antimony bulk material.

[0015] Optionally, the substrate, the buffer layer, the lower limiting layer and the upper limiting layer are N-type doped with gallium telluride or silicon; the contact layer is an N-type silicon-doped indium arsenide layer or an N-type gallium telluride-doped gallium antimony layer.

[0016] Another aspect of the present disclosure provides an inter-band cascade laser, comprising: an inter-band cascade laser epitaxial structure according to any embodiment of the present disclosure and a plurality of electrodes; wherein one of the plurality of electrodes is in contact with a contact layer, and another of the plurality of electrodes is in contact with a substrate.

[0017] (III) Beneficial effects

[0018] Compared with the prior art, the inter-band cascade laser epitaxial structure provided by the present disclosure has at least the following beneficial effects:

[0019] (1) The interband cascade laser epitaxial structure disclosed in the present invention can confine electrons and holes in the electron-hole recombination zone by arranging the electron-hole recombination zone between the electron injection zone and the hole injection zone in multiple periods of injection recombination stacks, thereby enhancing the interaction between electrons and holes, thereby improving the optical gain and reducing the device threshold current.

[0020] (2) The interband cascade laser epitaxial structure disclosed in the present invention can further concentrate electrons to the InGaSb layer by providing an electron transport layer on one or both sides of the electron-hole recombination layer, and has a higher optical gain than the traditional W-type quantum well.

[0021] (3) The inter-band cascade laser epitaxial structure disclosed in the present invention increases the control dimension of the laser operating wavelength by adjusting the thickness of each layer of the electron-hole recombination zone, and can achieve fine control of the laser operating wavelength. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] The above and other objects, features and advantages of the present disclosure will become more apparent through the following description of the embodiments of the present disclosure with reference to the accompanying drawings, in which:

[0023] Figure 1A A schematic diagram showing a layer structure of an inter-band cascade laser epitaxial structure according to an embodiment of the present disclosure; Figure 1B The layer structure diagram of the active cascade region of the inter-band cascade laser according to the embodiment of the present disclosure is schematically shown; Figure 1C A schematic diagram showing a layer structure of an electron-hole recombination zone of an inter-band cascade laser according to an embodiment of the present disclosure; Figure 1D Schematically shows a layer structure diagram of a hole injection region of an inter-band cascade laser according to an embodiment of the present disclosure;

[0024] Figure 2 A diagram schematically showing a comparison between an energy band simulation diagram of an electron-hole recombination zone of a quantum well structure according to an embodiment of the present disclosure and an energy band simulation diagram of a traditional W-type quantum well;

[0025] Figure 3 The growth flow chart of the inter-band cascade laser epitaxial structure according to an embodiment of the present disclosure is schematically shown.

[0026] [Description of Reference Numerals]

[0027] 1-substrate; 2-buffer layer; 3-lower confinement layer; 4-lower waveguide layer; 5-active cascade region; 51-injection composite stack; 511-electron injection region; 512-hole injection region; 5121-hole transport stack; 513-electron-hole recombination region; 5131-electron-hole recombination stack; 5132-electron transport stack; 6-upper waveguide layer; 7-upper confinement layer; 8-contact layer. DETAILED DESCRIPTION

[0028] In order to make the objectives, technical solutions and advantages of the present disclosure more clearly understood, the present disclosure is further described in detail below in combination with specific embodiments and with reference to the accompanying drawings.

[0029] It should be noted that in the drawings or descriptions, similar or identical parts use the same figure numbers. The technical features in the various embodiments exemplified in the specification can be freely combined to form a new solution without conflict. In addition, each claim can be used as an embodiment alone or the technical features in each claim can be combined as a new embodiment. In the drawings, the shape or thickness of the embodiment can be expanded and simplified or conveniently indicated. Furthermore, the elements or implementations not shown or described in the drawings are in a form known to a person of ordinary skill in the art. In addition, although demonstrations of parameters containing specific values ​​may be provided herein, it should be understood that the parameters do not need to be exactly equal to the corresponding values, but can be approximated to the corresponding values ​​within an acceptable error tolerance or design constraint.

[0030] Unless there are technical obstacles or contradictions, the above-mentioned various embodiments of the present disclosure can be freely combined to form additional embodiments, and these additional embodiments are all within the protection scope of the present disclosure.

[0031] Although the present disclosure is described in conjunction with the accompanying drawings, the embodiments disclosed in the accompanying drawings are intended to exemplify the preferred embodiments of the present disclosure and should not be construed as limiting the present disclosure. The dimensional ratios in the accompanying drawings are merely illustrative and should not be construed as limiting the present disclosure.

[0032] Although some embodiments of the present general inventive concept have been shown and described, it will be appreciated by those skilled in the art that changes may be made to these embodiments without departing from the principles and spirit of the present general inventive concept, the scope of which is defined by the claims and their equivalents.

[0033] First, the related terms of the embodiments of the present disclosure are explained as follows:

[0034] Superlattice: A multilayer film in which two different components are grown alternately in thin layers ranging from a few nanometers to tens of nanometers and maintain strict periodicity. In fact, it is a specific form of layered fine composite material.

[0035] Bulk material: refers to materials with three-dimensional spatial structure, uniform crystalline or amorphous substances.

[0036] Figure 1A The layer structure diagram of the inter-band cascade laser epitaxial structure according to an embodiment of the present disclosure is schematically shown. Figure 1B The diagram schematically shows the layer structure of the active cascade region of an inter-band cascade laser according to an embodiment of the present disclosure.

[0037] According to the embodiments of the present disclosure, Figure 1A As shown, the inter-band cascade laser epitaxial structure includes, for example: a substrate 1, a buffer layer 2, a lower confinement layer 3, a lower waveguide layer 4, an active cascade region 5, an upper waveguide layer 6, an upper confinement layer 7 and a contact layer 8 stacked in sequence. The lower confinement layer 3 is used to limit the leakage of laser light in the first direction, and the upper confinement layer 7 is used to limit the leakage of laser light in the second direction. The bandgap width of the lower waveguide layer 4 is between the lower confinement layer 3 and the active cascade region 5, and the bandgap width of the lower waveguide layer 4 is greater than the bandgap width of the active cascade region 5, and the refractive index of the lower waveguide layer 4 is greater than the refractive index of the lower confinement layer 3. The bandgap width of the upper waveguide layer 6 is between the upper confinement layer 7 and the active cascade region 5, and the bandgap width of the upper waveguide layer 6 is greater than the bandgap width of the active cascade region 5, and the refractive index of the upper waveguide layer 6 is greater than the refractive index of the upper confinement layer 7. And as Figure 1B As shown, the active cascade region 5, for example, includes one or more periods of injection composite stacks 51, the injection composite stacks 51 include an electron injection region 511, a hole injection region 512, and an electron-hole recombination region 513 arranged between the electron injection region 511 and the hole injection region 512, and electrons and holes recombine in the electron-hole recombination region 513 to emit light.

[0038] For example, the first direction may be a direction from the active cascade region 5 to the substrate 1, and the second direction may be a direction from the active cascade region 5 to the contact layer 8. The band gap widths of the materials of each layer from the active cascade region 5 to the first direction, the second direction to the corresponding confinement layer increase successively, and the refractive index decreases successively, so that the laser generated by the active cascade region 5 can be localized between the lower waveguide layer 4 and the upper waveguide layer 6 to avoid light leakage, so as to improve the optical gain. The active cascade region 5 may be an injection composite stack 51, which injects electrons into the electron-hole recombination region 513 through the electron injection region 511, and injects holes into the electron-hole recombination region 513 through the hole injection region 512, so that the electrons and holes can recombine and emit light in the electron-hole recombination region 513.

[0039] For example, in order to improve the light confinement effect, the refractive index of the lower waveguide layer 4 may be smaller than that of the active cascade region 5 , and the refractive index of the upper waveguide layer 6 may be smaller than that of the active cascade region 5 .

[0040] It is understandable that the active cascade region 5 can be a periodic injection composite stack 51, which can realize the composite luminescence of electrons and holes. In order to enhance the optical gain, the active cascade region 5 can also be a superposition of multiple periods of injection composite stacks 51. At the same time, in order to facilitate preparation and take into account the conductivity of the device, for example, 5 to 10 periods of injection composite stacks 51 can be set.

[0041] Figure 1C The layer structure of the electron-hole recombination zone of the interband cascade laser according to an embodiment of the present disclosure is schematically shown. Figure 1D The layer structure of the hole injection region of the interband cascade laser according to an embodiment of the present disclosure is schematically shown.

[0042] According to the embodiments of the present disclosure, Figure 1C As shown, the electron-hole recombination region 513 includes, for example, an electron-hole recombination stack 5131 and at least one electron transport stack 5132. The electron-hole recombination stack 5131 is used to recombine electrons and holes, and the electron-hole recombination stack 5131 includes, for example, an indium arsenide layer, an indium gallium antimony layer, and an indium arsenide layer stacked in sequence. The electron transport stack 5132 is used to concentrate electrons to the interface between the indium gallium antimony layer and the indium arsenic layer. The electron transport stack 5132 is disposed on at least one side of the electron-hole recombination stack 5131.

[0043] For example, the electron transport stack 5132 includes: an indium arsenide layer and an aluminum antimony layer stacked on each other. The multiple indium arsenide layers do not contact each other. The electron injection region 511 includes, for example: one or more periods of electron transport stacks (here, the material composition of the electron transport stack in the electron-hole recombination region is the same). The thickness of each indium arsenide layer in the electron injection region 511 gradually decreases along the direction pointing to the electron-hole recombination region 513. And / or Figure 1D As shown, the hole injection region 512 includes, for example: one or more periodic hole transport stacks 5121. The hole transport stacks 5121 include a gallium antimony layer and an aluminum antimony layer stacked on each other.

[0044] For example, the active cascade region 5 can be a repeating structure of 5-10 cycles, and the repeating structure is an InAs / AlSb electron injection region, an electron-hole recombination region 513, and a GaSb / AlSb hole injection region. The electron injection region 511 can be a 5-10 pair InAs / AlSb structure, and the thickness of the InAs layer gradually decreases, so as to achieve high-efficiency electron injection into the electron-hole recombination region 513. The electron injection region 511 can be, for example, in, The hole injection region 512 may be 1 to 3 pairs (eg, 2 pairs) of GaSb / AlSb structures, for example,

[0045] For example, the electron-hole recombination region 513 may be a quantum well structure of InAs / AlSb / InAs / InGaSb / InAs / AlSb / InAs. InAs can achieve different operating wavelengths by changing the thickness of each layer of the electron-hole recombination zone 513 .

[0046] According to the embodiment of the present disclosure, the thickness of each layer of the electron-hole recombination zone 513 and the composition of the InGaSb layer are determined according to the operating wavelength of the interband cascade laser. The thickness control rule of the InAs layer is opposite to the thickness control rule of the AlSb layer, and the thickness control rule of the InAs layer is the same as the thickness control rule of the InGaSb layer.

[0047] For example, the operating wavelength of the laser can be increased by reducing the thickness of the AlSb layer, or by increasing the thickness of the InAs layer, or by increasing the thickness of the InGaSb layer or reducing the In component of InGaSb. Conversely, the operating wavelength of the laser can be reduced by increasing the thickness of the AlSb layer, or by reducing the thickness of the InAs layer, or by reducing the thickness of the InGaSb layer or increasing the In component of InGaSb. By controlling the thickness of each layer of the electron-hole recombination zone 513 to perform fine energy band design, the interaction between electrons and holes can be enhanced, the radiation recombination efficiency of electron-hole pairs can be improved, and thus the device performance can be improved.

[0048] According to an embodiment of the present disclosure, in order to better limit the recombination of electrons in the electron-hole recombination zone 513 , an aluminum antimony layer may be disposed between the hole injection zone 512 and the electron-hole recombination zone 513 .

[0049] For example, a layer is inserted between the electron-hole recombination zone 513 and the hole injection zone 512. (For example ) of AlSb (on the GaSb side of the hole injection region 512) to prevent electrons from penetrating into the hole injection region.

[0050] According to an embodiment of the present disclosure, the substrate 1 is lattice matched with the material of at least one of the buffer layer 2, the lower confinement layer 3, the lower waveguide layer 4, the active cascade region 5, the upper waveguide layer 6, the upper confinement layer 7, and the contact layer 8. The material of the substrate 1 is, for example, indium arsenic or gallium antimony. The lower confinement layer 3 is, for example, a superlattice in which an indium arsenic layer and an aluminum antimony layer are superimposed on each other, or an aluminum gallium arsenic antimony body material, or an aluminum indium arsenic antimony body material. The material of the lower waveguide layer 4 is, for example, indium arsenic or gallium antimony, or an aluminum gallium arsenic antimony body material, or an aluminum indium arsenic antimony body material. The material of the upper waveguide layer 6 is, for example, indium arsenic or gallium antimony, or an aluminum gallium arsenic antimony body material, or an aluminum indium arsenic antimony body material. And the upper confinement layer 7 is, for example, a superlattice in which an indium arsenic layer and an aluminum antimony layer are superimposed on each other, or an aluminum gallium arsenic antimony body material, or an aluminum indium arsenic antimony body material. The substrate 1, the buffer layer 2, the lower confinement layer 3, and the upper confinement layer 7 are, for example, N-type doped with gallium telluride or silicon. The contact layer is, for example, an N-type silicon-doped indium arsenide layer or an N-type gallium telluride-doped gallium antimony layer.

[0051] For example, the GaSb substrate is an N-type doped substrate with a thickness of 500-600 microns (e.g., 550 microns). The GaSb buffer layer is N-type doped with a thickness of about 0.2 microns. The lower confinement layer 3 and the upper confinement layer 7 are N-type doped InAs / AlSb superlattice or AlGaAsSb bulk material with a thickness of about 2 microns. The lower waveguide layer 4 and the upper waveguide layer 6 are undoped GaSb with a thickness of about 0.3 microns. The contact layer 8 is an N-type silicon-doped InAs layer with a thickness of about 0.2 microns.

[0052] For example, in order to achieve a concentration balance between electrons and holes in the electron-hole recombination zone 513 , the indium arsenide layer in the electron injection zone 511 may be doped with N-type silicon.

[0053] Figure 2 The diagram schematically shows a comparison between an energy band simulation diagram of an electron-hole recombination zone of a quantum well structure according to an embodiment of the present disclosure and an energy band simulation diagram of a traditional W-type quantum well.

[0054] According to the embodiments of the present disclosure, Figure 2As shown, (a) is an energy band simulation diagram of the electron-hole recombination zone of the quantum well structure of the embodiment of the present disclosure, and (b) is an energy band simulation diagram of the traditional W-type quantum well. The AlSb layer inserted at 5nm and 10nm in the electron-hole recombination zone of the quantum well structure of the embodiment of the present disclosure significantly improves the energy of the conduction band, thereby concentrating the distribution of the electron wave function to the interface of InGaSb. The calculated result of the electron-hole wave function overlap integral of the quantum well structure of the embodiment of the present disclosure is, for example, 51.5%, while the calculated result of the electron-hole wave function overlap integral of the traditional W-type quantum well is, for example, 42.7%. From the calculated wave function distribution, it can be seen that the structure of the present disclosure allows electrons and holes to be more strongly confined in the same space, thereby enhancing the interaction between electrons and holes. From a theoretical point of view, the optical gain of the device will also be enhanced, thereby improving the device performance.

[0055] Another aspect of the present disclosure provides an inter-band cascade laser, for example, comprising: an inter-band cascade laser epitaxial structure of any embodiment of the present disclosure and a plurality of electrodes, wherein one of the plurality of electrodes contacts the contact layer 8 , and another of the plurality of electrodes contacts the substrate 1 .

[0056] For example, the inter-band cascade laser can adopt a ridge waveguide structure, such as a double-channel ridge waveguide structure. In the disclosed embodiment, the depth of the ridge waveguide structure formed by etching can be any position below the upper surface of the upper limiting layer 7 and above the lower surface of the upper waveguide layer 6, and the width of the double-channel ridge waveguide can be a narrow strip of 5-35 μm, and for a single-structure strip waveguide structure, it can also be a wide strip of about 100-200 μm. It should be clear to those skilled in the art that the specific waveguide structure in this example can be multiple.

[0057] Figure 3 The growth flow chart of the inter-band cascade laser epitaxial structure according to an embodiment of the present disclosure is schematically shown.

[0058] According to the embodiments of the present disclosure, Figure 3 As shown, the growth method of the interband cascade laser epitaxial structure includes, for example:

[0059] S310, substrate inspection.

[0060] For example, a 2-inch GaSb (100-face growth) N-type doped substrate was taken out, and microscope inspection showed no obvious defects. Atomic force microscope scanning showed that the surface roughness was less than 0.5nm.

[0061] S320, substrate pretreatment.

[0062] For example, the substrate that meets the conditions in the first step is placed in the sample chamber of the molecular beam epitaxy equipment, and then degassed at 190°C for 1 hour in the sample chamber and 420°C for 1 hour in the buffer chamber. Finally, it is sent to the growth chamber for growth.

[0063] S330, high temperature deoxidation of substrate.

[0064] For example, the substrate is heated to 640-680°C in the growth chamber and maintained for 10-15 minutes to remove the oxide on the substrate surface. Generally, molecular beam epitaxy equipment is equipped with a reflection high-energy electron diffractometer to monitor the growth in situ, and the diffraction image can be observed to determine the deoxidation and growth of the substrate surface.

[0065] S340, growth of various epitaxial functional layers on the substrate.

[0066] For example, the substrate is cooled to 600-630°C (such as 610°C) to grow a GaSb buffer layer. The surface roughness of the obtained GaSb buffer layer is, for example, less than 0.1nm. If the lower confinement layer is an AlGaAsSb bulk material, the substrate needs to be heated to 630°C for growth; if the lower confinement layer is an InAs / AlSb superlattice, the substrate needs to be cooled to 520-560°C for growth. Then, the substrate temperature is maintained at around 550°C, and epitaxial growth of the lower waveguide layer GaSb, the active cascade region, the upper waveguide layer GaSb, the upper confinement layer and the contact layer are performed in sequence. In order to avoid high-temperature annealing of the light-emitting active layer, the temperature is no longer increased for growth after the active layer growth is completed.

[0067] In summary, the embodiments of the present disclosure provide an inter-band cascade laser epitaxial structure. By arranging the electron-hole recombination zone between the electron injection zone and the hole injection zone in multiple periods of injection recombination stacks, the electrons and holes can be confined in the electron-hole recombination zone, thereby enhancing the interaction between electrons and holes, thereby improving the optical gain and reducing the device threshold current.

[0068] The details not included in the method embodiment section are similar to those in the device embodiment section. Please refer to the device embodiment section and will not be repeated here.

[0069] It should be understood that the specific order or hierarchy of steps in the disclosed process is an example of an exemplary method. Based on design preferences, it should be understood that the specific order or hierarchy of steps in the process can be rearranged without departing from the scope of protection of the present disclosure. The attached method claims present the elements of the various steps in an exemplary order and are not intended to be limited to a specific order or hierarchy.

[0070] It should also be noted that the directional terms mentioned in the embodiments, such as "upper", "lower", "front", "back", "left", "right", etc., are only reference directions of the drawings and are not intended to limit the scope of protection of the present disclosure. Throughout the drawings, the same elements are represented by the same or similar reference numerals. Conventional structures or configurations will be omitted when they may cause confusion in the understanding of the present disclosure. In addition, the shapes, sizes, and positional relationships of the components in the drawings do not reflect the actual sizes, proportions, and actual positional relationships.

[0071] In the above detailed description, various features are grouped together in a single embodiment to simplify the disclosure. This method of disclosure should not be interpreted as reflecting an intention that the embodiments of the claimed subject matter require more features than are clearly stated in each claim. On the contrary, as reflected in the attached claims, the disclosure is in a state of having less than all the features of the disclosed individual embodiments. Therefore, the attached claims are hereby expressly incorporated into the detailed description, with each claim standing on its own as a separate preferred embodiment of the disclosure.

[0072] In addition, the terms "first" and "second" are used for descriptive purposes only and are not to be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined as "first" and "second" may explicitly or implicitly include one or more of the features. In the description of the present disclosure, the meaning of "multiple" is at least two, such as two, three, etc., unless otherwise clearly and specifically defined. With respect to the term "comprising" used in the specification or claims, the word is covered in a manner similar to the term "including", as explained in terms of "including," used as a transitional word in the claims. Any term "or" used in the specification of the claims is intended to mean "non-exclusive or".

[0073] The specific embodiments described above further illustrate the purpose, technical solutions and beneficial effects of the present disclosure. It should be understood that the above description is only a specific embodiment of the present disclosure and is not intended to limit the present disclosure. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present disclosure should be included in the protection scope of the present disclosure.

Claims

1. An interband cascade laser epitaxial structure, characterized in that: include: A substrate, a buffer layer, a lower confinement layer, a lower waveguide layer, an active cascade region, an upper waveguide layer, an upper confinement layer and a contact layer stacked in sequence; The lower limiting layer is used to limit the laser from leaking in a first direction, and the upper limiting layer is used to limit the laser from leaking in a second direction; The bandgap width of the lower waveguide layer is between the lower confinement layer and the active cascade region, and the bandgap width of the lower waveguide layer is greater than the bandgap width of the active cascade region, and the refractive index of the lower waveguide layer is greater than the refractive index of the lower confinement layer; The bandgap width of the upper waveguide layer is between the upper confinement layer and the active cascade region, and the bandgap width of the upper waveguide layer is greater than the bandgap width of the active cascade region, and the refractive index of the upper waveguide layer is greater than the refractive index of the upper confinement layer; and The active cascade region includes one or more periodic injection composite stacks, wherein the injection composite stack includes an electron injection region, a hole injection region, and an electron-hole recombination region arranged between the electron injection region and the hole injection region, and electrons and holes recombine in the electron-hole recombination region to emit light.

2. The interband cascade laser epitaxial structure according to claim 1, characterized in that: The electron-hole recombination zone comprises: an electron-hole recombination stack and at least one electron transport stack; The electron-hole composite stack is used to recombine electrons and holes, and the electron-hole composite stack includes an indium arsenide layer, an indium gallium antimony layer and an indium arsenide layer stacked in sequence; The electron transport stack is used to concentrate electrons to the interface between the InGaSb layer and the InAs layer; The electron transport stack is disposed on at least one side of the electron-hole recombination stack.

3. The interband cascade laser epitaxial structure according to claim 2, characterized in that: The electron transport stack comprises: Indium arsenic layers and aluminum antimony layers stacked on top of each other; Wherein, the multiple indium arsenide layers are not in contact with each other.

4. The interband cascade laser epitaxial structure according to claim 3, characterized in that: The thickness of each layer of the electron-hole recombination zone and the composition of the InGaSb layer are determined according to the operating wavelength of the interband cascade laser; as well as The thickness control rule of the indium arsenide layer is opposite to that of the aluminum antimony layer, and the thickness control rule of the indium arsenide layer is the same as that of the indium gallium antimony layer.

5. The interband cascade laser epitaxial structure according to claim 3, characterized in that: The electron injection region comprises: one or more periods of said electron transport stack; Wherein, the thickness of each indium arsenide layer in the electron injection region gradually decreases along the direction pointing to the electron-hole recombination region; and / or The hole injection region comprises: one or more periods of hole transport stacks; The hole transport stack comprises a gallium antimony layer and an aluminum antimony layer stacked on each other.

6. The interband cascade laser epitaxial structure according to claim 5, characterized in that: The indium arsenide layer in the electron injection region is doped with N-type silicon.

7. The interband cascade laser epitaxial structure according to claim 5, characterized in that: An aluminum antimony layer is arranged between the hole injection zone and the electron-hole recombination zone.

8. The interband cascade laser epitaxial structure according to claim 1, characterized in that: The substrate is lattice matched with a material of at least one of the buffer layer, the lower confinement layer, the lower waveguide layer, the active cascade region, the upper waveguide layer, the upper confinement layer, and the contact layer; Wherein, the material of the substrate is indium arsenic or gallium antimony; The lower limiting layer is a superlattice of an indium arsenic layer and an aluminum antimony layer superimposed on each other, or an aluminum gallium arsenic antimony body material, or an aluminum indium arsenic antimony body material; The material of the lower waveguide layer is indium arsenic or gallium antimony, or aluminum gallium arsenic antimony body material, or aluminum indium arsenic antimony body material; The material of the upper waveguide layer is indium arsenic or gallium antimony, or aluminum gallium arsenic antimony body material, or aluminum indium arsenic antimony body material; and The upper confinement layer is a superlattice of an indium arsenic layer and an aluminum antimony layer superimposed on each other, or an aluminum gallium arsenic antimony bulk material, or an aluminum indium arsenic antimony bulk material.

9. The interband cascade laser epitaxial structure according to claim 8, characterized in that: The substrate, the buffer layer, the lower confinement layer, and the upper confinement layer are N-type doped with gallium telluride or silicon; The contact layer is an N-type silicon-doped indium arsenic layer or an N-type gallium-tellurium-doped gallium-antimony layer.

10. An interband cascade laser, characterized in that: It comprises the interband cascade laser epitaxial structure according to any one of claims 1 to 9 and a plurality of electrodes; One of the plurality of electrodes is in contact with the contact layer, and another of the plurality of electrodes is in contact with the substrate.

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