Interband cascaded laser epitaxial structure and interband cascaded laser

Abstract

This disclosure provides an interband cascaded 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 sequentially; wherein, the lower confinement layer is used to restrict laser leakage in a first direction, and the upper confinement layer is used to restrict laser leakage in a second direction; the bandgap width of the lower waveguide layer is between that of the lower confinement layer and the active cascade region, and the bandgap width of the lower waveguide layer is greater than that of the active cascade region, and the refractive index of the lower waveguide layer is greater than that of the lower confinement layer; and the active cascade region includes one or more periodic injection recombination stacks, the injection recombination stacks including an electron injection region, a hole injection region, and an electron-hole recombination region disposed between the electron injection region and the hole injection region. Compared with a conventional W-type quantum well, the laser epitaxial structure provided by this disclosure exhibits stronger electron-hole interaction and higher optical gain.

Description

Technical Field

[0001] This disclosure relates to the field of semiconductor laser technology, and more particularly to an interband cascaded laser epitaxial structure and an interband cascaded laser. Background Technology

[0002] The mid-infrared spectral region, with its abundant characteristic gas absorption peaks, makes lasers operating in this band extremely valuable for applications in gas detection, industrial processing, and scientific research. Furthermore, as an important atmospheric transparency window, these devices also have significant applications in infrared countermeasures and wireless communication.

[0003] Interband cascaded lasers (ICLs) are crucial devices for realizing laser wavelengths in the 3–5 micrometer range. Because the electrons and holes in the radiative recombination region are confined to different material layers, these lasers can overcome the limitations of material band gaps on the operating wavelength, thus extending the operating wavelength range. However, this type II quantum well structure weakens electron-hole interaction, reduces optical gain, and hinders further reduction in the device's threshold current. Summary of the Invention

[0004] (a) Technical problems to be solved

[0005] To address the existing technical problems, this disclosure provides an interband cascaded laser epitaxial structure, which at least partially solves the above-mentioned technical problems.

[0006] (II) Technical Solution

[0007] This disclosure provides an epitaxial structure for an interband cascaded laser, 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 sequentially; wherein, the lower confinement layer is used to restrict laser leakage in a first direction, and the upper confinement layer is used to restrict laser leakage 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 recombination stacks, each injection recombination stack including an electron injection region, a hole injection region, and an electron-hole recombination region disposed between the electron injection region and the hole injection region, wherein electrons and holes recombine and emit light in the electron-hole recombination region.

[0008] Optionally, the electron-hole recombination region 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 arsenide layer stacked sequentially; the electron transport stack is used to concentrate electrons to the interface between the indium gallium antimony layer and the indium arsenide layer; the electron transport stack is disposed on at least one side of the electron-hole recombination stack.

[0009] Optionally, the electron transport stack includes: an indium arsenide layer and an aluminum antimony layer stacked on top of each other; wherein the multiple indium arsenide layers do not contact each other.

[0010] Optionally, the thickness of each layer in the electron-hole recombination region and the composition of the indium gallium antimony layer are determined according to the operating wavelength of the interband cascaded laser; and the thickness control rules of the indium arsenide layer are opposite to those of the aluminum antimony layer, while the thickness control rules of the indium arsenide layer are the same as those of the indium gallium antimony layer.

[0011] Optionally, the electron injection region includes: one or more periodic electron transport stacks; 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 includes: one or more periodic hole transport stacks; wherein the hole transport stacks include mutually superimposed gallium-antimony layers and aluminum-antimony layers.

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

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

[0014] Optionally, the substrate is lattice-matched with at least one of the following materials: buffer layer, lower confinement layer, lower waveguide layer, active cascade region, upper waveguide layer, upper confinement layer, and contact layer; wherein the substrate material is indium arsenide or gallium antimony; the lower confinement layer is a superlattice of indium arsenide and aluminum antimony layers, or aluminum gallium arsenide antimony bulk material, or aluminum indium arsenide antimony bulk material; the lower waveguide layer material is indium arsenide or gallium antimony, or aluminum gallium arsenide antimony bulk material, or aluminum indium arsenide antimony bulk material; the upper waveguide layer material is indium arsenide or gallium antimony, or aluminum gallium arsenide antimony bulk material, or aluminum indium arsenide antimony bulk material; and the upper confinement layer is a superlattice of indium arsenide and aluminum antimony layers, or aluminum gallium arsenide antimony bulk material, or aluminum indium arsenide antimony bulk material.

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

[0016] Another aspect of this disclosure provides an interband cascaded laser, comprising: an interband cascaded laser epitaxial structure according to any embodiment of this 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 interband cascaded laser epitaxial structure provided in this disclosure has at least the following advantages:

[0019] (1) The interband cascaded laser epitaxial structure disclosed herein, by setting the electron-hole recombination region between the electron injection region and the hole injection region in the injection recombination stack of multiple cycles, can confine electrons and holes within the electron-hole recombination region, enhance the interaction between electrons and holes, thereby improving optical gain and reducing device threshold current.

[0020] (2) The interband cascaded laser epitaxial structure disclosed herein can further concentrate electrons into the indium gallium antimony layer by setting electron transport stacks on one or both sides of the electron-hole recombination stack, which has higher optical gain than the traditional W-type quantum well.

[0021] (3) The interband cascaded laser epitaxial structure disclosed herein increases the dimension of laser operating wavelength control by adjusting the thickness of each layer of the electron-hole recombination region, thereby enabling fine control of the laser operating wavelength. Attached Figure Description

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

[0023] Figure 1A A schematic diagram illustrating the layer structure of an interband cascaded laser epitaxial structure according to an embodiment of the present disclosure is shown. Figure 1B This schematically illustrates the layer structure of the active cascade region of an interband cascaded laser according to an embodiment of the present disclosure; Figure 1C A schematic diagram illustrating the layer structure of the electron-hole recombination region of an interband cascaded laser according to an embodiment of the present disclosure is shown. Figure 1D A schematic diagram illustrating the layer structure of the hole injection region of an interband cascaded laser according to an embodiment of the present disclosure is shown.

[0024] Figure 2 The diagram schematically illustrates a comparison between a simulated band diagram of the electron-hole recombination region of a quantum well structure according to an embodiment of the present disclosure and a simulated band diagram of a conventional W-type quantum well.

[0025] Figure 3 A schematic diagram illustrating the growth process of an interband cascaded laser epitaxial structure according to an embodiment of the present disclosure is shown.

[0026] [Explanation of Labels in the Attached Image]

[0027] 1-Substrate; 2-Buffer layer; 3-Lower confinement layer; 4-Lower waveguide layer; 5-Active cascade region; 51-Injection recombination 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 Implementation

[0028] To make the objectives, technical solutions, and advantages of this disclosure clearer, the following detailed description is provided in conjunction with specific embodiments and the accompanying drawings.

[0029] It should be noted that similar or identical parts are referred to by the same reference numerals in the accompanying drawings or description. The technical features of the various embodiments exemplified in the specification can be freely combined to form new solutions without conflict. Furthermore, each claim can stand alone as an embodiment, or the technical features in the various claims can be combined to form new embodiments. In the drawings, the shape or thickness of the embodiments may be enlarged and indicated in a simplified or convenient manner. Moreover, elements or implementations not shown or described in the drawings are those known to those skilled in the art. Additionally, although this document provides examples of parameters containing specific values, it should be understood that the parameters need not be exactly equal to the corresponding values, but can approximate the corresponding values ​​within acceptable error tolerances or design constraints.

[0030] Unless there are technical obstacles or contradictions, the various embodiments described above in this disclosure can be freely combined to form other embodiments, all of which are within the protection scope of this disclosure.

[0031] Although this disclosure has been described in conjunction with the accompanying drawings, the embodiments disclosed in the drawings are intended to illustrate preferred embodiments of this disclosure and should not be construed as limiting the disclosure. The dimensions in the drawings are merely illustrative and should not be construed as limiting the disclosure.

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

[0033] First, the relevant terms and concepts in the embodiments of this disclosure are explained as follows:

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

[0035] Bulk materials: refer to materials with a three-dimensional spatial structure, such as uniform crystalline or amorphous substances.

[0036] Figure 1A A schematic diagram of the layer structure of an interband cascaded laser epitaxial structure according to an embodiment of the present disclosure is shown. Figure 1B The schematic diagram illustrates the layer structure of the active cascade region of an interband cascaded laser according to an embodiment of the present disclosure.

[0037] According to embodiments of this disclosure, such as Figure 1A As shown, the epitaxial structure of an interband cascaded laser 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 sequentially. The lower confinement layer 3 restricts laser leakage in a first direction, and the upper confinement layer 7 restricts laser leakage in a second direction. The bandgap width of the lower waveguide layer 4 is between that of the lower confinement layer 3 and the active cascade region 5, and the bandgap width of the lower waveguide layer 4 is greater than that of the active cascade region 5. The refractive index of the lower waveguide layer 4 is greater than that of the lower confinement layer 3. The bandgap width of the upper waveguide layer 6 is between that of the upper confinement layer 7 and the active cascade region 5, and the bandgap width of the upper waveguide layer 6 is greater than that of the active cascade region 5. The refractive index of the upper waveguide layer 6 is greater than that of the upper confinement layer 7. And as shown... Figure 1B As shown, the active cascade region 5 includes, for example, one or more periodic injection recombination stacks 51. The injection recombination stack 51 includes an electron injection region 511, a hole injection region 512, and an electron-hole recombination region 513 disposed between the electron injection region 511 and the hole injection region 512. Electrons and holes recombine and emit light in the electron-hole recombination region 513.

[0038] For example, the first direction can be from the active cascade region 5 to the substrate 1, and the second direction can be from the active cascade region 5 to the contact layer 8. The bandgap width of each layer of material from the active cascade region 5 towards the first direction, the second direction, and the corresponding confinement layer increases sequentially, while the refractive index decreases sequentially. This allows the laser generated by the active cascade region 5 to be localized between the lower waveguide layer 4 and the upper waveguide layer 6, preventing light leakage and improving optical gain. The active cascade region 5 can be an injection-recombination stack 51, where electrons are injected into the electron-hole recombination region 513 through the electron injection region 511, and holes are injected into the electron-hole recombination region 513 through the hole injection region 512, enabling electrons and holes to recombine and emit light in the electron-hole recombination region 513.

[0039] For example, to improve the light confinement effect, the refractive index of the lower waveguide layer 4 can be set to be less than the refractive index of the active cascade region 5, and the refractive index of the upper waveguide layer 6 can be set to be less than the refractive index of the active cascade region 5.

[0040] It is understandable that the active cascade region 5 can be a single-cycle injection-composite stack 51, enabling electron-hole recombination luminescence. To enhance optical gain, the active cascade region 5 can also be a stack of multiple cycles of injection-composite stacks 51. Furthermore, to facilitate fabrication and consider device conductivity, for example, 5 to 10 cycles of injection-composite stacks 51 can be used.

[0041] Figure 1C The schematic diagram illustrates the layer structure of the electron-hole recombination region of an interband cascaded laser according to an embodiment of the present disclosure. Figure 1D The diagram schematically illustrates the layer structure of the hole injection region of an interband cascaded laser according to an embodiment of the present disclosure.

[0042] According to embodiments of this disclosure, such as 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 for example, includes sequentially stacked indium arsenide, indium gallium antimony, and indium arsenide layers. The electron transport stack 5132 is used to concentrate electrons at the interface between the indium gallium antimony layer and the indium arsenide 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 stacked indium arsenide and aluminum antimony layers. The indium arsenide layers are not in contact with each other. The electron injection region 511 includes, for example, one or more periodic electron transport stacks (here referring to stacks with the same material composition as the electron transport stacks in the electron-hole recombination region). The thickness of each indium arsenide layer in the electron injection region 511 gradually decreases along the direction pointing towards the electron-hole recombination region 513. And / or as... 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 stacked gallium-antimony layers and aluminum-antimony layers.

[0044] For example, the active cascade region 5 can be a repeating structure with 5-10 cycles, where the repeating structure consists of an InAs / AlSb electron injection region 513, an electron-hole recombination region 513, and a GaSb / AlSb hole injection region. The electron injection region 511 can be 5-10 pairs of InAs / AlSb structures, with the InAs layer thickness gradually decreasing 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 can be 1 to 3 pairs (e.g., 2 pairs) of GaSb / AlSb structures, for example, it can be...

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

[0046] According to embodiments of this disclosure, the thickness of each layer of the electron-hole recombination region 513 and the composition of the indium gallium antimony layer are determined based on the operating wavelength of the interband cascaded laser. Furthermore, the thickness control rules for the indium arsenide layer are opposite to those for the aluminum antimony layer, while the thickness control rules for the indium arsenide layer are the same as those for the indium gallium antimony 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 decreasing the In composition of InGaSb. Conversely, the operating wavelength can be decreased by increasing the thickness of the AlSb layer, or by decreasing the thickness of the InAs layer, or by decreasing the thickness of the InGaSb layer or increasing the In composition of InGaSb. By controlling the thickness of each layer in the electron-hole recombination region 513 for fine bandgap design, the interaction between electrons and holes can be enhanced, the radiative recombination efficiency of electron-hole pairs can be improved, thereby enhancing device performance.

[0048] According to embodiments of this disclosure, in order to better restrict electron recombination in the electron-hole recombination region 513, an aluminum-antimony layer can be provided between the hole injection region 512 and the electron-hole recombination region 513.

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

[0050] According to embodiments of this disclosure, the substrate 1 is lattice-matched with at least one of the following materials: buffer layer 2, lower confinement layer 3, lower waveguide layer 4, active cascade region 5, upper waveguide layer 6, upper confinement layer 7, and contact layer 8. The substrate 1 is made of, for example, indium arsenide (IAR) or gallium antimony (GaSI). The lower confinement layer 3 is, for example, a superlattice of IAR and aluminum antimony layers, or a bulk aluminum gallium arsenide (AGaSI) material, or an AGaSI material. The lower waveguide layer 4 is made of, for example, IAR or gallium antimony, or a bulk aluminum gallium arsenide (AGaSI) material, or an AGaSI material. The upper waveguide layer 6 is made of, for example, IAR or gallium antimony, or a bulk aluminum gallium arsenide (AGaSI) material, or an AGaSI material. The upper confinement layer 7 is, for example, a superlattice of IAR and aluminum antimony layers, or a bulk aluminum gallium arsenide (AGaSI) material, or an AGaSI material. The substrate 1, buffer layer 2, lower confinement layer 3, and 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 micrometers (e.g., 550 micrometers). The GaSb buffer layer is N-type doped with a thickness of approximately 0.2 micrometers. The lower confinement layer 3 and the upper confinement layer 7 are N-type doped InAs / AlSb superlattice or AlGaAsSb bulk materials with a thickness of approximately 2 micrometers. The lower waveguide layer 4 and the upper waveguide layer 6 are undoped GaSb with a thickness of approximately 0.3 micrometers. The contact layer 8 is an N-type silicon doped InAs layer with a thickness of approximately 0.2 micrometers.

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

[0053] Figure 2 The diagram schematically illustrates a comparison between a simulated band structure of the electron-hole recombination region of a quantum well structure according to an embodiment of the present disclosure and a simulated band structure of a conventional W-type quantum well.

[0054] According to embodiments of this disclosure, such as Figure 2As shown, (a) is a simulated band structure diagram of the electron-hole recombination region of the quantum well structure according to an embodiment of the present disclosure, and (b) is a simulated band structure diagram of a conventional W-type quantum well. In the quantum well structure of the present disclosure, the AlSb layers inserted at 5nm and 10nm significantly increase the conduction band energy, thereby causing the distribution of the electron wavefunction to concentrate towards the InGaSb interface. The calculated result of the electron-hole wavefunction overlap integral of the quantum well structure of the present disclosure is, for example, 51.5%, while the calculated result of the electron-hole wavefunction overlap integral of the conventional W-type quantum well is, for example, 42.7%. From the calculated wavefunction 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, enhancing electron-hole interaction. Theoretically, the optical gain of the device will also be enhanced, thereby improving the device's operating performance.

[0055] This disclosure also provides an interband cascaded laser, which includes, for example, an interband cascaded laser epitaxial structure according to any embodiment of this disclosure and a plurality of electrodes. One of the plurality of electrodes is in contact with a contact layer 8, and another of the plurality of electrodes is in contact with a substrate 1.

[0056] For example, interband cascaded lasers can employ ridge waveguide structures, such as dual-channel ridge waveguide structures. In this embodiment, the depth of the etched ridge waveguide structure can be any position below the upper surface of the upper confinement layer 7 and above the lower surface of the upper waveguide layer 6. The width of the dual-channel ridge waveguide can be a narrow strip of 5-35 μm, or, for a single-structure strip waveguide structure, a wide strip of approximately 100-200 μm. Those skilled in the art will understand that various waveguide structures can be used in this example.

[0057] Figure 3 A schematic diagram illustrating the growth process of an interband cascaded laser epitaxial structure according to an embodiment of the present disclosure is shown.

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

[0059] S310, Substrate inspection.

[0060] For example, a 2-inch GaSb (100-faceted growth) N-type doped substrate was taken out. Microscopic examination showed no obvious defects, and atomic force microscopy showed that the surface roughness was less than 0.5 nm.

[0061] S320, substrate pretreatment.

[0062] For example, a substrate that meets the requirements in the first step is placed in the sample inlet chamber of a molecular beam epitaxy (MBE) device, and then degassed sequentially at 190°C in the sample inlet chamber for 1 hour, followed by degassed at 420°C in the buffer chamber for 1 hour. Finally, it is sent to the growth chamber for growth.

[0063] S330, substrate high-temperature deoxidation.

[0064] For example, the substrate is heated to 640–680°C in the growth chamber and held for 10–15 minutes to allow the oxide on the substrate surface to detach. Molecular beam epitaxy (MBE) equipment is typically equipped with a high-energy reflection electron diffractometer for in-situ growth monitoring, allowing observation of diffraction patterns to determine the deoxidation and growth status of the substrate surface.

[0065] S340, growth of each epitaxial functional layer on the substrate.

[0066] For example, the substrate is cooled to 600–630°C (e.g., 610°C) for GaSb buffer layer growth. The surface roughness of the resulting GaSb buffer layer is, for example, less than 0.1 nm. If the lower confinement layer is AlGaAsSb bulk material, the substrate temperature needs to be raised to 630°C for growth; if the lower confinement layer is InAs / AlSb superlattice, the substrate temperature needs to be lowered to 520–560°C for growth. Then, while maintaining the substrate temperature around 550°C, the 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 is performed sequentially. To avoid high-temperature annealing of the light-emitting active layer, no further heating is performed after the active layer growth is complete.

[0067] In summary, this disclosure presents an interband cascaded laser epitaxial structure. By placing the electron-hole recombination region between the electron injection region and the hole injection region in a multi-cycle injection recombination stack, electrons and holes can be confined within the electron-hole recombination region, enhancing the interaction between electrons and holes, thereby improving optical gain and reducing the device threshold current.

[0068] Details not covered in the method embodiment section are similar to those in the device embodiment section; please refer to the device embodiment section for further details, which 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 may be rearranged without departing from the scope of this disclosure. The appended method claims provide elements of various steps in an exemplary order and are not intended to limit the scope to a specific order or hierarchy.

[0070] It should also be noted that the directional terms mentioned in the embodiments, such as "up," "down," "front," "back," "left," and "right," are only for reference to the directions in the accompanying drawings and are not intended to limit the scope of protection of this disclosure. Throughout the drawings, the same elements are represented by the same or similar reference numerals. Conventional structures or constructions will be omitted when they may cause confusion in understanding this disclosure. Furthermore, the shapes, sizes, and positional relationships of the components in the drawings do not reflect their actual size, scale, or actual positional relationships.

[0071] In the detailed description above, various features are combined together in a single embodiment to simplify this disclosure. This approach to disclosure should not be construed as reflecting an intention that embodiments of the claimed subject matter require more features than are explicitly stated in each claim. Rather, as reflected in the appended claims, this disclosure is in a state of having fewer features than all of the features of the single disclosed embodiment. Therefore, the appended claims are hereby explicitly incorporated into the detailed description, with each claim representing a separate preferred embodiment of this disclosure.

[0072] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. Therefore, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of this disclosure, "a plurality of" means at least two, such as two, three, etc., unless otherwise expressly specified. The term "comprising" as used in the specification or claims is interpreted in a manner similar to the term "including," as "including" is used as a conjunction in the claims. The use of any term "or" in the specification or claims is intended to mean "non-exclusive or."

[0073] The specific embodiments described above further illustrate the purpose, technical solutions, and beneficial effects of this disclosure. It should be understood that the above descriptions are merely specific embodiments of this disclosure and are not intended to limit this disclosure. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this disclosure should be included within the protection scope of this disclosure.

Claims

1. A bandgap cascaded laser epitaxial structure, characterized in that, include: The substrate, buffer layer, lower confinement layer, lower waveguide layer, active cascade region, upper waveguide layer, upper confinement layer and contact layer are stacked in sequence. The lower confining layer is used to restrict laser leakage in the first direction, and the upper confining layer is used to restrict laser leakage in the second direction. The bandgap width of the lower waveguide layer is between that of the lower confinement layer and the active cascade region, and the bandgap width of the lower waveguide layer is greater than that of the active cascade region. The refractive index of the lower waveguide layer is greater than that of the lower confinement layer. The bandgap width of the upper waveguide layer is between that of the upper confinement layer and the active cascade region, and the bandgap width of the upper waveguide layer is greater than that of the active cascade region; the refractive index of the upper waveguide layer is greater than that of the upper confinement layer; and The active cascade region includes one or more periodic injection recombination stacks, each injection recombination stack including an electron injection region, a hole injection region, and an electron-hole recombination region disposed between the electron injection region and the hole injection region, wherein electrons and holes recombine to emit light in the electron-hole recombination region. The electron-hole recombination region 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 arsenide layer stacked sequentially; the electron transport stack is used to concentrate electrons at the interface between the indium gallium antimony layer and the indium arsenide layer; the electron transport stack is disposed on at least one side of the electron-hole recombination stack; The electron transport stack comprises: an indium arsenide layer and an aluminum antimony layer stacked on top of each other, wherein the plurality of indium arsenide layers do not contact each other.

2. The interband cascaded laser epitaxial structure according to claim 1, characterized in that, The thickness of each layer of the electron-hole recombination region and the composition of the indium gallium antimony layer are determined according to the operating wavelength of the interband cascaded laser. as well as The thickness control rule of the indium arsenide layer is the opposite of that of the aluminum antimony layer, while the thickness control rule of the indium arsenide layer is the same as that of the indium gallium antimony layer.

3. The interband cascaded laser epitaxial structure according to claim 1, characterized in that, The electron injection region includes: One or more cycles of the electron transport stack; Wherein, the thickness of each indium arsenide layer in the electron injection region gradually decreases along the direction pointing towards the electron-hole recombination region; and / or The hole injection region includes: One or more cycles of hole transport stacks; The hole transport stack includes a gallium-antimony layer and an aluminum-antimony layer that are stacked on top of each other.

4. The interband cascaded laser epitaxial structure according to claim 3, characterized in that, The indium arsenide layer in the electron injection region is doped with N-type silicon.

5. The interband cascaded laser epitaxial structure according to claim 3, characterized in that, An aluminum-antimony layer is disposed between the hole injection region and the electron-hole recombination region.

6. The interband cascaded laser epitaxial structure according to claim 1, characterized in that, The substrate is lattice-matched with at least one of the following: 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; The substrate is made of indium arsenide or gallium antimony. The lower confinement layer is a superlattice of indium arsenide layer and aluminum antimony layer superimposed on each other, or aluminum gallium arsenide antimony bulk material, or aluminum indium arsenide antimony bulk material; The material of the lower waveguide layer is indium arsenide or gallium antimony, or aluminum gallium arsenide antimony bulk material, or aluminum indium arsenide antimony bulk material; The upper waveguide layer is made of indium arsenide or gallium antimony, or aluminum gallium arsenide antimony bulk material, or aluminum indium arsenide antimony bulk material; and The upper confinement layer is a superlattice of indium arsenide and aluminum antimony layers superimposed on each other, or an aluminum gallium arsenide antimony bulk material, or an aluminum indium arsenide antimony bulk material.

7. The interband cascaded laser epitaxial structure according to claim 6, characterized in that, The substrate, the buffer layer, the lower confinement layer, and the upper confinement layer are N-type doped with gallium tellurium or silicon. The contact layer is an N-type silicon-doped indium arsenide layer or an N-type gallium telluride-doped gallium antimony layer.

8. A band-inter-cascaded laser, characterized in that, The invention includes the interband cascaded laser epitaxial structure as described in any one of claims 1 to 7 and a plurality of electrodes; wherein 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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