Interband cascaded photodetectors based on multi-interface strain compensation and their fabrication method

Abstract

This invention discloses an interband cascaded photodetector based on multi-interface strain compensation and its fabrication method. The detector structure, from bottom to top, includes: a substrate, an N-type contact layer, an M-layer stepped cascaded structure, and a P-type contact layer. The substrate is made of GaSb material, and the number of M layers in the stepped cascaded structure is a positive integer. The N-type contact layer is a superlattice structure with multi-interface strain compensation. Strain compensation is achieved through multiple interfaces in the N-type contact layer and the stepped cascaded structure. This invention achieves high-quality growth of a high-performance antimony-based interband cascaded photodetector.

Description

Technical Field

[0001] This invention relates to the field of interband cascaded photodetectors, and more specifically, to an interband cascaded photodetector based on multi-interface strain compensation and its fabrication method. Background Technology

[0002] Interband cascaded photodetectors (ICIPs) based on type-II superlattices have attracted extensive research due to their ability to operate at high temperatures in the mid-to-long wavelength range and their high carrier collection efficiency. Successive studies have been conducted on mid-to-long wavelength ICIPs operating above room temperature, interband cascaded focal plane arrays operating at 180 K, the discovery and explanation of electrical gain phenomena, and the demonstration of high-frequency devices from 1.3 GHz to 10 GHz. These studies have made significant progress in understanding the advantages of ICIs, producing encouraging results in the short-wave red to very long wavelength range, opening up possibilities for room-temperature infrared imaging systems and high-speed sensor networks, and will drive their continued development.

[0003] However, the complex epitaxial structure of ICIPs presents significant challenges during device epitaxy. ICIP devices exhibit a complex cascaded step structure, with each step containing an InAs / GaSb superlattice (SL) absorber layer, an AlSb / GaSb SL electron barrier layer, and an InAs / AlSb SL hole barrier layer. Achieving ideal strain compensation within these numerous superlattice structures is a major challenge in interband cascade growth, particularly in the InAs / AlSb SL hole barrier layer. To block holes and ensure efficient electron tunneling, the AlSb layer is typically only a few atoms thick (monolayer), while the InAs layer is often over 20 μM thick. Lattice mismatch between the InAs and GaSb substrates during growth leads to strain accumulation, resulting in lattice defects such as dislocations and stacking faults, which have a detrimental impact on device performance. Therefore, achieving ideal strain compensation during ICIP device growth is crucial for improving the overall performance of ICIPs.

[0004] Currently, in the growth schemes of such strained superlattice materials, some studies use ternary alloy structures with InAs substrates to avoid lattice mismatch. However, this also brings problems such as alloy composition control, the high cost of InAs substrates, and the inability to fabricate them in large sizes. Another approach is to use InSb layers to compensate for the difference in lattice constants between the InAs layer and the GaSb substrate in the superlattice. This is achieved by inserting InSb layers on both sides of the InAs layer to form a double interface layer, thus achieving ideal strain compensation. However, for the InAs / AlSb SL hole barrier layer region in ICIP devices, in order to effectively balance the tensile stress caused by the excessively thick InAs layer, the required InSb interface layer thickness also needs to be increased accordingly. The lattice constant of InSb is much greater than that of GaSb. When the InSb interface layer thickness exceeds a certain threshold, the ability of the double InSb interface to compensate for strain gradually decreases, resulting in incomplete relaxation during material growth. This leads to various new defects in the material, reducing the performance of ICIP devices.

[0005] Currently, existing technologies are insufficient to achieve high-quality ICIP device growth. Therefore, designing new antimony-based ICIP growth schemes is crucial for improving the overall performance of ICIPs and promoting the realization of new ICIP designs and concepts.

[0006] Chinese invention application No. 201820557199.1 discloses a "Long-wavelength superlattice infrared detector based on interband cascade structure." This patent discloses a structure that utilizes three binary compounds, InAs / GaSb / AlSb, to form superlattices with different period thicknesses and multiple quantum well materials, constituting a long-wavelength superlattice infrared detector based on an interband cascade structure. Its technical solution aims to reduce the dark current of the device and obtain a long-wavelength device with high sensitivity and high detectivity. Therefore, this patent does not address the same technical problem as the present invention, nor does it provide any technical guidance for solving the technical problem of the present invention. Summary of the Invention

[0007] To address the technical problem of existing cascaded detectors where the strain compensation capability of the double InSb interface gradually decreases when the InSb interface layer thickness exceeds a certain threshold, leading to incomplete relaxation during material growth and the generation of various new defects in the material, thus reducing the performance of ICIP devices, this invention provides an interband cascaded photodetector based on multi-interface strain compensation and its fabrication method. The technical solution adopted by this invention is as follows:

[0008] The first aspect of the present invention provides an interband cascaded photodetector based on multi-interface strain compensation. The detector structure comprises, from bottom to top, a substrate, an N-type contact layer, an M-layer stepped cascaded structure layer, and a P-type contact layer, wherein the number of stepped cascaded structure layers M is a positive integer; the N-type contact layer is a superlattice structure with multi-interface strain compensation; and the P-type contact layer is made of GaSb material.

[0009] As a preferred embodiment, the number of layers M in the stepped interlocking structure is 4.

[0010] As a preferred embodiment, the N-type contact layer is made of 22 monolayer InAs / 4 monolayer AlSb superlattice material.

[0011] As a preferred embodiment, the stepped interlayer structure comprises, from bottom to top, a hole barrier layer, an absorption layer, and an electron barrier layer, wherein the hole barrier layer is a multi-interface strain-compensated superlattice structure.

[0012] As a preferred embodiment, the hole barrier layer is made of a multi-period 22 monolayer InAs / 4 monolayer AlSb superlattice material, and the hole barrier layer includes several InAs layers and several AlSb layers, wherein several InSb interface layers are inserted into the InAs layers.

[0013] As a preferred embodiment, the absorber layer is made of an 8-monolayer InAs / 8-monolayer GaSb superlattice material.

[0014] As a preferred embodiment, the electronic barrier layer is made of a 4-monolayer AlSb / 13-monolayer GaSb superlattice material.

[0015] A second aspect of the present invention provides a method for fabricating an interband cascaded photodetector based on multi-interface strain compensation, the method comprising:

[0016] The total thickness of the InSb interface layer required for strain compensation is obtained based on the thickness of the InAs layer and the thickness of the AlSb layer in the InAs / AlSb SL hole barrier layer of the interband cascaded photodetector.

[0017] The number of InSb interface layers required is determined based on the total thickness of the required InSb interface layers. The thickness of a single InSb interface layer shall not exceed 0.8 monolayers and shall not be less than 0.4 monolayers. Then, the position of each InSb interface layer is determined.

[0018] As a preferred approach, before growth, the substrate is pre-degassed, followed by deoxidation in the growth chamber. After the temperature is lowered to a preset value, a high-temperature GaSb buffer is grown for a preset time. The recombination transition temperature of the GaSb surface is tested and calibrated as Tc. Finally, at a temperature of Tc-15°C, a pre-designed hole barrier layer, absorption layer, electron barrier layer, and P-type contact layer are grown from bottom to top using the molecular beam epitaxy system. The molecular beam epitaxy system includes two In source furnaces, which are used to grow InAs and InSb interface layers in the superlattice material, respectively.

[0019] As a preferred embodiment, the total thickness of the InSb interface layer is calculated as follows:

[0020] InSb thickness = 0.1 × (InAs thickness - AlSb thickness);

[0021] The number of InSb interfaces is set to 3, the growth rate of InAs ranges from 0.45 ML / s to 0.55 ML / s, the growth rate of InSb ranges from 0.095 ML / s to 0.105 ML / s, and the growth rates of GaSb and AlSb range from 0.55 ML / s to 0.65 ML / s. The InSb interface layers are evenly distributed, and the InSb interface layers are implemented using two preset shutter speed settings.

[0022] Compared with the prior art, the beneficial effects of this invention are:

[0023] This invention effectively eliminates the tensile stress caused by the increased thickness of the InAs layer by inserting different numbers of InSb interface layers into the InAs layer, while reducing the compressive stress caused by the excessive thickness of the InSb interface layer. This reduces the formation of mound-like defects, thereby significantly improving the crystal quality of the hole barrier layer. The internal crystal quality is higher, the surface smoothness is higher, and the number of internal penetrating dislocations is significantly reduced. This provides a better epitaxial basis for subsequent InAs / GaSb and AlSb / GaSb SL, and thus epitaxially produces ICIP detectors of the best quality, which is crucial for improving the overall performance of ICIP. Attached Figure Description

[0024] Figure 1 HRXRD characterization of the hole barrier layer for the device using the traditional dual-interface strain compensation method provided in this embodiment;

[0025] Figure 2 The image shows the HRXRD characterization of the hole barrier layer corresponding to the device of the present invention provided in this embodiment.

[0026] Figure 3This is a structural diagram of an interband cascaded photodetector based on multi-interface strain compensation provided in this embodiment;

[0027] Figure 4 This is a schematic diagram illustrating the formation mechanism of pore-like defects on the surface of the InAs / AlSb SL hole barrier layer at the double InSb layer interface provided in this embodiment.

[0028] Figure 5 A schematic diagram of the hole barrier layer structure of the interband cascaded photodetector based on multi-interface strain compensation provided in this embodiment.

[0029] Figure 6 A schematic diagram of the source furnace shutter setting method 1 for the InAs / AlSb SL structure growth process of the interband cascaded photodetector fabrication method based on multi-interface strain compensation provided in this embodiment;

[0030] Figure 7 A schematic diagram of source furnace shutter setting mode 2 for the InAs / AlSb SL structure growth process of the interband cascaded photodetector fabrication method based on multi-interface strain compensation provided in this embodiment;

[0031] Figure 8 A schematic diagram of the start-up time of each source furnace during the growth of the InAs / AlSb SL hole barrier layer of the interband cascaded photodetector based on multi-interface strain compensation provided in this embodiment.

[0032] Figure 9 The elemental distribution diagram within a single period of the InAs / AlSb SL hole barrier layer of the interband cascaded photodetector based on multi-interface strain compensation provided in this embodiment;

[0033] Figure 10 The AFM image corresponding to the device of the present invention provided in this embodiment;

[0034] Figure 11 AFM image of ICIP grown using the conventional dual-interface strain compensation method provided in this embodiment;

[0035] Figure 12 The characterization result diagram corresponding to the device of the present invention provided in this embodiment;

[0036] Figure 13 The image shows the characterization results of the conventionally dual-interface-grown ICIP device provided in this embodiment.

[0037] Explanation of reference numerals in the attached figures: 1. Substrate; 2. N-type contact layer; 3. Stepped layer structure; 3 / 31. Hole barrier layer; 3 / 32. Absorption layer; 3 / 33. Electron barrier layer; 4. P-type contact layer. Detailed Implementation

[0038] The accompanying drawings are for illustrative purposes only and should not be construed as limiting the invention.

[0039] It should be understood that the described embodiments are merely some, not all, of the embodiments of this application. All other embodiments obtained by those skilled in the art based on the embodiments of this application without creative effort are within the scope of protection of the embodiments of this application.

[0040] The terminology used in the embodiments of this application is for the purpose of describing particular embodiments only and is not intended to limit the embodiments of this application. The singular forms “a,” “the,” and “the” used in the embodiments of this application and the appended claims are also intended to include the plural forms unless the context clearly indicates otherwise. It should also be understood that the term “and / or” as used herein refers to and includes any or all possible combinations of one or more of the associated listed items.

[0041] In the following description, when referring to the accompanying drawings, unless otherwise indicated, the same numbers in different drawings represent the same or similar elements. The embodiments described in the following exemplary embodiments do not represent all embodiments consistent with this application. Rather, they are merely examples of apparatuses and methods consistent with some aspects of this application as detailed in the appended claims. In the description of this application, it should be understood that the terms "first," "second," "third," etc., are used only to distinguish similar objects and are not necessarily used to describe a specific order or sequence, nor should they be construed as indicating or implying relative importance. Those skilled in the art can understand the specific meaning of the above terms in this application according to the specific circumstances.

[0042] Furthermore, in the description of this application, unless otherwise stated, "multiple" means two or more. "And / or" describes the relationship between related objects, indicating that three relationships can exist. For example, A and / or B can represent: A alone, A and B simultaneously, or B alone. The character " / " generally indicates that the preceding and following related objects are in an "or" relationship. The invention will be further described below with reference to the accompanying drawings and embodiments.

[0043] The present invention will be further described below with reference to the accompanying drawings and embodiments.

[0044] Example 1

[0045] Please refer to Figure 3This embodiment provides a band-cascaded photodetector based on multi-interface strain compensation. The detector structure includes, from bottom to top: a substrate 1, an N-type contact layer 2, an M-layer stepped cascaded structure layer 3, and a P-type contact layer 4, wherein the number of layers M of the stepped cascaded structure layer 3 is a positive integer; the N-type contact layer 2 is a superlattice structure with multi-interface strain compensation; and the P-type contact layer 4 is made of GaSb material.

[0046] For details, please refer to Figure 1 and Figure 2 , Figure 1 and Figure 2 HRXRD characterization of the InAs / AlSb SL hole barrier layer 3 / 31 in ICIP devices epitaxially grown using both the conventional dual-interface strain compensation method and the multi-interface strain compensation scheme employed in this invention is presented. Through this invention, the crystal quality of the InAs / AlSb SL hole barrier layer 3 / 31 is significantly improved, exhibiting higher internal crystal quality, greater surface smoothness, and a significant reduction in the number of internal penetrating dislocations. This provides a better epitaxial foundation for subsequent InAs / GaSb and AlSb / GaSb SL epitaxy, ultimately leading to the epitaxy of ICIP detectors with optimal quality, which is crucial for improving the overall performance of ICIPs. The multilayer InSb interfacial stress balance growth method proposed in this invention provides a new approach for growing superlattice materials with large InAs layers, and is universally applicable to the growth of very long wavelength InAs / GaSb SL, InAs / InSb SL, and InAsSb digital alloys.

[0047] In one specific embodiment, the number of layers M of the stepped interlocking structure layer 3 is 4.

[0048] In one specific embodiment, the N-type contact layer 2 is made of 22 monolayer InAs / 4 monolayer AlSb superlattice material.

[0049] In a specific embodiment, the stepped interlocking structure layer 3 includes, from bottom to top, a hole barrier layer 3 / 31, an absorption layer 3 / 32, and an electron barrier layer 3 / 33, wherein the hole barrier layer 3 / 31 is a superlattice structure with multi-interface strain compensation.

[0050] For details, please refer to Figure 4 , Figure 4 This invention demonstrates the structural effect of a 3 / 31 InAs / AlSb SL hole barrier layer at a double InSb layer interface and the formation mechanism of porosity defects on the material surface under non-ideal strain compensation. In this invention, by inserting different numbers of InSb layers into the InAs layer and designing the thickness and position of each InSb interface layer, an ideal strain compensation effect is achieved.

[0051] For details, please refer to Figure 5 A schematic diagram of the 3 / 31 InAs / AlSb SL hole barrier layer structure of an ICIP device grown using the multi-interface strain compensation method is shown, illustrating the InSb interfaces at both ends and the middle of the InAs layer. The number, location, and thickness of the InSb interfaces can be set according to requirements. In this invention: the InAs layer thickness is 22 monolayers, the AlSb layer thickness is 4 monolayers, the number of InSb interface layers is set to 3, and the thickness of each interface is controlled at 0.8 monolayers.

[0052] In one specific embodiment, the hole barrier layer 3 / 31 is made of a multi-period 22 monolayer InAs / 4 monolayer AlSb superlattice material. The hole barrier layer 3 / 31 includes several InAs layers and several AlSb layers, wherein several InSb interface layers are inserted into the InAs layers.

[0053] In one specific embodiment, the absorber layer 3 / 32 is made of an 8-monolayer InAs / 8-monolayer GaSb superlattice material.

[0054] In one specific embodiment, the electronic barrier layer 3 / 33 is made of a 4-monolayer AlSb / 13-monolayer GaSb superlattice material.

[0055] Example 2

[0056] This embodiment provides a method for fabricating an interband cascaded photodetector based on multi-interface strain compensation, the method comprising:

[0057] The total thickness of the InSb interface layer required for strain compensation is obtained based on the thickness of the InAs layer and the thickness of the AlSb layer in the InAs / AlSb SL hole barrier layer of the interband cascaded photodetector.

[0058] The number of InSb interface layers required is determined based on the total thickness of the required InSb interface layers. The thickness of a single InSb interface layer shall not exceed 0.8 monolayers and shall not be less than 0.4 monolayers. Then, the position of each InSb interface layer is determined.

[0059] In one specific embodiment, before growth, the substrate is pre-degassed, followed by deoxidation in the growth chamber. After the temperature is lowered to a preset value, a high-temperature GaSb buffer is grown for a preset time. The recombination transition temperature of the GaSb surface is tested and calibrated as Tc. Finally, at a temperature of Tc-15°C, a pre-designed hole barrier layer, absorption layer, electron barrier layer, and P-type contact layer are grown from bottom to top using the molecular beam epitaxy system. The molecular beam epitaxy system includes two In source furnaces, which are used to grow InAs and InSb interface layers in the superlattice material, respectively.

[0060] Specifically, before growth, the N+ substrate is pre-degassed at 200℃ and 420℃, then deoxidized at 640℃ in the growth chamber, and then the temperature is lowered to 600℃ to grow a high-temperature GaSb buffer for 30 minutes. The temperature is then lowered to test the reconstruction transition temperature of the GaSb surface and calibrated as Tc. Finally, at a temperature of Tc-15℃, a pre-designed hole barrier layer, absorption layer, electron barrier layer and P-type contact layer are grown from bottom to top using the molecular beam epitaxy system. The molecular beam epitaxy system includes two In source furnaces, which are used to grow the InAs and InSb interface layers in the superlattice material, respectively.

[0061] In a specific embodiment, the total thickness of the InSb interface layer is calculated as follows:

[0062] InSb thickness = 0.1 × (InAs thickness - AlSb thickness);

[0063] The number of InSb interfaces is set to 3, the growth rate of InAs is 0.5 ML / s, the growth rate of InSb is 0.1 ML / s, and the growth rate range of GaSb and AlSb is 0.6 ML / s. The InSb interface layer is evenly distributed. The InSb interface layer is implemented in two preset shutter settings.

[0064] For details, please refer to Figure 6 , Figure 6 This demonstrates the source furnace shutter setting method 1 for the growth process of InAs / AlSb SL structures with multi-boundary strain compensation. The specific sequence is Sb / In / InAs / In / Sb / Sb / In / InAs / In / Sb / AlSb. Please refer to [reference needed]. Figure 7 , Figure 7 This invention demonstrates a second method for setting the source furnace shutter for the InAs / AlSb SL structure growth process with strain compensation at multiple InSb interfaces. The specific sequence is: InSb / no / InAs / no / InSb / no / InAs / no / InSb / no / AlSb. After determining the required number, thickness, and location of InSb interfaces and the InAs layer thickness, appropriate growth rates and the opening and closing sequence of the equipment shutter are designed. In this invention, the number of interfaces is set to 3, the InAs growth rate is 0.5 monolayers / s, the InSb growth rate is 0.1 monolayers / s, the GaSb and AlSb growth rates are 0.6 monolayers / s, the InSb interfaces are uniformly distributed, and shutter setting 1 is used.

[0065] For details, please refer to Figure 8 , Figure 8The turn-on time of each source furnace during the growth of the InAs / AlSb SL hole barrier layer of the ICIP device grown by the multi-interface strain compensation method is determined by the thickness of the InAs layer and the thickness of the AlSb layer. In this invention, the specific turn-on times correspond to 6s / 6s / 22s / 3s / 3s / 3s / 3s / 22s / 6s / 6s / 1.4s.

[0066] For details, please refer to Figure 9 , Figure 9 To determine the elemental distribution within a single period of the InAs / AlSb SL hole barrier layer in an ICIP device, the distribution pattern of the InSb interface layer was confirmed by observing the distribution of Sb atoms. In this invention, Sb atoms were observed to be mainly concentrated at both ends and the middle of the InAs layer, confirming the formation of a three-InSb interface layer.

[0067] For details, please refer to Figure 10 , Figure 10 The AFM image shows the microstructure of the ICIP grown using the multi-boundary strain compensation method in this invention, displaying a surface area of ​​10 × 10 μm. 2 The atomic steps within the region have a very smooth surface, with a root mean square (RMS) roughness as low as [missing value]. Figure 11 The AFM image of the ICIP grown using the traditional dual-interface strain compensation method, used as a reference in this invention, shows a large number of dislocation defects and low sample flatness. The AFM results confirm that the novel epitaxial scheme designed in this invention can significantly improve the surface quality of the sample.

[0068] For details, please refer to Figure 12 , Figure 12 The HR-XRD characterization results of ICIP grown using the multi-boundary strain compensation method in this invention show a high-intensity diffraction peak and a clear fifth-order satellite diffraction peak. The coincidence of the zero-order diffraction peak with the substrate peak further confirms the perfect lattice matching between the epitaxial material and the substrate. The full width at half maximum (FWHM) of the first-order satellite peak is only 29 arcsec, reflecting extremely high interface quality. Figure 13 The HR-XRD characterization results for ICIP grown using the traditional dual-interface strain compensation method, used as a reference in this invention, show that the satellite peaks of the HR-XRD tested sample are almost invisible, indicating that the internal periodic arrangement of the material has been severely disrupted. The HR-XRD characterization results confirm that the novel epitaxial scheme designed in this invention can significantly improve the internal crystal quality of the sample.

[0069] Obviously, the above embodiments of the present invention are merely examples for clearly illustrating the present invention, and are not intended to limit the implementation of the present invention. Those skilled in the art can make other variations or modifications based on the above description. It is neither necessary nor possible to exhaustively describe all embodiments here. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the scope of protection of the claims of the present invention.

Claims

1. A cascaded photodetector based on multi-interface strain compensation, characterized in that, The detector structure comprises, from bottom to top, a substrate (1), an N-type contact layer (2), an M-layer stepped interlocking structure layer (3), and a P-type contact layer (4). The substrate (1) is made of GaSb material, and the number of layers M of the stepped interlocking structure layer (3) is a positive integer. The N-type contact layer (2) is a superlattice structure with multi-interface strain compensation. The P-type contact layer (4) is made of GaSb material. The stepped interlocking structure layer (2) includes, from bottom to top, a hole barrier layer (3 / 31), an absorption layer (3 / 32), and an electron barrier layer (3 / 33), wherein the hole barrier layer is a superlattice structure with multi-interface strain compensation. The hole barrier layer (3 / 31) is made of a multi-period 22 monolayer InAs / 4 monolayer AlSb superlattice material. The hole barrier layer (3 / 31) includes several InAs layers and several AlSb layers, wherein several InSb interface layers are inserted into the InAs layers. The absorption layer (3 / 32) is made of an 8-monolayer InAs / 8-monolayer GaSb superlattice material; The electronic barrier layer (3 / 33) is made of a 4-monolayer AlSb / 13-monolayer GaSb superlattice material; The InAs layer is 22 monolayers thick, the AlSb layer is 4 monolayers thick, the number of InSb interface layers is set to 3, and the thickness of each interface layer is controlled at 0.8 monolayers. The source furnace shutter setting method 1 for the InAs / AlSb SL structure growth process is Sb / In / InAs / In / Sb / Sb / In / InAs / In / Sb / AlSb; The source furnace shutter setting method 2 for the InAs / AlSb SL structure growth process is as follows: InSb / no / InAs / no / InSb / no / InAs / no / InSb / no / AlSb.

2. The interband cascaded photodetector based on multi-interface strain compensation according to claim 1, characterized in that, The number of layers M of the stepped interlocking structure (3) is 4.

3. The interband cascaded photodetector based on multi-interface strain compensation according to claim 1, characterized in that, The N-type contact layer (2) is made of 22 monolayer InAs / 4 monolayer AlSb superlattice material.

4. A method for fabricating an interband cascaded photodetector based on multi-interface strain compensation according to claim 1, characterized in that, The method includes: The total thickness of the InSb interface layer required for strain compensation is obtained based on the thickness of the InAs layer and the thickness of the AlSb layer in the InAs / AlSb SL hole barrier layer of the interband cascaded photodetector. The number of InSb interface layers required is determined based on the total thickness of the required InSb interface layers, wherein the thickness of a single InSb interface layer shall not exceed 0.8 monolayers and shall not be less than 0.4 monolayers; then the position of each InSb interface layer is determined.

5. The method for fabricating an interband cascaded photodetector based on multi-interface strain compensation according to claim 4, characterized in that, The preparation method further includes: Before growth, the substrate is pre-degassed, followed by deoxidation in the growth chamber. After the temperature is lowered to a preset value, a high-temperature GaSb buffer is grown for a preset time. The recombination transition temperature of the GaSb surface is tested and calibrated as Tc. Finally, at a temperature of Tc - 15 ℃, a pre-designed hole barrier layer, absorption layer, electron barrier layer, and P-type contact layer are grown from bottom to top using the molecular beam epitaxy system. The molecular beam epitaxy system includes two In source furnaces, which are used to grow InAs and InSb interface layers in the superlattice material, respectively.

6. The method for fabricating an interband cascaded photodetector based on multi-interface strain compensation according to claim 4, characterized in that, The total thickness of the InSb interface layer is calculated as follows: InSb thickness = 0.1 × (InAs thickness - AlSb thickness); The number of InSb interfaces is set to 3, the growth rate of InAs ranges from 0.45 ML / s to 0.55 ML / s, the growth rate of InSb ranges from 0.095 ML / s to 0.105 ML / s, and the growth rates of GaSb and AlSb range from 0.55 ML / s to 0.65 ML / s. The InSb interface layers are evenly distributed, and the InSb interface layers are implemented using two preset shutter speed settings.

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