Quantum cascade laser ultrahigh strain material component and thickness control method

Abstract

The invention provides an ultrahigh strain material component and thickness control method for a quantum cascade laser, and relates to the technical field of semiconductor lasers. The control method is based on a strain compensation calibration method, a first superlattice layer and a second superlattice layer which are the same in thickness are constructed, a strain balance superlattice is formed, it is guaranteed that the whole epitaxial layer is free of strain relative to a substrate, the problem that the growth thickness of a large-strain material is small is solved, the peak position accuracy and the peak intensity during XRD testing are further improved, and the test accuracy is improved. And the half-peak width is narrow, so that the accuracy of the components of the backstepping material is improved.

Description

Technical Field

[0001] This invention relates to the field of semiconductor laser technology, specifically a method for controlling the composition and thickness of ultra-high strain materials for quantum cascade lasers. Background Technology

[0002] Quantum cascade lasers (QCLs), as semiconductor laser devices operating with intrinsically monopole carriers, have established an irreplaceable technological advantage in the mid-infrared to terahertz spectral range (3-300 μm) since the first room-temperature lasing was achieved by Bell Labs in 1994. This is due to their unique inter-subband transition mechanism and customizable bandgap engineering characteristics. Through a precisely designed semiconductor heterojunction superlattice structure, this device utilizes the quantum confinement effect to form discrete quantum states within the conduction band. It then achieves multi-level electron tunneling and photon cascade emission through periodically arranged quantum well / barrier units. A single electron can traverse dozens of active regions to generate equivalent photon gain, thus overcoming the physical constraint of the traditional laser wavelength being limited by the material's bandgap. Based on this principle, QCL can not only achieve milliwatt-level continuous wave output within the 4-12μm atmospheric window, but also extend the working band to the 1.5-300μm range through strain-compensated epitaxy technology, making it a core light source for gas molecule fingerprint recognition (such as trace detection of CO, CH4, NOx, etc.), non-invasive diagnosis of biological tissues, laser spectral telemetry of hazardous chemicals, free-space optical communication, and infrared countermeasures systems.

[0003] Quantum cascade lasers consist of a core structure composed of hundreds to nearly a thousand nanometer-thick InGaAs / InAlAs superlattices stacked periodically. To achieve high power output, the active region requires an ultra-high strain material system (strain > 1.5%), and a three-dimensional carrier confinement barrier must be constructed through bandgap engineering. This necessitates simultaneously satisfying two key parameters: firstly, the precise control of the composition of each layer (e.g., Ga...). x In (1-x) The deviation of the Ga component x value in As must be controlled within ±0.005. Secondly, the thickness accuracy of the monolayer must be ensured to reach the atomic level (±0.2 nm). Experiments show that when the component deviates from the design value by 0.007, the quantum well conduction band and subband spacing will shift by more than 10 meV, resulting in a sharp decrease in energy level lifetime, severely weakening the population inversion efficiency and exacerbating nonradiative recombination of charge carriers.

[0004] After maintenance, the flow field characteristics of the reaction chamber of a metal-organic chemical vapor deposition (MOCVD) equipment are prone to drift. Therefore, parameter calibration is required after each maintenance cycle through 5-8 trial growths.

[0005] Currently, the traditional calibration process uses a technique combining monolayer growth with in-situ X-ray diffraction (XRD) detection. That is, Figure 7As shown, Ga is first grown on the substrate. x In (1-x) The As layer was then analyzed in situ by X-ray diffraction (XRD) to detect the grown Ga. x In (1-x) The composition of the As layer is compared with the target composition. If the error is outside the preset range, the flow rate of the TMGa source is adjusted, and the growth test is performed again until the error is within the preset range. Ga is then completed. x In (1-x) After the growth calibration of the As layer, such as Figure 8 As shown, the same method is used to complete Al. y In (1-y) Growth calibration of the As layer.

[0006] This method has the following two main problems: First, to achieve higher carrier confinement and reduce thermal escape, quantum cascade lasers often require materials with high strain. However, these materials can only be grown in very thin layers (critical thickness typically <20 nm) to avoid lattice mismatch. Ultrathin epitaxial layers result in significant broadening of XRD characteristic peaks (FWHM > 1000 arcsec). When attempting to infer composition from XRD peak positions, the insufficient signal-to-noise ratio of the ultrathin epitaxial layer's XRD signal leads to inaccurate composition characterization with large errors (up to ±0.015). This makes it impossible to determine the precise composition of the material, resulting in calibration difficulties.

[0007] Second, traditional methods require Ga during calibration. x In (1-x) As layer and Al y In (1-y) The As layer is calibrated separately during growth, which is inefficient. Summary of the Invention

[0008] To address the aforementioned issues, this application provides a method for controlling the composition and thickness of ultra-high strain materials in quantum cascade lasers, which not only enables the growth calibration of materials with large strain but also effectively improves the calibration efficiency.

[0009] The technical solution adopted by this invention to solve its technical problem is: A method for controlling the composition and thickness of ultra-high strain materials in quantum cascade lasers includes the following steps: S1, determine the target composition of the ultra-high strain material in the active region; S2, design the first superlattice layer and the second superlattice layer. The materials of the first and second superlattice layers are the same as the target group of the active region ultra-high strain material determined in step S1. In the first superlattice layer, Ga... x In(1-x) The thickness of the As layer is A, and the Al y In (1-y) The thickness of the As layer is B, and the Ga in the second superlattice layer... x In (1-x) The thickness of the As layer is B, and the Al... y In (1-y) The thickness of the As layer is A; S3, the first superlattice layer and the second superlattice layer are grown sequentially on the substrate to obtain an epitaxial wafer; S4, XRD testing and analysis were performed on the epitaxial wafer to determine Ga x In (1-x) As layer and Al y In (1-y) Material composition and thickness of the As layer; S5, Calculate Ga x In (1-x) As layer and Al y In (1-y) Thickness error and composition error of the As layer; S6, determine whether the error is within the preset range; 6.1 If all errors are less than or equal to the preset error, then perform full-structure growth of the quantum cascade laser; 6.2 If any error exceeds the preset error, adjust the parameters and repeat steps S3-S5.

[0010] Furthermore, S3 includes the following steps: 3.1 Place the substrate in the MOCVD reaction chamber, heat it to about 840℃, introduce a PH3 source for pretreatment, then cool it to 700℃-730℃, introduce TMIn, and grow an InP buffer layer with a thickness of 100-500nm. 3.2 Turn off the PH3 source and introduce TMGa, TMIn, and AsH3 sources. Maintain an ambient temperature of 600-700℃ to grow Ga. x In (1-x) As layer; 3.3 Turn off the TMGa source and introduce the TMAl source. Maintain an ambient temperature of 600-700℃ to grow Al. y In (1-y) As layer; 3.4 Repeat steps 3.2 and 3.3 20-50 times; 3.5 Turn off the TMAl source and introduce the TMGa source. Maintain an ambient temperature of 600-700℃ to grow Ga. x In (1-x) As layer; 3.6 Turn off the TMGa source and introduce the TMAl source. Maintain an ambient temperature of 600-700℃ to grow Al. y In (1-y) As layer; 3.7 Repeat steps 3.5 and 3.6, repeating them the same number of times as in step 3.4.

[0011] Furthermore, in step 3.1, the pretreatment time is 5 minutes, and after pretreatment, the temperature is lowered to 700℃, and the growth thickness of the InP buffer layer is 300nm.

[0012] Furthermore, in steps 3.2, 3.3, 3.5 and 3.6, the ambient temperature is 680°C.

[0013] Furthermore, both the first and second superlattice layers comprise 30 periods of Ga. x In (1-x) As layer and Al y In (1-y) As layer.

[0014] Furthermore, the target composition of the active region ultra-high strain material is In. 0.669 Ga 0.331 As / In 0.362 Al 0.638 As.

[0015] Furthermore, Ga in the first superlattice layer x In (1-x) The thickness of the As layer and the Al content in the second superlattice layer y In (1-y) The thickness of the As layers is 4 nm in all layers. Al in the first superlattice layer y In (1-y) The thickness of the As layer and the Ga content in the second superlattice layer x In (1-x) The thickness of the As layer is 5nm.

[0016] Furthermore, S4 includes the following steps: 4.1 Calculate the single-period thickness d1 of the first superlattice layer and the single-period thickness d2 of the second superlattice layer; 4.2 Calculation of Ga x In (1-x) The growth rate of the As layer, y1, and Al y In (1-y) The growth rate of the As layer is y2; 4.3 Calculation of Ga in the first and second superlattice layers x In (1-x) As layer and Al y In(1-y) The thickness of a single As layer; 4.4 The average lattice constants a1 and a2 of the first and second superlattice layers are obtained based on the zero-order satellite peak positions of the first and second superlattice layers; 4.5 Setting Ga in the first superlattice layer x In (1-x) As layer and Al y In (1-y) The number of unit cells in the As layer are c1 and z1, respectively, and they satisfy the relationship c1 + z1 = d1 / a1. Let the Ga in the second superlattice layer be... x In (1-x) As layer and Al y In (1-y) The number of unit cells in layer As are c2 and z2, respectively, and they satisfy the relationship c2 + z2 = d2 / a2. According to the formula...

[0017] The lattice constant of the GaxIn(1-x)As layer was calculated. and the lattice constant of the AlyIn(1-y)As layer ; 4.6 Based on the lattice constant of the GaxIn(1-x)As layer obtained in step 4.5 The lattice constants of the AlyIn(1-y)As layer were determined, and the compositions of the GaxIn(1-x)As and AlyIn(1-y)As layers were obtained.

[0018] Furthermore, the preset error in step S6 is 2%.

[0019] The beneficial effects of this invention are: 1. The embodiments of this application provide a method for controlling the composition and thickness of ultra-high strain materials for quantum cascade lasers. Based on a strain compensation calibration method, by constructing a first superlattice layer and a second superlattice layer of the same thickness and forming a strain-balanced superlattice, it ensures that the entire epitaxial layer is strain-free relative to the substrate. This not only solves the problem of thin thickness in the growth of high strain materials, but also improves the accuracy of peak position and peak intensity during XRD testing, as well as the half-peak width, thereby improving the accuracy of inferring the material composition.

[0020] 2. The method for controlling the composition and thickness of ultra-high strain materials for quantum cascade lasers provided in this application embodiment can simultaneously control the composition and thickness of Ga... x In (1-x) As layer and Al y In (1-y) The growth calibration of the As layer effectively improves calibration efficiency. Attached Figure Description

[0021] Figure 1 A flowchart illustrating a method for controlling the composition and thickness of ultra-high strain materials in a quantum cascade laser, provided as an embodiment of this application; Figure 2 This is a schematic diagram of the structure of the epitaxial wafer obtained in step S3; Figure 3 The XRD pattern of the epitaxial wafer obtained in step S3; Figure 4 To obtain Ga using traditional methods x In (1-x) XRD pattern of As epitaxial wafer; Figure 5 To obtain Al using traditional methods y In (1-y) XRD pattern of As epitaxial wafer; Figure 6 This is a comparison chart showing the power output characteristics of quantum cascade laser chips prepared according to the material compositions determined in the embodiments and comparative examples of this application.

[0022] Figure 7 To employ a single-layer growth combined with in-situ XRD detection technique for Ga x In (1-x) Process flow diagram for calibration of As epitaxial wafers; Figure 8 To employ a single-layer growth combined with in-situ XRD detection technique for Al y In (1-y) Process flow diagram for calibrating As epitaxial wafers.

[0023] In the diagram: 1. Substrate; 2. Ga x In (1-x) As layer; 3. Al y In (1-y) As layer. Detailed Implementation

[0024] To enable those skilled in the art to better understand the technical solutions in this application, the technical solutions in the embodiments of this application will be described in detail below with reference to the accompanying drawings. The described embodiments are merely a part of the embodiments of this application, and not all of them. All other embodiments obtained by those skilled in the art based on the embodiments of this application without creative effort should fall within the protection scope of this application.

[0025] like Figure 1 As shown, a method for controlling the composition and thickness of ultra-high strain materials in quantum cascade lasers includes the following steps: S1. Based on the stacked structure of the quantum cascade laser, the target composition of the ultra-high strain material in the active region is determined.

[0026] As a specific implementation, the target composition of the active region ultra-high strain material in this embodiment is Ga. x In (1-x) As / Al y In (1-y) As, where x = 0.669 and y = 0.362.

[0027] S2, design the first superlattice layer and the second superlattice layer based on the target composition of the active region ultra-high strain material determined in step S1.

[0028] The materials of the first and second superlattice layers are the same as the target group of ultra-high strain materials in the active region determined in step S1. That is, the first superlattice layer is made of Ga. x In (1-x) As layer 2 and Al y In (1-y) The As layers are formed by overlapping 3 layers, and the overlapping period is the same.

[0029] Ga in the first superlattice layer x In (1-x) The thickness of As layer 2 is A, and the Al y In (1-y) The thickness of As layer 3 is B; Ga in the second superlattice layer x In (1-x) The thickness of As layer 2 is B, and the Al y In (1-y) The thickness of layer 3 (As) is A. Thickness A and thickness B are not equal.

[0030] As one specific implementation, in this embodiment, Ga in the first superlattice layer x In (1-x) The thickness of As layer 2 and the Al content in the second superlattice layer y In (1-y) The thickness of As layer 3 is equal, all being 4 nm; Al in the first superlattice layer y In (1-y) The thickness of As layer 3 and the Ga in the second superlattice layer x In (1-x) The thickness of As layer 2 is equal, both being 5nm; S3, according to the design in step S2, the first superlattice layer and the second superlattice layer are grown sequentially on substrate 1 to obtain the following... Figure 2 The epitaxial wafer shown.

[0031] 3.1 Place substrate 1 in the MOCVD reaction chamber, heat it to about 840℃, introduce a PH3 source for pretreatment, then cool it to 700℃-730℃, introduce TMIn, and grow an InP buffer layer with a thickness of 100-500nm. In one specific implementation, the pretreatment time in this embodiment is 5 minutes, and the temperature is reduced to 700°C after pretreatment (i.e., the reaction temperature in the reaction chamber is 700°C). The growth thickness of the InP buffer layer is 300 nm.

[0032] 3.2 Turn off the PH3 source and introduce TMGa, TMIn, and AsH3 sources. Maintain an ambient temperature of 600-700℃ and grow Ga under compressive strain. x In (1-x) As layer 2, with a growth thickness of 4nm.

[0033] 3.3 Turn off the TMGa source and introduce the TMAl source. Maintain an ambient temperature of 600-700℃ to grow tensile strain Al. y In (1-y) As layer 3, with a growth thickness of 5nm.

[0034] 3.4 Repeat steps 3.2 and 3.3 20-50 times.

[0035] 3.5 Turn off the TMAl source and introduce the TMGa source. Maintain an ambient temperature of 600-700℃ to grow compressive strain Ga. x In (1-x) As layer 2, with a growth thickness of 5nm.

[0036] 3.6 Turn off the TMGa source and introduce the TMAl source. Maintain an ambient temperature of 600-700℃ to grow tensile strain Al. y In (1-y) As layer 3, with a growth thickness of 4nm.

[0037] 3.7 Repeat steps 3.5 and 3.6, repeating them the same number of times as in step 3.4.

[0038] In one specific implementation, steps 3.2 and 3.3 are repeated 29 times in this embodiment, and the resulting first and second superlattice layers both include 30 periods of Ga. x In (1-x) As layer 2 and Al y In (1-y) As layer 3.

[0039] In one specific implementation, the ambient temperature in steps 3.2, 3.3, 3.5 and 3.6 of this embodiment is 680°C.

[0040] S4. Perform XRD analysis on the epitaxial wafer prepared in step S3 to determine Ga... x In (1-x) As layer 2 and Al y In (1-y) Material composition and thickness of As layer 3.

[0041] 4.1 According to the formula (1) In the formula: d is the thickness of one period of the superlattice; m and n are the order numbers of the satellite peaks, respectively; and These are the diffraction angles of the corresponding satellite peaks; It is the X-ray wavelength of the device.

[0042] Calculate the single-period thickness d1 of the first superlattice layer and the single-period thickness d2 of the second superlattice layer.

[0043] 4.2 Based on Ga in the first superlattice layer x In (1-x) Al in As layer 2 and the second superlattice layer y In (1-y) The growth time of As layer 3 x 1, Al in the first superlattice layer y In (1-y) Ga in As layer 3 and the second superlattice layer x In (1-x) The growth time x2 of As layer 2, combined with the single-cycle thickness d1 of the first superlattice layer and the single-cycle thickness d2 of the second superlattice layer obtained in step 4.1, is solved by a two-variable linear equation. (2) The growth rates y1 of GaxIn(1-x)As layer 2 and y2 of AlyIn(1-y)As layer 3 were calculated.

[0044] 4.3 Based on Ga in the first superlattice layer x In (1-x) As layer 2 and Al y In (1-y) The growth time of As layer 3 was calculated separately for Ga in the first superlattice layer. x In (1-x) The single-layer thickness of As layer 2 and Al y In (1-y) The thickness of As layer 3. Based on the Ga in the second superlattice layer. x In (1-x) As layer 2 and Al y In (1-y) The growth time of As layer 3 was calculated separately for Ga in the second superlattice layer. x In (1-x) The single-layer thickness of As layer 2 and Al y In (1-y) The thickness of a single layer of As layer 3.

[0045] 4.4 The average lattice constant a1 of the first superlattice layer is obtained based on the 0th-order satellite peak position of the first superlattice layer; the average lattice constant a2 of the second superlattice layer is obtained based on the 0th-order satellite peak position of the second superlattice layer.

[0046] 4.5 Setting Ga in the first superlattice layer x In (1-x) As layer 2 and Al y In (1-y) The number of unit cells in As layer 3 are c1 and z1, respectively, and they satisfy the relationship c1 + z1 = d1 / a1; the Ga in the second superlattice layer is set to... x In (1-x) As layer 2 and Al y In (1-y) The number of unit cells in layer 3 of As is c2 and z2, respectively, and they satisfy the relationship c2+z2=d2 / a2.

[0047] For Ga x In (1-x) As layer 2, then there is (3) For Al y In (1-y) As layer 3, then there is (4) Equations were constructed using formulas (3) and (4) to calculate Ga. x In (1-x) The lattice constant of As layer 2 And Al y In (1-y) The lattice constant of As layer 3 .

[0048] 4.6 Based on the Ga obtained in step 4.5 x In (1-x) The lattice constant of As layer 2 And Al y In (1-y) The lattice constant of As layer 3 was obtained to obtain Ga x In (1-x) As layer 2 and Al y In (1-y) The components of As layer 3.

[0049] S5, Calculate Ga x In (1-x) As layer 2 and Al y In (1-y) Thickness error and composition error of As layer 3.

[0050] 5.1 The Ga in the first superlattice layer obtained in step S4 x In (1-x) As layer 2 and Al y In (1-y) The thickness of As layer 3 is compared with the target thickness to calculate the Ga content of the first superlattice layer. x In (1-x) As layer 2 and Al y In (1-y) Thickness error of As layer 3.

[0051] 5.2 The Ga2 obtained in step S4 is then processed into the second superlattice layer. x In (1-x) As layer 2 and Al y In (1-y) The thickness of As layer 3 is compared with the target thickness to calculate the Ga content of the second superlattice layer. x In (1-x) As layer 2 and Al y In (1-y) Thickness error of As layer 3.

[0052] 5.3 Take the Ga obtained in step S4 x In (1-x) As layer 2 and Al y In (1-y) The composition of As layer 3 is compared with the target composition, and Ga is calculated. x In (1-x) As layer 2 and Al y In (1-y) The composition error of As layer 3.

[0053] S6, determine whether the error is within the preset range.

[0054] 6.1 If the errors obtained in step S5 (including thickness error and composition error) are all less than or equal to the preset error, then the full structure growth of the quantum cascade laser is performed to obtain the quantum cascade laser chip.

[0055] 6.2 If any error obtained in step S5 is greater than the preset error, adjust the parameters and repeat steps S3-S5 until all errors obtained in step S5 are less than or equal to the preset error. When the thickness error is greater than the preset error, adjust the growth time; when the composition error is greater than the preset error, adjust the flow rates of the TMAl and TMGa sources.

[0056] In one specific implementation, the preset error in step S6 of this embodiment is 2%.

[0057] By constructing a first superlattice layer and a second superlattice layer of the same thickness, and causing the first superlattice layer to exhibit tensile strain (Al in the first superlattice layer)y In (1-y) The thickness of As layer 3 is greater than that of Ga. x In (1-x) The thickness of As layer 2), the second superlattice layer exhibits compressive strain (Al in the second superlattice layer). y In (1-y) The thickness of As layer 3 is less than that of Ga. x In (1-x) The thickness of As layer 2 is increased, thus achieving strain equilibrium between the first and second superlattice layers. This ensures that the entire epitaxial layer is strain-free relative to substrate 1, preventing lattice mismatch even with increased growth thickness, thus solving the problem of thin XRD characteristic peak broadening in high-strain material growth. Furthermore, as... Figure 3 As shown, by making the first superlattice layer exhibit tensile strain and the second superlattice layer exhibit compressive strain, it is possible to effectively avoid the overlap of XRD diffraction peaks of the first and second superlattice layers, making the peak shapes of the first and second superlattice layers clearly distinguishable.

[0058] By comparison Figure 3 , Figure 4 and Figure 5 As can be seen, compared with traditional methods, the XRD characteristic peaks obtained by the quantum cascade laser ultra-high strain material composition and thickness control method provided in this application embodiment not only have high intensity and narrow half-peak width, but also clearly distinguishable peak shapes and precise peak positions, thus better reflecting the true material composition and effectively improving the accuracy of material composition inversion. Since the material composition can be accurately inverted with each calibration, the quantum cascade laser ultra-high strain material composition and thickness control method provided in this application embodiment generally requires only 2-3 repetitions to obtain the required accurate material composition and thickness, significantly improving efficiency compared to traditional methods.

[0059] Furthermore, using a quantum cascade laser chip obtained through conventional calibration as a comparative example, and comparing the comparative example with the quantum cascade laser chip obtained in the embodiments of this application, significant differences in performance were found. Figure 6 As shown, compared with the comparative example, the quantum cascade laser chip obtained in this application embodiment has higher output power and slope efficiency, lower threshold current density, and is more in line with theoretical values, indicating that the growth composition and thickness of its active region are more accurate.

[0060] Other embodiments obtained by those skilled in the art based on the embodiments provided in this application by combining, splitting, or reorganizing the embodiments of this application do not exceed the protection scope of this application.

[0061] The above detailed embodiments have provided a detailed explanation of the purpose, technical solutions, and beneficial effects of the embodiments of this application. The above are merely specific embodiments of the embodiments of this application and are not intended to limit the protection scope of the embodiments of this application. That is, any modifications, equivalent substitutions, improvements, etc., made on the basis of the embodiments of this application should be included within the protection scope of the embodiments of this application.

Claims

1. A method for controlling the composition and thickness of ultra-high strain materials in quantum cascade lasers, characterized in that: Includes the following steps, S1, determine the target composition of the ultra-high strain material in the active region; S2, design the first superlattice layer and the second superlattice layer. The materials of the first and second superlattice layers are the same as the target group of the active region ultra-high strain material determined in step S1. In the first superlattice layer, Ga... x In (1-x) The thickness of the As layer (2) is A, and the Al in the first superlattice layer is... y In (1-y) The thickness of the As layer (3) is B, and the Ga in the second superlattice layer x In (1-x) The thickness of the As layer (2) is B, and the Al in the second superlattice layer y In (1-y) The thickness of As layer (3) is A; S3, the first superlattice layer and the second superlattice layer are grown sequentially on the substrate (1) to obtain an epitaxial wafer; S4, XRD testing and analysis were performed on the epitaxial wafer to determine Ga x In (1-x) As layer (2) and Al y In (1-y) Material composition and thickness of As layer (3); S5, Calculate Ga x In (1-x) As layer (2) and Al y In (1-y) Thickness error and composition error of As layer (3); S6, determine whether the error is within the preset range; 6.1 If all errors are less than or equal to the preset error, then perform full-structure growth of the quantum cascade laser; 6.2 If any error exceeds the preset error, adjust the parameters and repeat steps S3-S5.

2. The method for controlling the composition and thickness of ultra-high strain materials for quantum cascade lasers according to claim 1, characterized in that: S3 includes the following steps: 3.1 Place the substrate (1) into the MOCVD reaction chamber, heat it to about 840℃, introduce a PH3 source for pretreatment, then cool it down to 700℃-730℃, introduce TMIn, and grow an InP buffer layer with a thickness of 100-500nm. 3.2 Turn off the PH3 source and introduce TMGa, TMIn, and AsH3 sources. Maintain an ambient temperature of 600-700℃ to grow Ga. x In (1-x) As layer (2); 3.3 Turn off the TMGa source and introduce the TMAl source. Maintain an ambient temperature of 600-700℃ to grow Al. y In (1-y) As layer (3); 3.4 Repeat steps 3.2 and 3.3 20-50 times; 3.5 Turn off the TMAl source and introduce the TMGa source. Maintain an ambient temperature of 600-700℃ to grow Ga. x In (1-x) As layer (2); 3.6 Turn off the TMGa source and introduce the TMAl source. Maintain an ambient temperature of 600-700℃ to grow Al. y In (1-y) As layer (3); 3.7 Repeat steps 3.5 and 3.6, repeating them the same number of times as in step 3.

4.

3. The method for controlling the composition and thickness of ultra-high strain materials in a quantum cascade laser according to claim 2, characterized in that: In step 3.1, the pretreatment time is 5 minutes, and after pretreatment, the temperature is reduced to 700℃. The growth thickness of the InP buffer layer is 300nm.

4. The method for controlling the composition and thickness of ultra-high strain materials for quantum cascade lasers according to claim 2, characterized in that: In steps 3.2, 3.3, 3.5 and 3.6, the ambient temperature is 680°C.

5. The method for controlling the composition and thickness of ultra-high strain materials for quantum cascade lasers according to claim 1, characterized in that: Both the first and second superlattice layers comprise 30 periods of Ga. x In (1-x) As layer (2) and Al y In (1-y) As layer (3).

6. The method for controlling the composition and thickness of ultra-high strain materials for quantum cascade lasers according to claim 1, characterized in that: The target composition of the active region ultra-high strain material is In. 0.669 Ga 0.331 As / In 0.362 Al 0.638 As.

7. The method for controlling the composition and thickness of ultra-high strain materials for quantum cascade lasers according to claim 6, characterized in that: Ga in the first superlattice layer x In (1-x) The thickness of the As layer (2) and the Al in the second superlattice layer y In (1-y) The thickness of the As layer (3) is 4 nm. In the first superlattice layer, Al y In (1-y) The thickness of the As layer (3) and the Ga in the second superlattice layer x In (1-x) The thickness of the As layer (2) is 5 nm.

8. The method for controlling the composition and thickness of ultra-high strain materials for quantum cascade lasers according to claim 1, characterized in that: S4 includes the following steps: 4.1 Calculate the single-period thickness d1 of the first superlattice layer and the single-period thickness d2 of the second superlattice layer; 4.2 Calculation of Ga x In (1-x) The growth rates y1 and Al of As layer (2) y In (1-y) The growth rate y2 of As layer (3); 4.3 Calculation of Ga in the first and second superlattice layers x In (1-x) As layer (2) and Al y In (1-y) The thickness of a single layer of As layer (3); 4.4 The average lattice constants a1 and a2 of the first and second superlattice layers are obtained based on the zero-order satellite peak positions of the first and second superlattice layers; 4.5 Setting Ga in the first superlattice layer x In (1-x) As layer (2) and Al y In (1-y) The number of unit cells in the As layer (3) are c1 and z1, respectively, and they satisfy the relationship c1+z1=d1 / a1. Let the Ga in the second superlattice layer be... x In (1-x) As layer (2) and Al y In (1-y) The number of units in layer As (3) are c2 and z2, respectively, and they satisfy the relationship c2+z2=d2 / a2. According to the formula... The lattice constant of GaxIn(1-x)As layer (2) was calculated. Lattice constant of AlyIn(1-y)As layer (3) ; 4.6 The lattice constant of the GaxIn(1-x)As layer (2) obtained in step 4.

5. The lattice constants of the GaxIn(1-x)As layer (2) and the composition of the GaxIn(1-x)As layer (2) and the GaxIn(1-y)As layer (3) were determined.

9. The method for controlling the composition and thickness of ultra-high strain materials for quantum cascade lasers according to claim 1, characterized in that: The preset error in step S6 is 2%.

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