Growth method of superlattice material and superlattice material

Abstract

The invention provides a superlattice material and a growth method thereof, and the growth method comprises the following steps: S1, growing an AlSb / AlAsSb superlattice, and growing an AlSb layer; s2, infiltrating the grown AlSb / AlAsSb for a design time under the protection of an Sb beam, keeping an As shutter closed in the process, and opening an As valve to a proper opening degree at the same time, so that an As beam is gradually dispersed into a cavity; s3, adjusting the opening degree of an As valve step by step, introducing the As source into the growth cavity in a gradually increasing manner at the rate, and correspondingly reducing the Sb source flow step by step; s4, switching the background protection beam current into an As protection beam current; and S5, growing an InAs / InAsSb superlattice. According to the method, after the AlSb / AlAsSb superlattice is grown and before the InAs / InAsSb superlattice is initially grown, an Sb protection stage and a controlled As protection beam gradient conversion step are introduced, the interface between the AlSb / AlAsSb and the InAs / InAsSb can be close to an ideal atomic-scale steep interface through cooperative control over Sb and As, and accurate control over the multicomponent compound superlattice components is achieved.

Description

Technical Field

[0001] This invention belongs to the field of semiconductor material molecular beam epitaxy manufacturing technology, specifically relating to a method for growing superlattice materials and superlattice materials. Background Technology

[0002] Group III-V superlattice materials, especially those comprising InAs / InAsSb and AlSb / AlAsSb systems, have shown great application potential in infrared detection, lasers, and high-temperature electronic devices. For example, InAs / InAsSb strained superlattices are ideal materials for fabricating high-performance mid-to-long-wave infrared detectors, while AlSb / AlAsSb materials are often used as ideal barrier or contact layers. The electrical and optical properties of these superlattice materials are fundamentally limited by their interface quality. The steepness and clarity of the interface directly determine the accuracy of the superlattice band structure, thus becoming a prerequisite for its photoelectric performance.

[0003] The ideal interface for superlattice materials requires atomically steepness, meaning that elemental mixing between different material layers is limited to a minimum. However, in vapor phase epitaxy processes such as molecular beam epitaxy or metal-organic chemical vapor deposition, the residual and incomplete transformation of the vapor background (especially the Group V element background) within the growth chamber when switching from one material to another is the main cause of elemental mixing at the interface. This mixing forms a broadened interface transition region, disrupting the periodic potential field of the superlattice and significantly degrading its electrical and optical properties, such as shortening minority carrier lifetime, increasing dark current, and reducing photocurrent.

[0004] Especially in the preparation of AlSb / AlAsSb and InAs / InAsSb heterojunctions, the high purity and abrupt transition of the V group background have become the core bottlenecks. AlSb / AlAsSb has extremely low As and extremely high Sb content, while InAs / InAsSb has extremely high As and extremely low Sb content. To achieve interface quality control, it is necessary to solve the interface turbidity problem caused by the Sb element memory effect and the competitive adsorption of As and Sb when transitioning from a strong Sb environment to a strong As environment; specifically:

[0005] (1) Extreme gas phase environment switching: When growing AlSb / AlAsSb, a high Sb beam current (Sb-rich environment) needs to be maintained to ensure crystal quality; while when growing high-quality InAs / InAsSb, it is necessary to switch to an As-rich environment, and the As beam current needs to be precisely controlled within a certain range. If the As beam current is too large, other defects will be introduced. This means that the growth background needs to be switched from one extreme (high Sb / low As) to another extreme (low Sb / high As).

[0006] (2) Strong "memory effect" of Sb: Due to the high adhesion coefficient and low volatility of antimony (Sb), it is very easy to deposit and remain on the growth cavity and substrate surface during the growth process. This characteristic leads to a strong "memory effect", making it difficult to quickly and completely remove the residual Sb when switching from a high Sb environment (such as growing AlSb / AlAsSb) to a low Sb environment (such as growing InAs / InAsSb). In traditional direct switching or simple pause methods, the residual Sb will continue to participate in the reaction in the initial stage of InAs / InAsSb layer growth, resulting in the formation of an uncontrollable and broadened InAsSb mixed crystal region at the interface, which seriously damages the interface steepness.

[0007] (3) Sensitivity of InAs / InAsSb superlattice to As atmosphere: The initial surface of InAs is extremely sensitive to the background atmosphere of the growth cavity. If a large amount of As is introduced in order to remove the Sb background as soon as possible, the excessive As will reduce the mobility of In, making it easier to form island-like structures. In addition, the excessive As residue will cause the composition of InAsSb to be unstable, which will also harm the accuracy of the band structure.

[0008] (4) The dilemma of “Sb protection” and “overdoping”: Introducing a “protection phase” that allows only Sb to pass through during the switching process helps stabilize the interface. However, the duration of this phase (“Sb protection time”) is an extremely critical parameter. If the protection time is insufficient, it will be unable to effectively isolate the impact of As and remove the group III residues, and the interface will still be coarsened. If the protection time is too long, excessive Sb will be incorporated into the subsequently grown InAs layer, forming artificial, undesigned Sb doping or InAsSb mixed crystal region. This will also artificially widen the interface and change the expected band structure of the material.

[0009] In summary, conventional gas source switching methods in existing technologies, whether through direct switching or simple growth interruption, cannot effectively solve the interfacial mixing problem inherent in the transition from an extremely Sb-rich environment to an As-rich environment, caused by element memory effect and competitive adsorption. Existing technologies neither recognize the specific contradictions faced in this particular material system transition nor provide a process control method that can precisely balance "Sb protection" and "prevention of overdoping." Summary of the Invention

[0010] The purpose of this invention is to provide a method for growing superlattice materials, which can at least solve some of the defects existing in the prior art.

[0011] To achieve the above objectives, the present invention adopts the following technical solution:

[0012] A method for growing superlattice materials, used to control the growth process of superlattice materials containing AlSb / AlAsSb and InAs / InAsSb heterostructures, includes the following steps:

[0013] S1, grow an AlSb / AlAsSb superlattice, ending with the growth of an AlSb layer;

[0014] S2. Immerse the grown AlSb / AlAsSb superlattice under the protection of the Sb beam for the designed time, while keeping the As shutter closed during this process and opening the As valve to allow the As beam to diffuse into the cavity.

[0015] S3. Adjust the opening of the As valve so that the As source rate is introduced into the growth chamber in a gradual manner, while reducing the Sb source flow rate in stages accordingly.

[0016] S4. Switch the background protection beam to the As protection beam;

[0017] S5, grow InAs / InAsSb superlattice.

[0018] Furthermore, in S1, the process of growing the AlSb / AlAsSb superlattice is as follows: AlSb layers and AlAsSb layers are grown alternately, and the last layer ends with the growth of an AlSb layer, with a designed pause time between adjacent AlSb layers and AlAsSb layers.

[0019] Furthermore, the growth pause time t1 between adjacent AlSb layers and AlAsSb layers is 2-6 s.

[0020] Further, step S2 includes: after completing the growth of the final AlSb layer, closing the Al source shutter, lowering the Al source furnace to standby temperature, keeping the As shutter closed, opening the As valve, and adjusting the As valve to a1+(a2-a1) / n, while keeping the Sb shutter open with the Sb valve opening degree b1, so that the grown AlSb / AlAsSb is immersed in the Sb beam for a time t2 under protection; where a1 is the As valve opening degree required for normal growth of the AlSb / AlAsSb superlattice in step S1, a2 is the As valve opening degree required for normal growth of the InAs / InAsSb superlattice in step S5, and a1<a2; n is the designed number of steps to open the As valve, n≤4; b1 is the Sb valve opening degree required for normal growth of the AlSb / AlAsSb superlattice in step S1.

[0021] Furthermore, in S2, the growing AlSb / AlAsSb superlattice is immersed in Sb beam protection for a time t2 of no more than 30s.

[0022] Furthermore, in step S3, the specific control process for introducing the As source into the growth chamber while simultaneously reducing the Sb source flow rate in stages is as follows:

[0023] Increase valve As to a1+2(a2-a1) / n, while decreasing valve Sb to b1-(b1-b2) / n, for time T1; then increase valve As further to a1+3(a2-a1) / n, while decreasing valve Sb to b1-2(b1-b2) / n, for time T2; then increase valve As further to a1+4(a2-a1) / n, while decreasing valve Sb to b1-3(b1-b2) / n, for time T3, and so on, until valve As is increased to a2. The opening degree; where a1 is the As valve opening degree required for normal growth of AlSb / AlAsSb superlattice in step S1, a2 is the As valve opening degree required for normal growth of InAs / InAsSb superlattice in step S5, and a1 < a2; n is the designed number of steps to open the As valve, n ≤ 4; b1 is the Sb valve opening degree required for normal growth of AlSb / AlAsSb superlattice in step S1, and b2 is the Sb valve opening degree required for normal growth of InAs / InAsSb superlattice in step S5.

[0024] Furthermore, the duration of each opening step of the As valve, T1, T2, and T3, is no greater than 10 seconds.

[0025] Furthermore, in S4, the specific control process for switching the background protection beam to the As protection beam is as follows: the As shutter is opened, the Sb shutter is closed, the Sb valve is adjusted to b2, and the As protection is maintained for t3 time; where b2 is the Sb valve opening required for normal growth of the InAs / InAsSb superlattice in step S5; t3≤10s.

[0026] Furthermore, in S5, the process of growing the InAs / InAsSb superlattice is as follows:

[0027] S51. Simultaneously open the In and As source furnace shutters to complete the InAs layer growth, then close the In and As source furnace shutters and pause the growth design time.

[0028] S52. Open the In, As, and Sb source furnace shutters to complete the InAsSb layer growth, then close the In, As, and Sb source furnace shutters to pause the growth design time.

[0029] S53. Repeat the above S51-S52 process until the growth of the InAs / InAsSb layer is completed.

[0030] Specifically, the opening degree of valves As and Sb in step S4 of the entire process of S51-S53 is maintained.

[0031] In addition, the present invention also provides a superlattice material, which is a superlattice material containing AlSb / AlAsSb and InAs / InAsSb heterojunctions prepared by the above-mentioned superlattice material growth method.

[0032] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0033] The superlattice material growth method provided by this invention introduces an Sb protection stage and a controlled As protection beam gradient conversion step after the growth of AlSb / AlAsSb layers and before the initiation of InAs / InAsSb layer growth. By utilizing the synergistic control of Sb and As, the interface between AlSb / AlAsSb and InAs / InAsSb can be made close to an ideal atomic-level steep interface, achieving precise control of the superlattice composition of multi-component compounds. Furthermore, it can solve the technical difficulties of extreme gas phase environment switching, the strong memory effect of Sb, the sensitivity of InAs surface to the growth environment, and the dilemma of Sb protection versus overdoping in the prior art. The prepared superlattice material exhibits lower defect density, stronger room temperature photoluminescence intensity, narrower half-width at half-maximum, and longer minority carrier lifetime.

[0034] The present invention will now be described in further detail with reference to the accompanying drawings. Attached Figure Description

[0035] Figure 1 This is a flowchart of the superlattice material growth process in an embodiment of the present invention;

[0036] Figure 2 This is a schematic diagram illustrating the control of superlattice material growth in an embodiment of the present invention;

[0037] Figure 3 This is an atomic force microscope image of the superlattice material prepared in Example 1 of this invention;

[0038] Figure 4 This is the XRD pattern of the superlattice material prepared in Example 1 of this invention;

[0039] Figure 5 These are atomic force microscope images of the superlattice materials prepared in the comparative examples of this invention;

[0040] Figure 6 This is the XRD pattern of the superlattice material prepared in the comparative example of this invention. Detailed Implementation

[0041] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0042] To address the interfacial element mixing problem caused by extreme group V background transformation during the integration of existing AlSb / AlAsSb and InAs / InAsSb superlattice material systems, this embodiment provides a superlattice material growth method to control the growth process of superlattice materials containing AlSb / AlAsSb and InAs / InAsSb heterostructures, thereby achieving atomically steep interfaces. The specific process is as follows: Figure 1 As shown, it includes the following steps:

[0043] S1, grow an AlSb / AlAsSb superlattice, ending with the growth of an AlSb layer.

[0044] S2. Immerse the grown AlSb / AlAsSb superlattice under the protection of the Sb beam for the designed time, while keeping the As shutter closed during this process and opening the As valve to allow the As beam to diffuse into the cavity.

[0045] S3. Adjust the opening of the As valve to gradually increase the rate of the As source into the growth chamber, while simultaneously reducing the flow rate of the Sb source in stages.

[0046] S4. Switch the background protection beam to the As protection beam.

[0047] S5, grow InAs / InAsSb superlattice.

[0048] The technical solution disclosed in this embodiment introduces a Sb protection stage and a controlled As protection beam gradient conversion step after the growth of AlSb / AlAsSb superlattice and before the initiation of InAs / InAsSb superlattice. By utilizing the synergistic control of Sb and As, the interface between AlSb / AlAsSb and InAs / InAsSb can be made close to the ideal atomic-level steep interface, thus achieving precise control of the composition of multi-component superlattice compounds.

[0049] In some embodiments, the step of growing the AlSb / AlAsSb superlattice in S1 can be implemented as follows: AlSb layers and AlAsSb layers are grown alternately, with the last layer being an AlSb layer, and a designed pause time between adjacent AlSb and AlAsSb layers. Specifically, first, an AlSb layer is grown; after the AlSb layer is grown, there is a pause time t1, then an AlAsSb layer is grown, followed by another pause time t1, and then another AlSb layer is grown, and so on, until the AlSb / AlAsSb growth is completed; wherein, the pause time t1 is determined according to the valve opening and closing speed, and can be 2~6s. In this embodiment, a growth pause is inserted between the growth of the AlSb layer and the AlAsSb layer, which improves the interface quality at the junction of the AlSb layer and the AlAsSb layer.

[0050] To facilitate the subsequent introduction of the Sb protection stage, the cycle of growing the AlSb / AlAsSb superlattice in this embodiment ends with the AlSb layer. If the cycle ends with AlAsSb, a separate AlSb growth step needs to be added later, and the growth process is the same as in the cycle.

[0051] After the growth of AlSb / AlAsSb superlattices and before the initiation of InAs / InAsSb superlattice growth, a controlled "Group V background gradient conversion step" is introduced to solve the problem of interfacial element mixing caused by extreme Group V background conversion during the integration of AlSb / AlAsSb and InAs / InAsSb superlattice material systems. This "Group V background gradient conversion step" is not a simple gas source switching, but a precision process involving specific timing and flow rate coordinated control. Specifically, the introduction of Sb source is precisely controlled, while the introduction of As source is carried out in a gradual manner. By coordinating the control of the introduced Sb and As, an atomically steep interface is achieved.

[0052] In some embodiments, the specific control process for introducing the Sb protection phase can be implemented in the following manner:

[0053] After the AlSb layer growth of the AlSb / AlAsSb superlattice is completed in the final cycle in step S1 above, the Al source shutter is closed, the Al source furnace is cooled to standby temperature, the As shutter is kept closed, the As valve is opened, and the As valve is adjusted to a1+(a2-a1) / n, while the Sb shutter is kept open with the Sb valve opening degree b1, so that the grown AlSb / AlAsSb is immersed in the Sb beam for a time t2 under protection. Here, a1 is the As valve opening degree required for normal growth of the AlSb / AlAsSb superlattice in step S1, a2 is the As valve opening degree required for subsequent normal growth of the InAs / InAsSb superlattice, and a1 < a2; n is the designed number of times the As valve is opened in stages, generally designed to be n≤4; b1 is the Sb valve opening degree required for normal growth of the AlSb / AlAsSb superlattice in step S1. Optionally, the immersion time t2 of the grown AlSb / AlAsSb under the Sb beam protection is not greater than 30s. In this embodiment, Sb is introduced after the growth of the AlSb / AlAsSb layer and before the start of the growth of the InAs / InAsSb layer. This utilizes the high adhesion coefficient and low volatility of Sb to ensure that the AlSb epitaxial surface is adequately protected by the Sb beam and is not oxidized, thereby improving the interface quality. At the same time as the Sb is introduced, the As valve is opened. Utilizing the dispersibility of As, the As beam gradually diffuses into the cavity without affecting the AlSb epitaxial surface, thus playing a pre-control role in the subsequent gradual introduction of As.

[0054] To avoid the problem of switching between extreme gas phase environments when the growth background changes from one extreme (high Sb / low As) to another extreme (low Sb / high As), this embodiment adopts a gradual introduction method for the As source, while reducing the Sb source flow rate step by step.

[0055] In some embodiments, the specific control process for introducing the As source into the growth chamber and simultaneously reducing the Sb source flow rate in steps in S3 is as follows:

[0056] After the Sb protection phase in step S2 ends, the As valve is increased to a1+2(a2-a1) / n, while the Sb valve is decreased to b1-(b1-b2) / n, for a duration of T1. Then, the As valve is increased again to a1+3(a2-a1) / n, while the Sb valve is decreased to b1-2(b1-b2) / n, for a duration of T2. The As valve is then increased again to a1+4(a2-a1) / n, while the Sb valve is decreased to b1-3(b1-b2) / n, for a duration of T3, and so on, until... The As valve is adjusted to an opening degree of a2; where a1 is the As valve opening degree required for normal growth of the AlSb / AlAsSb superlattice in step S1, a2 is the As valve opening degree required for normal growth of the InAs / InAsSb superlattice in step S5, and a1 < a2; n is the designed number of steps for opening the As valve, n ≤ 4; b1 is the Sb valve opening degree required for normal growth of the AlSb / AlAsSb superlattice in step S1, and b2 is the Sb valve opening degree required for normal growth of the InAs / InAsSb superlattice in step S5. Optionally, the duration of each As valve opening step, T1, T2, and T3, is no greater than 10s. In this embodiment, by controlling the synergistic introduction of Sb and As (i.e., gradually increasing the introduction of As while gradually decreasing the Sb flow rate), the technical problems existing in the prior art, such as extreme gas phase environment switching, the strong "memory effect" of Sb, the sensitivity of the InAs surface to the growth environment, and the dilemma of "Sb protection" versus "overdoping", are successfully solved. This allows for a leapfrog improvement in the interface quality of AlSb / AlAsSb and InAs / InAsSb heterojunctions.

[0057] In some embodiments, the specific control process for switching the background protection beam to the As protection beam in step S4 is as follows: the As shutter is opened, the Sb shutter is closed, the Sb valve is adjusted to b2, and the As protection is maintained for a time t3; wherein, b2 is the Sb valve opening required for normal growth of the InAs / InAsSb superlattice in step S5; t3≤10s.

[0058] In some embodiments, the process of growing the InAs / InAsSb superlattice in step S5 is as follows: The In and As source furnace shutters are opened simultaneously to complete the InAs layer growth. The In and As source furnace shutters are then closed for a pause of t4. The In, As, and Sb source furnace shutters are then opened to complete the InAsSb layer growth. The In, As, and Sb source furnace shutters are then closed for another pause of t4. This process is repeated until the InAs / InAsSb layer growth is complete. Throughout the process, the As and Sb valves maintain the opening degree of the As and Sb valves in step S4; where t4 is 2-6 seconds. Similarly, in this embodiment, a growth pause is inserted between the growth of the InAs and InAsSb layers during the InAs / InAsSb superlattice growth process, improving the interface quality at the junction of the InAs and InAsSb layers.

[0059] The specific process and effects of growing superlattice materials using the present invention are illustrated below through specific embodiments.

[0060] Example 1:

[0061] This embodiment prepares a superlattice material with the following specific structure:

[0062] AlSb / AlAs x1 Sb 1-x1 AlSb / AlAs x1 Sb 1-x1 The superlattice thickness is 0.5 μm, and x1 is 0.215.

[0063] InAs / InAs x2 Sb 1-x2 InAs / InAs x2 Sb 1-x2 The superlattice thickness is 2.5 μm, and x² is 0.642.

[0064] The specific preparation process is as follows:

[0065] (1) According to Figure 2 The AlSb / AlAsSb superlattice is grown sequentially using a medium shutter speed. The shutters of the Al and Sb source furnaces are opened. After the AlSb layer growth is completed, the shutters of the Al and Sb source furnaces are closed, and the process is paused for 2 seconds. During the pause, the As source furnace valve is pre-opened to 10%, and the As beam current is approximately 1E-6 Torr. After the AlAsSb layer growth begins, the shutters of the Al, As, and Sb source furnaces are opened. After the AlAsSb layer growth is completed, the shutters of the Al, As, and Sb source furnaces and the As source furnace valve are closed, and the process is paused for 2 seconds. This cycle is repeated until the AlSb / AlAsSb layer growth is completed. Throughout the process, the Sb source furnace valve position is kept constant at 60%, and the Sb beam current is approximately 1E-6 Torr.

[0066] (2) Close the shutters of Al, As, and Sb source furnaces and the valve of the As source furnace, pause for 2 seconds, and grow another AlSb layer according to the process scheme in (1).

[0067] (3) Close the Al source shutter, reduce the Al source furnace to standby temperature, keep the As shutter closed, open the As valve, and adjust the As valve appropriately to 13%, while keeping the Sb valve opening unchanged at 60%, and keep it for 20s to ensure that AlSb / AlAsSb is immersed in the Sb beam for 20s under the protection of the Sb beam.

[0068] (4) Continue to increase the As valve to 16% and at the same time decrease the Sb valve to 52%, and continue for 10 seconds; slowly and orderly increase the proportion of As that may remain on the sample. At this time, the Sb protection beam current will decrease and the duration should not be too long.

[0069] (5) Continue to increase the As valve to 19%, at which point the As beam current is about 2E-6 Torr. This position is the valve opening required for InAs / InAsSb superlattice growth. At the same time, decrease the Sb valve to 44% and continue for 10 seconds.

[0070] (6) Open the As shutter, close the Sb shutter, reduce the Sb valve to 36%, and the Sb beam current is about 6E-7 Torr. Hold for 20s. At this time, the background protection beam current is switched to the appropriate As protection beam current.

[0071] (7) Growth of InAs / InAsSb superlattice: Simultaneously open the shutters of the In and As source furnaces. After the InAs layer growth is completed, close the shutters of the In and As source furnaces and pause for 2 seconds. Then open the shutters of the In, As, and Sb source furnaces. After the InAsSb layer growth is completed, close the shutters of the In, As, and Sb source furnaces and pause for 2 seconds. Repeat this process until the InAs / InAsSb layer growth is completed. The As / Sb valve remains stationary throughout the process.

[0072] Comparative Example 1:

[0073] This comparative example prepares a superlattice material with the same specific structure as in Example 1 above. The preparation process is roughly the same as in Example 1 above. The difference lies in the control method for the introduction of Sb and As after the growth of AlSb / AlAsSb and before the initiation of InAs / InAsSb growth.

[0074] The specific preparation process of the superlattice material in this comparative example is as follows:

[0075] (1) According to Figure 2The AlSb / AlAsSb superlattice is grown sequentially using a medium shutter speed. The shutters of the Al and Sb source furnaces are opened. After the AlSb layer growth is completed, the shutters of the Al and Sb source furnaces are closed, and the process is paused for 2 seconds. During the pause, the As source furnace valve is pre-opened to 10%, and the As beam current is approximately 1E-6 Torr. After the AlAsSb layer growth begins, the shutters of the Al, As, and Sb source furnaces are opened. After the AlAsSb layer growth is completed, the shutters of the Al, As, and Sb source furnaces and the As source furnace valve are closed, and the process is paused for 2 seconds. This cycle is repeated until the AlSb / AlAsSb layer growth is completed. Throughout the process, the Sb source furnace valve position is kept constant at 60%, and the Sb beam current is approximately 1E-6 Torr.

[0076] (2) Close the shutters of Al and As source furnaces, reduce the Al source furnace to standby temperature, keep the As valve open, and increase the As valve to 40% to allow the As beam to be fully diffused into the cavity, while keeping the Sb beam size unchanged, and pause for 1 minute.

[0077] (3) Keep the Sb source furnace shutter open and the Sb source furnace valve position unchanged. Adjust the As valve to 19%. At this time, the As beam current is about 2E-6 Torr. This position is the valve opening required for InAs / InAsSb superlattice growth.

[0078] (4) Open the As shutter, close the Sb shutter, reduce the Sb valve to 36%, and the Sb beam current is about 6E-7 Torr. At this time, the background protection beam current is switched to the appropriate As protection beam current.

[0079] (5) Growth of InAs / InAsSb superlattice: Simultaneously open the shutters of the In and As source furnaces. After the InAs layer growth is completed, close the shutters of the In and As source furnaces and pause for 2 seconds. Then open the shutters of the In, As, and Sb source furnaces. After the InAsSb layer growth is completed, close the shutters of the In, As, and Sb source furnaces and pause for 2 seconds. Repeat this process until the InAs / InAsSb layer growth is completed. The As / Sb valve remains stationary throughout the process.

[0080] The superlattice materials prepared in Example 1 and Comparative Example 1 were tested using atomic force microscopy, and the results are as follows: Figure 3 and Figure 5 As shown, the superlattice materials prepared in Example 1 and Comparative Example 1 were subjected to XRD (X-ray diffraction) tests, and the results are as follows: Figure 4 and Figure 6 As shown.

[0081] in, Figure 3 (a) shows the test results of the superlattice material sample prepared in Example 1 in the range of 10 × 10 μm. Figure 3 (b) The test results of the superlattice material prepared in Example 1 in the 80×80μm range are presented by [the relevant data source]. Figure 3 It can be seen that the epitaxial wafers grown by the superlattice material method of the present invention have atomic-level steps; Figure 4 The XRD test results of the superlattice material prepared in Example 1 are provided by [the relevant authority / organization]. Figure 4 It can be seen that the sample has a very narrow half-width (29), indicating that the crystal quality is excellent and the interface is clear.

[0082] Figure 5 (a) shows the test results of the superlattice material sample prepared in Comparative Example 1 in the range of 10 × 10 μm. Figure 5 (b) The test results of the superlattice material prepared in Comparative Example 1 in the 80 × 80 μm range are presented by [the relevant data source]. Figure 5 It can be seen that the epitaxial surface grown in Comparative Example 1 is a three-dimensional island-shaped growth. Figure 6 The XRD test results of the superlattice material prepared in Comparative Example 1 are presented by... Figure 6 It can be seen that the sample has a wide half-peak width, a blurred interface, and poor crystal quality.

[0083] The above comparison results fully demonstrate that the growth method of the present invention can reduce the interface width between AlSb / AlAsSb and InAs / InAsSb from 3-4 atomic layers in the traditional method to less than 1 atomic layer, which is close to the ideal atomic-level steep interface, and achieves precise control of the superlattice composition of multi-component compounds.

[0084] The above examples are merely illustrative of the present invention and do not constitute a limitation on the scope of protection of the present invention. All designs that are the same as or similar to the present invention are within the scope of protection of the present invention.

Claims

1. A method for growing a superlattice material, characterized in that, The growth process of superlattice materials containing AlSb / AlAsSb and InAs / InAsSb heterostructures includes the following steps: S1, grow an AlSb / AlAsSb superlattice, ending with the growth of an AlSb layer; S2. Immerse the grown AlSb / AlAsSb superlattice under the protection of the Sb beam for the designed time, while keeping the As shutter closed during this process and opening the As valve to allow the As beam to diffuse into the cavity. S3. Adjust the opening of the As valve in stages to gradually increase the As source rate into the growth chamber, while correspondingly reducing the Sb source flow rate in stages. S4. Switch the background protection beam to the As protection beam; S5, grow InAs / InAsSb superlattice.

2. The method for growing superlattice materials as described in claim 1, characterized in that, In S1, the process of growing the AlSb / AlAsSb superlattice is as follows: AlSb layers and AlAsSb layers are grown alternately, and the last layer ends with the growth of an AlSb layer. The growth pause time between adjacent AlSb layers and AlAsSb layers is designed.

3. The method for growing superlattice materials as described in claim 2, characterized in that, The growth pause time t1 between adjacent AlSb layers and AlAsSb layers is 2-6 s.

4. The method for growing superlattice materials as described in claim 1, characterized in that, S2 includes: After completing the growth of the final AlSb layer, the Al source shutter is closed, the Al source furnace is cooled to standby temperature, the As shutter is kept closed, the As valve is opened, and the As valve is adjusted to a1+(a2-a1) / n. At the same time, the Sb shutter is kept open, and the Sb valve opening is b1, so that the grown AlSb / AlAsSb is immersed in the Sb beam for a time t2 under protection. Here, a1 is the As valve opening required for normal growth of AlSb / AlAsSb superlattice in step S1, a2 is the As valve opening required for normal growth of InAs / InAsSb superlattice in step S5, and a1<a2; n is the designed number of times the As valve is opened in stages, n≤4; b1 is the Sb valve opening required for normal growth of AlSb / AlAsSb superlattice in step S1.

5. The method for growing superlattice materials as described in claim 1 or 4, characterized in that, In S2, the growing AlSb / AlAsSb superlattice is immersed in Sb beam protection for a time t2 not greater than 30s.

6. The method for growing superlattice materials as described in claim 1 or 4, characterized in that, In step S3, the specific control process for introducing the As source into the growth chamber while simultaneously reducing the Sb source flow rate in stages is as follows: Increase valve As to a1+2(a2-a1) / n, while decreasing valve Sb to b1-(b1-b2) / n, for time T1; then increase valve As further to a1+3(a2-a1) / n, while decreasing valve Sb to b1-2(b1-b2) / n, for time T2; then increase valve As further to a1+4(a2-a1) / n, while decreasing valve Sb to b1-3(b1-b2) / n, for time T3, and so on, until valve As is increased to a2. The opening degree; where a1 is the As valve opening degree required for normal growth of AlSb / AlAsSb superlattice in step S1, a2 is the As valve opening degree required for normal growth of InAs / InAsSb superlattice in step S5, and a1 < a2; n is the designed number of steps to open the As valve, n ≤ 4; b1 is the Sb valve opening degree required for normal growth of AlSb / AlAsSb superlattice in step S1, and b2 is the Sb valve opening degree required for normal growth of InAs / InAsSb superlattice in step S5.

7. The method for growing superlattice materials as described in claim 6, characterized in that, The duration of each opening step of the As valve, T1, T2, and T3, is no greater than 10 seconds.

8. The method for growing superlattice materials as described in claim 1, characterized in that, In step S4, the specific control process for switching the background protection beam to the As protection beam is as follows: the As shutter is opened, the Sb shutter is closed, the Sb valve is adjusted to b2, and the As protection is maintained for t3 time; where b2 is the Sb valve opening required for normal growth of the InAs / InAsSb superlattice in step S5; t3≤10s.

9. The method for growing superlattice materials as described in claim 1, characterized in that, In S5, the process of growing the InAs / InAsSb superlattice is as follows: S51. Simultaneously open the In and As source furnace shutters to complete the InAs layer growth, then close the In and As source furnace shutters and pause the growth design time. S52. Open the In, As, and Sb source furnace shutters to complete the InAsSb layer growth, then close the In, As, and Sb source furnace shutters to pause the growth design time. S53. Repeat the above S51-S52 process until the growth of the InAs / InAsSb layer is completed. Specifically, the opening degree of valves As and Sb in step S4 of the entire process of S51-S53 is maintained.

10. A superlattice material, characterized in that: A superlattice material comprising AlSb / AlAsSb and InAs / InAsSb heterostructures prepared by the superlattice material growth method according to any one of claims 1-9.

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