Surface reconstruction method and device for tellurium-zinc-cadmium-based tellurium-cadmium-mercury molecular beam epitaxy
By performing surface reconstruction treatment on the zinc tellurium substrate, including wet chemical treatment, heating removal of the surface layer and growth buffer layer, the epitaxial instability caused by substrate dislocation and defects is solved, and the stable mass production of high-quality mercury cadmium tellurium films is achieved.
Patent Information
- Application Number
- CN202411650018.6
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2024-11-19
- Publication Date
- 2025-02-28
AI Technical Summary
Existing zinc tellurium cadmium substrates are prone to cause dislocation and surface defects during single crystal growth and wet chemical treatment, resulting in unstable molecular beam epitaxial process and inability to achieve stable mass production.
The surface reconstruction method is adopted, including wet chemical treatment of the zinc tellurium substrate, heating to remove water gas and oxide layers, growing the zinc tellurium homogeneous buffer layer and mercury cadmium tellurium superlattice buffer layer, and finally performing continuous gradient adjustment of the components during the epitaxial process to generate a band gap gradient change buffer led by the cadmium telluride layer.
Through the surface reconstruction method, the unfavorable epitaxial surface state of the substrate intrinsics can be avoided to the greatest extent, and a high flatness and low defect surface can be obtained, the epitaxial yield rate can be improved, and the dependence on the substrate's own properties can be reduced. It is suitable for large-scale production and high-quality mercury cadmium tellur film epitaxial.
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Figure CN119530967A_ABST
Abstract
Description
Technical Field
[0001] The present application relates to the field of molecular beam epitaxy technology for mercury cadmium telluride materials, and in particular to a surface reconstruction method and device for cadmium zinc telluride-based mercury cadmium telluride molecular beam epitaxy. Background Art
[0002] Currently, infrared focal plane detectors are undergoing a development transition from the third generation to a newer generation of detectors. The development of related fields is pointing to technical directions such as ultra-large-scale, high-sensitivity, and wide-spectrum detection, which have higher requirements for material quantum efficiency and response spectrum. Mercury cadmium telluride material has high quantum efficiency and can cover shortwave to very long wave bands. Therefore, it is currently the most widely used material system for infrared focal planes.
[0003] The existing epitaxial process cannot shield the dislocations and surface defects of the CdZnTe substrate caused during the single crystal growth and wet chemical treatment, making the epitaxial process unstable and unable to achieve a stable batch molecular beam epitaxy process. An additional substrate screening step is required, which greatly increases the requirements for the substrate and seriously reduces the process efficiency.
[0004] In view of this, how to provide a highly compatible CdZnTe-based HgCdTe thin film molecular beam epitaxy process so as to minimize the influence of substrate state on the HgCdTe thin film has become a technical problem that urgently needs to be solved. Summary of the invention
[0005] The embodiments of the present application provide a surface reconstruction method for CdZnTe-based HgCdTe molecular beam epitaxy and a surface reconstruction device for CdZnTe-based HgCdTe molecular beam epitaxy, which are used to solve the problem that the current substrate state has a great influence on the HgCdTe film.
[0006] In a first aspect of an embodiment of the present application, a surface reconstruction method for CdZnTe-based HgCdTe molecular beam epitaxy is provided, comprising:
[0007] Performing wet chemical treatment on the cadmium zinc telluride substrate to obtain a cadmium zinc telluride substrate sample;
[0008] Heating the cadmium zinc telluride substrate sample placed in a sample loading chamber of a molecular beam epitaxy device to obtain a first substrate sample from which moisture is removed;
[0009] The first substrate sample placed in the growth chamber of the molecular beam epitaxy equipment is subjected to a heating treatment to obtain a second substrate sample where the surface oxide layer and the damage layer are removed;
[0010] Perform epitaxy of a cadmium zinc telluride homogeneous buffer layer, and after the reflection electron diffractometer image remains unchanged, lower the temperature corresponding to the second substrate sample to room temperature;
[0011] The second substrate sample on which the epitaxy of the cadmium zinc telluride homogeneous buffer layer is completed is subjected to growth of a mercury cadmium telluride superlattice buffer layer within an epitaxy temperature range to obtain a third substrate sample;
[0012] The third substrate sample placed in the HgCdTe chamber is subjected to HgCdTe epitaxial film growth, and the components are continuously gradient-adjusted during the epitaxial growth process to generate a bandgap gradient change buffer led by the CdTe layer.
[0013] In a second aspect of an embodiment of the present application, a surface reconstruction device for CdZnTe-based HgCdTe molecular beam epitaxy is provided, comprising:
[0014] A first processing module is configured to perform a wet chemical treatment on the cadmium zinc telluride substrate to obtain a cadmium zinc telluride substrate sample;
[0015] A second processing module is configured to heat the cadmium zinc telluride substrate sample placed in the sample loading chamber of the molecular beam epitaxy device to obtain a first substrate sample with moisture removed;
[0016] A third processing module is configured to heat the first substrate sample placed in the growth chamber of the molecular beam epitaxy equipment to obtain a second substrate sample with the surface oxide layer and the damage layer removed;
[0017] The epitaxy module is configured to perform epitaxy of a cadmium zinc telluride homogeneous buffer layer, and after the reflection electron diffractometer image remains unchanged, reduce the temperature corresponding to the second substrate sample to room temperature;
[0018] A generation module is configured to grow a HgCdTe superlattice buffer layer on the second substrate sample on which the CdZnTe homogeneous buffer layer is epitaxially grown within an epitaxial temperature range to obtain a third substrate sample;
[0019] The regulating module is configured to perform HgCdTe epitaxial film growth on the third substrate sample placed in the HgCdTe chamber, and to perform continuous gradient regulation on the components during the epitaxial growth process to generate a band gap gradient variation buffer with the CdTe layer as the leader.
[0020] The present application provides a surface reconstruction method for CdZnTe-based HgCdTe molecular beam epitaxy, comprising: wet chemical treatment of a CdZnTe substrate to obtain a CdZnTe substrate sample; heating the CdZnTe substrate sample placed in a sample loading chamber of a molecular beam epitaxy device to obtain a first substrate sample with moisture removed; heating the first substrate sample placed in a growth chamber of a molecular beam epitaxy device to obtain a second substrate sample with a surface oxide layer and a damage layer removed; epitaxy of a CdZnTe homogeneous buffer layer, and after a reflection electron diffractometer image remains unchanged, lowering the temperature corresponding to the second substrate sample to room temperature; growing a HgCdTe superlattice buffer layer on the second substrate sample after the epitaxy of the CdZnTe homogeneous buffer layer is completed within an epitaxy temperature range to obtain a third substrate sample; and growing a HgCdTe epitaxial thin film on the third substrate sample placed in a HgCdTe chamber, and continuously gradient adjusting the components during the epitaxial growth process to generate a bandgap gradient variation buffer with a CdT layer as the leader.
[0021] By using the surface reconstruction method for CdZnTe-based HgCdTe molecular beam epitaxy provided in the embodiment of the present application, the intrinsic unfavorable epitaxial surface state of the substrate can be avoided to the greatest extent. At the same time, the surface state before epitaxy is modified by inserting a CdZnTe homogeneous buffer layer and a superlattice relaxation layer to obtain a high-flatness and low-defect surface. The defects of the substrate or other substrate state factors that are unfavorable for epitaxy are basically not transmitted to the epitaxial film, which greatly improves the epitaxial yield, reduces the dependence on the properties of the substrate itself, and is conducive to large-scale production and high-quality HgCdTe film epitaxy.
[0022] The above description is only an overview of the technical solution of the present application. In order to more clearly understand the technical means of the present application, which can be implemented in accordance with the contents of the specification, and in order to make the above and other purposes, features and advantages of the present application more obvious and easy to understand, the specific implementation methods of the present application are listed below. BRIEF DESCRIPTION OF THE DRAWINGS
[0023] Various other advantages and benefits will become apparent to those of ordinary skill in the art by reading the detailed description of the preferred embodiments below. The accompanying drawings are only for the purpose of illustrating the preferred embodiments and are not to be considered as limiting the present application. Also, the same reference symbols are used throughout the accompanying drawings to represent the same components. In the accompanying drawings:
[0024] Figure 1 A schematic flow chart of a surface reconstruction method for CdZnTe-based HgCdTe molecular beam epitaxy provided in an embodiment of the present application;
[0025] Figure 2 A flow chart for implementing a surface reconstruction method for CdZnTe-based HgCdTe molecular beam epitaxy provided in an embodiment of the present application;
[0026] Figure 3 A schematic structural diagram of a surface reconstruction device for CdZnTe-based HgCdTe molecular beam epitaxy provided in an embodiment of the present application. DETAILED DESCRIPTION
[0027] The exemplary embodiments of the present disclosure will be described in more detail below with reference to the accompanying drawings. Although the exemplary embodiments of the present disclosure are shown in the accompanying drawings, it should be understood that the present disclosure can be implemented in various forms and should not be limited by the embodiments set forth herein. On the contrary, these embodiments are provided to enable a more thorough understanding of the present disclosure and to fully convey the scope of the present disclosure to those skilled in the art.
[0028] Molecular beam epitaxy is one of the current high-quality HgCdTe thin film epitaxy process technologies, and among the various substrates suitable for HgCdTe thin film epitaxy, CdZnTe substrate is currently recognized as the best substrate. CdZnTe is in the same family as HgCdTe, and is an infrared-transmitting material that is compatible with back-illuminated infrared detector technology. At the same time, the lattice constant of CdZnTe substrate can be adjusted by substrate zinc composition to fully match that of HgCdTe, so it theoretically has the ability to epitaxially grow low-dislocation HgCdTe materials.
[0029] In actual molecular beam epitaxy, HgCdTe thin films grown on CdZnTe substrates have not fully achieved the theoretical extremely low dislocation growth. Since CdZnTe is a ternary pseudo-binary solid solution compound, during the directional solidification process, there is low solubility of tellurium and the capture of inclusion components by interface defects. Therefore, it is difficult for its single crystal growth to achieve nearly dislocation-free growth similar to single crystal systems such as silicon / germanium. Single crystal ingots produced by directional solidification methods usually have component inhomogeneity, dislocations or large-sized defects caused by component inclusions. The defects or inclusions in these crystals are usually impossible to remove and will remain in the CdZnTe crystals in large quantities and be exposed to the surface during the process of single crystal cutting, grinding and polishing into epitaxial-grade substrates, forming substrate surface defects. The non-equilibrium characteristics of the molecular beam epitaxy process determine that the dislocations and other defects of the CdZnTe substrate cannot be shielded during the epitaxial process, but will be transmitted to the epitaxial film to form more defects and continue to be amplified in the subsequent epitaxial process, causing serious deterioration of the quality of the epitaxial film and even epitaxial failure. This is also the main source of defects in CdZnTe-based HgCdTe films.
[0030] Since the CdZnTe material itself is a II-VI compound, its composition characteristics make it extremely easy to oxidize. In the preparation process of single crystal substrates, it needs to be exposed to air for a long time for cutting and slicing, and undergo multiple processes related to chemical corrosion. There must be a certain thickness of damage layer and oxide layer on its surface. Therefore, CdZnTe substrates for epitaxy do not have the possibility of preparing epi-ready products in the traditional sense. They must be wet chemically treated before entering the molecular beam epitaxial growth chamber to remove the surface damage layer and oxide layer to expose the fresh surface. The secondary oxidation of the fresh surface can be completed by simple treatment in the molecular beam epitaxy chamber. At present, the wet chemical treatment process mostly adopts bromine methanol etching. However, since bromine methanol is selectively corroded on the surface of CdZnTe substrate, and the surface state of substrate cannot maintain high consistency like single crystal silicon, it is very easy to change the surface state of substrate due to the deviation of wet chemical process, so the surface properties cannot be completely retained. The surface after etching usually has component deviation (such as tellurium-rich surface) and roughness deterioration. The process of removing the surface tellurium-rich layer by heating treatment often introduces other surface degradation problems, such as further deviation of component and appearance of amorphous layer on the surface, which affects the progress of epitaxial process. Under the current process conditions, even substrates with good surface state are difficult to achieve good epitaxial-grade surface after entering the cavity. The substrate needs to be pre-treated or screened before entering the cavity to ensure that the substrate surface has low defects and inclusions, and can maintain good surface state after entering the cavity, so as to achieve low-defect HgCdTe film epitaxy.
[0031] The currently commonly used CdZnTe-based HgCdTe thin film molecular beam epitaxy process requires additional screening in the substrate step to obtain high-quality substrates, and to evaluate the substrate morphology in the subsequent pretreatment and epitaxy process to formulate a specific growth plan, and to monitor the growth during the growth process. This is not conducive to standardized and unified large-scale production, and it is difficult to continuously optimize the process. At the same time, this type of method cannot change the substrate state, and therefore cannot ensure that the epitaxial film is not affected by substrate defects or dislocations, which can easily lead to epitaxy failure, greatly increase production costs, and make it difficult to give full play to the advantages of low dislocation epitaxy of CdZnTe-based HgCdTe materials.
[0032] See also Figure 1 , Figure 1 A schematic diagram of a surface reconstruction method for CdZnTe-based HgCdTe molecular beam epitaxy provided in an embodiment of the present application. Figure 1 As shown, the specific steps include the following steps.
[0033] Step S102: performing wet chemical treatment on the CdZnTe substrate to obtain a CdZnTe substrate sample;
[0034] Step S104: heating the CdZnTe substrate sample placed in the sample loading chamber of the molecular beam epitaxy equipment to obtain a first substrate sample from which moisture is removed;
[0035] Step S106: heating the first substrate sample placed in the growth chamber of the molecular beam epitaxy equipment to obtain a second substrate sample with the surface oxide layer and the damaged layer removed;
[0036] Step S108: performing epitaxy of a cadmium zinc telluride homogeneous buffer layer, and after the reflection electron diffractometer image remains unchanged, lowering the temperature corresponding to the second substrate sample to room temperature;
[0037] Step S110: growing a HgCdTe superlattice buffer layer on the second substrate sample after epitaxy of the CdZnTe homogeneous buffer layer is performed within an epitaxy temperature range to obtain a third substrate sample;
[0038] Step S112: performing HgCdTe epitaxial film growth on the third substrate sample placed in the HgCdTe chamber, and performing continuous gradient adjustment on the components during the epitaxial growth process to generate a bandgap gradient change buffer with the CdTe layer as the leader.
[0039] Specifically, the embodiment of the present application starts with substrate wet chemical treatment and ends with molecular beam epitaxy, and requires the use of molecular beam epitaxy equipment to perform two epitaxy processes of silicon-based cadmium telluride and mercury cadmium telluride. A series of treatments are performed on the processed epitaxial-grade cadmium zinc telluride substrate to achieve high-compatibility and low-dislocation density epitaxy, so that low-defect and low-dislocation mercury cadmium telluride film epitaxy can be performed on any cadmium zinc telluride substrate that can be screened. The process is as follows:
[0040] 1. The CdZnTe substrate is subjected to wet chemical treatment with a low concentration of bromine methanol solution.
[0041] 2. The substrate sample enters the sample chamber of the molecular beam epitaxy equipment and is heated to remove moisture.
[0042] 3. The CdZnTe substrate that has been heated and dehydrated is placed in a molecular beam epitaxy chamber to remove the surface oxide layer / damage layer. After the substrate temperature reaches the maximum temperature, the Hg (mercury) beam is turned on to protect the substrate surface. The substrate is then cooled and the CdZnTe homogeneous buffer layer is grown epitaxially. The substrate is cooled to room temperature after the RHEED (reflection high energy electron diffractometer) image remains unchanged. The RHEED device consists of a high energy electron gun and a fluorescent screen.
[0043] 4. After the substrate with the epitaxial CdZnTe (cadmium zinc telluride) homogeneous buffer layer is set to the epitaxial temperature range, a HgTe / HgCdTe (mercury cadmium telluride) superlattice buffer layer is grown.
[0044] 5. The substrate with the surface superlattice buffer layer growth continues to grow HgCdTe epitaxial thin films in the HgCdTe chamber. During the epitaxial process, the components are continuously adjusted in gradient. The CdTe (cadmium telluride) layer is epitaxially grown first, and then after the CdTe epitaxy of about 100-300nm is completed, the Hg and Te source furnace beams are turned on, and the CdTe / Te composition is gradually adjusted to increase the Te beam ratio, so that the CdTe / Te ratio is gradually reduced to the vicinity of the component in the required band. The first formed CdTe layer acts as a wide bandgap buffer layer to shield the carriers of the superlattice layer from diffusing into the HgCdTe layer.
[0045] See also Figure 2 , Figure 2 A flow chart of an implementation of a surface reconstruction method for CdZnTe-based HgCdTe molecular beam epitaxy provided in an embodiment of the present application.
[0046] like Figure 2 As shown, shielding of the surface tellurium-rich layer / buffer layer is achieved through multi-step buffer layer epitaxy.
[0047] First, the epitaxial cadmium zinc telluride substrate is mounted on a cleaning fixture and immersed in a bromine methanol cleaning solution, and is quickly rinsed (within 1 minute) with a low concentration of bromine methanol solution. After cleaning, the surface is cleaned with methanol and quickly blown dry.
[0048] The substrate sample is then loaded onto a clamping substrate fixture for molecular beam epitaxy and fixedly contacted with the fixture through indium bonding. It is then loaded onto a chamber trolley and placed into the sample loading chamber of the molecular beam epitaxy equipment. The sample is then evacuated and heated to remove moisture after the vacuum degree reaches a value better than 6×10-7 torr.
[0049] Secondly, after the heated and degassed CdZnTe substrate and fixture are cooled to room temperature, they are transferred into the growth chamber of the molecular beam epitaxy equipment and heated again to remove the oxide layer formed on the surface due to exposure to air after cleaning. The surface state changes of the substrate are monitored by reflective RHEED, and the temperature of the substrate manipulator heating disk is set between 300-500°C according to the properties of the substrate and the state of the RHEED image to remove the surface oxide layer / damage layer. After the substrate temperature reaches the highest temperature, the Hg beam is turned on to protect the substrate surface. The Hg beam and temperature are kept unchanged during the whole process. After the surface oxide layer pattern shown in the RHEED image disappears, the temperature is lowered and the CdZnTe homogeneous buffer layer is epitaxially grown. After the RHEED image remains unchanged, the temperature is lowered to room temperature.
[0050] Then, the substrate with the epitaxial CdZnTe homogeneous buffer layer is heated to the epitaxial temperature and then the HgTe / HgCdTe superlattice buffer layer is grown. The buffer layer growth is terminated after the RHEED image is monitored until the image is basically unchanged.
[0051] Finally, for the substrate with the surface superlattice buffer layer growth completed, the Hg source furnace beam and the Te source furnace beam are first turned off in the growth chamber to grow the CdTe layer. Then, after the epitaxy of the CdTe layer of about 100-300nm is completed, the Hg and Te source furnace beams are turned on, and the CdTe / Te composition is gradually adjusted to increase the Te beam ratio. At the same time, the epitaxial temperature is adjusted to gradually reduce the CdTe / Te ratio to near the composition of the required band, and a bandgap gradient buffer layer with the CdTe layer as the leader is formed between the HgCdTe epitaxial film and the superlattice layer, which is used to shield the carriers of the superlattice layer from diffusing into the HgCdTe layer, so that the superlattice layer only serves as a lattice relaxation layer.
[0052] By adopting the method provided in the embodiment of the present application, the intrinsic adverse epitaxial surface state of the substrate can be avoided to the greatest extent. At the same time, the surface state before epitaxy is modified by inserting a cadmium zinc telluride homogeneous buffer layer and a superlattice relaxation layer to obtain a high-flatness and low-defect surface. The defects of the substrate or other substrate state factors that are not conducive to epitaxy are basically not transmitted to the epitaxial film, which greatly improves the epitaxial yield, reduces the dependence on the properties of the substrate itself, and is conducive to large-scale production and high-quality mercury cadmium telluride film epitaxy.
[0053] Corresponding to the above method embodiment, this specification also provides an embodiment of a surface reconstruction device for CdZnTe-based HgCdTe molecular beam epitaxy, Figure 3 The schematic diagram of the structure of a surface reconstruction device for CdZnTe-based HgCdTe molecular beam epitaxy provided in an embodiment of the present application. Figure 3 As shown, the device comprises:
[0054] The first processing module 302 is configured to perform a wet chemical treatment on the CdZnTe substrate to obtain a CdZnTe substrate sample;
[0055] The second processing module 304 is configured to heat the CdZnTe substrate sample placed in the sample loading chamber of the molecular beam epitaxy device to obtain a first substrate sample with moisture removed;
[0056] The third processing module 306 is configured to heat the first substrate sample placed in the growth chamber of the molecular beam epitaxy equipment to obtain a second substrate sample with the surface oxide layer and the damage layer removed;
[0057] The epitaxy module 308 is configured to perform epitaxy of the CdZnTe homogeneous buffer layer, and after the reflection electron diffractometer image remains unchanged, reduce the temperature corresponding to the second substrate sample to room temperature;
[0058] The generating module 310 is configured to perform growth of a HgCdTe superlattice buffer layer on the second substrate sample on which the epitaxy of the CdZnTe homogeneous buffer layer is completed within an epitaxy temperature range to obtain a third substrate sample;
[0059] The adjustment module 312 is configured to perform HgCdTe epitaxial film growth on the third substrate sample placed in the HgCdTe chamber, and perform continuous gradient adjustment on the components during the epitaxial growth process to generate a bandgap gradient change buffer with the CdTe layer as the leader.
[0060] In an optional embodiment, the first processing module 302 is further configured to:
[0061] The cadmium zinc telluride substrate is subjected to wet chemical treatment with a low concentration of bromine methanol solution to obtain a cadmium zinc telluride substrate sample.
[0062] In an optional embodiment, the third processing module 306 is further configured to:
[0063] The first substrate sample placed in the growth chamber of the molecular beam epitaxy equipment is heat treated, the state changes of the surface of the first substrate sample are monitored by a reflection electron diffractometer, and the heating temperature is set based on the properties of the first substrate sample and the state of the reflection electron diffractometer to obtain a second substrate sample with the surface oxide layer and damage layer removed.
[0064] In an optional embodiment, after the third processing module 306, the following steps are included:
[0065] The protection module is configured to turn on the Hg beam to protect the surface of the second substrate sample when the temperature of the second substrate sample reaches a maximum temperature.
[0066] In an optional embodiment, the generation module 310 includes:
[0067] The ending module is configured to end the buffer layer generation when the image state remains unchanged through the reflection electron diffractometer image monitoring.
[0068] In an optional embodiment, the adjustment module 312 is further configured to:
[0069] The Hg source furnace beam and the Te source furnace beam are turned off to grow the cadmium telluride layer. After the epitaxy of the cadmium telluride layer is completed, the Hg source furnace beam and the Te source furnace beam are turned on to gradually adjust the composition of the cadmium telluride to generate a bandgap gradient buffer layer with the cadmium telluride layer as the leader.
[0070] By using the device provided in the embodiment of the present application, the intrinsic adverse epitaxial surface state of the substrate can be avoided to the greatest extent. At the same time, the surface state before epitaxy is modified by inserting a cadmium zinc telluride homogeneous buffer layer and a superlattice relaxation layer to obtain a high-flatness and low-defect surface. The defects of the substrate or other substrate state factors that are not conducive to epitaxy are basically not transmitted to the epitaxial film, which greatly improves the epitaxial yield, reduces the dependence on the properties of the substrate itself, and is conducive to large-scale production and high-quality mercury cadmium telluride film epitaxy.
[0071] Each embodiment in this specification is described in a progressive manner, and the same or similar parts between the embodiments can be referred to each other, and each embodiment focuses on the differences from other embodiments. In particular, for the surface reconstruction device for CdZnTe-based HgCdTe molecular beam epitaxy, since it is basically similar to the surface reconstruction method embodiment for CdZnTe-based HgCdTe molecular beam epitaxy, the description is relatively simple, and the relevant parts can be referred to the partial description of the surface reconstruction method embodiment for CdZnTe-based HgCdTe molecular beam epitaxy.
[0072] It should be noted that the above is a description of a specific embodiment of the present specification. Other embodiments are within the scope of the appended claims. In some cases, the actions or steps recorded in the claims can be performed in an order different from that in the embodiments and still achieve the desired results. In addition, the processes depicted in the accompanying drawings do not necessarily require the specific order or continuous order shown to achieve the desired results. In some embodiments, multitasking and parallel processing are also possible or may be advantageous. Secondly, those skilled in the art should also be aware that the embodiments described in the specification are all preferred embodiments, and the actions and modules involved are not necessarily required by the embodiments of the present specification.
[0073] In the above embodiments, the description of each embodiment has its own emphasis. For parts that are not described in detail in a certain embodiment, reference can be made to the relevant descriptions of other embodiments.
[0074] The preferred embodiments of this specification disclosed above are only used to help explain this specification. The optional embodiments do not describe all the details in detail, nor do they limit the invention to only the specific implementation methods described. Obviously, many modifications and changes can be made according to the content of the embodiments of this specification. This specification selects and specifically describes these embodiments in order to better explain the principles and practical applications of the embodiments of this specification, so that technicians in the relevant technical field can well understand and use this specification. This specification is only limited by the claims and their full scope and equivalents.
Claims
1. A surface reconstruction method for CdZnTe-based HgCdTe molecular beam epitaxy, characterized in that: include: Performing wet chemical treatment on the cadmium zinc telluride substrate to obtain a cadmium zinc telluride substrate sample; Heating the cadmium zinc telluride substrate sample placed in a sample loading chamber of a molecular beam epitaxy device to obtain a first substrate sample from which moisture is removed; The first substrate sample placed in the growth chamber of the molecular beam epitaxy equipment is subjected to a heating treatment to obtain a second substrate sample where the surface oxide layer and the damage layer are removed; Perform epitaxy of a cadmium zinc telluride homogeneous buffer layer, and after the reflection electron diffractometer image remains unchanged, lower the temperature corresponding to the second substrate sample to room temperature; The second substrate sample on which the epitaxy of the cadmium zinc telluride homogeneous buffer layer is completed is subjected to growth of a mercury cadmium telluride superlattice buffer layer within an epitaxy temperature range to obtain a third substrate sample; The third substrate sample placed in the HgCdTe chamber is subjected to HgCdTe epitaxial film growth, and the components are continuously gradient-adjusted during the epitaxial growth process to generate a bandgap gradient change buffer led by the CdTe layer.
2. The method according to claim 1, characterized in that: The step of subjecting the CdZnTe substrate to a wet chemical treatment to obtain a CdZnTe substrate sample comprises: The cadmium zinc telluride substrate is subjected to wet chemical treatment with a low concentration of bromine methanol solution to obtain a cadmium zinc telluride substrate sample.
3. The method according to claim 1, characterized in that The step of heating the first substrate sample placed in the growth chamber of the molecular beam epitaxy equipment to obtain a second substrate sample with the surface oxide layer and the damage layer removed comprises: The first substrate sample placed in the growth chamber of the molecular beam epitaxy equipment is heat treated, the state changes of the surface of the first substrate sample are monitored by a reflection electron diffractometer, and the heating temperature is set based on the properties of the first substrate sample and the state of the reflection electron diffractometer to obtain a second substrate sample with the surface oxide layer and damage layer removed.
4. The method according to claim 3, characterized in that After the first substrate sample placed in the growth chamber of the molecular beam epitaxy equipment is heated to obtain a second substrate sample where the surface oxide layer and the damaged layer are removed, the method comprises: When the temperature of the second substrate sample reaches the highest temperature, the Hg beam is turned on to protect the surface of the second substrate sample.
5. The method according to claim 1, characterized in that The second substrate sample on which the epitaxy of the cadmium zinc telluride homogeneous buffer layer is completed is set to an epitaxial temperature range for growth of a mercury cadmium telluride superlattice buffer layer to obtain a third substrate sample, comprising: The buffer layer formation is terminated when the image state remains unchanged through reflection electron diffractometer image monitoring.
6. The method according to claim 1, characterized in that The step of growing a mercury cadmium telluride epitaxial film on the third substrate sample placed in the mercury cadmium telluride chamber and continuously adjusting the composition in a gradient manner during the epitaxial growth process comprises: The Hg source furnace beam and the Te source furnace beam are turned off to grow the cadmium telluride layer. After the epitaxy of the cadmium telluride layer is completed, the Hg source furnace beam and the Te source furnace beam are turned on to gradually adjust the composition of the cadmium telluride to generate a bandgap gradient buffer layer with the cadmium telluride layer as the leader.
7. A surface reconstruction device for CdZnTe-based HgCdTe molecular beam epitaxy, characterized in that: include: A first processing module is configured to perform a wet chemical treatment on the cadmium zinc telluride substrate to obtain a cadmium zinc telluride substrate sample; A second processing module is configured to heat the cadmium zinc telluride substrate sample placed in the sample loading chamber of the molecular beam epitaxy device to obtain a first substrate sample with moisture removed; A third processing module is configured to heat the first substrate sample placed in the growth chamber of the molecular beam epitaxy equipment to obtain a second substrate sample with the surface oxide layer and the damage layer removed; The epitaxy module is configured to perform epitaxy of a cadmium zinc telluride homogeneous buffer layer, and after the reflection electron diffractometer image remains unchanged, reduce the temperature corresponding to the second substrate sample to room temperature; A generation module is configured to grow a HgCdTe superlattice buffer layer on the second substrate sample on which the CdZnTe homogeneous buffer layer is epitaxially grown within an epitaxial temperature range to obtain a third substrate sample; The regulating module is configured to perform HgCdTe epitaxial film growth on the third substrate sample placed in the HgCdTe chamber, and to perform continuous gradient regulation on the components during the epitaxial growth process to generate a band gap gradient variation buffer with the CdTe layer as the leader.