In-situ heat treatment method and heterojunction structure of mercury cadmium telluride thin film doped by molecular beam epitaxy
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- Filing Date
- 2022-10-08
- Publication Date
- 2026-08-11
Smart Images
Figure CN115911177B_ABST
Abstract
Description
Technical Field
[0001] This application relates to the field of semiconductor technology, and in particular to a method for in-situ thermal treatment of mercury cadmium telluride thin films via molecular beam epitaxy and a heterojunction structure. Background Technology
[0002] With the development of infrared focal plane array (IFA) technology, third-generation IFA has become a research focus, placing higher demands on HgCdTe IFA technology. Multilayer epitaxial fabrication of heterogeneous structures is one of the research challenges. In-situ doping using molecular beam epitaxy (MBE) can achieve n- and p-type doping of HgCdTe materials. Multilayer structures can be designed for HgCdTe materials, and multiple pn junctions can be fabricated for the fabrication of dual-color and multi-color HgCdTe infrared detectors.
[0003] In-situ doping of mercury cadmium telluride (MCT) refers to the introduction of impurities during the growth of MCT. n-type doping is relatively easy, with In being one of the preferred elements due to its low diffusivity, ease of introducing Hg sites, and high activation potential. However, p-type doping is more difficult. Researchers both domestically and internationally have conducted extensive work on in-situ p-type doping techniques for MBE, typically employing conventional planar As doping methods. However, As has a low adhesion coefficient and is highly sensitive to substrate temperature. To achieve the target As doping concentration, a lower growth temperature must be selected within the growth window.
[0004] Furthermore, since molecular beam epitaxy (MBE) of mercury cadmium telluride (HCDT) is a tellurium-rich growth process, aspartate (As) occupies mercury vacancies during doping, requiring further heat treatment to achieve p-type activation of the HCDT thin film. Typically, As activation requires a two-step annealing process: high-temperature saturated mercury vapor pressure annealing and low-temperature mercury vacancy elimination annealing. High-temperature heat treatment requires approximately 300°C to 450°C to achieve As acceptor activation. These high temperatures place stringent requirements on the process environment and can also adversely affect the surface material. The influence of high-temperature-induced component interdiffusion on the composition of HCDT epitaxial materials is also significant. Summary of the Invention
[0005] This application provides a method for in-situ heat treatment of mercury cadmium telluride (MCT) thin films via molecular beam epitaxy and a heterojunction structure, which is used to design the structure of MCT materials to achieve n- and p-type doping of MCT materials, and to obtain MCT heterojunction materials without heat treatment or only through low-temperature heat treatment.
[0006] This application provides a method for in-situ heat treatment of mercury cadmium telluride thin films via molecular beam epitaxy, including:
[0007] Substrate preparation;
[0008] A p-type doped layer is grown on the substrate;
[0009] The p-type doped layer is prepared by: taking cadmium telluride, cadmium arsenide, and mercury telluride as one cycle, and repeating this cycle multiple times to form a superlattice structure to obtain the p-type doped layer.
[0010] Optionally, the thickness of each cadmium telluride, cadmium arsenide, and mercury telluride layer in the p-type doped layer is 1 nm to 10 nm, and the thickness of each layer in the same period can be different.
[0011] Optionally, the method for preparing the p-type doped layer further includes:
[0012] The superlattice structure formed is placed in a mercury-saturated atmosphere and heated at a target temperature for a specified time.
[0013] Optional, also includes:
[0014] After growing an n-type doped layer on the substrate, the p-type doped layer is then grown; or
[0015] After growing the p-type doped layer on the substrate, an n-type doped layer is then grown.
[0016] Optionally, the n-type doped layer is an In-doped mercury cadmium telluride layer, and the composition of the In-doped mercury cadmium telluride is 0.2-0.4%, with an In doping concentration of 1×10⁻⁶. 15 cm -3 ~1×10 17 cm -3 The thickness of the n-type doped layer is 3μm to 20μm.
[0017] Optionally, the substrate preparation includes sequentially growing an arsenic, zinc telluride buffer layer, and a cadmium telluride buffer layer on the surface of the substrate material.
[0018] This application also proposes a molecular beam epitaxy mercury cadmium telluride heterojunction structure, including...
[0019] Substrate;
[0020] A p-type doped layer is grown on the substrate;
[0021] The p-type doped layer is formed by repeating three layers of cadmium telluride, cadmium arsenide, and mercury telluride in a cycle to form a superlattice structure.
[0022] This application also proposes a semiconductor device including the aforementioned molecular beam epitaxy mercury cadmium telluride heterojunction structure.
[0023] In this embodiment, by treating cadmium telluride, cadmium arsenide, and mercury telluride as a cycle, and repeating this cycle multiple times to form a superlattice structure and a p-type doped layer, a cadmium telluride-mercury heterojunction material can be obtained without heat treatment or only through low-temperature heat treatment.
[0024] The above description is only an overview of the technical solution of this application. In order to better understand the technical means of this application and to implement it in accordance with the contents of the specification, and to make the above and other objects, features and advantages of this application more obvious and understandable, the following are specific embodiments of this application. Attached Figure Description
[0025] Various other advantages and benefits will become apparent to those skilled in the art upon reading the following detailed description of preferred embodiments. The accompanying drawings are for illustrative purposes only and are not intended to limit the scope of this application. Furthermore, the same reference numerals denote the same parts throughout the drawings. In the drawings:
[0026] Figure 1 This is a structural example of an in-situ doped mercury cadmium telluride heterojunction material according to an embodiment of this application;
[0027] Figure 2 This is an example of a structure of an in-situ doped mercury cadmium telluride heterojunction material after heat treatment, according to an embodiment of this application. Detailed Implementation
[0028] Exemplary embodiments of the present disclosure will now be described in more detail with reference to the accompanying drawings. While exemplary embodiments of the present disclosure are shown in the drawings, it should be understood that the present disclosure may be implemented in various forms and should not be limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the disclosure to those skilled in the art.
[0029] This application provides a method for in-situ heat treatment of mercury cadmium telluride thin films via molecular beam epitaxy, including:
[0030] The substrate is prepared; the substrate described in this example can be a general substrate or a composite substrate.
[0031] A p-type doped layer is grown on the substrate;
[0032] The p-type doped layer is prepared as follows: cadmium telluride, cadmium arsenide, and mercury telluride are treated as one cycle, and multiple cycles are repeated to form a superlattice structure to obtain the p-type doped layer. The specific number of cycles can be set according to actual needs, for example, hundreds of cycles can be repeated to form a superlattice structure.
[0033] In some embodiments, the method further includes: growing an n-type doped layer on the substrate and then growing a p-type doped layer; or growing an n-type doped layer on the substrate and then growing a p-type doped layer.
[0034] like Figure 1As shown, the p-type doped layer in this example is a multilayer structure. The multilayer structure film can be further stacked with an n-type doped layer or a p-type doped layer on top of any n-type doped layer or p-type doped layer.
[0035] This application proposes to use cadmium telluride, cadmium arsenide, and mercury telluride as a cycle, and specifically utilizes cadmium arsenide in one cycle to cyclically prepare a superlattice structure through multiple cycles. Thus, mercury cadmium telluride heterojunction material can be obtained without heat treatment or with only simple heat treatment.
[0036] In some embodiments, the thickness of each cadmium telluride, cadmium arsenide, and mercury telluride layer in the p-type doped layer is 1 nm to 10 nm, and the thickness of each layer in the same period can be different. For example, the thicknesses of the cadmium telluride, cadmium arsenide, and mercury telluride layers can be set to 5 nm, 2 nm, and 6 nm, respectively.
[0037] In some embodiments, the method for preparing the p-type doped layer further includes:
[0038] The superlattice structure formed is placed in a mercury-saturated atmosphere and heated at a target temperature for a specified time.
[0039] Specifically, in-situ doped cadmium telluride (CdT) materials can form cadmium telluride (CdM) pn junctions through low-temperature heat treatment. Low-temperature heat treatment involves placing the in-situ doped CdT material in a mercury-saturated atmosphere and heating it for 10–72 hours, with a selectable heating temperature between 180°C and 250°C.
[0040] In some embodiments, the n-type doped layer is an In-doped mercury cadmium telluride layer, and the composition of the In-doped mercury cadmium telluride is 0.2 to 0.4, with an In doping concentration of 1 × 10⁻⁶. 15 cm -3 ~1×10 17 cm -3 The thickness of the n-type doped layer is 3μm to 20μm.
[0041] In some embodiments, fabricating the substrate includes sequentially growing an arsenic, zinc telluride buffer layer, and a cadmium telluride buffer layer on the surface of a substrate material. When the substrate is a composite substrate, it can be fabricated based on a 211-oriented cadmium telluride, silicon, or gallium arsenide substrate material. The composite substrate can be fabricated by sequentially growing an arsenic, zinc telluride buffer layer, and a cadmium telluride buffer layer on the surface of the 211-oriented cadmium telluride, silicon, or gallium arsenide substrate. In some examples, the thickness of the zinc telluride buffer layer in the composite substrate ranges from 5-300 nm, and the thickness of the cadmium telluride buffer layer ranges from 5 μm to 10 μm.
[0042] This application also proposes an implementation example of an in-situ heat treatment method for doped mercury cadmium telluride thin films via molecular beam epitaxy, comprising the following steps:
[0043] In-situ doped heterojunction mercury cadmium telluride material is a multilayer thin film, which consists of a silicon-based composite substrate, an n-type doped layer, and a p-type doped layer.
[0044] The silicon-based composite substrate is a single-crystal silicon with a 211 crystal orientation, and arsenic, zinc telluride buffer layers and cadmium telluride buffer layers are grown on the silicon surface.
[0045] Specifically, the arsenic layer is formed by depositing a layer of arsenic atoms on the surface of a single crystal silicon, the zinc telluride buffer layer is 100 nm thick, and the cadmium telluride buffer layer is 6 μm thick.
[0046] The n-type doped layer is located on the silicon-based composite substrate and has a thickness of 5 μm.
[0047] Specifically, the n-type doping is In doping, the mercury cadmium telluride composition is 0.3, and the In doping concentration is 1×10⁻⁶. 16 cm -3 .
[0048] The p-type doped layer sits atop the n-type doped layer and consists of a superlattice structure of cadmium telluride, cadmium arsenide, and mercury telluride layers, with each layer cycling 200 times. The thicknesses of the cadmium telluride, cadmium arsenide, and mercury telluride layers are 5 nm, 2 nm, and 6 nm, respectively.
[0049] Will Figure 1 The cadmium telluride-mercury heterojunction material was heat-treated at 250°C for 72 hours in a mercury-saturated atmosphere to obtain the following results: Figure 2 The in-situ doped mercury cadmium telluride heterojunction material is shown.
[0050] In-situ doped mercury cadmium telluride heterojunction materials are called annealed silicon-based composite substrates, annealed n-type doped layers, and annealed p-type doped layers. The annealed silicon-based composite substrates are unchanged from those before heat treatment. The annealed n-type doped layer, under a mercury-saturated atmosphere, will eliminate the residual mercury vacancies in the mercury cadmium telluride material.
[0051] like Figure 2 As shown, after annealing, the p-type doped layer changes from a superlattice structure of cadmium telluride, cadmium arsenide, and mercury telluride in a 200-cycle cycle to a bulk mercury cadmium telluride material. The arsenic in cadmium arsenide is uniformly distributed in the bulk mercury cadmium telluride as an acceptor, which is the p-type doped layer after annealing.
[0052] The molecular beam epitaxy in-situ doped mercury cadmium telluride (MCH) heterojunction material structure design of this application embodiment allows for multilayer structure design of MCH materials, fabricating multiple pn junction structures. The doping concentration and composition of the MCH material are controlled by the p-type doping growth period and the doped layer thickness. This application utilizes a single low-temperature heat treatment to activate the p-type MCH dopant elements; more accurately, it uses low-temperature annealing through element interdiffusion in the material to transform the p-type doped layer superlattice structure into bulk MCH material. The low-temperature heat treatment simultaneously prevents the diffusion of In from the n-type layer to the p-type layer.
[0053] This application also proposes a molecular beam epitaxy mercury cadmium telluride heterojunction structure, including...
[0054] Substrate;
[0055] A p-type doped layer is grown on the substrate;
[0056] The p-type doped layer is formed by repeating three layers of cadmium telluride, cadmium arsenide, and mercury telluride in a cycle to form a superlattice structure.
[0057] In this embodiment of the application, the heterojunction structure substrate or composite substrate is located at the bottom, and the n-type doped layer or p-type doped layer is located above the substrate or composite substrate, which can be stacked to form an adjustable heterojunction structure.
[0058] In this embodiment, the heterojunction structure consists of a p-type doped layer composed of cadmium telluride, cadmium arsenide, and mercury telluride, forming a superlattice structure with hundreds of cycles. Arsenic acts as an acceptor, directly providing holes without the need for high-temperature annealing for acceptor activation. A low-temperature heat treatment step enables interdiffusion of the cadmium telluride, cadmium arsenide, and mercury telluride superlattice structure, forming an As-occupied Te-site mercury telluride material. The low-temperature heat treatment temperature prevents In diffusion from the n-type layer into the p-type layer.
[0059] The growth period of the p-type doped layer in the heterojunction structure of this application embodiment can be adjusted, and the thickness of each monolayer in the superlattice structure can be controlled to determine the doping concentration and the composition of the mercury cadmium telluride material.
[0060] This application also proposes a semiconductor device including the aforementioned molecular beam epitaxy mercury cadmium telluride heterojunction structure.
[0061] It should be noted that, in this document, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Unless otherwise specified, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes that element.
[0062] The sequence numbers of the embodiments in this application are for descriptive purposes only and do not represent the superiority or inferiority of the embodiments.
[0063] The embodiments of this application have been described above with reference to the accompanying drawings. However, this application is not limited to the specific embodiments described above. The specific embodiments described above are merely illustrative and not restrictive. Those skilled in the art can make many other forms under the guidance of this application without departing from the spirit and scope of the claims. All of these forms are within the protection scope of this application.
Claims
1. A method for preparing an in-situ doped mercury cadmium telluride thin film via molecular beam epitaxy, characterized in that, The in-situ doped heterojunction mercury cadmium telluride film is a multilayer structure, consisting of a silicon-based composite substrate, an n-type doped layer, and a p-type doped layer, with the n-type doped layer located on top of the silicon-based composite substrate. The method includes: Substrate preparation; A p-type doped layer is grown on the substrate by molecular beam epitaxy; The p-type doped layer is prepared by: taking cadmium telluride, cadmium arsenide, and mercury telluride as one cycle, and repeating multiple cycles to form a superlattice structure to obtain the p-type doped layer; The method for preparing the p-type doped layer further includes: The superlattice structure is placed in a mercury-saturated atmosphere and heated at a target temperature for a specified duration, wherein the target temperature is between 180°C and 250°C and the specified duration is 10-72 hours.
2. The method for preparing in-situ doped mercury cadmium telluride thin films via molecular beam epitaxy as described in claim 1, characterized in that, The thickness of each layer of cadmium telluride, cadmium arsenide, and mercury telluride in the p-type doped layer is 1 nm to 10 nm.
3. The method for preparing in-situ doped mercury cadmium telluride thin films via molecular beam epitaxy as described in claim 1, characterized in that, Also includes: After growing an n-type doped layer on the substrate, the p-type doped layer is then grown. or After growing the p-type doped layer on the substrate, an n-type doped layer is then grown.
4. The method for preparing in-situ doped mercury cadmium telluride thin films via molecular beam epitaxy as described in claim 3, characterized in that, The n-type doped layer is an In-doped mercury cadmium telluride layer, and the composition of the In-doped mercury cadmium telluride is 0.2-0.4, the In-doped concentration is 1×10 15 cm -3 -1×10 17 cm -3 , and the thickness of the n-type doped layer is 3-20 μm.
5. The method for preparing in-situ doped mercury cadmium telluride thin films via molecular beam epitaxy as described in claim 1, characterized in that, The substrate preparation involves sequentially growing arsenic, zinc telluride buffer layers, and cadmium telluride buffer layers on the surface of the substrate material.
6. A molecular beam epitaxy mercury cadmium telluride heterojunction structure, characterized in that, The mercury cadmium telluride heterojunction structure is a multilayer thin film. The multilayer structure consists of a silicon-based composite substrate, an n-type doped layer, and a p-type doped layer. The n-type doped layer is located on top of the silicon-based composite substrate. The mercury cadmium telluride heterojunction structure includes... Substrate; A p-type doped layer was grown on the substrate by molecular beam epitaxy; The p-type doped layer is formed by repeating cadmium telluride, cadmium arsenide, and mercury telluride layers multiple times to form a superlattice structure. The superlattice structure is then placed in a mercury-saturated atmosphere and heated at a target temperature for a specified duration, with the target temperature being between 180°C and 250°C and the specified duration being 10-72 hours.
7. A semiconductor device, characterized in that, Including the molecular beam epitaxial mercury cadmium telluride heterojunction structure as described in claim 6.