Two-dimensional transition metal chalcogenide heterojunction memristor and application thereof
Two-dimensional transition metal sulfose selenide heterojunctions were prepared by molecular beam epitaxy and chemical vapor deposition, which solved the problems of low film quality and high-temperature sulfidation in the prior art. This method enables high-quality heterojunctions with fast switching and low power consumption, and is suitable for logic circuits, resistive switching memory, neuromorphic computing and artificial intelligence.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- SHANGHAI JIAOTONG UNIV
- Filing Date
- 2022-10-31
- Publication Date
- 2026-06-02
AI Technical Summary
Existing two-dimensional transition metal chalcogenides are insufficient to meet the requirements for expanding the bandgap range of semiconductors. Vertically stacked heterojunctions suffer from problems such as easy wrinkling of thin films, difficulty in removing polymer layers, and poor adhesion. Traditional preparation methods result in low film quality and require extremely high temperatures for high-temperature vulcanization.
Transition metal selenides were prepared by molecular beam epitaxy and then sulfided by chemical vapor deposition to form high-quality two-dimensional transition metal sulfose selenide heterojunctions. Sulfur atoms were used to replace selenium atoms to form covalent bonds, and annealing was then performed to prepare high-quality two-dimensional transition metal sulfose selenide heterojunctions.
A high-quality two-dimensional transition metal sulfose selenide heterojunction was realized, featuring fast switching process, high-density integration and low power consumption, making it suitable for mass production and application in logic circuits, resistive switching memory, neuromorphic computing and artificial intelligence.
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Figure CN115568277B_ABST
Abstract
Description
Technical Field
[0001] This invention belongs to the field of two-dimensional heterojunction and information storage technology, and relates to a two-dimensional transition metal sulfoselenide heterojunction memristor and its application. Background Technology
[0002] Two-dimensional transition metal chalcogenides and their heterojunctions are attracting increasing attention as the building blocks of various electronic and optoelectronic devices, particularly for future memristors and synaptic devices in brain-inspired neuromorphic computing systems. However, simple binary transition metal chalcogenides cannot meet the growing demand for expanding the bandgap range of semiconductors. To meet the increasingly diverse needs of device integration and systems, there is an urgent need to develop two-dimensional semiconductors with a wider bandgap range, and alloying and constructing heterojunctions are common strategies.
[0003] Two-dimensional heterostructures, formed by vertically stacking or planar assembling two-dimensional materials, can combine the excellent physical properties of different two-dimensional materials, maximizing their diverse characteristics. The layers in vertically stacked heterostructures are connected by relatively weak van der Waals forces, while those in laterally assembled heterostructures are connected by chemical bonds. Due to the maturity of exfoliation and transfer technologies, two-dimensional heterostructures formed by vertical stacking have seen significant development. However, problems remain, such as film wrinkling during the transfer process, difficulty in removing polymer layers, and the presence of air bubbles between components. These issues make it difficult for vertically stacked heterostructures to meet the demands of large-scale production.
[0004] Chinese patent ZL201910779092.0 discloses a memristor with a two-dimensional material heterojunction and its fabrication method. The memristor, from bottom to top, includes a substrate, a bottom electrode layer, a two-dimensional material heterojunction layer, and a top electrode layer. The two-dimensional material heterojunction layer, serving as an intermediate dielectric layer, is a two-layer stacked structure composed of two different metal sulfide compounds, with each layer corresponding to one of the metal sulfide compounds. The two-layer metal thin film prepared by magnetron sputtering in this patent has low quality, with poor bonding between the metal layers. Furthermore, the two metal layers experience stress concentration due to their different coefficients of thermal expansion when heated to high temperatures, leading to film rupture. In addition, this patent subsequently uses direct sulfidation of the two metal layers to prepare a transition metal sulfide heterojunction. Because the bond energy between the metal elements is relatively high, extremely high temperatures (500-1000℃) are required to achieve sulfidation. Summary of the Invention
[0005] The purpose of this invention is to provide a two-dimensional transition metal sulfide selenide heterojunction memristor and its application, which has advantages such as fast switching process, high density integration, and lower power consumption.
[0006] The objective of this invention can be achieved through the following technical solutions:
[0007] One of the technical solutions of the present invention provides a two-dimensional transition metal sulfose selenide heterojunction memristor, which consists of a substrate, a bottom electrode layer, a resistive switching functional layer and a top electrode layer from bottom to top, wherein the resistive switching functional layer is a two-dimensional transition metal sulfose selenide heterojunction layer.
[0008] Furthermore, the preparation process of the two-dimensional transition metal sulfoselenide heterojunction layer includes the following steps:
[0009] (1) Preparation of transition metal selenides by molecular beam epitaxy;
[0010] (2) Transition metal selenides were sulfided by chemical vapor deposition to obtain transition metal sulfose selenides;
[0011] (3) Annealing the transition metal sulfose selenide completes the process.
[0012] Furthermore, in step (1), the chemical composition of the transition metal selenide is MSe x The number of layers is m, x≥1, m≥1, where M is a transition metal element.
[0013] More preferably, in step (1), the target source used in molecular beam epitaxy is transition metal element M and selenium.
[0014] More preferably, the transition metal element M is platinum or palladium.
[0015] Furthermore, in step (2) of the chemical vapor deposition method, the sulfur source used for sulfidation is hydrogen sulfide or elemental sulfur, and the chemical composition of the resulting transition metal sulfoselenide is MSe. y S (x -y), y < x.
[0016] Furthermore, in step (2) of the chemical vapor deposition method, the substrate temperature is 100-800℃ and the sulfidation time is 1-500min.
[0017] Furthermore, in step (3), the annealing temperature is 100-500℃ and the time is 1-48h.
[0018] Furthermore, the substrate is an inorganic material or an organic polymer material with a thickness of 1-1000 μm.
[0019] Furthermore, the bottom electrode layer and the top electrode layer are made of one or more of metals, alloys, conductive oxides or conductive nitrides, and have a thickness of 10-1000 nm.
[0020] This invention utilizes molecular beam epitaxy to prepare high-quality single transition metal selenide films without the risk of film rupture. Furthermore, under mild conditions, sulfur atoms partially replace selenium atoms to form transition metal sulfoselenide heterojunctions. These in-situ formed heterojunctions are of high quality and atomic level.
[0021] The second technical solution of the present invention provides an application of a two-dimensional transition metal sulfose selenide heterojunction memristor, which is used in logic circuits, resistive switching memory, neuromorphic computing, and artificial intelligence.
[0022] Molecular beam epitaxy (MBE) offers advantages such as low growth rate and low substrate temperature, allowing for precise control of thickness, structure, and composition. This is beneficial for growing high-quality two-dimensional transition metal selenide films with atomic-level thickness. Sulfur (S) and selenium (Se) are group-agent elements with similar chemical properties, but sulfur has a stronger oxidizing power than selenium. During high-temperature reactions, sulfur atoms can replace selenium atoms in transition metal selenides, forming two-dimensional transition metal sulfoselenide heterojunctions. This heterojunction can improve the electrical characteristics and thermal stability of memristors and can also simulate biological neural synapses for applications in neuromorphic computing and brain-like computing.
[0023] The two-dimensional transition metal sulfose selenide heterojunction memristor of the present invention has advantages such as fast switching process, high-density integration and lower power consumption, and can be applied to logic circuits, resistive switching memory, neuromorphic computing, artificial intelligence and other fields.
[0024] Compared with the prior art, the present invention has the following advantages:
[0025] (1) Molecular beam epitaxy (MBE) allows for highly precise control over the morphological parameters of grown two-dimensional materials, such as the number of layers, surface structure, and stoichiometry, enabling the preparation of high-quality two-dimensional transition metal selenide films. Chemical vapor deposition (CVD) can sulfide transition metal selenides to obtain transition metal sulfoselenides (LMS), and the degree of sulfidation and heterojunction structure can be controlled by adjusting the reaction conditions. The composition and number of film layers of two-dimensional transition metal sulfoselenides directly affect the bandgap structure, thereby regulating their electrical and optical properties.
[0026] (2) The one-dimensional edge contact in a two-dimensional transition metal sulfoselenide heterojunction can provide a very small contact area and low contact impedance at the atomic level. Meanwhile, the two-dimensional materials on both sides of the one-dimensional interface are connected by covalent bonds. The strong covalent bonds ensure the stability of the interface in the two-dimensional heterojunction and also improve the photonic and electronic device performance of the heterojunction, making it of great research and application value in fields such as field-effect transistors, light-emitting diodes, photodetectors, spintronic devices, and sensors.
[0027] (3) Two-dimensional transition metal sulfose selenide heterojunction memristors have advantages such as fast switching process, high density integration and lower power consumption. They are also compatible with traditional silicon-based CMOS processes, suitable for large-scale production, and are expected to be used in fields such as neural synapses, image recognition, and logic computing. Attached Figure Description
[0028] Figure 1 These are the molecular structural formulas of transition metal selenides and transition metal sulfoses provided by this invention;
[0029] Figure 2 This is a schematic diagram of the transition metal sulfose selenide heterojunction memristor provided by the present invention.
[0030] Explanation of markings in the diagram:
[0031] 1. Selenium atom; 2. Chemical bond; 3. Transition metal atom; 4. Sulfur atom; 5. Substrate; 6. Bottom electrode layer; 7. Resistive switching functional layer; 8. Top electrode layer. Detailed Implementation
[0032] The present invention will now be described in detail with reference to the accompanying drawings and specific embodiments. These embodiments are based on the technical solution of the present invention and provide detailed implementation methods and specific operating procedures. However, the scope of protection of the present invention is not limited to the following embodiments.
[0033] In the following embodiments, unless otherwise specified, the raw materials or processing techniques are conventional commercially available raw materials or conventional processing techniques in the art.
[0034] The structure of the two-dimensional transition metal sulfose selenide heterojunction memristor provided by this invention can be found in [reference needed]. Figure 2 As shown, from bottom to top, it consists of a substrate 5, a bottom electrode layer 6, a resistive switching functional layer 7, and a top electrode layer 8. The resistive switching functional layer 7 is a two-dimensional transition metal sulfose selenide heterojunction layer. Furthermore, the preparation process of the two-dimensional transition metal sulfose selenide heterojunction layer involves first obtaining a transition metal selenide, then sulfiding the transition metal selenide to obtain a transition metal sulfose selenide, and finally annealing to obtain the two-dimensional transition metal sulfose selenide heterojunction. The molecular structures of the transition metal selenide and the transition metal sulfose selenide are as follows: Figure 1 As shown, it consists of selenium atoms 1 and sulfur atoms 4 connected to transition metal atoms 3 by chemical bond 2.
[0035] The memristor with the above structure will be further explained below with reference to specific embodiments.
[0036] Example 1:
[0037] A silicon wafer was used as the substrate, and high-purity palladium (Pd) and high-purity selenium (Se) (purity 99.999%) were used as the target sources. The substrate was placed inside the vacuum chamber of the molecular beam epitaxy (MBE) equipment. Multi-stage vacuuming was performed on the MBE chamber using mechanical pumps, molecular pumps, ion pumps, and titanium sublimation pumps to achieve a bulk vacuum level of 10⁻⁶. -8 pa. Set the base temperature to 500℃.
[0038] The deposition rate of palladium (Pd) is set to... The deposition rate of selenium (Se) is A 10-layer two-dimensional transition metal sulfide with the chemical composition PdSe2 was obtained.
[0039] Elemental sulfur was used as the sulfur source, and argon was used as the protective gas. The substrate with PdSe2 grown was placed in a chemical vapor deposition chamber, and the sulfidation temperature was 500℃ for 30 min. The two-dimensional transition metal sulfide was transformed into a two-dimensional transition metal sulfoselenide with the chemical composition PdSeS after sulfidation.
[0040] The above two-dimensional transition metal sulfose selenide was vacuum annealed at 300°C for 12 h.
[0041] Example 2:
[0042] Most of the components are the same as in Example 1, except that in this example, the number of layers of the two-dimensional transition metal sulfide is 4.
[0043] Example 3:
[0044] The two-dimensional transition metal sulfoselenide is almost identical to Example 1, except that in this example, the chemical composition of the two-dimensional transition metal sulfoselenide is PdSe. 1.5 S 0.5 .
[0045] Example 4:
[0046] The two-dimensional transition metal sulfoselenide is almost identical to Example 1, except that in this example, the chemical composition of the two-dimensional transition metal sulfoselenide is PdSe. 0.5 S 1.5 .
[0047] Example 5:
[0048] A 20 nm gold (Au) layer was deposited on a clean and flat 100 μm SiO2 / Si substrate as the bottom electrode layer. Then, the two-dimensional transition metal sulfose selenide heterojunction from Example 1 was transferred to the bottom electrode as the resistive switching functional layer. Finally, another 20 nm gold (Au) layer was deposited as the top electrode layer to form a two-dimensional transition metal sulfose selenide heterojunction memristor.
[0049] Example 6:
[0050] Using the memristor described in Example 5 as the basic unit, a cross-array structure memristor is fabricated to achieve in-memory computing integration and improve computational parallelism and energy efficiency.
[0051] The above description of the embodiments is provided to enable those skilled in the art to understand and use the invention. It will be apparent to those skilled in the art that various modifications can be made to these embodiments, and the general principles described herein can be applied to other embodiments without inventive effort. Therefore, the present invention is not limited to the above embodiments, and any improvements and modifications made by those skilled in the art based on the disclosure of the present invention without departing from the scope of the invention should be within the protection scope of the present invention.
Claims
1. A two-dimensional transition metal sulfoselenide heterojunction memristor, characterized in that, From bottom to top, the structure consists of a substrate, a bottom electrode layer, a resistive switching functional layer, and a top electrode layer, wherein the resistive switching functional layer is a two-dimensional transition metal sulfose selenide heterojunction layer. The preparation process of the two-dimensional transition metal sulfoselenide heterojunction layer includes the following steps: (1) Preparation of transition metal selenides using molecular beam epitaxy; (2) Transition metal selenides were sulfided by chemical vapor deposition to obtain transition metal sulfoses. (3) Annealing the transition metal sulfoselenide completes the process; In step (1), the chemical composition of the transition metal selenide is MSe x The number of layers is m, x≥1, m≥1, where M is a transition metal element; In step (1), the target source used in molecular beam epitaxy is transition metal element M and selenium; The transition metal element M is platinum or palladium; In step (2) of the chemical vapor deposition method, the sulfur source used for sulfidation is hydrogen sulfide or elemental sulfur, and the chemical composition of the resulting transition metal sulfoselenide is MSe. y S (x-y) y < x; In step (2) of the chemical vapor deposition method, the substrate temperature is 100~800℃ and the sulfidation time is 1~500min; In step (3), the annealing temperature is 100~500℃ and the time is 1~48h.
2. The two-dimensional transition metal sulfoselenide heterojunction memristor according to claim 1, characterized in that, The substrate is an inorganic material or an organic polymer material, with a thickness of 1-1000 μm; The bottom electrode layer and the top electrode layer are made of one or more of metals, conductive oxides or conductive nitrides, and have a thickness of 10-1000 nm.
3. The application of a two-dimensional transition metal sulfoselenide heterojunction memristor as described in claim 1 or 2, characterized in that, This memristor is used in logic circuits, resistive switching memory, neuromorphic computing, or artificial intelligence.