Thin-layer two-dimensional oxide material and preparation and application thereof

Abstract

The application discloses a kind of thin layer two-dimensional oxide materials and its preparation and application, by first to substrate gas plasma treatment, then oxide is chemically vapor deposited on the substrate after gas plasma treatment, so as to be able to grow thin layer two-dimensional oxide material, especially suitable for growing the thickness controllable thin layer two-dimensional high dielectric constant oxide material.The thin layer two-dimensional oxide material is standing thin layer and obliquely grown on substrate, thinner than general CVD grown oxide material, and easy to transfer, suitable for making high-performance low-power consumption memristor, and can also be extended to be applied in the preparation of fin field effect transistor.

Description

Technical Field

[0001] This invention belongs to the field of materials preparation technology, specifically relating to a thin-layer two-dimensional oxide material and its preparation and application. Background Technology

[0002] A memristor, or resistive random access memory (RRAM), is a non-linear resistive element with memory function. It is the fourth type of passive circuit element after resistors, inductors, and capacitors. A typical memristor structure is a three-layer "sandwich" structure, consisting of a top electrode, a bottom electrode, and a resistive switching layer sandwiched between two metal electrodes. A voltage is applied to the top electrode, and the bottom electrode is grounded. A positive voltage is applied between the top and bottom electrodes for testing. The device's resistance reversibly changes between a high-resistance state (HRS) and a low-resistance state (LRS) in response to changes in the external voltage signal. Its typical current-voltage curve is a hysteresis loop that crosses the origin. That is, under voltage scanning conditions, a memristor can exhibit high levels (corresponding to a low-resistance state) and low levels (corresponding to a high-resistance state), corresponding to the states "0" and "1," thus enabling data storage. Memristors have been proven to be used in novel storage devices and neuromorphic devices.

[0003] Different resistive switching layer materials and electrode materials exhibit different switching mechanisms, resulting in varying memristor performance. Past research has revealed many materials with resistive switching effects, and memristors fabricated from different types of materials often display different resistive switching characteristics. Compared to other resistive switching materials, binary metal oxides offer advantages such as simple structure, easy control of material composition, and compatibility with CMOS processes, thus attracting greater attention from industry. For example, Spansion uses CuO... x Samsung uses NiO, while Macronix from Taiwan uses WO3. x And NEC uses TaO x However, traditional memristors based on oxides as dielectric layers have some problems that need to be solved: First, the resistive switching performance of memristors needs to be further improved; second, the stability of memristors needs to be improved; and finally, the resistive switching process of memristors reported so far mostly involves ion migration, and the phenomenon of ions passing through the electrodes and causing device failure is prone to occur during ion migration.

[0004] Two-dimensional materials possess unique advantages in solving the aforementioned problems due to their superior physical, chemical, and mechanical properties. Reports of resistive switching phenomena in thin-film materials date back to the 1960s, but these failed to attract widespread attention due to limitations in thin-film material fabrication technology at the time. In recent years, with the rapid development of material fabrication technology and the size limitations encountered by traditional memory, RRAM based on two-dimensional materials has once again attracted the attention of semiconductor companies and researchers. Currently, two-dimensional material memristors have become a research hotspot due to their advantages such as ultra-thin thickness at the atomic level, low power consumption, small size, and excellent flexibility. Their resistive switching layers are generally between 0.1 nm and 100 nm thick, using two-dimensional materials such as MoS2 and WS2. Furthermore, whether memristors are used in memory, logic computing, or neural synapse bionics, they must meet the requirements of high performance and low power consumption. However, existing memristors generally suffer from small resistance changes, high operating voltages, and high power consumption. When the conduction mechanism of a memristor is a conductive filament mechanism, the thickness of the two-dimensional material determines the level of its set voltage; the thinner the material, the lower the set voltage. Moreover, thin two-dimensional materials with atomic layer thickness have the potential to be applied to electronic devices with better miniaturization and higher integration in the post-Moore era.

[0005] The fabrication of two-dimensional (2D) materials typically employs chemical vapor deposition (CVD) and mechanical exfoliation methods. However, the fabrication of thin-layer (e.g., ultrathin at the atomic layer level) 2D materials usually requires complex deposition techniques, such as atomic layer deposition (ALD). Furthermore, the issue of thickness control remains a significant challenge in traditional CVD 2D material growth techniques. While CVD is considered an effective technique for fabricating large-area, high-quality 2D materials, for certain oxides with high dielectric constants, the weak interlayer forces allow for the growth of thick layers on silica substrates with high surface atomic diffusion barriers. This thickness is difficult to control, making it challenging to obtain controllably grown thin-layer 2D materials. This uncontrollable thickness growth severely limits the development and application of 2D memristors. Additionally, CVD-grown oxides need to be transferred to electrodes; if wet chemical methods are used, the unavoidable use of organic materials can negatively impact memristor performance. Summary of the Invention

[0006] In view of this, the present invention provides a thin-layer two-dimensional oxide material, its preparation, and its application. By first treating the substrate with gas plasma, and then chemically vapor-depositing oxides on the gas plasma-treated substrate, a thin-layer two-dimensional oxide material can be grown, which is particularly suitable for growing thin-layer two-dimensional high-dielectric-constant oxide materials with controllable thickness. This thin-layer two-dimensional oxide material is an upright thin layer grown obliquely on the substrate, thinner than oxide materials grown by conventional CVD, and easier to transfer. It is suitable for fabricating high-performance, low-power memristors, and can also be extended to the fabrication of fin field-effect transistors.

[0007] To achieve the above objectives, the present invention adopts the following technical solution:

[0008] The present invention provides a thin-layer two-dimensional oxide material, which is a thin-layer two-dimensional oxide material deposited on a silicon wafer substrate treated with gas plasma. The two-dimensional oxide material is an upright thin layer and is obliquely grown on the silicon wafer substrate treated with gas plasma.

[0009] In some specific embodiments of the present invention, the oxide is molybdenum trioxide, bismuth oxide, or antimony oxide.

[0010] In some specific embodiments of the present invention, the silicon substrate is a SiO2 / Si substrate with an oxide layer thickness of 285 nm.

[0011] Meanwhile, the present invention also provides a method for preparing the thin-layer two-dimensional oxide material, comprising:

[0012] Step S1: The silicon wafer substrate is subjected to gas plasma treatment, wherein the gas is argon, air, oxygen or nitrogen, to obtain a plasma-treated substrate.

[0013] Step S2: Deposit oxide powder onto the plasma-treated substrate in a carrier gas via chemical vapor deposition to obtain an erected thin-layer two-dimensional oxide material; or, react chalcogenide or halide powder with oxygen in a carrier gas and deposit it onto the plasma-treated substrate via chemical vapor deposition to obtain an erected thin-layer two-dimensional oxide material; the carrier gas is argon or nitrogen.

[0014] In some specific embodiments of the present invention, in step S1, the silicon substrate is a SiO2 / Si substrate with an oxide layer thickness of 285 nm.

[0015] In some specific embodiments of the present invention, the SiO2 / Si substrate used in step S1 is cleaned in the following steps before use: the SiO2 / Si substrate is ultrasonically treated with acetone and isopropanol for 10 minutes respectively, and then rinsed with deionized water multiple times to obtain a cleaned SiO2 / Si substrate.

[0016] In some specific embodiments of the present invention, in step S1, the power of the plasma treatment is 30-100W, the time is 5-20min, and the flow rate of the gas is 5-20sccm.

[0017] In some specific embodiments of the present invention, in step S1, the power of the plasma treatment is 50W, the treatment time is 10min, and the flow rate of the gas is 8sccm.

[0018] In some specific embodiments of the present invention, step S2 includes:

[0019] Molybdenum disulfide or antimony iodide powder is placed on a high-temperature resistant carrier, and the high-temperature resistant carrier is placed in the central heating zone of the tube furnace; then the plasma-treated substrate is placed on the outlet side of the tube furnace at a distance of 10 to 30 cm from the center of the tube furnace.

[0020] Carrier gas of 200-300 sccm is introduced into the tubular furnace and introduced continuously for 10-20 minutes;

[0021] Then, adjust the flow rate of the carrier gas to 40-70 sccm and introduce 4-10 sccm of oxygen. While continuously introducing the carrier and oxygen, gradually heat up the tubular furnace until the temperature of the central heating zone of the tubular furnace reaches 700-800°C, and then hold the reaction at that temperature for 5-15 minutes.

[0022] After the reaction is complete, the material is allowed to cool naturally to obtain a thin layer of two-dimensional oxide material grown on the substrate.

[0023] In some specific embodiments of the present invention, in step S2, the heating rate is 25-40°C / min, preferably 35°C / min.

[0024] In some specific embodiments of the present invention, in step S2, the plasma-treated substrate is placed on the outlet side of the tube furnace at a position 18 cm away from the center of the tube furnace.

[0025] In some specific embodiments of the present invention, in step S2, the high-temperature resistant carrier is a quartz boat or a graphite boat.

[0026] In some specific embodiments of the present invention, in step S2, the flow rate of the carrier gas is adjusted to 60 sccm, and the flow rate of the oxygen is 5 sccm.

[0027] In some specific examples of the present invention, in step S2, the temperature of the heat preservation reaction is 770°C and the heat preservation reaction time is 7 min.

[0028] In some specific embodiments of the present invention, step S2 includes:

[0029] Bismuth oxide powder is placed on a high-temperature resistant carrier, and the high-temperature resistant carrier is placed in the central heating zone of a tube furnace; then the plasma-treated substrate is placed on the outlet side of the tube furnace at a distance of 10-30 cm from the center of the tube furnace.

[0030] Carrier gas of 200-300 sccm is introduced into the tubular furnace and introduced continuously for 10-20 minutes;

[0031] Then, adjust the flow rate of the carrier gas to 40-70 sccm and continue to introduce it; at the same time, gradually heat up the tubular furnace until the temperature of the central heating zone of the tubular furnace reaches 600-700℃, and then keep it at that temperature for 5-15 minutes.

[0032] After the reaction is complete, the material is allowed to cool naturally to obtain a thin layer of two-dimensional oxide material grown on the substrate.

[0033] In some specific embodiments of the present invention, in step S2, the heating rate is 25-40°C / min, preferably 35°C / min.

[0034] In some specific embodiments of the present invention, in step S2, the plasma-treated substrate is placed on the outlet side of the tube furnace at a position 18 cm away from the center of the tube furnace.

[0035] In some specific embodiments of the present invention, in step S2, the high-temperature resistant carrier is a quartz boat or a graphite boat.

[0036] In some specific embodiments of the present invention, in step S2, the flow rate of the carrier gas is adjusted to 60 sccm.

[0037] In some specific embodiments of the present invention, in step S2, the temperature of the heat preservation reaction is 670°C and the heat preservation reaction time is 7 min.

[0038] Furthermore, the present invention also provides applications of the aforementioned thin-film two-dimensional oxide material, particularly in memristors or fin field-effect transistors.

[0039] In this invention, by first treating the substrate with gas plasma and then chemically vapor-depositing oxides on the plasma-treated substrate, thin-layer two-dimensional oxide materials can be grown, especially thin-layer two-dimensional high-dielectric-constant oxide materials with controllable thickness. These thin-layer two-dimensional oxide materials are upright and obliquely grown on the substrate, much thinner than oxide materials grown by conventional CVD (e.g., two orders of magnitude thinner), easier to transfer, and have an on / off ratio as high as 10. 4It has a significant switching current difference and a set voltage of only 0.5V, making it very suitable for making high-performance, low-power memristors. It can also be extended to the fabrication of fin field-effect transistors.

[0040] Compared with the prior art, the present invention has the following beneficial technical effects:

[0041] This invention successfully prepared thin-film two-dimensional materials of high-dielectric-constant oxides, such as molybdenum trioxide, bismuth oxide, and antimony oxide, using gas plasma processing and chemical vapor deposition. Due to the stability of these high-dielectric-constant materials, the current in the low-resistivity state of memristors constructed from them is very small, enabling high on / off ratios and stable memristor effects, resulting in high performance and low power consumption. The on / off ratio of memristors constructed from these thin-film two-dimensional oxide materials can reach up to 10. 4 It has a significant switching current difference and a set voltage of only 0.5V.

[0042] Furthermore, the thin-layer two-dimensional oxide material prepared by the method of this invention possesses both ultra-thin thickness and oblique growth characteristics, making it particularly suitable for preparing thin-layer two-dimensional materials for which thick oxide layers can be easily grown on silicon substrates. Because this thin-layer two-dimensional oxide material is very easy to transfer and has excellent performance, it can be conveniently used to fabricate high-performance, low-power memristors, and can also be extended to the fabrication of Fin Field-Effect Transistors (FinFETs). Attached Figure Description

[0043] Figure 1 The diagram shown is a schematic diagram of the thin-layer two-dimensional oxide material growth method of the present invention;

[0044] Figure 2 The diagram shown is a schematic diagram illustrating the temperature change over time in the central temperature zone of the tubular furnace in Example 1.

[0045] Figure 3 The image shows the Raman spectrum of the thin-layer two-dimensional molybdenum trioxide material prepared in Example 1;

[0046] Figure 4 The image shown is a scanning electron microscope image of the thin-layer two-dimensional molybdenum trioxide material prepared in Example 1;

[0047] Figure 5 The image shown is an atomic force microscope image of the thin-layer two-dimensional molybdenum trioxide material prepared in Example 1;

[0048] Figure 6 The image shown is an optical microscope image of the thin-layer two-dimensional molybdenum trioxide material grown in Example 1;

[0049] Figure 7The diagram shown is a schematic representation of the transfer results of the thin-layer two-dimensional molybdenum trioxide material grown in Example 1.

[0050] Figure 8 The image shown is an optical microscope image of the molybdenum trioxide prepared in Comparative Example 1.

[0051] Figure 9 The image shows a comparison between the thickness of the thin-layer two-dimensional molybdenum trioxide material in Example 1 and the thickness of the molybdenum trioxide prepared in Comparative Example 1.

[0052] Figure 10 The image shown is an optical microscope image of the thin-layer two-dimensional molybdenum trioxide material prepared in Example 4;

[0053] Figure 11 The image shows the Raman spectrum of the thin-layer two-dimensional bismuth oxide material prepared in Example 6;

[0054] Figure 12 The image shown is a scanning electron microscope image of the thin-layer two-dimensional bismuth oxide material prepared in Example 6;

[0055] Figure 13 The image shown is an atomic force microscope image of the thin-layer two-dimensional bismuth oxide material prepared in Example 6;

[0056] Figure 14 The image shown is an optical microscope image of the thin-layer two-dimensional bismuth oxide material grown in Example 6;

[0057] Figure 15 The image shows the Raman spectrum of the thin-layer two-dimensional antimony oxide material prepared in Example 7;

[0058] Figure 16 The image shown is a scanning electron microscope image of the thin-layer two-dimensional antimony oxide material prepared in Example 7;

[0059] Figure 17 The figure shows the thickness measurement results of the thin-layer two-dimensional antimony oxide material prepared in Example 7;

[0060] Figure 18 The image shown is an optical microscope image of the thin-layer two-dimensional antimony oxide material grown in Example 7;

[0061] Figure 19 The diagram shown is a schematic of the device structure of the thin-film molybdenum trioxide memristor grown in Example 1.

[0062] Figure 20 The figure shown is a device performance diagram of the thin-film molybdenum trioxide memristor grown in Example 1;

[0063] Figure 21 The figure shows 16 sets of IV curves for the molybdenum trioxide memristor of Example 8 after a single cycle.

[0064] Figure 22 The figure shows the IV curves of 16 single cycles of the molybdenum trioxide memristor in Comparative Example 2.

[0065] Figure 23 The figure shows a comparison of the turn-on voltage (average) of the molybdenum trioxide memristor of Example 8 and the molybdenum trioxide memristor of Comparative Example 2. Detailed Implementation

[0066] To better illustrate the present invention and facilitate understanding of its technical solutions, the present invention will be further described in detail below with reference to specific embodiments.

[0067] Unless otherwise specified, all reagents or instruments used in the following examples are commercially available products. The substrate is a silicon wafer with an oxide layer thickness of 285 nm, referred to as a SiO2 / Si substrate or silicon wafer substrate.

[0068] like Figure 1 As shown, a method for growing a thin-layer oxide material includes:

[0069] (1) First, the silicon wafer substrate is subjected to gas plasma treatment;

[0070] (2) The chalcogenide or halide powder is reacted with oxygen in a carrier gas and deposited onto the aforementioned gas plasma-treated substrate by chemical vapor deposition to obtain an erect thin-layer two-dimensional oxide material; or, the oxide powder is deposited onto the aforementioned gas plasma-treated substrate by chemical vapor deposition in a carrier gas to obtain an erect thin-layer two-dimensional oxide material.

[0071] The growth of thin-layer oxide materials in this invention is carried out inside a quartz tube, such as... Figure 1 As shown, the quartz tube is a hollow cylindrical tube, 1m in length, 2.5cm in outer diameter, and 3mm in wall thickness. It has openings at both the left and right ends, each fitted with a metal flange, corresponding to the inlet and outlet ends respectively, used to control gas flow and exhaust. This quartz tube is installed on a tube furnace, which is a single-temperature zone furnace, a heating furnace containing an independent temperature zone located in the center of the furnace; this zone is also known as the central temperature zone.

[0072] Please see the following examples for details.

[0073] Example 1: Preparation of thin-layer molybdenum trioxide

[0074] (1) The SiO2 / Si substrate (SiO2 oxide layer thickness is 285nm) was ultrasonically treated with acetone and isopropanol for 10 minutes respectively to remove the impurities adsorbed on the surface; then the residual organic solvent (acetone and isopropanol) was rinsed off with deionized water to obtain a cleaned SiO2 / Si substrate.

[0075] (2) The cleaned SiO2 / Si substrate is placed in a plasma cleaner for argon plasma treatment. The pressure is pumped to 10Pa to ignite the plasma. 8sccm of argon gas is introduced and the power is increased to 50W for 10min to obtain a plasma-treated silicon wafer substrate.

[0076] (3) Place 10 mg of molybdenum disulfide powder in a quartz boat (the quartz boat is located in the central area of ​​the tube furnace). Place the plasma-treated silicon wafer substrate obtained in step (2) at the downstream end of the tube furnace (the side near the outlet end, i.e., the outlet side) and 18 cm away from the center of the tube furnace. Before the reaction starts, first introduce argon gas at a flow rate of 200 sccm into the quartz tube and continue to introduce it for 10 min to purge the air in the quartz tube. Then change the flow rate of argon gas (as a carrier gas) to 60 sccm and continue to introduce argon gas. At the same time, continue to introduce oxygen gas at a flow rate of 5 sccm into the quartz tube and start heating the central area of ​​the quartz tube with a heating furnace at a heating rate of 35 °C / min. When the central temperature area of ​​the tube furnace reaches the set temperature of 770 °C, keep the reaction at this temperature for 7 min and then stop heating the furnace. Let the central temperature area cool naturally to room temperature and take out the substrate with the grown product. In this process, argon gas is used as a carrier gas to mix oxygen and molybdenum dioxide powder to produce a chemical reaction, thereby growing molybdenum trioxide on the surface of SiO2 / Si substrate.

[0077] The temperature change curve of the central temperature zone of the tubular furnace is as follows: Figure 2 As shown.

[0078] Structural characterization:

[0079] Raman spectroscopy analysis was performed on the product obtained in Example 1: the sample was excited using a laser beam with a wavelength of 532 nm to obtain its Raman spectrum, as shown below. Figure 3 As shown, the Raman spectrum reveals two very strong scattering peaks, located at 282 cm⁻¹. -1 and 818cm -1 , respectively corresponding to B of molybdenum trioxide 1g and A g The vibration mode indicates that the material grown on the SiO2 / Si substrate surface in this embodiment is molybdenum trioxide.

[0080] The product obtained in Example 1 was analyzed by scanning electron microscopy, and its SEM image is shown below. Figure 4 As shown, the scale bar in the figure is 30 μm. (From...) Figure 4 As can be seen, in this embodiment, the molybdenum trioxide grown on the SiO2 / Si substrate is erected on the substrate surface.

[0081] The product obtained in Example 1 was analyzed by atomic force microscopy, and its AFM image is shown below. Figure 5As shown. By Figure 5 As can be seen, the thickness of the sample is about 3 nm, indicating that the molybdenum trioxide grown on the SiO2 / Si substrate in this embodiment is a thin layer of molybdenum trioxide.

[0082] The product obtained in Example 1 was analyzed by optical microscopy, and the results are as follows: Figure 6 As shown in the figure, most of the molybdenum trioxide is a thin layer and grows obliquely.

[0083] A transfer experiment was performed on the product obtained in Example 1 to test the ease of transfer of the thin layer of molybdenum trioxide grown on the SiO2 / Si substrate in this example. Specifically, a PDMS film substrate was pressed onto the product obtained in Example 1, and the morphology on the PDMS film was observed under an optical microscope. Figure 7 As shown, it can be observed that there is a large amount of molybdenum trioxide on the PDMS film, which means that it is very easy to transfer the thin layer of molybdenum trioxide grown on the SiO2 / Si substrate surface in this embodiment.

[0084] Comparative Example 1

[0085] (1) The SiO2 / Si substrate (SiO2 oxide layer thickness is 285nm) was ultrasonically treated with acetone and isopropanol for 10 minutes respectively to remove the impurities adsorbed on the surface; then the residual organic solvent (acetone and isopropanol) was rinsed off with deionized water to obtain a cleaned SiO2 / Si substrate.

[0086] (2) Place 10 mg of molybdenum disulfide powder in a quartz boat (the quartz boat is located in the central area of ​​the tube furnace). Place the untreated ordinary SiO2 / Si substrate in the downstream (near the outlet end, i.e., the outlet side) of the tube furnace and 18 cm away from the center of the tube furnace. Before the reaction starts, first introduce argon gas at a flow rate of 200 sccm into the quartz tube and continue to introduce it for 10 min to purge the air in the quartz tube. Then change the flow rate of argon gas (as a carrier gas) to 60 sccm and continue to introduce argon gas. At the same time, continue to introduce oxygen gas at a flow rate of 5 sccm into the quartz tube and start heating the central area of ​​the quartz tube with a heating furnace at a heating rate of 35 °C / min. When the central temperature zone of the tube furnace (i.e. the central heating zone) reaches the set temperature of 770 °C, hold the reaction at this temperature for 7 min and then stop heating the furnace. Let the central temperature zone cool naturally to room temperature and take out the substrate with the grown product. In this process, argon gas is used as a carrier gas to mix oxygen and molybdenum dioxide powder to produce a chemical reaction that grows molybdenum trioxide on the surface of SiO2 / Si substrate.

[0087] The product obtained in Comparative Example 1 was analyzed by optical microscopy, and the results are as follows: Figure 8As shown, it can be observed that molybdenum trioxide is grown in layers. The thickness of the thin layer of two-dimensional molybdenum trioxide grown on the SiO2 / Si substrate in Example 1 is compared with that of the molybdenum trioxide synthesized in Comparative Example 1. Figure 9 As shown. Figure 9 In this context, W / O plasma pretreatment corresponds to the molybdenum trioxide material in Comparative Example 1, while W plasma pretreatment corresponds to the thin-layer molybdenum trioxide two-dimensional material in Example 1. Figure 9 It can be clearly seen that the thickness of the thin layer of molybdenum trioxide grown on the SiO2 / Si substrate in Example 1 is two orders of magnitude thinner than the thickness of the molybdenum trioxide synthesized in Comparative Example 1.

[0088] Example 2: Preparation of thin-layer molybdenum trioxide

[0089] (1) The SiO2 / Si substrate (SiO2 oxide layer thickness is 285nm) was ultrasonically treated with acetone and isopropanol for 10 minutes respectively to remove the impurities adsorbed on the surface; then the residual organic solvent (acetone and isopropanol) was rinsed off with deionized water to obtain a cleaned SiO2 / Si substrate.

[0090] (2) The cleaned SiO2 / Si substrate is placed in a plasma cleaner for air plasma treatment. The pressure is pumped to 10Pa to ignite the plasma. 5sccm of air is introduced and the power is increased to 50W for 20min to obtain a plasma-treated silicon wafer substrate.

[0091] (3) Place 10 mg of molybdenum disulfide powder in a quartz boat (the quartz boat is located in the central area of ​​the tube furnace). Place the plasma-treated silicon wafer substrate obtained in step (2) at the downstream end of the tube furnace (the side near the outlet end, i.e., the outlet side) and 18 cm away from the center of the tube furnace. Before the reaction starts, first introduce argon gas at a flow rate of 200 sccm into the quartz tube and continue to introduce it for 10 min to purge the air in the quartz tube. Then change the flow rate of argon gas (as a carrier gas) to 70 sccm and continue to introduce argon gas. At the same time, continue to introduce oxygen gas at a flow rate of 5 sccm into the quartz tube and start heating the central area of ​​the quartz tube with a heating furnace at a heating rate of 35 °C / min. When the central temperature area of ​​the tube furnace reaches the set temperature of 770 °C, keep the reaction at this temperature for 7 min and then stop heating the furnace. Let the central temperature area cool naturally to room temperature and take out the substrate with the grown product. In this process, argon gas is used as a carrier gas to mix oxygen and molybdenum dioxide powder to produce a chemical reaction, thereby growing molybdenum trioxide on the surface of SiO2 / Si substrate.

[0092] Structural characterization of the product obtained in Example 2 reveals that the material grown on the SiO2 / Si substrate in this example is molybdenum trioxide, which is a thin two-dimensional material erected on the substrate surface. Moreover, this thin layer is grown obliquely on the substrate and is very easy to transfer.

[0093] Example 3: Preparation of thin-layer molybdenum trioxide

[0094] (1) The SiO2 / Si substrate (SiO2 oxide layer thickness is 285nm) was ultrasonically treated with acetone and isopropanol for 10 minutes respectively to remove the impurities adsorbed on the surface; then the residual organic solvent (acetone and isopropanol) was rinsed off with deionized water to obtain a cleaned SiO2 / Si substrate.

[0095] (2) The cleaned SiO2 / Si substrate is placed in a plasma cleaner for argon plasma treatment. The pressure is pumped to 10Pa to ignite the plasma. 8sccm of argon gas is introduced and the power is increased to 100W for 10 minutes to obtain a plasma-treated silicon wafer substrate.

[0096] (3) Place 10 mg of molybdenum disulfide powder in a quartz boat (the quartz boat is located in the central area of ​​the tube furnace). Place the plasma-treated silicon wafer substrate obtained in step (2) at the downstream end of the tube furnace (the side near the outlet end, i.e., the outlet side) and 18 cm away from the center of the tube furnace. Before the reaction starts, first introduce argon gas at a flow rate of 200 sccm into the quartz tube and continue to introduce it for 10 min to purge the air in the quartz tube. Then change the flow rate of argon gas (as a carrier gas) to 70 sccm and continue to introduce argon gas. At the same time, continue to introduce oxygen gas at a flow rate of 5 sccm into the quartz tube and start heating the central area of ​​the quartz tube with a heating furnace at a heating rate of 35 °C / min. When the central temperature area of ​​the tube furnace reaches the set temperature of 770 °C, keep the reaction at this temperature for 7 min and then stop heating the furnace. Let the central temperature area cool naturally to room temperature and take out the substrate with the grown product. In this process, argon gas is used as a carrier gas to mix oxygen and molybdenum dioxide powder to produce a chemical reaction, thereby growing molybdenum trioxide on the surface of SiO2 / Si substrate.

[0097] Structural characterization of the product obtained in Example 3 reveals that the material grown on the SiO2 / Si substrate in this example is molybdenum trioxide, which is a thin two-dimensional material erected on the substrate surface. Moreover, this thin layer is grown obliquely on the substrate and is very easy to transfer.

[0098] Example 4: Preparation of thin-layer molybdenum trioxide

[0099] (1) The SiO2 / Si substrate (SiO2 oxide layer thickness is 285nm) was ultrasonically treated with acetone and isopropanol for 10 minutes respectively to remove the impurities adsorbed on the surface; then the residual organic solvent (acetone and isopropanol) was rinsed off with deionized water to obtain a cleaned SiO2 / Si substrate.

[0100] (2) The cleaned SiO2 / Si substrate is placed in a plasma cleaner for argon plasma treatment. The pressure is pumped to 10Pa to ignite the plasma. Argon gas is introduced at 15sccm and the power is increased to 55W for 10min to obtain a plasma-treated silicon wafer substrate.

[0101] (3) Place 10 mg of molybdenum disulfide powder in a quartz boat (the quartz boat is located in the central area of ​​the tube furnace). Place the plasma-treated silicon wafer substrate obtained in step (2) at the downstream end of the tube furnace (the side near the outlet end, i.e., the outlet side) and 18 cm away from the center of the tube furnace. Before the reaction starts, first introduce argon gas at a flow rate of 200 sccm into the quartz tube and continue to introduce it for 10 min to purge the air in the quartz tube. Then change the flow rate of argon gas (as a carrier gas) to 40 sccm and continue to introduce argon gas. At the same time, continue to introduce oxygen gas at a flow rate of 5 sccm into the quartz tube and start heating the central area of ​​the quartz tube with a heating furnace at a heating rate of 30 °C / min. When the central temperature area of ​​the tube furnace reaches the set temperature of 770 °C, keep the reaction at this temperature for 7 min and then stop heating the furnace. Let the central temperature area cool naturally to room temperature and take out the substrate with the grown product. In this process, argon gas is used as a carrier gas to mix oxygen and molybdenum dioxide powder to produce a chemical reaction, thereby growing molybdenum trioxide on the surface of SiO2 / Si substrate.

[0102] Structural characterization of the product obtained in Example 4 revealed that the material grown on the SiO2 / Si substrate in this example is molybdenum trioxide, a thin two-dimensional material erected on the substrate surface. Furthermore, this thin layer is grown obliquely on the substrate, making it very easy to transfer. Its optical microscope image is shown below. Figure 10 As shown, it can be seen that the molybdenum trioxide thin layer obtained in Example 4 is thicker than that in Example 1.

[0103] Example 5: Preparation of Thin-Layer Molybdenum Trioxide

[0104] (1) The SiO2 / Si substrate (SiO2 oxide layer thickness is 285nm) was ultrasonically treated with acetone and isopropanol for 10 minutes respectively to remove the impurities adsorbed on the surface; then the residual organic solvent (acetone and isopropanol) was rinsed off with deionized water to obtain a cleaned SiO2 / Si substrate.

[0105] (2) The cleaned SiO2 / Si substrate is placed in a plasma cleaner for argon plasma treatment. The pressure is pumped to 10Pa to ignite the plasma. Argon gas is introduced at 15sccm and the power is increased to 50W for 15min to obtain a plasma-treated silicon wafer substrate.

[0106] (3) Place 10 mg of molybdenum disulfide powder in a quartz boat (the quartz boat is located in the central area of ​​the tube furnace). Place the plasma-treated silicon wafer substrate obtained in step (2) downstream of the tube furnace (on the side near the outlet end, i.e., the outlet side) and 18 cm away from the center of the tube furnace. Before the reaction starts, first introduce nitrogen gas at a flow rate of 200 sccm into the quartz tube and continue to introduce it for 10 min to purge the air in the quartz tube. Then change the flow rate of nitrogen gas (as a carrier gas) to 40 sccm and continue to introduce nitrogen gas. At the same time, continue to introduce oxygen gas at a flow rate of 5 sccm into the quartz tube and start heating the central area of ​​the quartz tube with a heating furnace at a heating rate of 30 °C / min. When the central temperature area of ​​the tube furnace rises to the set temperature of 770 °C, keep the reaction at this temperature for 7 min and then stop heating the furnace. Let the central temperature area cool naturally to room temperature and take out the substrate with the grown product. In this process, nitrogen is used as a carrier gas to mix oxygen and molybdenum dioxide powder to produce a chemical reaction, and molybdenum trioxide is grown on the surface of SiO2 / Si substrate.

[0107] Structural characterization of the product obtained in Example 5 reveals that the material grown on the SiO2 / Si substrate in this example is molybdenum trioxide, which is a thin two-dimensional material erected on the substrate surface. Moreover, this thin layer is grown obliquely on the substrate and is very easy to transfer.

[0108] Experiments have shown that, in Examples 1-5, the thickness of the grown thin-layer two-dimensional oxide material can be controlled by changing the time or power of the gas plasma treatment in step (1). Moreover, thin-layer two-dimensional materials with an atomic-level thickness of up to 3 nm can be obtained.

[0109] Example 6: Preparation of thin-layer bismuth oxide

[0110] (1) The SiO2 / Si substrate (SiO2 oxide layer thickness is 285nm) was ultrasonically treated with acetone and isopropanol for 10 minutes respectively to remove the impurities adsorbed on the surface; then the residual organic solvent (acetone and isopropanol) was rinsed off with deionized water to obtain a cleaned SiO2 / Si substrate.

[0111] (2) The cleaned SiO2 / Si substrate is placed in a plasma cleaner for argon plasma treatment. The pressure is pumped to 10Pa to ignite the plasma. 10sccm of argon gas is introduced, the power is set to 50W, and the treatment time is 5min to obtain a plasma-treated silicon wafer substrate.

[0112] (3) Place 10 mg of bismuth iodide powder in a quartz boat (the quartz boat is located in the central area of ​​the tube furnace). Place the plasma-treated silicon wafer substrate obtained in step (2) downstream of the tube furnace (on the side near the outlet end, i.e., the outlet side) and 18 cm away from the center of the tube furnace. Before the reaction starts, first introduce argon gas at a flow rate of 200 sccm into the quartz tube and continue to introduce it for 10 min to purge the air in the quartz tube. Then change the flow rate of argon gas (as a carrier gas) to 60 sccm and continue to introduce argon gas. At the same time, continue to introduce oxygen gas at a flow rate of 5 sccm into the quartz tube and start heating the central area of ​​the quartz tube with a heating furnace at a heating rate of 35 °C / min. When the central temperature area of ​​the tube furnace reaches the set temperature of 770 °C, keep the reaction at this temperature for 7 min and then stop heating the furnace. Let the central temperature area cool naturally to room temperature and take out the substrate with the grown product. In this process, argon gas is used as a carrier gas to mix oxygen and bismuth iodide powder to produce a chemical reaction, thereby growing bismuth oxide on the surface of SiO2 / Si substrate.

[0113] Structural characterization:

[0114] Raman spectroscopy analysis was performed on the product obtained in Example 6: the Raman spectrum of the sample was obtained by exciting the sample with a laser beam with a wavelength of 532 nm, as shown below. Figure 11 As shown. The Raman spectrum reveals two very strong scattering peaks, located at 84 cm⁻¹. -1 and 150cm -1 These correspond to two characteristic peaks of bismuth oxide, thus confirming that the material grown on the SiO2 / Si substrate in this embodiment is bismuth oxide.

[0115] The product obtained in Example 6 was analyzed by scanning electron microscopy, and its SEM image is shown below. Figure 12 As shown, the scale bar in the figure is 3 μm. (From...) Figure 12 As can be seen, in this embodiment, the bismuth oxide grown on the SiO2 / Si substrate is erected on the substrate surface.

[0116] The product obtained in Example 6 was analyzed by atomic force microscopy, and its AFM image is shown below. Figure 13 As shown. By Figure 13 As can be seen, the thickness of the sample is about 6 nm, indicating that the bismuth oxide grown on the SiO2 / Si substrate in this embodiment is a thin layer of bismuth oxide.

[0117] The product obtained in Example 6 was analyzed by optical microscopy, and the results are as follows: Figure 14 As shown in the figure, most of the bismuth oxide is a thin layer and grows obliquely.

[0118] Example 7: Preparation of thin-layer antimony oxide

[0119] (1) The SiO2 / Si substrate (SiO2 oxide layer thickness is 285nm) was ultrasonically treated with acetone and isopropanol for 10 minutes respectively to remove the impurities adsorbed on the surface; then the residual organic solvent (acetone and isopropanol) was rinsed off with deionized water to obtain a cleaned SiO2 / Si substrate.

[0120] (2) The cleaned SiO2 / Si substrate is placed in a plasma cleaner for argon plasma treatment. The pressure is pumped to 10Pa to ignite the plasma. 8sccm of argon gas is introduced, the power is set to 50W, and the treatment time is 15min to obtain a plasma-treated silicon wafer substrate.

[0121] (3) Place 10 mg of antimony oxide powder in a quartz boat (located in the central area of ​​the tube furnace). Place the plasma-treated silicon wafer substrate obtained in step (2) downstream of the tube furnace (on the side near the outlet, i.e., the outlet side) and 18 cm from the center of the tube furnace. Before the reaction begins, introduce argon gas at a flow rate of 200 sccm into the quartz tube for 10 min to purge the air from the quartz tube. Then, change the flow rate of argon gas (as a carrier gas) to 60 sccm and continue introducing argon gas. At the same time, start heating the central area of ​​the quartz tube with a heating furnace at a heating rate of 35 °C / min. When the central temperature zone of the tube furnace reaches the set temperature of 670 °C, hold the reaction at this temperature for 7 min, then stop heating the furnace. Allow the central temperature zone to cool naturally to room temperature and remove the substrate with the grown product. In this process, argon gas acts as a carrier gas, causing the antimony oxide powder to undergo a phase change and grow antimony oxide on the surface of the SiO2 / Si substrate.

[0122] Structural characterization:

[0123] Raman spectroscopy analysis was performed on the product obtained in Example 7: the Raman spectrum of the sample was obtained by exciting the sample with a laser beam with a wavelength of 532 nm, as shown below. Figure 15 As shown, the Raman spectrum reveals two very strong scattering peaks, located at 189 cm⁻¹. -1 303cm -1 The characteristic peaks correspond to antimony oxide and silicon wafer, respectively, thus confirming that the material grown on the SiO2 / Si substrate surface in this embodiment is antimony oxide.

[0124] The product obtained in Example 7 was analyzed by scanning electron microscopy, and its SEM image is shown below. Figure 18 As shown, the scale bar in the figure is 4 μm. (From...) Figure 16 As can be seen, in this embodiment, the antimony oxide grown on the SiO2 / Si substrate is erected on the substrate surface.

[0125] The product obtained in Example 7 was analyzed by atomic force microscopy, and its AFM image is shown below. Figure 17 As shown. By Figure 17 As can be seen, the thickness of the sample is approximately 84 nm, indicating that the bismuth oxide grown on the SiO2 / Si substrate in this embodiment is a thin layer of antimony oxide.

[0126] The product obtained in Example 7 was analyzed by optical microscopy, and the results are as follows: Figure 18 As shown in the figure, most of the antimony oxide is in thin layers and grows obliquely.

[0127] It should be noted that the argon gas in step (3) of the above embodiments can also be replaced by other inert gases or nitrogen.

[0128] The quartz boats or graphite boats used in the above embodiments are all high-temperature resistant carriers, and corundum boats or other commonly used high-temperature resistant carriers can be used as substitutes.

[0129] Example 8: Molybdenum trioxide memristor device

[0130] Fabrication: A memristor was fabricated using a silver electrode as the bottom electrode, graphene as the metal top electrode, and a thin layer of two-dimensional molybdenum trioxide material prepared in Example 1 as the dielectric resistive switching layer. A schematic diagram of the memristor structure is shown below. Figure 19 As shown, it has a sandwich structure, with a silver electrode as the bottom electrode, a thin layer of grown two-dimensional molybdenum trioxide material as the middle functional layer, and graphene as the top electrode.

[0131] The memristor fabrication process is as follows: First, photoresist is spin-coated onto a clean silicon wafer. Then, the shape of the bottom electrode is etched using photolithography. Next, silver metal is evaporated onto the silicon wafer using thermal evaporation to form a 50nm silver film. Then, acetone is used to remove the remaining photoresist, leaving the prepared bottom electrode. Subsequently, a thin layer of two-dimensional molybdenum trioxide material from Example 1 is transferred onto the silver electrode using a PDMS film. Then, mechanically exfoliated graphene (purchased from Shenzhen Six Carbon Technology Co., Ltd.) is transferred onto the thin layer of two-dimensional molybdenum trioxide using a PDMS film. In this way, a molybdenum trioxide memristor can be fabricated.

[0132] Performance testing of molybdenum trioxide memristors

[0133] DC IV testing of the device was performed using the DC voltage module of a 2450 source meter. The probe station was moved and the knob adjusted to place the two probes onto the two electrodes of the device under test. The positive voltage scan range was 0 to 1V, and the negative voltage scan range was 0 to -2V. The voltage change at each measurement point was 0.02V. During the test, the voltage was first increased from 0V to 1V, turning on the device and then returning to 0V. The voltage was then decreased negatively to -4V, switching the device from a low-resistance state to a high-resistance state and then returning to 0V. This process completed one cycle. Figure 20 The above-prepared memristor exhibits its IV curve after 150 cycles. Figure 20 It can be seen that the memristor made from the thin-layer two-dimensional molybdenum trioxide material obtained in Example 1 of this invention has excellent performance: before the device is turned on, the current does not increase with the voltage, demonstrating that the dielectric layer has good insulation properties; the device's turn-on voltage range is concentrated around 0.5V, and the operating current is 10... -4 A indicates that the device has low power consumption and low power consumption characteristics; within 150 cycles, the memristor stably changes from a high-resistance state to a low-resistance state and maintains a relatively close voltage to the set voltage, which exceeds the number of cycles for most memristor devices; moreover, its switching ratio can reach as high as 10. 4 It has a significant switching current difference.

[0134] Comparative Example 2: Molybdenum trioxide memristor device

[0135] The molybdenum trioxide memristor device was fabricated using the same method as in Example 8, except that the molybdenum trioxide material prepared in Comparative Example 1 was used as the dielectric resistive switching layer. Specifically: first, photoresist was spin-coated onto a clean silicon wafer; then, the shape of the bottom electrode was etched using photolithography; next, silver metal was evaporated onto the silicon wafer using thermal evaporation to form a 50nm silver film; then, the remaining photoresist residue was removed using acetone, leaving the prepared bottom electrode. Subsequently, the molybdenum trioxide material from Comparative Example 1 was transferred onto the silver electrode using a PDMS film, and then mechanically exfoliated graphene was transferred onto the molybdenum trioxide using the PDMS film, thereby obtaining the molybdenum trioxide memristor.

[0136] Similarly, the performance of the molybdenum trioxide memristor of this comparative example was tested using the same method as described in Example 8. The difference is that here, the IV curve of one cycle was tested, and 16 sets of data were tested at different voltage scan ranges, such as... Figure 22 As shown.

[0137] Under the same conditions, the performance of the molybdenum trioxide memristor in Example 8 was also tested, and 16 sets of data were obtained, such as... Figure 21 As shown.

[0138] Depend on Figure 21As can be seen, the turn-on voltage of the molybdenum trioxide memristor in Example 8 is very small, and the change in turn-on voltage is also very small; Figure 22 As can be seen, the turn-on voltage of the molybdenum trioxide memristor in Comparative Example 2 is very large, and the turn-on voltage varies greatly.

[0139] right Figure 21 The average value of the turn-on voltage of the 16 sets of data is taken, and then... Figure 22 The average value of the turn-on voltage from the 16 sets of data was compared. The comparison results of the average turn-on voltage are as follows: Figure 23 As shown. Figure 23 In the examples, W / O plasma pretreatment corresponds to the molybdenum trioxide memristor in Comparative Example 2, while W plasma pretreatment corresponds to the molybdenum trioxide memristor in Example 8. Figure 23 As can be seen, the turn-on voltage of the molybdenum trioxide memristor in Example 8 is 0.5V, while the turn-on voltage of the molybdenum trioxide memristor in Comparative Example 2 is 2V. Obviously, the former has significantly lower power consumption than the latter.

[0140] In summary, this invention successfully prepares a thin-layer two-dimensional oxide material by first subjecting the SiO2 / Si substrate to other plasma treatments and then performing chemical vapor deposition in a tube furnace. This thin-layer two-dimensional oxide material is an upright, high-dielectric-constant oxide layer, and its oblique growth makes it very easy to transfer; only a PMDA film is needed for easy transfer. Since wet transfer is not required, much organic residue can be reduced. Therefore, this invention provides a simple method to prepare high-dielectric-constant oxide thin-layer two-dimensional materials that are difficult to obtain in existing technologies, making it more suitable for fabricating low-power memristors. Furthermore, its oblique morphology allows for its application in the fabrication of Fin Field-Effect Transistors (FinFETs).

[0141] Finally, it should be noted that the above embodiments are for illustrative purposes only and are not intended to limit the scope of protection of the present invention. Furthermore, it should be understood that after reading the technical content of this invention, those skilled in the art can make various modifications, alterations, or variations to the invention, and all such equivalent forms also fall within the scope of protection defined by the appended claims.

Claims

1. A thin-layer two-dimensional oxide material, characterized in that, The two-dimensional oxide material is a thin layer of two-dimensional oxide material formed by chemical vapor deposition on a silicon wafer substrate treated with gas plasma. The two-dimensional oxide material is an upright thin layer that is obliquely grown on the silicon wafer substrate treated with gas plasma. The gas is argon, air, oxygen or nitrogen. The power of the plasma treatment is 30~100 W, the time is 5~20 min, the flow rate of the gas is 5~20 sccm, and the oxide is molybdenum trioxide, bismuth oxide or antimony oxide.

2. The thin-film two-dimensional oxide material as described in claim 1, characterized in that, The silicon wafer substrate is a SiO2 / Si substrate with an oxide layer thickness of 285 nm.

3. The method for preparing a thin-film two-dimensional oxide material as described in claim 1 or 2, comprising: Step S1: The silicon wafer substrate is subjected to gas plasma treatment, wherein the gas is argon, air, oxygen or nitrogen, to obtain a plasma-treated substrate. The power of the plasma treatment is 30~100 W, the time is 5~20 min, and the flow rate of the gas is 5~20 sccm. Step S2: Deposit oxide powder onto the plasma-treated substrate in a carrier gas via chemical vapor deposition to obtain an erected thin-layer two-dimensional oxide material; or, react chalcogenide or halide powder with oxygen in a carrier gas and deposit it onto the plasma-treated substrate via chemical vapor deposition to obtain an erected thin-layer two-dimensional oxide material; the carrier gas is argon or nitrogen.

4. The method for preparing a thin-layer two-dimensional oxide material as described in claim 3, characterized in that, In step S1, the silicon substrate is a SiO2 / Si substrate with an oxide layer thickness of 285 nm.

5. The method for preparing a thin-film two-dimensional oxide material as described in claim 3 or 4, characterized in that, Step S2 includes: Molybdenum disulfide or bismuth iodide powder is placed on a high-temperature resistant carrier, and the high-temperature resistant carrier is placed in the central heating zone of a tube furnace; then the plasma-treated substrate is placed on the outlet side of the tube furnace at a distance of 10-30 cm from the center of the tube furnace. 200-300 sccm of carrier gas is introduced into the tubular furnace and continued for 10-20 minutes. Then, adjust the flow rate of the carrier gas to 40~70 sccm and introduce 4~10 sccm of oxygen. While continuously introducing the carrier and oxygen, gradually heat up the tubular furnace until the temperature of the central heating zone of the tubular furnace reaches 700~800 ℃, and then hold the reaction at that temperature for 5~15 min. After the reaction is complete, the material is allowed to cool naturally to obtain a thin layer of two-dimensional oxide material grown on the substrate.

6. The method for preparing a thin-film two-dimensional oxide material as described in claim 3 or 4, characterized in that, Step S2 includes: Antimony oxide powder is placed on a high-temperature resistant carrier, and the high-temperature resistant carrier is placed in the central heating zone of a tube furnace; then the plasma-treated substrate is placed on the outlet side of the tube furnace at a distance of 10-30 cm from the center of the tube furnace. 200-300 sccm of carrier gas is introduced into the tubular furnace and continued for 10-20 minutes. Then, adjust the flow rate of the carrier gas to 40~70 sccm and continue to introduce it; at the same time, gradually heat up the tubular furnace until the temperature of the central heating zone of the tubular furnace reaches 600~700 ℃, and then keep it at that temperature for 5~15 minutes. After the reaction is complete, the material is allowed to cool naturally to obtain a thin layer of two-dimensional oxide material grown on the substrate.

7. The application of the thin-film two-dimensional oxide material as described in claim 1 or 2, characterized in that, The thin-film two-dimensional oxide material as described in claim 1 or 2 is used to fabricate memristors or fin field-effect transistors.

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