Double-layered metal dichalcogenides, synthesis thereof and use thereof

Abstract

The present disclosure generally relates to bilayer metal dichalcogenides, methods for forming bilayer metal dichalcogenides, and use of bilayer metal dichalcogenides in quantum electronic devices. In one aspect, a device is provided. The device includes a gate electrode, a substrate disposed over at least a portion of the gate electrode, and a bottom layer comprising a first metal dichalcogenide disposed over at least a portion of the substrate. The device further includes a top layer comprising a second metal dichalcogenide, the top layer disposed over at least a portion of the bottom layer, the first metal dichalcogenide and the second metal dichalcogenide being the same or different. The device further includes a source electrode and a drain electrode disposed over at least a portion of the top layer.

Description

[0001] Inventor : Avetik Harutyunyan; Xufan Li Technical Field

[0002] This disclosure generally relates to bilayer metal dichalcogenides, methods for forming bilayer metal dichalcogenides, and the use of bilayer metal dichalcogenides in quantum electronic devices (e.g., quantum computing, quantum sensing, and quantum communication). Background Technology

[0003] Quantum dots are nanoscale semiconductor particles capable of transmitting electrons. Due to quantum mechanics, quantum dots exhibit optical and electronic properties that differ from larger particles. Traditionally, quantum dots have been attractive for optical and energy applications because they are confined to the nanoscale in three-dimensional space, resulting in size-dependent band gaps. As quantum computing and information processing become increasingly important, quantum dots have become a platform for various qubits, forming the cornerstone of quantum information. The emergence of thin, two-dimensional (2D) transition metal chalcogenides (TMDs) fabricated to nanometer-level widths presents a new family of quantum dot nanostructures.

[0004] Quantum dots for TMDs have been synthesized using solution-based methods. However, the lack of size distribution and the ability to manipulate individual quantum dots remain challenges for such fabrication methods. Photolithographic patterning and electrostatic gating methods have also been used to fabricate individual quantum dots for 2D TMDs. However, these methods tend to introduce contamination. Furthermore, it is difficult to form small (sub-20 nm or sub-10 nm) quantum dots using photolithographic patterning or electrostatic gating. Moreover, due to the aforementioned challenges in their synthesis, it is impossible to fabricate devices comprising such small-sized quantum dots.

[0005] There is a need for new and improved bilayer metal disulfides and methods for forming bilayer metal disulfides that overcome one or more of the aforementioned defects. Summary of the Invention

[0006] This disclosure generally relates to bilayer metal dichalcogenides, methods for forming bilayer metal dichalcogenides, and the use of bilayer metal dichalcogenides in quantum electronic devices (e.g., quantum computing, quantum sensing, and quantum communication).

[0007] In one aspect, an apparatus is provided. The apparatus includes a gate electrode, a substrate disposed over at least a portion of the gate electrode, and a bottom layer including a first metal dichalcogenide disposed over at least a portion of the substrate. The apparatus also includes a top layer including a second metal dichalcogenide disposed over at least a portion of the bottom layer, wherein the first metal dichalcogenide and the second metal dichalcogenide may be the same or different. The apparatus further includes a source electrode and a drain electrode disposed over at least a portion of the top layer.

[0008] In another aspect, a method is provided. The method includes: positioning a substrate in a chamber; and thermally depositing a salt, metal particles, a first precursor including Mo, W, or combinations thereof, and a second precursor including S, Se, Te, or combinations thereof on the substrate to form a multilayer structure. The multilayer structure includes: a bottom layer disposed over at least a portion of the substrate and a top layer disposed over at least a portion of the bottom layer, the bottom layer comprising a first metal dichalcogenide and the top layer comprising a second metal dichalcogenide.

[0009] In another aspect, a method is provided. The method includes cooling a device at a temperature of about 1 K to about 80 K, the device comprising: a gate electrode; a substrate disposed above at least a portion of the gate electrode; a bottom layer comprising a first metal dichalcogenide disposed above at least a portion of the substrate; a top layer comprising a second metal dichalcogenide disposed above at least a portion of the bottom layer, the first and second metal dichalcogenides being the same or different; and a source electrode and a drain electrode disposed above at least a portion of the top layer. The method further includes applying a voltage to the gate electrode to control electron flow between one or more of the source electrode, drain electrode, bottom layer, or top layer. Attached Figure Description

[0010] The patent or application document contains at least one color drawing. A copy of the published patent or patent application with color drawings will be provided by the office upon request and payment of the necessary fees.

[0011] To enable a detailed understanding of the foregoing features of this disclosure, the disclosure, which has been briefly outlined above, can be described in more detail by reference to various aspects, some of which are illustrated in the accompanying drawings. However, it should be noted that the drawings illustrate only exemplary aspects and should not be considered as limiting its scope, as other equally effective aspects are permissible with respect to this disclosure.

[0012] Figure 1A This is a side view of an exemplary double-layer structure according to at least one aspect of this disclosure.

[0013] Figure 1B yes Figure 1A The top view of the double-layer structure shown.

[0014] Figure 1C These are examples of exemplary serrated edge constructions of nanoribbons and exemplary armchair edge constructions according to at least one aspect of this disclosure.

[0015] Figure 1D This is an example of an exemplary double-layer structure having an AA'(2H) stacked configuration according to at least one aspect of this disclosure.

[0016] Figure 1E This is an example of an exemplary double-layer structure having an AB(3R) stacked configuration according to at least one aspect of this disclosure.

[0017] Figure 1F This is an example of an exemplary double-layer structure having a twisted stacking configuration according to at least one aspect of this disclosure.

[0018] Figure 2 This is an exemplary apparatus for forming a metal dichalcogenide bilayer structure according to at least one aspect of the present disclosure.

[0019] Figure 3 Selected operations of an exemplary process for forming a metal dichalcogenide bilayer structure according to at least one aspect of this disclosure are shown.

[0020] Figure 4A It is based on at least one aspect of this disclosure. Figure 3 A top view of an exemplary multilayer structure formed during the process.

[0021] Figure 4B It is based on at least one aspect of this disclosure Figure 4A The cross-sectional view of the multi-layered structure is shown.

[0022] Figure 4C This is a top view of an exemplary multilayer structure after the bottom portion of the multilayer structure has been converted into a removable layer, according to at least one aspect of this disclosure.

[0023] Figure 4D It is based on at least one aspect of this disclosure Figure 4C The cross-sectional view of the multi-layered structure is shown.

[0024] Figure 4E This is a top view of an exemplary dual-layer structure disposed above a substrate after the etchable layer has been removed, according to at least one aspect of this disclosure.

[0025] Figure 4F It is based on at least one aspect of this disclosure Figure 4E The cross-sectional view of the double-layer structure is shown.

[0026] Figure 4GThis is a top view of an exemplary multilayer structure after the bottom layer and top layer of the multilayer structure have been converted into removable layers, according to at least one aspect of this disclosure.

[0027] Figure 4H It is based on at least one aspect of this disclosure Figure 4G The cross-sectional view of the multi-layered structure is shown.

[0028] Figure 4I This is a top view of an exemplary single-layer structure disposed above a substrate after the removal of a removable layer, according to at least one aspect of this disclosure.

[0029] Figure 4J It is based on at least one aspect of this disclosure Figure 4I The diagram shows a cross-sectional view of a single-layer structure.

[0030] Figure 5 It is an exemplary device incorporating an exemplary dual-layer structure according to at least one aspect of this disclosure.

[0031] Figure 6A An exemplary high-angle annular dark-field scanning transmission electron microscope (HAADF-STEM) image of a bilayer having an AA'(2H) stacked structure is shown according to at least one aspect of this disclosure.

[0032] Figure 6B An exemplary HAADF-STEM image of a two-layer structure having an AB(3R) stacked configuration is shown according to at least one aspect of this disclosure.

[0033] Figure 6C An exemplary HAADF-STEM image of a double layer having a twisted stacked structure is shown according to at least one aspect of this disclosure.

[0034] Figure 6D It corresponds to Figure 6C An exemplary Fast Fourier Transform (FFT) pattern of a HAADF-STEM image.

[0035] Figure 7 These are exemplary scanning electron microscope (SEM) images of nanoribbon devices with different channel lengths between the source and drain electrodes, according to at least one aspect of this disclosure.

[0036] Figure 8A An exemplary transfer curve of an 8nm wide nanoribbon device with a 400nm channel length is shown according to at least one aspect of the present disclosure.

[0037] Figure 8BExemplary output characteristics of an 8nm thick nanoribbon device with a 400nm channel length at varying back gate voltages of 300 Kelvin (K) (solid line) and 15K (dashed line) according to at least one aspect of this disclosure are shown.

[0038] Figure 8C An exemplary transfer curve of a nanoribbon with a varying width and a channel length of 200 nm at 15 K and a bias voltage of 30 mV, according to at least one aspect of the present disclosure, is shown.

[0039] Figure 8D Exemplary transfer curves of a 20 nm thick nanoribbon device according to at least one aspect of this disclosure at various temperatures are shown.

[0040] Figure 9A This is an exemplary conductivity diagram of an exemplary device according to at least one aspect of this disclosure.

[0041] Figure 9B This is an exemplary conductivity diagram of an exemplary device according to at least one aspect of this disclosure.

[0042] Figure 10A An exemplary HAADF-STEM image (scale: 5 nm) of a monolayer MoS2 nanoribbon is shown according to at least one aspect of this disclosure.

[0043] Figure 10B It is based on at least one aspect of this disclosure. Figure 10A An exemplary HAADF-STEM image of a portion of a monolayer MoS2 nanoribbon imaged at a higher magnification (scale: 1 nm).

[0044] Figure 10C It is based on at least one aspect of this disclosure. Figure 10A Exemplary HAADF-STEM images of different portions of a monolayer MoS2 nanoribbon imaged at higher magnification (scale: 1 nm).

[0045] Figure 11 A schematic diagram of an exemplary process for forming twisted bilayer nanoribbons according to at least one aspect of the present disclosure is shown.

[0046] Figure 12 This is an exemplary SEM image showing an example of twisted stacked bilayer MoS2 nanoribbons according to at least one aspect of this disclosure.

[0047] For ease of understanding, the same reference numerals are used where possible to denote common elements in the figures. It is conceivable that elements and features of one example may be advantageously combined in other examples without further detail. Detailed Implementation

[0048] This disclosure generally relates to bilayer metal dichalcogenides, methods for forming bilayer metal dichalcogenides, and the use of bilayer metal dichalcogenides in quantum electronic devices (e.g., quantum computing, quantum sensing, and quantum communication). The processes described herein can form, for example, bilayer structures, such as nanoribbons. The inventors have found that metal nanoparticles can reduce the width of the bilayer to about 20 nm or less (e.g., about 8 nm or less). The bilayer structure can be incorporated into devices such as field-effect transistors (FETs). The bilayer structure exhibits, for example, width-dependent Coulomb blocking oscillations, which can enable quantum transport at high temperatures (e.g., up to about 80 Kelvin or higher). In some examples, the inventors show that the quantum oscillations can be controlled, for example, by the width of the bilayer structure and the stacking configuration of the layers in the bilayer structure. The bilayer structure and devices incorporating the bilayer structure enable tunability of the QD transport characteristics of metal dichalcogenides.

[0049] Reducing the width of two-dimensional materials to quasi-one-dimensional nanostructures (called nanoribbons) adds another degree of freedom to engineered devices utilizing the electronic behavior of nanoribbons. However, experimental results regarding 2D TMD nanoribbons, particularly for those with widths of 30 nm or less, are scarce due to, for example, a lack of directly synthesized materials that ensure the preservation of their inherent properties. Current methods for fabricating monolayer TMDs rely on top-down techniques, such as photolithographic dicing or etching on monolayer films or sheets. Recently, direct growth of monolayer MoS2 ribbons with widths of 50 nm to 100 nm has been achieved using salt-assisted growth and substrate-oriented epitaxy or edge-oriented epitaxy processes.

[0050] Adding a second layer of TMD provides further capability to tune the formed electronic structure through, for example, interlayer stacking and twisting. However, bilayer TMD nanoribbons have not been reported to date. In some examples, bilayer TMD nanoribbons with widths from about 8 nm to about 100 nm have been grown using metal-based nanoparticles. The metal-based nanoparticles can be used, for example, to control the growth of the layers, and the diameter of the metal-based nanoparticles can, for example, control the width of the layers. Quantum transport behavior has been observed in these nanoribbons, enabling the use of bilayer structures in quantum electronic devices at high temperatures (e.g., greater than 4 K).

[0051] Bilayer metal dichalcogenides

[0052] The aspects of this disclosure generally relate to bilayer metal disulfides, such as bilayer transition metal disulfides. Figure 1AAn exemplary bilayer structure 100 according to at least one aspect of this disclosure is shown. These bilayer structures can be used with devices such as quantum electronic devices, as described below. The bilayer structure 100 includes a bottom layer 105 comprising or composed of a first metal dichalcogenide. A top layer 110 is disposed over at least a portion of the bottom layer 105. The top layer 110 comprises or is composed of the same metal dichalcogenide as the bottom layer or a second metal dichalcogenide, or is composed of the same metal dichalcogenide as the bottom layer or a second metal dichalcogenide. The bottom layer 105 has a thickness (H1), and the top layer has a thickness (H2). The thicknesses of the bottom layer 105 and / or the top layer 110 may independently be about 1 nm or less, such as about 0.8 nm or less, such as from about 0.5 nm. In some aspects, the thickness of the bottom layer 105 is greater than, less than, or equal to the thickness of the top layer 110. The total thickness of the bilayer metal dichalcogenide is determined by atomic force microscopy (AFM).

[0053] The bottom layer 105 and the top layer 110 may be separated by a gap 115 (also known as a van der Waals gap) with a non-zero thickness, such as about 0.5 nm or less, such as about 0.4 nm or less, such as about 0.3 nm or less, such as about 0.2 nm or less, such as about 0.1 nm or less. A double-layer structure without gap 115 is also envisioned.

[0054] The bottom layer 105 has a width (W1), and the top layer has a width (W2). The width of the bottom layer 105 and / or the top layer 110 may be independently 1 μm or less, such as from about 500 nm or less, such as about 400 nm or less, such as about 200 nm or less, such as about 1 nm or more and / or about 100 nm or less, such as about 90 nm or less, such as about 80 nm or less, such as about 70 nm or less, such as about 60 nm or less, such as about 50 nm or less, such as about 40 nm or less, such as about 30 nm or less, such as about 20 nm or less, such as about 15 nm or less, such as about 10 nm or less, such as about 9 nm or less, such as about 8 nm or less, such as about 7 nm or less, such as about 6 nm or less, such as about 5 nm or less, such as about 4 nm or less, such as about 3 nm or less, such as about 2 nm or less, such as about 1 nm or less. In some aspects, the widths of the bottom layer 105 and / or the top layer 110 may independently be from about 1 nm to about 40 nm, such as from about 2 nm to about 35 nm, such as from about 5 nm to about 30 nm, such as from about 6 nm to about 25 nm, such as from about 8 nm to about 20 nm, such as from about 10 nm to about 15 nm. In some aspects, the width of the bottom layer 105 is greater than, less than or equal to the width of the top layer 110. For example, the widths of individual layers of the bottom layer 105 and the top layer 110, and the total width of the bilayer structure 100, are determined by scanning electron microscopy (SEM).

[0055] As described above, the bottom layer 105 comprises or is composed of a first metal disulfide, and the top layer 110 comprises or is composed of a second metal disulfide. In some aspects, the first metal disulfide and / or the second metal disulfide is a transition metal disulfide. The first metal disulfide and the second metal disulfide may be the same or different. The first metal disulfide and / or the second metal disulfide may include MoS2, MoSe2, MoTe2, WS2, WSe2, WTe2, and combinations thereof.

[0056] The bottom layer 105 may be in the form of a strip or a nanoribbon. The top layer 110 may be in the form of a strip or a nanoribbon. Strips and nanoribbons are essentially planar structures. As used herein, the term "strip" refers to an elongated structure, i.e., a structure with an aspect ratio greater than 500, optionally greater than 1000. As used herein, the term "nanoribbon" refers to a strip having at least one dimension at the nanometer scale, for example, a strip having a width of about 1 nm to 500 nm or about 1 nm to 100 nm.

[0057] In at least one aspect, the bottom layer 105 is in the form of a single nanoribbon and / or the top layer 110 is in the form of a single nanoribbon. As determined by SEM, the aspect ratio of the nanoribbon may be greater than about 1000, such as about 1000 to 20000, such as about 5000 to about 10000.

[0058] As determined by high-angle annular dark-field scanning transmission electron microscopy (HAADF-STEM), at least a portion of the nanoribbons exhibits a substantially uniform edge structure. In one example, such as... Figure 1C As shown, a substantially uniform edge configuration may include a serrated edge 122, an armchair edge 124, or a combination thereof, as determined by HAADF-STEM.

[0059] In a bilayer structure (e.g., a bilayer nanoribbon), the bottom layer 105 and the top layer 110 can be stacked in various orientations. Figures 1D to 1F An exemplary stacked structure of bilayer nanoribbons is shown. The stacking structure was determined by HAADF-STEM. Specifically, Figure 1D The AA'(2H) stacked structure is shown. Figure 1E The AB(3R) stacked construction is shown. Figure 1F Twisted stacked structures (e.g., moiré patterns) are shown. In Figures 1D to 1F In this system, metal atoms are represented by the number 152, and chalcogen group element atoms are represented by the number 154.

[0060] Compared to Figure 1EThe twisted stacking structure shown allows control over the interlayer twist angle (°) between the two layers of a bilayer structure, enabling, for example, different electronic structures to be obtained based on this angle. The interlayer twist angle can be from about 1° to about 20°, such as from about 2° to about 18°, from about 4° to about 16°, from about 6° to about 14°, or from about 8° to about 12°. It is envisioned that the interlayer twist angle can be larger or smaller. The interlayer twist angle is measured from HAADF-STEM using a Fast Fourier Transform (FFT). The following description... Figures 6A to 6C It shows Figure 1D An exemplary HAADF-STEM image of the AA'(2H) stacked structure shown. Figure 1E The AB(3R) stacked construction shown, and Figure 1F The twisted stacking structure is shown. The bilayer structure formed by the process described herein may have an AA'(2H) stacking structure, an AB(3R) stacking structure, a twisted stacking structure, or a combination thereof. Figure 6D Showing from Figure 6C The FFT pattern of HAADF-STEM in the image has two sets of hexagonal patterns corresponding to the top and bottom layers, respectively, and the rotation angle between the patterns is the twist angle of the two layers.

[0061] Various stacking structures can be controlled by the growth conditions. Regarding the formation of bilayers with twisted stacking structures, any suitable method can be used, such as manually stacking one monolayer nanoribbon on top of another monolayer nanoribbon by rotating it at an angle, as described below and in the Examples section.

[0062] As a non-limiting example of a bilayer nanoribbon used to form a twisted stacked structure, a first monolayer nanoribbon disposed on a film (e.g., a poly(methyl methacrylate) (PMMA) film) is positioned above a substrate on which a second monolayer nanoribbon is disposed. The position of the first monolayer nanoribbon relative to the second monolayer nanoribbon can be parallel or substantially parallel, as determined by, for example, optical microscopy. The film on which the first monolayer nanoribbon is disposed is then rotated greater than about 0° and less than about 180°, such as 1° to about 45°, such as about 5° to about 30°, such as about 10° to about 20°. In some aspects, the film is rotated about 2° to about 18°, such as about 4° to about 16°, such as about 6° to about 14°, such as about 8° to about 12°. After rotating the film on which the first monolayer nanoribbon is disposed, the film is then placed on a substrate on which the second monolayer nanoribbon is disposed. The film can then be removed, for example, by immersing it in a suitable solvent (such as acetone) for about 1 hour or longer (such as about 5 hours to about 24 hours, such as about 10 hours to about 15 hours) to form a bilayer nanoribbon structure with a twisted stacked structure on the substrate.

[0063] In some aspects, the bilayer nanoribbon structure in the twisted stacking configuration may have an interlayer twist angle greater than about 0° and less than about 180°, such as 1° to about 45°, such as about 5° to about 30°, such as about 10° to about 20°. In some aspects, the film is rotated about 2° to about 18°, such as about 4° to about 16°, such as about 6° to about 14°, such as about 8° to about 12°.

[0064] Process for forming a double-layer metal dichalcogenide structure

[0065] The present invention also generally relates to a process for forming a double-layer metal dichalcogenide structure. Figure 2 An exemplary device 200 for forming the two-layer structure described herein is shown. Device 200 is merely a non-limiting illustration. Modifications and alterations to device 200 are contemplated.

[0066] Apparatus 200 includes a reaction chamber 207, such as a chemical vapor deposition chamber. The reaction chamber 207 is coupled to a gas tank 210 via lines 213a and 213b. The gas tank 210 contains a carrier gas, such as a non-reactive gas, such as He, Ar, Kr, Ne, Xe, N2, or combinations thereof. Line 213b is coupled to the reaction chamber 207 via line 217 and inlet 220, allowing the carrier gas (e.g., Ar) to flow into the reaction chamber 207. An effervescent device 212 containing water 214 is disposed along line 213a. Here, the carrier gas enters the effervescent device 212 and forms a humidified carrier gas (e.g., a mixture of carrier gas and water, such as Ar + H2O). The mixture of carrier gas and water (e.g., in vapor form) can then flow into the reaction chamber 207 via line 217 and inlet 220.

[0067] As shown in the figure, pipeline 213a can be coupled to pipeline 213b via connector / valve 219, allowing the gas flowing through pipelines 213a and 213b to enter reaction chamber 207 via inlet 220 and pipeline 217. Alternatively, pipeline 213a exiting bubbler 212 can be directly coupled to reaction chamber 207 instead of connector / valve 219, allowing the gas flowing through pipeline 213a and the gas flowing through pipeline 213b to enter reaction chamber through different inlets.

[0068] Along each of the pipelines 213a and 213b are mass flow controllers 215a and 215b. The mass flow controllers 215a and 215b are used, for example, to measure and / or control the amount of liquid / gas flowing through the pipelines 213a and 213b. A dew point hygrometer 218 is coupled to pipeline 217 and is used to measure the moisture content of the gas entering the reaction chamber 207. For example, the moisture content of the gas entering the reaction chamber 207 can be adjusted by using the mass flow controllers 215a and 215b to adjust the flow rate (FR) of the carrier gas flowing through pipeline 213b. C) and the flow rate (FR) of the humidifying carrier gas flowing through pipeline 213a C+H2O ) to control: FR C+H2O / (FR C +FR C+H2O The gas can leave the reaction chamber 207 through outlet 228.

[0069] During operations such as depositing a metal dichalcogenide layer, a substrate 201 is disposed within a reaction chamber 207. For example... Figure 2 As shown, a first tray 203, containing a salt 204, a metal 205, and a first precursor 226 comprising Mo, W, or combinations thereof, is also located in the reaction chamber 207. A second tray 224 is used to contain a second precursor 222 comprising chalcogenide atoms (e.g., S, Se, Te, or combinations thereof). The first tray 203 and the second tray 224 may have any shape and size. The term "tray" is not particularly limited, and suitable trays include, but are not limited to, weighing boats, crucibles, flasks, or other containers capable of withstanding temperature drifts in the processes disclosed herein.

[0070] Heating can be performed using a heating mechanism, for example, by using one or more heating wires 211a, 211b above and / or below the first tray 203 and the second tray 224, such as in an oven or other suitable apparatus known in the art. As described below, the heating wires 211a, 211b can provide different amounts of heat to different locations within the chamber. For example, heating wire 211a can operate at a first temperature T1, while heating wire 211b can operate at a second temperature T2.

[0071] Figure 3 Selected operations of an exemplary process 300 for forming a bilayer structure (e.g., a bilayer metal dichalcogenide) according to at least one aspect are shown. Available Figure 2 The apparatus 200 shown is used to form process 300.

[0072] Process 300 includes setting or positioning a substrate 201 in a reaction chamber 207, such as a quartz tube, in operation 310. The substrate 201 may be covered by a mask 202 having a patterned shape. According to some aspects, the substrate 201 may be a non-reactive material suitable for the process described herein. Examples of substrates available according to this disclosure include, but are not limited to, substrates comprising or composed of: SiO2, Si, c-sapphire, fluorophlogopite, SrTiO3, hexagonal boron nitride (h-BN), or combinations thereof. It should be understood that while a SiO2 substrate is used herein as an exemplary substrate, any suitable substrate may be used in addition to or in place of this substrate.

[0073] The process also includes depositing salt, metal, a first precursor, and a second precursor on substrate 201 to form a multilayer structure comprising a bottom layer and a top layer. The multilayer structure can be deposited using a chemical vapor deposition (CVD) method.

[0074] The bottom layer is disposed above at least a portion of the substrate, and the top layer is disposed above at least a portion of the bottom layer. The top layer comprises a metal dichalcogenide, and the bottom layer comprises metal dichalcogenides, which may be the same or different. Figure 4A and Figure 4B Top and cross-sectional views of the double-layered structure formed during operation 320 are shown respectively. Figure 4A In the diagram, arrows indicate the growth direction of the structure. The bilayer structure 400 includes a bottom layer 415 (also referred to as a monolayer) and a top layer 420 (also referred to as another monolayer) terminated by metal nanoparticles 410. The top layer 420 may include metal nanoparticles 410 (e.g., metal 205). See the cross-sectional view of the bilayer structure 400. Figure 4B As shown, the bottom layer 415 includes an unexposed portion 430 (i.e., the portion of the bottom layer 415 on which the top layer 420 is disposed) and an exposed portion 425 (i.e., the portion of the bottom layer 415 on which the top layer 420 is not disposed).

[0075] The metal dichalcogenide bands, such as MoS2 bands, formed in operation 320 can have a length of less than about 1 mm, such as less than about 0.7 mm. The metal nanoparticles 410 control the width of the grown top layer 420. For example, when MoS2 is grown on substrate 405 using Ni nanoparticles, operation 320 can produce a bottom layer of MoS2 that is wider than the top layer of MoS2.

[0076] In some respects, the bottom layer 415 has a width of about 5 μm or less (such as about 2 μm or less, such as about 1 μm or less), and the top layer 420 (e.g., a bilayer structure) has a width of about 500 nm or less. The width of the top layer 420 may be the width described above with respect to the bilayer structure 100.

[0077] In some respects, Salt 204 may include, but is not limited to, sodium and potassium salts, such as NaBr, NaCl, KBr, KCl, and combinations thereof. It should be understood that while NaBr is used herein as an exemplary salt, any suitable salt may be used as a supplement or substitute. As used herein, the term "salt" refers to an electrically neutral ionic compound having one or more cations and one or more anions.

[0078] Metal 205 can be a transition metal, such as Ni, Fe, or a combination thereof. Metal 205 (which can be in the form of particles, e.g., nanoparticles) promotes the growth of structures comprising metal dichalcogenides. For example, metal 205 in particle form promotes heterogeneous nucleation of the bottom layer and homoepitaxial tip growth of the top layer via a gas-liquid-solid (VLS) mechanism, wherein the width of the top layer can be controlled by the particle diameter of the metal particles. In this example, both the bottom and top layers are or include metal dichalcogenides.

[0079] The reactants used in operation 320 include a first precursor 206 and a second precursor 222. The first precursor includes Mo, W, or combinations thereof (e.g., metal oxides), and the second precursor includes S, Se, Te, or combinations thereof. At least one of the plurality of TMD layers formed includes Mo, W, or combinations thereof, and S, Se, Te, or combinations thereof. In some examples, the formed bilayer structure includes a top layer and a bottom layer, the top layer comprising a transition metal dichalcogenide, and the bottom layer comprising a transition metal dichalcogenide.

[0080] As an example of operation 320, substrate 201 is positioned above first tray 203. First tray 203, wherein salt 204, metal 205, and first precursor 206 are disposed, can be heated at a first temperature (T1), and second tray 224, wherein second precursor 222 is disposed, can be heated at a second temperature (T2) to deposit salt 204 (e.g., NaBr), metal 205 (e.g., Ni), first precursor 206 (such as metal oxides, such as MoO2 powder), and second precursor 222 (e.g., chalcogens, such as sulfur powder) onto substrate 201. Second tray 224 may be located in device 200 upstream of first tray 203 relative to the flow of carrier gas and / or water through inlet 220. Depending on some aspects, heating may be performed using heating mechanisms, for example, using one or more heating wires 211a above and / or below first tray 203, and one or more heating wires 211b above and / or below second tray 224, such as in an oven or other suitable apparatus known in the art. After an appropriate period of time, a multilayer structure is formed on the substrate.

[0081] During operation 320, the second tray 224 is heated to a second temperature T2 by a carrier gas (e.g., a non-reactive gas) stream, a carrier gas and water (H2O) stream, or a combination thereof. The carrier gas, carrier gas and H2O, or both, flow through inlet 220.

[0082] According to some aspects, the first temperature T1 can be from about 600°C to about 900°C, such as from about 650°C to about 850°C, such as from about 700°C to about 800°C, such as from about 740°C to about 800°C, such as from about 750°C, or about 770°C. According to at least one aspect, the first temperature can be achieved by increasing the temperature, for example, by increasing the temperature from room temperature to the first temperature. For example, according to some aspects, the first temperature can be achieved by increasing the temperature from room temperature to the first temperature at a rate of about 10°C / min to about 70°C / min, such as from about 20°C / min to about 40°C / min. As used herein, the term "room temperature" means a temperature of about 15°C to about 25°C. In some aspects, the second temperature T2 is from about 50°C to about 350°C, such as from 100°C to about 300°C, such as from about 150°C to about 250°C, such as from about 175°C to about 225°C. Alternatively, according to some aspects, the second temperature may be from about 250°C to about 650°C, such as from about 300°C to about 600°C, such as from about 350°C to about 550°C, such as about 450°C. According to at least one aspect, the second temperature can be achieved by increasing the temperature, for example, by increasing the temperature from room temperature to the second temperature. For example, according to some aspects, the second temperature can be achieved by increasing the temperature from room temperature to the second temperature at a rate of about 10°C / minute to about 70°C / minute, such as from about 20°C / minute to about 40°C / minute.

[0083] In at least one aspect, the time period for depositing the multilayer structure in operation 320 is about 1 minute or longer and / or about 10 hours or shorter, such as about 1 minute to about 1 hour, such as about 1 to about 30 minutes, such as about 1 to about 15 minutes, such as about 3 to 15 minutes.

[0084] During operation 320, depending on some aspects, a carrier gas, a mixture of carrier gas and water, or both, flows into the reaction chamber through the aforementioned inlet 220. The H2O concentration (FR) in the carrier gas and water mixture... C+H2O The concentration of H2O can be about 100 ppm or higher and / or about 5,000 ppm or lower, such as about 250 ppm to about 4,000 ppm, such as about 500 ppm to about 3,000 ppm, such as about 1,000 ppm to about 2,500 ppm, such as about 1,500 ppm to about 2,000 ppm. The H2O concentration can be adjusted by changing the flow rate of the carrier gas (FR). C ), the flow rates of carrier gas and water (FR) C+H2O Controlled by flow rate ratios of ) and / or the following:

[0085] FR C+H2O / (FR C +FR C+H2O )

[0086] In some respects, the flow rate is higher than FR. C / (FRC +FR C+H2O The ratio is approximately 0.01:1 to approximately 0.5:1, such as approximately 0.05:1 to approximately 0.25:1, such as approximately 0.1:1 to approximately 0.2:1.

[0087] Operation 320 may include one or more of the following parameters:

[0088] (a) For 1×1cm 2 Up to 5×5cm 2 Substrate size, carrier gas flow rate (FR) C It can be from about 10 sccm to about 100 sccm, such as from about 40 sccm to about 80 sccm.

[0089] (b) For 1×1cm 2 Up to 5×5cm 2 Substrate of a certain size, carrier gas + H2O (FR) C+H2O The flow rate can be from about 1 sccm to about 100 sccm, such as from about 10 sccm to about 40 sccm.

[0090] (c) The weight ratio of salt 204 to the first precursor 206 may be from about 0.01:1 to about 1:1, such as from about 0.05:1 to about 1:1, such as from about 0.1:1 to about 1:1.

[0091] (d) The weight ratio of metal 205 to first precursor 206 may be from about 0.02:1 to about 1:1, such as from about 0.05:1 to about 1:1, such as from about 0.1:1 to about 1:1, such as from about 0.2:1 to about 1:1.

[0092] (e) The weight ratio of the first precursor 206 to the second precursor 222 may be from about 1:1 to about 200:1, such as from about 20:1 to about 150:1, such as from about 50:1 to about 100:1.

[0093] Process 300 also includes transforming at least a portion (e.g., the bottom layer 415) of the bilayer structure 400 into a removable portion 445 (e.g., an etchable portion, such as an oxidized portion) in operation 330. The removable portion 445 of the bottom layer may be a metal oxide. The transformation in operation 330 can be performed by subjecting at least a portion of the bottom layer 415 to ultraviolet-ozone (UVO) treatment.

[0094] In some non-limiting examples, the UVO treatment may include placing a bilayer structure 400 in a UVO cleaner with UV light. A substrate on which the bilayer structure 400 is deposited (e.g., by a CVD process as described herein) may be placed in the UVO cleaner at a distance from the UV light, such that the bilayer structure 400 is provided with sufficient UVO intensity to oxidize the desired portion (e.g., the bottom layer 415). According to some aspects, the distance between the UV light and the desired portion of the bilayer structure 400 may be from about 0.1 cm to about 5 cm, such as from about 0.5 cm to 3.2 cm. According to some aspects, the UVO treatment may be performed at a temperature of about 20°C to about 200°C for about 5 minutes to 2 hours, and optionally for about 8 minutes to 1 hour.

[0095] Figure 4C and Figure 4D Top and cross-sectional views of the multilayer structure 440 formed by operation 330 are shown respectively. For example, when the bottom layer 415 is MoS2, at least a portion of the MoS2 in the bottom layer 415 can be converted to MoO3 by treatment with ozone and UV light, while the top layer 420 containing MoS2 remains unchanged or substantially unchanged. For example, the exposed portion 425 of the bottom layer 415 is oxidized.

[0096] Process 300 also includes removing at least a portion (e.g., oxidized portion of MoO3) of the removable portion 445 of the bottom layer 415 in operation 340. Figure 4E and Figure 4F Top and cross-sectional views of the structure 450 after the removal process of operation 340 are shown respectively. In one example, the top layer MoS2 420 and the unexposed portion 430 (e.g., the unoxidized layer MoS2) are the aforementioned bilayer structure 100.

[0097] Removing at least a portion of the removable portion 445 may include etching the multilayer structure 440 such that the top layer MoS2420 remains unchanged or substantially unchanged. Etching refers to any suitable subtractive manufacturing process in which one or more substances are removed from a surface using an etchant. According to some aspects, etching may include subjecting the multilayer structure 440 to an etching treatment sufficient to separate the oxidized portions of the multilayer structure 440 from its remaining portions (e.g., unoxidized portions). After etching, a rinsing operation may be performed, for example, with water, to remove any residual etchant.

[0098] Etching can be performed by subjecting the multilayer structure 440 to an etchant through immersion, soaking, or other means. The etchant may include hydroxides, such as potassium hydroxide (KOH), lithium hydroxide, sodium hydroxide (NaOH), or combinations thereof. The etchant may be provided in the form of a solution, such as an aqueous solution. In some aspects, the hydroxide concentration of the etchant may be from about 0.1M to about 10M, such as from about 0.5M to about 2M, such as from about 0.75M to about 1.5M, such as from about 1M to about 1.25M.

[0099] In an illustrative but non-limiting example, the etching process may include immersing a multilayer structure having at least one oxidized portion (e.g., removable portion 445) in a hydroxide solution for a sufficient time to remove the oxidized portion. This time may be, for example, about 1 hour or less, such as about 30 minutes or less, such as about 5 minutes or less, such as about 1 minute or less, such as about 1 second to about 1 minute, such as about 10 seconds to about 30 seconds.

[0100] In some respects, and as Figure 4G and Figure 4H As shown, operation 330 may additionally or alternatively include oxidizing at least a portion of the bottom layer 415 and at least a portion of the top layer 420. Oxidation, such as UVO treatment, forms a multilayer structure 470, which includes an oxidized top layer 472 and oxidized portions of the bottom layer (e.g., removable portions 475). As an example, when the bottom layer 415 and the top layer 420 are MoS2, portions of the top layer 420 and the bottom layer 415 are converted to MoO3. The UVO treatment has been described above.

[0101] In these and other aspects, and such as Figure 4I and Figure 4J As shown, operation 340 may additionally or alternatively include removing at least a portion of the removable portion 475 and removing at least a portion of the oxide top layer 472 to form structure 480. Structure 480 includes unexposed portions 430, such as a monolayer of metal dichalcogenide, like a monolayer MoS2 nanoribbon, disposed above substrate 405. As an example, the oxide portions (e.g., MoO3) of the top layer MoO3 and the bottom layer may include etching, such that the MoO3 portions of the top and bottom layers are removed. Removal operations such as etching and optional cleaning operations have been discussed above.

[0102] It should be understood that although processes for directly growing patterned MoS2 bilayer structures include using molybdenum dioxide (MoO2) as a first precursor 206 or using metal oxides and sulfur (S) as a second precursor 222, various bilayer structures can be prepared according to the processes described herein. For example, according to some aspects, bilayer structures may include tungsten disulfide (WS2) and / or molybdenum diselenide (MoSe2) by using tungsten dioxide (WO2) and / or tungsten trioxide (WO3) as described herein as a first precursor 206 and / or by using selenium (Se) as a second precursor 222. Other suitable precursors may be used to form metal dichalcogenides represented by the formula ME2.

[0103] equipment

[0104] This disclosure also relates to devices, such as quantum devices, that incorporate a bilayer structure produced by the process described herein. The devices may be characterized as electronic and / or optoelectronic devices. Figure 5 An exemplary device 500 incorporating a dual-layer structure according to at least one aspect of the present disclosure is shown. For example, device 500 may include a substrate 502 and a dual-layer structure 504 positioned thereon. Dual-layer structure 504 may be represented by dual-layer structure 100, or by structure 450 when the dual-layer structure is disposed over at least a portion of the substrate.

[0105] Device 500 may also include components (such as source electrode 506) for introducing current through the double-layer structure 504, a gate electrode 508 (e.g., a back gate electrode) for supplying potential or charge to source electrode 506, and a drain electrode 510 for receiving current from source electrode 506 based on the charge supplied to source electrode 506. The channel 512 between source electrode 506 and drain electrode 510 may have a length of about 1 μm or less, such as about 500 nm or less, such as about 50 nm to about 450 nm, such as about 100 nm to about 400 nm, such as about 150 nm to about 350 nm, such as about 200 nm to about 300 nm. Source electrode 506 and drain electrode 510 may be independently made of or include any suitable material such as graphene, glassy carbon, copper, nickel, silver, aluminum, gold, platinum, palladium, bismuth, or combinations thereof. The gate electrode 508 may be made of or include any suitable material such as highly doped silicon, graphene, carbon nanotubes, or combinations thereof.

[0106] In some examples, device 500 may operate as a field-effect transistor (FET) (such as a back-gate field-effect transistor (BG-FET)) or otherwise include a field-effect transistor. A BG-FET is a type of transistor that uses an electric field to control the flow of current through at least three terminals or electrodes (gate, source, and drain). In operation, a voltage (V0) may be applied to the back gate electrode. BG This alters the conductivity between the drain and source electrodes. A drain-source voltage (V) can be applied. DS This can be used to generate current, for example, between the source and drain electrodes. Manipulation of various voltages and currents allows electrons to move through various components of the device.

[0107] The process of using equipment

[0108] This disclosure also generally relates to devices (e.g., device 500) incorporating the dual-layer structure described herein. Such devices have applications in, for example, sensors, bioimaging, batteries, electrochemical water splitting, wastewater treatment, supercapacitors, photodetectors, and optoelectronic applications. The devices can operate at temperatures above the prior art, for example, above about 1K, such as about 4K to about 100K, such as about 4K to about 80K, such as about 4K to about 60K.

[0109] In some respects, devices (e.g., device 500) can be used to control electrons, such as controlling spin, charge, or both. Here, and in some respects, a voltage can be applied to the gate electrode to modulate the energy levels of the MoS2 nanoribbon, thereby allowing or preventing electrons from tunneling from the source electrode into the nanoribbon and / or from the nanoribbon out to the drain electrode.

[0110] In at least one aspect, the process using device 500 includes cooling the device to a temperature of about 1K or higher, such as about 4K to about 100K, such as about 4K to about 80K, such as about 4K to about 60K. The process also includes applying a voltage to a gate electrode (e.g., gate electrode 508). The voltage applied to the gate electrode may be about -80V to about 80V, such as about -60V to about 60V, such as about -40V to about 40V, such as about -20V to about 20V. In at least one aspect, the voltage applied to the gate electrode is about -80V to 0V, such as about -70V to about -10V, such as about -60V to about -20V, such as about -50V to about -30V. In another aspect, the voltage applied to the gate electrode is about 0V to about 80V, such as about 10V to about 70V, such as about 20V to about 60V, such as about 30V to about 50V. A source-drain bias voltage (e.g., about 50 mV or lower, such as about 10 mV to about 50 mV, or about 20 mV to about 40 mV) may also be applied. The voltage applied to the gate electrode controls the flow of electrons between one or more of the source electrode 506, the drain electrode 510, the bottom layer of the bilayer structure (e.g., bottom layer 105), and / or the top layer of the bilayer structure (e.g., top layer 110). The voltage applied to the gate electrode may also modulate the energy levels of the bilayer structure to allow and / or prevent electrons from tunneling from the source electrode into a portion of the bilayer structure and / or from a portion of the bilayer structure out to the drain electrode. In some aspects, a magnetic field may be applied to the device to control the spin of electrons. The applied magnetic field may be about 1 T to about 14 T, such as about 2 T to about 12 T, such as about 4 T to about 10 T, or such as about 6 T to about 8 T.

[0111] The following embodiments are provided to provide a complete disclosure and description of how to prepare and use various aspects of this disclosure for those skilled in the art, and are not intended to limit the scope of the aspects of this disclosure. Efforts have been made to ensure the accuracy of the numbers used (e.g., quantities, dimensions, etc.), but some experimental errors and biases should be taken into account.

[0112] Example

[0113] 1. Characterization

[0114] Using QUANTA from FEI TMThe synthesized MoS2 bands were characterized using a FEG 650 scanning electron microscope (SEM) operated at 10 kV. High-angle annular dark-field scanning transmission electron microscopy (HAADF-STEM) images were acquired using a Nion UltraSTEM equipped with a probe aberration corrector (convergence angle of 31 mrad) operated at 60 kV. Atomic force microscopy was performed using a Bruker Dimension Icon atomic force microscope. The interlayer twist angle was determined from the HAADF-STEM images by fast Fourier transform.

[0115] Samples for HAADF-STEM characterization were prepared using a wet transfer process. First, poly(methyl methacrylate) (PMMA) 495A4 (MicroChem) was spin-coated onto a monolayer SiO2 / Si substrate at 3500 rpm for 60 seconds. The PMMA-coated substrate was then floated on a 1M KOH solution, which etched the silicon dioxide epitaxial layer, causing the PMMA film and bands to float on the solution surface. The film was rinsed several times in deionized water to remove residual KOH. The cleaned film was then scooped onto a 20 nm thick QUANTIFOIL porous carbon film (~2 μm pore size) supported by a 200-mesh Au TEM grid, and subsequently immersed in acetone for 12 hours to remove PMMA and obtain a clean sample surface. Finally, the transferred sample was annealed in vacuum at 200 °C to remove the solvent.

[0116] 2. Exemplary two-layer synthesis

[0117] MoS2 bands were synthesized by CVD in a tube furnace system equipped with a 1” quartz tube. In the experimental setup, two separate carrier gas (e.g., Ar) lines were connected to the tube furnace. One line carried out the gas at a predetermined flow rate (referred to as FR). Ar One line enters directly into the reaction chamber, while another line passes through a small bubbler containing approximately 2 ml of deionized water to generate humidified Ar. This is done at a specific flow rate (referred to as FR). Ar+H2O The humidified Ar is then fed into the reaction. Therefore, the moisture content in the humidified Ar carrier gas can be adjusted by changing the ratio FR. Ar+H2O / (FR Ar +FR Ar+H2O It is controlled by a dew point hygrometer (Easidew Online, Rotronic Instrument Corp.) installed near the inlet of the reaction chamber and measured by a dew point hygrometer.

[0118] In an exemplary growth run, a mixture of ~1.5 mg of MoO2 + NaBr + Ni was heated to ~770°C at a specific weight ratio of 1:0.05:0.1, while ~0.1 g of S, placed upstream of the MoO2, was heated to 200°C. The gas flow rate ratio FR... Ar+H2O / (FR Ar +FR Ar+H2O The percentage is ~10%, for example, FR 72 sccm. Ar With 8sccm FR Ar+H2O This indicates a moisture content of approximately 3000 ppm, as measured by a dew point transmitter installed at the gas inlet of the tube. A 285 nm SiO2 / Si substrate cleaned with acetone and isopropanol was used as the growth substrate, placed face down on top of the precursor. The typical growth time at approximately 770 °C was approximately 3 minutes. The grown strip was treated with UV-ozone (Jelight Company Inc.) in air at approximately room temperature for approximately 8 minutes, then immersed in a 1 M KOH solution for approximately 10 seconds, and rinsed in deionized water to remove residual KOH.

[0119] 3. Exemplary device manufacturing and electrical performance measurement.

[0120] Electron beam lithography patterning was performed using a Nanobeam n64 electron beam writing system, with the electron beam operating at an accelerating voltage of 80 kV. In the Angstrom EvoVac deposition system, a Ti / Au metal electrode (10 nm / 50 nm) was deposited on top of a MoS2 nanoribbon, with a deposition vacuum level below 5 × 10⁻⁶ kV. –7 Torr. Transfer measurements under variable temperatures were performed in a CTI-Cryogenics Model 22 refrigerator using a Keysight B1500A semiconductor device parameter analyzer.

[0121] 4. Exemplary stacking construction

[0122] The stacked construction of a two-layer structure was studied. Figures 6A to 6C Exemplary HAADF-STEM images of two-layer structures in various stacked configurations are shown. Specifically, Figure 6A The double-layer structure of AA'(2H) stacking is shown. Figure 6B The double-layer AB(3R) stacked structure is shown. Figure 6C A double-layered, twisted stacked structure is shown. Based on the corresponding HAADF-STEM image ( Figure 6C FFT pattern of ) Figure 6D The interlayer twist angle was determined to be approximately 10°.

[0123] 5. Electrical performance of an exemplary bilayer MoS2 nanoribbon-based FET device

[0124] To investigate the electrical properties of bilayer MoS2 nanoribbons, a back-gate field-effect transistor (BG-FET) using Ti / Au as the source and drain electrodes was fabricated. Figure 7 An exemplary SEM image of a device incorporating bilayer MoS2 nanoribbons 702 is shown, in which the source electrode and drain electrode 704 are separated by different channel lengths.

[0125] Figure 8A Exemplary transfer curves for a ~8 nm wide nanoribbon, measured at temperatures of 15 K and 300 K, are shown, where the transfer curves are relative to the back gate voltage (V0). BG The drain-source current (I) was plotted. DS The channel length, such as the length between the source and drain electrodes, is approximately 400 nm. The device incorporates an 8 nm wide bilayer MoS2 nanoribbon. For this example, a 100 mV bias voltage was applied to the device. Data indicate that the device exhibits typical n-type behavior, with an on / off ratio of approximately 10. 4 .

[0126] Figure 8B Exemplary output characteristics of the same device are shown at varying back-gate voltages of 300K (solid line) and 15K (dashed line), where the output characteristics are relative to the drain-source voltage (V0). DS The drain-source current (I) was plotted. DS The channel length of the device is approximately 400 nm. Even at 15 K, the linear output curve indicates that Ti / Au has very good ohmic contact on the nanoribbon.

[0127] Figure 8C Exemplary transfer curves for BG-FETs on bilayer MoS2 nanoribbons with different widths (approximately 8 nm, approximately 20 nm, approximately 50 nm, and approximately 420 nm) at temperatures up to ~15 K are shown, where the transfer curves are relative to the back gate voltage (V0). BG The drain-source current (I) was plotted. DS The channel length between the source and drain electrodes of each device is approximately 200 nm. For this example, a bias voltage of 30 mV is applied to each BG-FET device. For nanoribbons with a width of approximately 8 nm and approximately 20 nm, significant periodic oscillations in the drain-source current as a function of the back gate voltage are observed at a drain-source bias voltage of 30 mV. This periodic oscillation in the transfer curve indicates the quantum dot behavior of the nanoribbons, where the periodic oscillations can be attributed to single-electron transitions due to Coulomb blocking.

[0128] Figure 8DAn exemplary transfer curve for a BG-FET incorporating a ~20 nm wide bilayer MoS2 nanoribbon, with a channel length of ~200 nm between the source and drain electrodes, is shown, illustrating temperature-dependent Coulomb blocking oscillations, where the vertical dashed line indicates periodic oscillation peaks. Significant periodic oscillations of the drain-source current as a function of the back gate voltage are observed at a drain-source bias of 30 mV. This data indicates that Coulomb blocking oscillations are observable at temperatures ranging from approximately 15 K to approximately 60 K. Notably, Coulomb blocking oscillations in the TMD structure are only observed at temperatures below 4 K. Therefore, this data demonstrates that the bilayer structure described herein operates at much higher temperatures compared to conventional TMD structures.

[0129] Figure 9A and Figure 9B Two exemplary BG-FET devices are shown as drain-source voltages (V) at 15K. DS ) and back gate voltage (V BG The conductivity graphs of the functions of the two exemplary BG-FET devices are shown. The two devices combine a ~8nm wide bilayer MoS2 nanoribbon with channel lengths of 100nm and 200nm between the source and drain electrodes, respectively. Figure 9A and Figure 9B The vertical dashed line in the image highlights the Coulomb blocking rhombus. Figure 9A and Figure 9B The data were determined by measuring the transfer curves with varying source-drain voltages and plotting two-dimensional conductivity diagrams. The data revealed the quantum dot behavior of the bilayer nanoribbon. Coulomb diamonds of different sizes exhibited different quantum dot behaviors, such as charging energy and effective capacitance, at different channel lengths.

[0130] In summary, the results demonstrate that the quantum dot behavior in bilayer TMD nanoribbons can be controlled, for example, by adjusting the width of the nanoribbons and the length of the channel. The data also show that quantum phenomena are observed in bilayer TMD nanoribbons at high temperatures.

[0131] 6. Exemplary single-layer synthesis

[0132] Monolayer MoS2 strips were synthesized via CVD in a tube furnace system equipped with a 1” quartz tube. In the experimental setup, two separate carrier gas (e.g., Ar) lines were connected to the tube furnace. One line operated at a predetermined flow rate (referred to as FR). Ar One line enters directly into the reaction chamber, while another line passes through a small bubbler containing approximately 2 ml of deionized water to generate humidified Ar. This is done at a specific flow rate (referred to as FR). Ar+H2O The humidified Ar is then fed into the reaction. Therefore, the moisture content in the humidified Ar carrier gas can be adjusted by changing the ratio FR. Ar+H2O / (FRAr +FR Ar+H2O The temperature is controlled by a dew point hygrometer (Easidew Online, Rotronic Instrument Corp.) installed near the inlet of the reaction chamber. In an exemplary growth run, ~1.5 mg of a MoO2 + NaBr + Ni mixture is heated to ~770°C at a specific weight ratio of 1:0.05:0.1, while ~0.1 g of S, placed upstream of the MoO2, is heated to 200°C. The gas flow rate ratio FR... Ar+H2O / (FR Ar +FR Ar+H2O The percentage is ~10%, for example, FR 72 sccm. Ar With 8sccm FR Ar+H2O This indicates a moisture content of ~3000 ppm, as measured by a dew point transmitter installed at the gas inlet of the tube. A 285 nm SiO2 / Si substrate cleaned with acetone and isopropanol was used as the growth substrate, placed face down on top of the precursor. The typical growth time at ~770 °C was ~3 minutes.

[0133] The grown strips were treated in air at approximately room temperature with UV-ozone (Jelight Company Inc.), then soaked in a KOH solution, and washed in deionized water to remove residual KOH. Figures 10A to 10C These are exemplary HAADF-STEM images showing monolayer MoS2 nanoribbons formed at various resolutions. Specifically, Figure 10A This is a low-magnification view (scale: 5nm). Figure 10B and Figure 10C It is by Figure 10A The box in the image indicates an atomic resolution view (scale: 1 nm) of a portion of MoS2. This data indicates the formation of a monolayer of MoS2.

[0134] 7. Exemplary Formation of Twisted Bilayer Nanoribbons

[0135] Figure 11A schematic diagram of an exemplary process for forming twisted bilayer nanoribbons according to some embodiments is shown. In operation 1110, a monolayer nanoribbon 1118 picked up by a poly(methyl methacrylate) (PMMA) film 1116 is placed above a substrate 1112 on which a monolayer nanoribbon 1114 is disposed. The PMMA film 1116 is positioned parallel or substantially parallel to the substrate, such that the monolayer nanoribbon 1114 and the monolayer nanoribbon 1118 are parallel or substantially parallel, as observed by an optical microscope. The PMMA film 1116 on which the monolayer nanoribbons are disposed can be formed by spin-coating PMMA (e.g., PMMA495A4) onto a substrate such as a SiO2 substrate having a monolayer crystal at ~3500 rpm for ~60 seconds. The PMMA-coated substrate is then floated on a ~1M KOH solution that etches a silicon dioxide epitaxial layer, causing the PMMA film 1116 and the monolayer nanoribbon 1118 to float on the solution surface. The membrane was washed several times in deionized water to remove residual KOH.

[0136] In operation 1120, a PMMA film 1116 on which a monolayer nanoribbons 1118 are disposed is rotated by a certain amount, for example, greater than about 0° and less than about 180°. Larger or smaller angles are conceivable. After selecting the desired angle, in operation 1130, the PMMA film 1116 on which the monolayer nanoribbons 1118 are disposed is then stacked on a substrate 1112 on which a monolayer nanoribbons 1114 are disposed. Then in operation 1140, the PMMA film 1116 is removed using a suitable solvent such as acetone for about 5 to 24 hours to obtain a twisted bilayer nanoribbon 1122. Figure 12 This is an exemplary SEM image showing an example of twisted stacked bilayer MoS2 nanoribbons. The SEM image indicates that twisted bilayer nanoribbons can be formed.

[0137] Aspect List

[0138] Among other things, this disclosure also provides for aspects in which each may be considered to optionally include any other aspects:

[0139] Clause 1. An apparatus comprising:

[0140] Gate electrode;

[0141] A substrate disposed above at least a portion of the gate electrode;

[0142] The bottom layer includes a first metal dichalcogenide, and the bottom layer is disposed above at least a portion of the substrate;

[0143] The top layer, comprising a second metal dichalcogenide, is disposed above at least a portion of the bottom layer, wherein the first metal dichalcogenide and the second metal dichalcogenide may be the same or different; and

[0144] A source electrode and a drain electrode are disposed above at least a portion of the top layer.

[0145] Clause 1. The equipment as described in Clause 1, wherein:

[0146] As measured by scanning electron microscopy, the sublayer has a width of approximately 30 nm or less;

[0147] As measured by scanning electron microscopy, the top layer has a width of approximately 30 nm or less; or

[0148] It has both of these characteristics.

[0149] Clause 3. The equipment described in Clause 1 or Clause 2, wherein:

[0150] The width of the underlying layer is approximately 20 nm or less;

[0151] The width of the underlying layer is approximately 20 nm or less; or

[0152] It has both of these characteristics.

[0153] Clause 4. The equipment according to any one of Clauses 1 to 3, wherein:

[0154] The bottom layer is in the form of a single nanoribbon;

[0155] The top layer is in the form of a single nanoribbon; or

[0156] Their combination.

[0157] Clause 5. The equipment as described in Clause 4, wherein:

[0158] When the underlying layer is in the form of a single nanoribbon, at least a portion of the single nanoribbon of the underlying layer has a substantially uniform edge structure as determined by HAADF-STEM;

[0159] When the top layer is in the form of a single nanoribbon, at least a portion of the single nanoribbon in the top layer has a substantially uniform edge structure as determined by HAADF-STEM; or

[0160] Their combination.

[0161] Clause 6. The device according to Clause 5, wherein the substantially uniform edge configuration includes, for example, a serrated edge, an armchair edge, or a combination thereof as determined by HAADF-STEM.

[0162] Clause 7. The device according to any one of Clauses 1 to 6, wherein the stacking configuration of the bottom layer and the top layer is an AA'(2H) stacking configuration, an AB(3R) stacking configuration, or a twisted stacking configuration or a combination thereof as determined by HAADF-STEM.

[0163] Clause 8. The device according to Clause 7, wherein, as determined by fast Fourier transform from a HAADF-STEM image, when the stacked configuration includes a twisted stacked configuration, the interlayer twist angle between the bottom layer and the top layer is from about 1° to about 20°.

[0164] Clause 9. The device according to any one of Clauses 1 to 8, wherein the distance between the source electrode and the drain electrode is about 1 μm or less.

[0165] Clause 10. The device as described in Clause 9, wherein the distance is approximately 500 nm or less.

[0166] Clause 11. The device according to any one of Clauses 1 to 10, wherein the first metal disulfide and the second metal disulfide are the same.

[0167] Clause 12. The equipment according to any one of Clauses 1 to 11, wherein:

[0168] The first metal dichalcogenide includes MoS2, MoSe2, MoTe2, WS2, WSe2, WTe2, or combinations thereof;

[0169] The second metal dichalcogenide includes MoS2, MoSe2, MoTe2, WS2, WSe2, WTe2, or combinations thereof; or

[0170] It has both of these characteristics.

[0171] Clause 13. The device according to any one of Clauses 1 to 12, wherein the first metal dichalcogenide, the second metal dichalcogenide, or both comprise Mo.

[0172] Clause 14. The device according to any one of Clauses 1 to 13, wherein the first metal dichalcogenide, the second metal dichalcogenide, or both comprise MoS2.

[0173] Clause 15. A method comprising:

[0174] Positioning the substrate within the chamber; and

[0175] A multilayer structure is formed by thermally depositing salt, metal particles, a first precursor comprising Mo, W, or combinations thereof, and a second precursor comprising S, Se, Te, or combinations thereof on the substrate, the multilayer structure comprising:

[0176] A bottom layer, the bottom layer being disposed over at least a portion of the substrate, the bottom layer comprising a first metal dichalcogenide; and

[0177] The top layer is disposed above at least a portion of the bottom layer, and the top layer includes a second metal dichalcogenide.

[0178] Clause 16. The method as described in Clause 15, wherein the metal particles are located at one end of the top layer.

[0179] Clause 17. The methods described pursuant to Clause 15 or Clause 16 further include:

[0180] Transforming the exposed portion of the underlying layer into an oxidized portion; and

[0181] Remove the oxidized portion of the underlying layer.

[0182] Clause 18. The method according to any one of Clauses 15 to 17 further includes allowing water and carrier gas to flow into the chamber while depositing the multilayer structure.

[0183] Clause 19. A method comprising:

[0184] The device according to any one of clauses 1 to 14 is cooled at a temperature of about 1 K to about 80 K;

[0185] A voltage is applied to the gate electrode to control the electron flow between one or more of the source electrode, the drain electrode, the bottom layer, or the top layer.

[0186] Clause 20. The method according to Clause 19, wherein a magnetic field is applied to the device to control the spin of the electrons.

[0187] This document describes various aspects relating to bilayer metal dichalcogenides (MTDs), methods for forming MMDs, and their applications in quantum electronic devices (e.g., quantum computing, quantum sensing, and quantum communication). MMDs can take the form of nanoribbons, such as bilayer TMD nanoribbons, and can be formed with controllable widths using metal microparticles. The metal microparticles can play a dual role via a VLS growth mechanism, for example, promoting heterogeneous nucleation of the bottom layer and nucleation and homoepitaxial growth of the top layer, where the diameter of the metal microparticles defines the width of the layer. The nanoribbons can achieve quantum transport behavior at temperatures, for example, up to approximately 60 K. Bilayer TMD nanoribbons can be incorporated into devices such as FET devices.

[0188] It will be apparent from the foregoing general description and specific aspects that, while various forms have been illustrated and described, various modifications may be made without departing from the spirit and scope of this disclosure. Therefore, this disclosure is not intended to be limited thereto. Similarly, the term “comprising” is considered synonymous with the term “including.” Likewise, whenever the transitional phrase “comprising” precedes a composition, element, or group of elements, it should be understood that the same composition or group of elements is also contemplated to have the transitional phrases “consistently composed of,” “composed of,” “selected from,” or “is” preceding the detailed description of the composition or one or more elements, and vice versa; for example, the terms “comprising,” “consistently composed of,” and “composed of” also include the product of a combination of elements listed after that term.

[0189] For the purposes of this disclosure, and unless otherwise specified, all numerical values ​​in the detailed descriptions and claims herein are indicated by “about” or “approximately”, taking into account experimental errors and variations that would be expected by one of ordinary skill in the art. For the sake of brevity, only certain ranges are explicitly disclosed herein. However, a range beginning with any lower limit may be combined with any upper limit to enumerate ranges not explicitly enumerated, and a range beginning with any lower limit may be combined with any other lower limit to enumerate ranges not explicitly enumerated, and in the same manner, a range beginning with any upper limit may be combined with any other upper limit to enumerate ranges not explicitly enumerated. Furthermore, even if not explicitly enumerated, a range includes every point or individual value between its endpoints. Thus, each point or individual value may be used as its own lower or upper limit, combined with any other point or individual value or any other lower or upper limit, to enumerate ranges not explicitly enumerated.

[0190] As used herein, the indefinite article “a” or “an” shall mean “at least one” unless otherwise indicated by the contrary or by the context. For example, an aspect containing “a layer” includes aspects containing one, two or more layers, unless otherwise indicated by the contrary or by the context.

[0191] While the foregoing relates to aspects of this disclosure, other and further aspects of this disclosure may be designed without departing from the basic scope of the invention, the scope of which is defined by the appended claims.

Claims

1. A device, the device comprising: a gate electrode; a substrate disposed over at least a portion of the gate electrode; a bilayer structure, the bilayer structure comprising: a bottom layer comprising a first metal dichalcogenide, the bottom layer disposed over at least a portion of the substrate and having a width of 20 nm or less; a top layer comprising a second metal dichalcogenide, the top layer disposed over at least a portion of the bottom layer and having a width of 20 nm or less, the first metal dichalcogenide and the second metal dichalcogenide being the same or different; and a source electrode and a drain electrode disposed over at least a portion of the top layer.

2. The device of claim 1, wherein: the bottom layer is in the form of a single nanoribbon; the top layer is in the form of a single nanoribbon; or a combination thereof.

3. The device of claim 2, wherein: when the bottom layer is in the form of a single nanoribbon, at least a portion of the single nanoribbon of the bottom layer has a substantially uniform edge configuration as determined by HAADF-STEM; when the top layer is in the form of a single nanoribbon, at least a portion of the single nanoribbon of the top layer has a substantially uniform edge configuration as determined by HAADF-STEM; or a combination thereof. the substantially uniform edge configuration comprises a sawtooth edge, an armchair edge, or a combination thereof as determined by HAADF-STEM.

4. The apparatus of claim 3, wherein, the stacking configuration of the bottom layer and the top layer is an AA’(2H) stacking configuration, an AB(3R) stacking configuration, or a twisted stacking configuration, or a combination thereof as determined by HAADF-STEM.

5. The apparatus of claim 1, wherein, when the stacking configuration comprises a twisted stacking configuration, an interlayer twist angle between the bottom layer and the top layer as determined from a HAADF-STEM image by fast Fourier transform is from 1° to 20°.

6. The apparatus of claim 5, wherein, a distance between the source electrode and the drain electrode is 1 pm or less.

7. The apparatus of claim 1, wherein, the distance is 500 nm or less.

8. The apparatus of claim 7, wherein, the first metal dichalcogenide and the second metal dichalcogenide are the same.

9. The apparatus of claim 1, wherein, 10. The device of claim 1, wherein: the first metal dichalcogenide comprises MoS2, MoSe2, MoTe2, WS2, WSe2, WTe2, or a combination thereof; the second metal dichalcogenide comprises MoS2, MoSe2, MoTe2, WS2, WSe2, WTe2, or a combination thereof; or a combination thereof. the first metal dichalcogenide, the second metal dichalcogenide, or both comprise Mo.

11. The apparatus of claim 1, wherein, the first metal dichalcogenide, the second metal dichalcogenide, or both comprise MoS2.

12. The apparatus of claim 1, wherein, the device exhibits Coulomb blockade at 4K to 80K.

13. The apparatus of claim 1, wherein, 14. A method, the method comprising: positioning a substrate in a chamber; and thermally depositing a salt, metal particulates, a first precursor comprising Mo, W, or a combination thereof, and a second precursor comprising S, Se, Te, or a combination thereof on the substrate to form a multilayer structure, the multilayer structure comprising: ​ a bottom layer disposed over at least a portion of the substrate, the bottom layer comprising a first metal dichalcogenide and having a width of 20 nm or less; and a top layer disposed over at least a portion of the bottom layer, the top layer comprising a second metal dichalcogenide and having a width of 20 nm or less.

15. The method of claim 14, wherein, The metal particulate is located at one end of the top layer.

16. The method of claim 14, further comprising: converting an exposed portion of the bottom layer to an oxidized portion; and removing the oxidized portion of the bottom layer.

17. The method of claim 14, further comprising: Water and a carrier gas are flowed into the chamber while depositing the multilayer structure.

18. A method, comprising: cooling a device at a temperature of 1 K to 80 K, the device comprising: a gate electrode; a substrate disposed over at least a portion of the gate electrode; a bottom layer comprising a first metal dichalcogenide, the bottom layer disposed over at least a portion of the substrate and having a width of 20 nm or less; a top layer comprising a second metal dichalcogenide, the top layer disposed over at least a portion of the bottom layer and having a width of 20 nm or less, the first and second metal dichalcogenides being the same or different; and a source electrode and a drain electrode disposed over at least a portion of the top layer; and applying a voltage to the gate electrode to control electron flow between one or more of the source electrode, the drain electrode, the bottom layer, or the top layer.

19. The method of claim 18, wherein, applying a magnetic field to the device to control spin of the electrons.

20. The method of claim 18, wherein, Cooling a device comprises cooling the device to a temperature of 4 K to 80 K.

Images