Bias control based probabilistic bit device and method of making the same

Abstract

This invention relates to the field of probabilistic bit device technology, and particularly to a bias-controlled probabilistic bit device and its fabrication method. The probabilistic bit device comprises an electrode pair and probabilistic bit molecules connected between the electrode pairs. Its core framework consists of symmetrical or near-symmetrical ferrocene groups, with the two ferrocene units serving as equivalent redox active centers with similar redox potentials, laying the foundation for reversible state switching and uniform charge delocalization. The ferrocene units exhibit excellent chemical stability and exhibit no thermal degradation issues; the intermediate bridging group can regulate the electronic coupling strength, ensuring charge migration across sites while avoiding excessive coupling that could lead to steady-state merging. Results show that within a bias range of 260mV to 400mV, the probabilistic bit molecules can switch between reduced and mixed valence states, thereby achieving a transition in the proportion of high and low states in the device, ultimately constructing a stable and controllable bias-controlled probabilistic bit device.

Description

Technical Field

[0001] This invention relates to the field of probabilistic bit device technology, and in particular to a probabilistic bit device based on bias control and its fabrication method. Background Technology

[0002] Traditional computers use binary codes composed of 0s and 1s to represent information. Although traditional computers have evolved into complex and advanced devices, they still struggle with problems such as reasoning, reversible logic, sampling, and optimization. Probabilistic computing is conceptually similar to quantum computing. It uses probability bits as the basic unit of information, obtaining inputs from other probability bits and creating a weighted sum. Based on this weighted sum, the probability of the output can be obtained from the input. This computational method allows it to effectively solve some of the problems that plague classical computing. Furthermore, compared to qubits, probabilistic bits are not limited by conditions such as decoherence and low-temperature operation, and can operate stably at room temperature.

[0003] Currently, the mainstream probabilistic bits are mainly realized in two ways: one is by utilizing the random flipping of magnetic moments in a magnetic tunnel junction, and the other is by relying on spontaneous emission from a laser. The former is easier to integrate with traditional complementary metal-oxide-semiconductor (CMOS) processes to fabricate miniature devices; the latter has significant advantages in probabilistic bit generation rate and randomness quality. However, both methods currently face developmental bottlenecks: magnetic tunnel junctions rely on the flipping of magnetic moments to generate probabilistic bits, thus requiring precise control of current and magnetic fields to regulate the probability, resulting in a complex control system; while generating probabilistic bits via lasers requires sophisticated optical components and a large system architecture, leading to high costs.

[0004] Against this backdrop, single-molecule probabilistic bits, with their miniaturization potential and rich tunability, have gradually attracted widespread attention and are one of the important ways to break through the current bottlenecks in probabilistic computing. The advantages of single-molecule probabilistic bits are mainly reflected in two aspects: First, the jumping states of molecules originate from molecular-scale thermal fluctuations, quantum fluctuations, and conformational dynamics. These processes are essentially physically random processes, rather than probabilistic bits generated by deterministic algorithms, thus ensuring the high-quality randomness of the probabilistic bits; Second, as the smallest functional unit currently available, single-molecule devices require only extremely small current and voltage to drive a single molecule to jump states, and their power consumption is far lower than that of existing probabilistic bit systems. Despite these advantages, the development of single-molecule probabilistic bits still faces many challenges, among which the problems in coupling and integration are particularly prominent: First, the stability of single-molecule junctions is poor, making large-scale manufacturing difficult; second, the signal strength of single-molecule probabilistic bits is only at the nanoampere level, easily submerged by noise signals, resulting in significant difficulties in signal reading.

[0005] Therefore, there is an urgent need to develop a new type of probabilistic bit device. Summary of the Invention

[0006] The present invention aims to at least solve one of the technical problems existing in the related art. To this end, the first objective of the present invention is to provide a probabilistic bit device based on bias control; the second objective of the present invention is to provide a method for fabricating a probabilistic bit device based on bias control.

[0007] To achieve the first objective, the technical solution adopted by this invention is as follows: A probability bit device based on bias control includes an electrode pair and probability bit molecules, wherein the probability bit molecules are connected between the electrode pairs via ester bonds or amide bonds. The structural formula of the probability bit molecule is shown below: ; The bias voltage ranges from 260mV to 400mV.

[0008] The core of the probabilistic bit molecule is a symmetrical / near-symmetrical ferrocene group. The two ferrocene units are equivalent redox active centers with highly similar redox potentials, which provides the prerequisite for reversible state switching and uniform charge delocalization. The ferrocene units have strong chemical stability, fast redox kinetics at room temperature, and no thermal degradation issues. The intermediate bridging group precisely controls the electronic coupling strength between the two ferrocene units, ensuring that charges can migrate across sites while avoiding excessive coupling that could lead to steady-state merging.

[0009] In the absence of an external electric field, both ferrocene units are in a completely reduced state (electrically neutral), at which point the molecule has no additional mobile charge carriers. Electrons can only tunnel through the molecular framework, resulting in extremely low carrier density, which macroscopically manifests as a low-conductivity state. This state corresponds to the fundamental quiescent state of the probability qubits.

[0010] As shown below: ; When an external electric field (bias voltage) is applied, due to the near degeneracy of the redox potentials of the two ferrocene molecules, the molecule preferentially undergoes a reversible single-electron oxidation reaction rather than a multi-electron irreversible oxidation reaction. After losing one electron, a stable mixed-valence species is formed, with one ferrocene in the oxidized state and the other in the reduced state. The positive charge (hole) formed by the lost electron is no longer locally fixed, but achieves efficient delocalized resonance between the two ferrocene active centers through bridging groups. The reduced state and the mixed-valence state affect the molecular electron transport characteristics, corresponding to low-conductivity and high-conductivity states, respectively. Under low voltage conditions, the probability bit molecule is stable in the reduced state (manifesting as a low-conductivity state); as the bias voltage increases, the probability bit molecule begins to oxidize, and switching between the mixed state and the reduced state can occur; as the bias voltage continues to increase, the proportion of the mixed state increases, thereby increasing the proportion of the high-conductivity state, eventually achieving high-conductivity dominance and completing the transition from 0 to 1.

[0011] Furthermore, the electrode pair is a graphene point electrode pair.

[0012] Furthermore, a single probability bit molecule is connected between the electrode pairs.

[0013] Furthermore, the electrode pair is made of a single-layer graphene film.

[0014] Furthermore, the electrode pair is a nano-gap electrode pair.

[0015] To achieve the second objective, the technical solution adopted by this invention is as follows: A method for fabricating a bias-controlled probabilistic bit device, used to fabricate any of the bias-controlled probabilistic bit devices described above, includes the following steps: S100. Electrode pairs are fabricated on the substrate to obtain an electrode device; S200. The electrode device is immersed in an organic solution containing ferrocene group molecules, so that the ferrocene group molecules are connected between the electrode pairs to obtain a probability bit device based on bias control. The structural formula of the molecule containing the bisferrocene group is shown below: ; R1 and R2 are each independently selected from -OH or -NH2.

[0016] Further, in step S100, the material of the substrate is selected from silicon wafers.

[0017] Further, in step S100, the solvent of the organic solution is selected from pyridine.

[0018] Furthermore, the electrode pair is a terminally carboxylated graphene electrode.

[0019] Further, in step S200, R1 and R2 are both selected from -NH2, and the bisferrocene group molecules are connected between the electrode pairs through an amide condensation reaction.

[0020] Furthermore, the condensing agent for the amide condensation reaction is selected from 1-(3-dimethylaminopropyl)-3-ethylcarbodiimide hydrochloride.

[0021] The above-described one or more technical solutions in the embodiments of the present invention have at least one of the following technical effects: The present invention provides a bias-controlled probabilistic bit device, comprising an electrode pair and probabilistic bit molecules, wherein the probabilistic bit molecules are connected between the electrode pair via ester or amide bonds. The probabilistic bit molecules are selected from ferrocene-based functional molecules, with a symmetrical / near-symmetrical ferrocene group as their core skeleton. The two ferrocene units are equivalent redox active centers with highly similar redox potentials, providing a prerequisite for reversible state switching and uniform charge delocalization. The ferrocene units exhibit strong chemical stability and fast redox kinetics at room temperature, without thermal degradation issues. The intermediate bridging group precisely regulates the electronic coupling strength between the two ferrocene units, ensuring charge migration across sites while avoiding excessive coupling that could lead to steady-state merging. Detection results show that, with a bias increment of 20 mV, within the bias range of 260 mV to 400 mV, as the voltage increases, the probabilistic bit molecules switch between reduced and mixed valence states, resulting in a change in the proportion of high and low valence states in the device. This indicates that the voltage can regulate the strength of the current signal by controlling the molecular reduced state. Based on this, by adjusting the bias voltage, the probability of high and low states can be continuously controlled, thus successfully constructing a stable and controllable bias-controlled probability bit device.

[0022] Additional aspects and advantages of the invention will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention. Attached Figure Description

[0023] To more clearly illustrate the technical solutions in this invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of this invention. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0024] Figure 1 This is a schematic diagram of the probability bit device structure based on bias control provided in Embodiment 2 of the present invention.

[0025] Figure 2 This is the current-time (It) trajectory diagram of the probability bit device based on bias control provided in Embodiment 2 of the present invention.

[0026] Figure 3 This is a graph showing the proportion of conductivity states in the It curve provided in Embodiment 2 of the present invention.

[0027] Figure Labels 1. Electrode pair; 2. Probability bit molecule. Detailed Implementation

[0028] To make the objectives, technical solutions, and advantages of this invention clearer, the technical solutions of this invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of this invention. All other embodiments obtained by those skilled in the art based on the embodiments of this invention without creative effort are within the scope of protection of this invention. The following embodiments are used to illustrate this invention but should not be used to limit the scope of this invention.

[0029] In the following examples, unless otherwise specified, the experimental methods used are conventional methods, and the materials and reagents used are commercially available unless otherwise specified.

[0030] Example 1 A molecule containing a bisferrocene group was synthesized, with the structural formula shown below: ; The synthesis process is as follows: I. Synthesis of Compound 1 .

[0031] Under nitrogen protection, ferrocene (100 mg) and a magnetic stir bar were added to a dry Schlenk flask, and the gas was changed three times by evacuation and nitrogen purging. Then, anhydrous tetrahydrofuran (THF) (5 mL) was injected into the reaction flask, and magnetic stirring was started until the ferrocene was completely dissolved. The reaction flask was then placed in an ice-water bath at 0 °C to cool until the system temperature stabilized. Using a dry glass syringe, n-butyllithium (0.26 mL) was slowly added dropwise, controlling the dropping rate to ensure that the dropping process was completed within about 2 minutes. After the dropping was completed, the ice-water bath was removed, and the mixture was allowed to warm naturally to room temperature (about 25 °C) and the reaction was stirred for 1 hour. After the reaction was completed, the reaction flask was placed in an ice-water bath at 0 °C again to cool, and diethyl chloroformate (84 μL) was slowly added dropwise using a dry syringe. After the dropping was completed, the ice-water bath was removed, and the reaction solution was allowed to warm naturally. The mixture was brought to room temperature and stirred overnight (approximately 12-14 hours). After the reaction was complete, the reaction solution was slowly poured into a beaker containing ice water (20 mL) to terminate the reaction. Subsequently, the mixture was extracted with diethyl ether (3 × 15 mL). The organic phases obtained from the three extractions were combined, and the organic phase was washed once with 15 mL of saturated brine. The washed organic phase was dried with anhydrous sodium sulfate, allowed to stand for 30 min, and then filtered to remove the desiccant. The filtered organic phase was placed on a rotary evaporator, and the solvent was removed by rotary evaporation under reduced pressure to obtain the crude product. The crude product was purified by silica gel column chromatography (using a mixture of petroleum ether and ethyl acetate as the eluent, with an elution gradient of 10:1 to 5:1 v / v). The eluent fraction was collected, dried by rotary evaporation, and compound 1 was obtained. Its characterization data are shown below: 1 H NMR (500MHz, CDCl3): δ=3.78 (s, 1H), 3.66–3.58 (m, 2H), 3.38 (q, J=6.8, 4H), 1.16 (t, J=6.8, 6H); 13 C NMR (125MHz, CDCl3)): δ=173.11, 171.41, 163.96, 146.16, 78.87, 69.36, 69.28, 42.20, 32.00, 13.04; TOF-ESI (+) (m / z): C 15 H 13 FeNO 279.125.

[0032] II. Synthetic Compound 2 .

[0033] Take 120 mg of compound 1 prepared above and add it to a dry Schlenk flask. After repeating the evacuation and nitrogen purging operation three times, add 3 mL of anhydrous THF to the reaction flask and turn on magnetic stirring to completely dissolve compound 1. Then, add 72 μL of N,N,N',N'-tetramethylethylenediamine (TMEDA) using a dry syringe and continue stirring until the system is uniformly mixed. Place the reaction flask in a -78°C low-temperature bath and stir for 10 min to allow the system to cool fully to -78°C and maintain a stable temperature. Slowly add 0.34 mL of sec-butyllithium using a dry syringe, controlling the dropping rate (ensuring that the dropping process is completed within 3-5 min). After the dropping is completed, maintain the low-temperature condition of -78°C and continue stirring for 2 h.

[0034] In a separate dry container, add iodine (120 mg) and anhydrous THF (2 mL) to obtain an iodine THF solution. Slowly add this iodine solution dropwise to the reaction solution at -78°C using a dry syringe. After the addition is complete, allow the temperature to rise naturally to room temperature (approximately 25°C). Then, add saturated sodium thiosulfate aqueous solution (5 mL) to the reaction solution and stir until the brown color completely disappears. Next, extract the mixture with diethyl ether (3 × 15 mL). Combine the organic phases obtained from the three extractions, wash once with deionized water and once with saturated saline solution, then dry the organic phase with anhydrous sodium sulfate. After standing for 30 min, filter the solution. Place the filtered organic phase on a rotary evaporator and remove the solvent by rotary evaporation under reduced pressure to obtain the crude product. Purify the crude product using silica gel column chromatography (using a mixture of petroleum ether and ethyl acetate with a volume ratio of 20:1 to 10:1). Collect the eluent, evaporate the solvent, and obtain compound 2. Its characterization data are shown below: 1 H NMR (500MHz, CDCl3): δ=3.76 (dd, J=18.8, 1.0, 1H), 3.38 (q, J=6.8, 2H), 1.16 (t, J=6.8, 3H); 13 C NMR (125MHz, CDCl3): δ=173.60, 172.69, 159.08, 141.49, 83.33, 76.63, 55.56, 42.20, 13.04; TOF-ESI (+) (m / z): C 15 H 12 FeINO 405.2213.

[0035] III. Synthetic Compound 3 .

[0036] Add compound 2 (approximately 100 mg, 0.25 mmol) and hydrochloric acid (6 M, 2 mL) to a round-bottom flask, stir to mix thoroughly, and then heat under reflux for 3–4 hours, during which time the mixture is passed through a thin-layer chromatography (TLC) filter. Chromatography (TLC) was used to monitor the reaction progress until the starting material spot completely disappeared. After the reaction was completed, the reaction solution was cooled to room temperature (approximately 25°C), and extracted with ethyl acetate (3 × 10 mL). The organic phases obtained from the three extractions were combined, and the organic phases were washed with deionized water until the aqueous phase was neutral. The washed organic phase was dried with anhydrous sodium sulfate, allowed to stand for 30 min, filtered, and the solvent was removed by rotary evaporation to obtain an orange solid product. The orange solid product was dissolved in anhydrous dichloromethane (1 mL), and then 2 drops of N,N-dimethylformamide were added dropwise as a catalyst. After stirring evenly, thionyl chloride (50 μL, 0.7 mmol) was slowly added dropwise. After the addition was completed, the reaction was stirred at room temperature (approximately 25°C) for 2 h. After the reaction was completed, the solvent was removed by rotary evaporation under reduced pressure to obtain an acyl chloride intermediate. The acyl chloride intermediate was dissolved in acetone (1.5 mL) to obtain an acyl chloride intermediate acetone solution. The solution was placed in an ice-water bath and cooled until the system temperature stabilized.

[0037] In a separate dry container, add sodium azide (20 mg, 0.3 mmol) and deionized water (0.5 mL). Stir until the sodium azide is completely dissolved to obtain an aqueous solution of sodium azide. Use a syringe to add this aqueous solution of sodium azide dropwise to the above-mentioned ice-cold acetone solution of the acyl chloride intermediate. After the addition is complete, remove the ice-water bath and allow the temperature to rise naturally to room temperature. Continue stirring for 1 hour, then slowly pour the reaction solution into a beaker containing ice water (10 mL) to terminate the reaction. Extract the mixture with pentane (3 × 10 mL), combine the organic phases obtained from the three extractions, wash the organic phase with ice water until the aqueous phase is neutral, dry the washed organic phase with anhydrous sodium sulfate, let it stand for 30 minutes, filter, transfer the filtered organic phase to a round-bottom flask, and gently heat it in a water bath at 50–60 °C. After running for 1-2 hours, the mixture was cooled to room temperature. Then, hydrochloric acid (6M, 1.5 mL) was added, and the reaction was continued with stirring for 30 minutes. After the reaction was complete, the mixture was separated, and the aqueous phase was collected. The aqueous phase was washed once with dichloromethane, and the washed aqueous phase was cooled in an ice-water bath. Saturated sodium bicarbonate solution was slowly added dropwise under stirring to adjust the pH of the aqueous phase to 8-9. At this point, free amine gradually precipitated. The precipitated free amine was extracted with dichloromethane (3 × 10 mL). The dichloromethane organic phases obtained from the three extractions were combined, dried with anhydrous sodium sulfate, and allowed to stand for 30 minutes. Dry hydrogen chloride (HCl) gas was then introduced until the amount of solid precipitated in the system no longer increased. The precipitated solid was filtered, and the filter cake was washed 2-3 times with dichloromethane and then dried to obtain compound 3. Its characterization data are shown below: 1H NMR (500MHz, CDCl3): δ=3.20–3.13(m, 2H), 3.05(td, J=7.7, 1.0, 1H); 13 C NMR (125MHz, CDCl3): δ=173.69, 159.52, 143.18, 77.53, 72.22, 71.80, 53.59, 53.54; TOF-ESI (+) (m / z): C 11 H6FeIN 334.9313.

[0038] IV. Synthesis of target molecules .

[0039] Compound 3 (100 mg), anhydrous dichloromethane (5 mL), and a magnetic stir bar were added to a round-bottom flask. The magnetic stirrer was turned on, and the reaction flask was placed in an ice-water bath to cool until the system temperature stabilized. N,N-diisopropylethylamine (105 μL) was added to the cooled solution using a dry syringe, and the reaction was continued with stirring for 10 min. Then, di-tert-butyl carbonate (60 mg) was added to the reaction solution. After the addition was complete, the temperature was naturally raised to room temperature (approximately 25 °C), and the reaction was continued with stirring at room temperature for 4–6 h. After the reaction was completed, the solvent was removed by rotary evaporation under reduced pressure to obtain the crude product. The crude product was purified by silica gel column chromatography (using a mixture of petroleum ether and ethyl acetate as the eluent, with a volume ratio of petroleum ether to ethyl acetate of 15:1 to 10:1). The eluent was collected, and the solvent was evaporated to dryness to obtain an orange solid intermediate. Under nitrogen protection, the orange solid intermediate (100 mg), 1,4-diethynylbenzene (13.2 mg), tetrakis(triphenylphosphine)palladium (12.7 mg), cuprous iodide (4.2 mg), and anhydrous triethylamine (3 mL) were added sequentially to a dry Schlenk flask. After the addition was complete, the temperature was raised to 60℃–70℃, and the mixture was stirred. After 12 hours, allow the mixture to cool naturally to room temperature. Rinse the inner wall of the reaction flask repeatedly with ethyl acetate to remove catalyst and salt impurities. Then, filter the rinsed mixture, collect the filtrate, and evaporate the collected filtrate to dryness under reduced pressure to obtain the crude product. Purify the crude product using silica gel column chromatography (eluent is a mixture of petroleum ether and ethyl acetate, with a volume ratio of 20:1 to 10:1). Collect the eluent fraction, evaporate the solvent to dryness, and obtain an orange-red solid. Dissolve the orange-red solid in anhydrous dichloromethane (2 mL), and place the reaction flask in an ice-water bath. After cooling to a stable temperature, trifluoroacetic acid (2 mL) was slowly added. After the addition was complete, the mixture was allowed to naturally warm to room temperature (approximately 25°C) and stirred continuously for 2–4 hours. After the reaction was complete, the reaction solution was concentrated under reduced pressure to obtain a concentrate. Diethyl ether (5 mL) was added to the concentrate, and after stirring to dissolve, the solution was cooled in an ice-water bath. Under stirring, a 2M, 1 mL solution of hydrochloric acid in diethyl ether was slowly added dropwise. After the addition was complete, stirring was continued for 30 minutes, followed by filtration. The resulting filter cake was washed 2–3 times with diethyl ether and then dried to obtain the target molecule. Its characterization data are shown below: 1 H NMR (500MHz, CDCl3): δ=3.82–3.77 (m, 1H), 3.26–3.15 (m, 3H), 3.05 (td, J=7.7, 0.9, 1H), 2.63 (t, J=7.4, 1H); 13C NMR (125MHz, CDCl3): δ=132.19, 131.55, 128.65, 128.04, 127.77, 125.29, 122.97, 121.56, 121.11, 119.25, 115.1 6, 115.05, 108.63, 107.56, 96.02, 94.06, 61.16, 60.36, 50.94, 49.22, 46.17, 45.82, 44.58, 44.56, 41.13, 39.74; TOF-ESI (+) (m / z): C 32 H 28 Fe2N2552.1031.

[0040] Example 2 like Figure 1 As shown, the bias-controlled probability bit device includes an electrode pair 1 and a probability bit molecule 2, which is connected to the electrode pair 1 via amide bonds. The structural formula of the probability bit molecule is shown below: .

[0041] Its preparation process is as follows: 1. Photolithography and gold evaporation are performed on the silicon wafer to create alignment marks.

[0042] The silicon wafer cleaning process is as follows: Immerse the silicon wafer (1cm×1cm) in piranha solution (hydrogen peroxide and sulfuric acid volume ratio 3:7), heat at 120℃ for 1 hour, then maintain the temperature and sonicate for 3 minutes. Pour out the solution, add ultrapure water and sonicate for 3 minutes. Repeat the water washing three times, then clean with anhydrous ethanol once. Finally, dry the silicon wafer with a nitrogen gun and set it aside for later use.

[0043] The process of depositing gold marks is as follows: Take the silicon wafer that has been cleaned as described above, define the mark pattern using photolithography, and then deposit chromium (thickness of 8nm) and gold (thickness of 30nm) sequentially using a vacuum thermal evaporation coating machine. After the evaporation is completed, rinse with acetone to remove the photoresist and excess gold-chromium layer in non-patterned areas to obtain a silicon substrate with gold marks.

[0044] II. Growth of monolayer graphene films on copper foil using chemical vapor deposition.

[0045] Pretreatment of copper foil: Cut a section of copper foil and soak it in a 36% (volume fraction) acetic acid aqueous solution for 15 minutes, then rinse it with ethanol and dry it with a nitrogen gun for later use.

[0046] Graphene growth: The pretreated copper foil was placed on a glass slide and placed into a chemical vapor deposition (CVD) system. After vacuuming for 2 hours, the temperature was raised to 1030°C and hydrogen was introduced for annealing for 1.5 hours. The two gases were introduced at a volume ratio of methane to hydrogen of 1:5. After growth at a constant temperature for 25 minutes, the heating device was turned off and the sample was taken out after natural cooling to room temperature to obtain a copper foil-graphene composite structure.

[0047] III. Graphene surface protection and pretreatment of the back side of copper foil.

[0048] Spin coating and curing of polymethyl methacrylate (PMMA): The copper foil with monolayer graphene grown on it was cut open and flattened onto a glass slide with the graphene side facing up. PMMA adhesive was dripped onto the graphene surface and the sample was homogenized using a stepped homogenization process of 2000 r / min for 6 s and 4000 r / min for 40 s. The sample was then heated and cured at a constant temperature of 180℃ for 2 min to form a copper foil-graphene-PMMA composite structure.

[0049] Etching of the back side of the copper foil: The aforementioned copper foil-graphene-PMMA composite structure is placed in a reactive ion etching (RIE) machine, and oxygen plasma is used to lightly etch the back side of the copper foil to destroy the dense surface layer on the back side of the copper foil.

[0050] IV. Dissolving copper foil and transferring graphene film.

[0051] Copper foil etching: The copper foil-graphene-PMMA composite structure is cut into square pieces slightly smaller than the silicon wafer. The graphene side is placed in a 0.5 mol / L ferric chloride aqueous solution and left to stand for 1 hour to completely dissolve the copper foil, thus obtaining a PMMA-graphene film.

[0052] Graphene film rinsing and transfer: The PMMA-graphene film was rinsed sequentially with 0.5 mol / L hydrochloric acid solution, 0.25 mol / L hydrochloric acid solution, ultrapure water, 0.1 mol / L potassium hydroxide aqueous solution, ultrapure water, 0.1 mol / L hydrochloric acid solution, and ultrapure water. After rinsing, the graphene film was retrieved and attached to the surface of a silicon substrate with a gold mark, thus completing the transfer of the graphene film.

[0053] V. Preparation of graphene nano-gap electrodes.

[0054] Fabrication of graphene strips: Using a gold mark on a silicon substrate as a positioning reference, a strip pattern is defined at the center of the graphene film device using photolithography. Excess graphene is removed by oxygen plasma etching, and the photoresist is removed by acetone rinsing to obtain a silicon wafer-graphene strip.

[0055] Metal electrode evaporation: On the silicon wafer-graphene strip, the electrode pattern is defined by photolithography. Chromium (thickness of 30nm) and gold (thickness of 80nm) are deposited sequentially as metal electrodes using a thermal evaporation coating machine. After the evaporation is completed, the photoresist and excess metal outside the electrode area are removed with acetone. 169 pairs of adjacent electrode pairs are integrated on a single silicon wafer. Each pair of electrodes is formed by a graphene source electrode and a graphene drain electrode.

[0056] Electron beam lithography defines the etching template: PMMA adhesive is spin-coated again on the graphene strip, and electron beam lithography is used to expose between each pair of metal electrodes (the developer is prepared with methyl isobutyl ketone and isopropanol in a volume ratio of 1:3, and isopropanol is used as the fixer for development), to obtain the graphene array point electrodes; among them, the exposed dashed lines are located between each pair of metal electrodes, with a total length of 60μm, a single dashed line segment length of 150nm, and a line segment spacing of 40nm, which serve as the template for subsequent nano-gap etching.

[0057] RIE etching to prepare nanoscale gaps: The sample is placed in the RIE machine, and the exposed graphene under the PMMA dashed template is etched. After etching, a source-drain voltage of 1 V is applied to measure the circuit current. When the current is about 1 pA, it is determined that the nanoscale graphene gaps (target gap width is 40 nm) have been successfully prepared.

[0058] The sample that has passed the electrical test and completed the preparation of the 40nm nano-gap is placed in the RIE machine and treated with oxygen plasma to obtain a graphene nano-gap electrode pair containing carboxyl groups. After cleaning and drying, it is ready for use.

[0059] The process parameters for oxygen plasma etching are as follows: Oxygen purity ≥ 99.99%, oxygen flow rate 25 sccm, working pressure 30 mTorr, radio frequency power 35 W, processing time 20 s.

[0060] VI. The amide condensation reaction was used to connect the bisferrocene group-containing molecules obtained in Example 1 between the graphene nano-gap electrode pairs.

[0061] Preparation of amide condensation reaction system: Using pyridine as solvent, 1-(3-dimethylaminopropyl)-3-ethylcarbodiimide hydrochloride (EDC·HCl) and ferrocene group molecules were added separately and stirred evenly to obtain a reaction solution; wherein, the concentration of EDC·HCl was controlled at 50 mmol / L and the concentration of ferrocene group molecules was 10 mg / mL.

[0062] At room temperature (approximately 25°C), the aforementioned carboxyl-containing graphene nano-gap electrode sample was immersed in the prepared reaction solution, ensuring that the graphene point electrode and the nano-gap region were completely submerged in the solution. The reaction was allowed to proceed under light-protected conditions for at least 2 hours. After the reaction was completed, the sample was removed from the reaction solution and gently rinsed with anhydrous ethanol and ultrapure water in sequence. After rinsing, the sample was dried with nitrogen gas to obtain a probability bit device based on bias control.

[0063] VII. Testing.

[0064] Device electrical screening: The bias-controlled probabilistic bit devices were placed in a probe station test environment at room temperature (approximately 25°C) and free from electromagnetic interference, and the current signal of each electrode pair was detected. The screening criteria were: current signal fluctuation amplitude ≤5% and current value within the range of 10–100 pA. Probabilistic bit devices with stable current signals were selected and marked as electrode pairs to be tested, while devices with unstable signals, no current, or abnormally high / low current were rejected.

[0065] The selected electrode pairs to be tested are connected to the sample holder of the Physical Property Measurement System (PPMS) using conductive silver paste and gold wire for subsequent testing.

[0066] The connected sample holder was placed in a PPMS. At room temperature (approximately 25°C), the device current-time (It) curve was measured in 20mV increments within a bias range of 260mV (0.26V) to 400mV (0.4V). The results are as follows: Figure 2 As shown in the figure, we can see that: when the bias voltage is 0.26V to 0.30V, the pulse density is moderate, and the open / closed states alternate; when the bias voltage is around 0.32V, the current pulses are the most concentrated and have the highest frequency, indicating that the switching of molecules / channels is most active and the state switching is most frequent at this voltage; when the bias voltage is 0.36V to 0.40V, the pulses become significantly fewer and sparser, and the high current (open) state lasts longer, indicating that as the voltage increases, the molecules tend to stabilize in the open state.

[0067] Data analysis was performed on the collected It curves, and the proportion of high and low conductivity states in the curves was statistically analyzed. The results are as follows: Figure 3 As shown in the figure, we can see that at low voltage (0.26V~0.30V), the proportion of high state is less than 0.4, and molecules frequently switch between open and closed states, with the closed state being dominant; at medium voltage (0.32V~0.34V), the proportion of high state is about 0.5, and the open / closed state times are similar, making it a region with relatively active state switching; at high voltage (0.36V~0.40V), the proportion of high state is greater than 0.65, the open state is dominant, molecules are on for a long time, and switching events are significantly reduced.

[0068] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A probabilistic bit device based on bias control, characterized in that, It includes electrode pairs and probability bit molecules, wherein the probability bit molecules are connected between the electrode pairs by ester bonds or amide bonds; The structural formula of the probability bit molecule is shown below: ； The bias voltage range is 260mV to 400mV; The electrode pair is a nano-gap electrode pair.

2. The probability bit device based on bias control as described in claim 1, characterized in that, The electrode pair is a graphene point electrode pair.

3. The probability bit device based on bias control as described in claim 1, characterized in that, The electrode pairs are connected to a single probability bit molecule.

4. The probability bit device based on bias control as described in claim 1, characterized in that, The electrode pair is made of a single-layer graphene film.

5. A method for fabricating a probabilistic bit device based on bias control, characterized in that, The method for fabricating a bias-controlled probability bit device as described in any one of claims 1 to 4 comprises the following steps: S100: Prepare electrode pairs on the substrate to obtain an electrode device; S200. The electrode device is immersed in an organic solution containing ferrocene group molecules, so that the ferrocene group molecules are connected between the electrode pairs to obtain a probability bit device based on bias control. The structural formula of the molecule containing the bisferrocene group is shown below: ； R1 and R2 are each independently selected from -OH or -NH2.

6. The method for fabricating a probability bit device based on bias control as described in claim 5, characterized in that, In step S100, the substrate material is selected from silicon wafers.

7. The method for fabricating a probability bit device based on bias control as described in claim 5, characterized in that, In step S200, the solvent of the organic solution is selected from pyridine.

8. The method for fabricating a probability bit device based on bias control as described in claim 5, characterized in that, The electrode pair is a terminally carboxylated graphene electrode.

9. The method for fabricating a probability bit device based on bias control as described in claim 8, characterized in that, In step S200, R1 and R2 are both selected from -NH2, and the bisferrocene group molecules are connected between the electrode pairs through an amide condensation reaction.

10. The method for fabricating a probability bit device based on bias control as described in claim 9, characterized in that, The condensing agent for the amide condensation reaction is selected from 1-(3-dimethylaminopropyl)-3-ethylcarbodiimide hydrochloride.

Images