Nanoscale ionic synaptic transistor based on NbSe2 single layer

Abstract

The invention discloses an ionic synapse transistor based on a NbSe2 single layer, and belongs to the technical field of nano-sized electronic devices, the ionic synapse transistor is of a single-layer structure based on a NbSe2 material, the structures of the two ends of the ionic synapse transistor are the same as the intrinsic structure of a middle region and are both the NbSe2 single-layer structures, and the NbSe2 single-layer structures are arranged in the middle region of the ionic synapse transistor. And a source electrode and a drain electrode are respectively applied to two ends of the NbSe2, and the conversion of the ionic synapse transistor from a semiconductor state to a metal state is realized by controlling the adsorption and desorption of the single-layer structure NbSe2 to lithium ions through the grid electrode. The nanoscale ionic synapse transistor based on the NbSe2 single layer has the advantages of being ultrathin in structure, low in energy consumption, good in switching characteristic and memory characteristic and the like, and a depletion type ionic synapse transistor compact in structure can be manufactured according to actual needs.

Description

Technical Field

[0001] The present invention belongs to the technical field of nano-sized electronic devices, and particularly relates to a nano-scale ionic synaptic transistor based on a single layer of NbSe2. Background Art

[0002] With the rapid development of data-intensive fields such as artificial intelligence and the Internet of Things, the bottleneck of the von Neumann architecture and the memory wall problem have become increasingly prominent. Modern computing systems are facing huge challenges in terms of time and power consumption, and it is difficult to meet the urgent need for efficient processing of massive data sets. To solve this technical problem, researchers are committed to developing new electronic devices and related circuits to achieve a low-power, high-density memory-computation integrated architecture. The ionic synaptic transistor is an interface-type resistive random access memory, and its design inspiration comes from the human brain. By controlling the adsorption and desorption behavior of ions on the channel surface, this transistor can regulate the channel energy band, showing good tunability and non-volatility, and thus becoming a potential candidate in the field of synaptic devices.

[0003] Due to the high mobility, excellent scalability, and high mechanical flexibility of two-dimensional transition metal dichalcogenides (TMDs), they have potential application prospects in nanoelectronic devices and have attracted great attention. As a kind of transition metal dichalcogenide, NbSe2 consists of an atomic layer of Nb and two outer layers of Se, forming a trigonal prism structure. In its original form (2H), NbSe2 exhibits metallic properties, and it shows superconductivity coexisting with charge density waves at low temperatures. Liu et al. used NbSe2 as the injection source of the transistor to filter out high-energy electrons, making the subthreshold swing of the transistor lower than 60 mV / decade (Switching at Less Than 60 mV / Decade with a “Cold” Metal as the Injection Source[J], Phys. Rev. Applied 13, 064037 (2020)). Yin et al. obtained a good peak-to-valley ratio and peak current by forming a heterostructure of NbSe2 and NbS2 into a negative differential resistance effect diode (Negative Differential Resistance Effect in “Cold” Metal Heterostructure Diodes[J], IEEE Electron Device Lett. 43, 498 (2022)).

[0004] In recent years, Zhai et al. studied how to control the lithium (Li) embedding path in two-dimensional van der Waals heterojunctions, inducing a phase transition in the MoS2 structure and transforming the channel material from a semiconductor state to a metal state (Structural Transitions in Monolayer MoS2 by Lithium Adsorption[J], J. Phys. Chem. C 119, 10602 (2015)). Kim et al. revealed the relationship between ion species and the synaptic function of ionic synaptic transistors through electrochemical analysis methods, and found that ion size affects the dominant reaction of interfacial electrochemistry and is a key factor determining the basic characteristics of voltage-gated synapses (EGTs) (Dual‐Electrolyte Neuromorphic Transistor for Risk Detection and Image Processing[J], Adv Materials Technologies 2401617 (2024)). However, the above studies mainly focused on enhancement-mode ionic synaptic transistors, which are in a semiconductor state before lithium adsorption and transform into a metal state after adsorption, which may limit their energy efficiency and the flexibility of logic styles. Based on this, the present invention began to explore whether there are other two-dimensional materials that can be transformed from a metal state to a semiconductor state by adsorbing atoms or ions, so as to construct depletion-mode ionic synaptic transistors. So far, there is no relevant report in this regard. Summary of the Invention

[0005] The technical problem solved by the present invention is to provide a nanoscale ionic synaptic transistor based on a single layer of NbSe2. The ionic synaptic transistor is based on the single-layer structure of NbSe2 material. The structures at both ends are the same as the intrinsic structure in the middle region, and source and drain electrodes are respectively applied at both ends. By controlling the adsorption and desorption of lithium ions by the single layer of NbSe2 through the gate, the transition of the device between the semiconductor state and the metal state can be achieved, and thus the synaptic function can be realized.

[0006] The present invention adopts the following technical solution to solve the above technical problem. The ionic synaptic transistor based on a single layer of NbSe2 is characterized in that: the ionic synaptic transistor is based on the single-layer structure of NbSe2 material. The structures at both ends of the ionic synaptic transistor are the same as the intrinsic structure in the middle region, both being the single-layer structure of NbSe2, and source and drain electrodes are respectively applied at both ends. By controlling the adsorption and desorption of lithium ions by the single-layer structure of NbSe2 through the gate, the transition of the ionic synaptic transistor between the semiconductor state and the metal state can be achieved.

[0007] More preferably, when a positive gate voltage is applied to the gate of the ionic synaptic transistor, lithium ions are adsorbed on the surface of the single-layer structure NbSe2, and the resistivity of the ionic synaptic transistor increases; when a negative gate voltage is applied to the gate of the ionic synaptic transistor, lithium ions are detached from the surface of the single-layer structure NbSe2, and the resistivity of the ionic synaptic transistor decreases, realizing the switching function; when the gate voltage is removed, the resistivity of the middle channel of the single-layer structure NbSe2 will remain in the most recent writing state, realizing the memory function.

[0008] Compared with the prior art, the present invention has the following advantages and beneficial effects: The nanoscale ionic synaptic transistor based on the single-layer NbSe2 designed by the present invention has the characteristics of ultrathin structure, low energy consumption, good switching characteristics and memory characteristics, and a compact depletion-type ionic synaptic transistor can be fabricated according to actual needs. BRIEF DESCRIPTION OF THE DRAWINGS

[0009] Figure 1 FIG. is a schematic structural diagram of an ionic synaptic transistor based on a single-layer NbSe2 under different lithium-ion adsorption behaviors. Different adsorption behaviors are realized by applying a gate voltage to the gate. In the upper figure, the left and right electrode regions are NbSe2, and the middle channel region is Li-NbSe2. In the lower figure, both the left and right electrode regions and the middle channel region are NbSe2.

[0010] Figure 2 FIG. is the voltage-current curve of an ionic synaptic transistor based on a single-layer NbSe2 under different lithium-ion adsorption behaviors. DETAILED DESCRIPTION OF THE INVENTION

[0011] The above content of the present invention will be further described in detail below through examples, but it should not be understood that the scope of the above subject matter of the present invention is limited to the following examples. Any technology implemented based on the above content of the present invention belongs to the scope of the present invention. EXAMPLE

[0012] The present invention constructs a depletion-type ionic synaptic transistor composed of a single-layer NbSe2 structure. The present invention designs a device model through the use of a new generation of full-functional materials science calculation and simulation platform QuantumATK (Smidstrup, et al., QuantumATK: an integrated platform of electronic and atomic-scale modelling tools [J]. J. Phys.: Condens. Matter 32, 015901 (2020)), and measures its performance.

[0013] By measuring its electronic transport properties such as the volt-ampere characteristic curve, the adsorption behavior of lithium ions in the depletion-type ion synaptic transistor based on monolayer NbSe2 was revealed for the first time, providing relevant theoretical basis and device model construction schemes for further designing and realizing depletion-type ion synaptic transistors with ultra-thin structures, low energy consumption, high on-off ratio, and good memory characteristics.

[0014] The realization of the switching and storage functions of this nano-scale depletion-type ion synaptic transistor based on monolayer NbSe2 can be completed according to the following steps: As shown in Figure 1 , place the monolayer structure NbSe2 on a substrate such as silicon dioxide. Drain and source electrodes are respectively applied to both ends of the monolayer structure NbSe2, and the migration direction of ions in the electrolyte is controlled by the gate.

[0015] When a forward bias and a reverse bias are respectively applied to both sides of the depletion-type ion synaptic transistor constructed above, and a positive or negative gate voltage is applied to the gate, the current passing through the structure of this depletion-type ion synaptic transistor can be determined by the Landauer-Buttiker formula:

[0016] When the gate voltage is removed in the transistor constructed above, the resistivity of the depletion-type ion synaptic transistor maintains the previous writing state, and the storage state of the transistor is read by applying a forward bias and a reverse bias to both sides of the depletion-type ion synaptic transistor respectively, realizing the memory function of the transistor.

[0017] When the bias voltage is from -0.3V to 0.3V, its current-voltage curve is as shown in Figure 2 . This depletion-type ion synaptic transistor exhibits perfect switching characteristics and can reach the lowest operating voltage under a bias voltage of ±0.2V, as shown in the inset of Figure 2 .

[0018] The ion-type synaptic transistor device designed by the present invention based on monolayer NbSe2 has the characteristics of an ultra-thin structure, low energy consumption, good switching characteristics, and good memory characteristics, and a compact depletion-type ion synaptic transistor can be fabricated according to actual needs.

[0019] The above embodiments describe the basic principles, main features, and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited by the above embodiments. What is described in the above embodiments and the specification only illustrates the principles of the present invention. Without departing from the scope of the principles of the present invention, the present invention will have various changes and improvements, and these changes and improvements all fall within the protection scope of the present invention.

Claims

1. An ionic synaptic transistor based on a single layer of NbSe2, characterized in that: The ionic synaptic transistor is a single-layer structure based on the NbSe2 material. The structures at both ends of the ionic synaptic transistor are the same as the intrinsic structure in the middle region, both being the NbSe2 single-layer structure. Source and drain electrodes are respectively applied at both ends thereof, and the adsorption and desorption of lithium ions by the NbSe2 single-layer structure are controlled through the gate to achieve the transition of the ionic synaptic transistor between the semiconductor state and the metal state.

2. The ionic synaptic transistor based on a single layer of NbSe2 according to claim 1, wherein: When a positive gate voltage is applied to the gate of the ionic synaptic transistor, lithium ions are adsorbed on the surface of the NbSe2 single-layer structure, and the resistivity of the ionic synaptic transistor increases; when a negative gate voltage is applied to the gate of the ionic synaptic transistor, lithium ions are detached from the surface of the NbSe2 single-layer structure, and the resistivity of the ionic synaptic transistor decreases, realizing the switching function; when the gate voltage is removed, the resistivity of the middle channel of the NbSe2 single-layer structure will remain in the most recent writing state, realizing the memory function.

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