KR101754675B1 - Resistance switchable composite material having dopamine conjugated nanoparticle and memory device using the same - Google Patents
Resistance switchable composite material having dopamine conjugated nanoparticle and memory device using the same Download PDFInfo
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- KR101754675B1 KR101754675B1 KR1020150127157A KR20150127157A KR101754675B1 KR 101754675 B1 KR101754675 B1 KR 101754675B1 KR 1020150127157 A KR1020150127157 A KR 1020150127157A KR 20150127157 A KR20150127157 A KR 20150127157A KR 101754675 B1 KR101754675 B1 KR 101754675B1
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- oxide nanoparticles
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Abstract
The present invention relates to a new type of resistance-changing composite material, wherein transition metal oxide nanoparticles in which dopamine is chemically bonded are dispersed in an insulating matrix.
Further, the memory element according to the present invention includes: a lower electrode; An active layer formed on the lower electrode and composed of a composite material in which transition metal oxide nanoparticles doped with dopamine are dispersed in an insulating matrix; And an upper electrode formed on the active layer.
The present invention has an effect of providing a novel resistance-changing composite material having analog characteristics and exhibiting a unique behavior in which hysteresis increases as the voltage increases, by dispersing dopamine in the transition metal oxide and then dispersing it in the matrix.
Further, the storage element of the present invention using such a composite material has the effect of providing a storage element exhibiting a resistance change type characteristic and / or a nonvolatile characteristic.
Further, there is an effect that a brain nerve simulation element including the nonvolatile memory element of the present invention as a memorizer can be constituted.
Description
BACKGROUND OF THE INVENTION 1. Field of the Invention [0001] The present invention relates to a material whose resistance changes according to a voltage and a memory element using the same, and more particularly, to a novel resistance-changing composite material and a resistance variable memory element using the same.
Currently, DRAMs and flash memories are the most commonly used memory devices in the electronics industry. Among them, flash memory is widely used as a storage medium because of its process similarity with DRAM, relatively simple line width implementation through simple structure, and nonvolatile memory. However, after sub-30 nm, there are problems such as increase in process difficulty, deterioration of electrical characteristics, power consumption due to high operating voltage which is the inherent limit, and slow operation speed.
Resistive RAM (ReRAM), which is nonvolatile, low power, highly integrated, and can operate at a high speed, has been actively researched as a new memory device that solves these problems. ReRAM is a memory that reads / writes on / off by using a characteristic of a material whose resistance changes according to a bias sweep. The ReRAM is a memory that performs unipolar switching and bipolar switching according to resistance switching behavior. It is divided into bipolar switching.
Although a clear mechanism for each change behavior is not known, it is generally known that unipolar switching is caused by the generation and destruction of a conducting path in the oxide film caused by dielectric breakdown. In the case of bipolar switching, Or a change in the schottky barrier height due to the behavior of oxygen vacancies in the oxygen vacancies, or oxygen deficient phase formation.
Furthermore, the resistance variable memory element has been attracting attention as a nonvolatile memory element and a possible use as a memristor. A memristor is a combination of a memory and a resistor. It is a memory element that memorizes all the previous states. The memristor memorizes the direction and amount of the current just passed even when the power supply is disconnected.
Memistors are recognized as one of the basic components of an electrical circuit together with resistors, capacitors and inductors. Memistors are generally similar to resistors in that they perform various roles that resistors are responsible for, The resistance can be changed according to the direction and the magnitude of the voltage and the ability to memorize the previous resistance even if the voltage is cut off. Therefore, the memristor is a new concept device that can construct a new logic circuit such as a terabit memory, a defect recognition device by a neural network circuit configuration, and belongs to the next generation memory related field based on nanotechnology.
However, conventional memristors have disadvantages in that the active layer is composed of several layers, and the forming process also requires a vacuum deposition method.
SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems of the prior art, and it is an object of the present invention to provide a novel resistance-changing composite material and various devices using the same.
In order to achieve the above object, the resistance-variable composite material according to the present invention is characterized in that transition metal oxide nanoparticles in which dopamine is chemically bonded are dispersed in an insulating matrix.
The present invention provides a new resistance-changing composite material in which dopamine, which is a neurotransmitter, is bound to a transition metal oxide, which has been studied for its application as a resistance-changing material, and then dispersed in a matrix.
Preferably, the transition metal oxide is at least one material selected from ZnO, TiO 2 , Fe 2 O 3 and NiO, and the matrix is at least one material selected from PVP, PMMA, PS and PVK.
And transition metal oxide nanoparticles in which dopamine is chemically bonded are preferably bonded to dopamine through a carboxyl group formed on the surface of transition metal oxide nanoparticles.
The resistance-changing composite material of the present invention constituted as described above exhibits an analog type characteristic in which the resistance increases according to an applied voltage among the characteristics of the resistance-change switching element. In addition, it exhibits a unique characteristic that the hysteresis increases as the voltage increases.
At this time, in order to obtain such characteristics, it is preferable that the proportion of the transition metal oxide nanoparticles in which the dopamine included in the composite material is chemically bonded is in the range of 0.05 to 20 wt%.
A storage element according to the present invention includes: a lower electrode; An active layer formed on the lower electrode and composed of a composite material in which transition metal oxide nanoparticles doped with dopamine are dispersed in an insulating matrix; And an upper electrode formed on the active layer.
Preferably, the transition metal oxide is at least one material selected from ZnO, TiO 2 , Fe 2 O 3 and NiO, and the matrix is at least one material selected from PVP, PMMA, PS and PVK.
And transition metal oxide nanoparticles in which dopamine is chemically bonded are preferably bonded to dopamine through a carboxyl group formed on the surface of transition metal oxide nanoparticles.
Such a memory element may be a resistance variable memory element in which the active layer functions as a resistance variable layer, and in particular may be a nonvolatile memory element in which the active layer functions as a gate insulating layer which is a resistance change element.
For this property, it is preferable that the proportion of the transition metal oxide nanoparticles in which dopamine contained in the active layer is chemically bonded is in the range of 0.05 to 20 wt%. Further, the thickness of the active layer is preferably 200 nm or more, because if the thickness of the active layer is less than 200 nm, the active layer can operate as a digital type.
A method of manufacturing such a resistance-change type memory element includes: preparing a substrate; Forming a lower electrode on the substrate surface; Forming a resistance-variable layer on the surface of the lower electrode; And forming an upper electrode on the surface of the resistance variable layer, wherein the step of forming the resistance variable layer comprises: chemically bonding dopamine to the transition metal oxide nanoparticle; Dissolving the doped transition metal oxide nanoparticles and the insulating matrix material in a solvent; Applying a solution in which the dopant-bound transition metal oxide nanoparticles and a matrix material are dissolved to the surface of the lower electrode; And a step of evaporating the solvent.
Preferably, the step of chemically bonding dopamine to the transition metal oxide nanoparticles is performed by forming a carboxyl group on the surface of the transition metal oxide nanoparticles and attaching dopamine to the carboxyl group. The step of forming a carboxyl group on the surface of the transition metal oxide nanoparticles can be performed using anhydrous succinic acid or glutaraldehyde after generating a hydroxyl group (-OH) on the surface of the transition metal oxide nanoparticles. Further, it is preferable that the step of attaching dopamine to the carboxyl group formed on the surface of the transition metal oxide nanoparticles is performed through EDC / NHS treatment.
And the transition metal oxide is at least one material selected from ZnO, TiO 2 , Fe 2 O 3 and NiO, and the matrix is preferably at least one material selected from PVP, PMMA, PS and PVK.
A neuron modeling device according to another embodiment of the present invention is a neuromorphic device including a memristor device, and is characterized in that the nonvolatile memory device is used as a memristor device.
With respect to the remaining components of the brain-nerve simulation device, other techniques than the non-volatile memory device of this embodiment can be applied without limitations, so a detailed description is omitted.
The present invention constructed as described above can provide a novel resistance-changing composite material exhibiting a characteristic behavior that has analog characteristics and hysteresis increases as the voltage increases by dispersing dopamine in the transition metal oxide and then dispersing it in the matrix It is effective.
The storage element of the present invention using such a composite material has the effect of being able to provide a storage element exhibiting resistance change type characteristics and / or nonvolatile characteristics.
Further, there is an effect that a brain nerve simulation element including the nonvolatile memory element of the present invention as a memorizer can be constituted.
1 is a schematic diagram showing a structure of a memory element according to an embodiment of the present invention.
FIGS. 2 to 4 show a process of chemically bonding ZnO nanoparticles and dopamine according to an embodiment of the present invention.
5 is an IV curve measured for the memory element of this embodiment.
6 is an IV curve measured for the storage element of the comparative example.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Referring to the accompanying drawings, embodiments of the present invention will be described in detail.
1 is a schematic diagram showing a structure of a memory element according to an embodiment of the present invention.
The memory device of this embodiment has a structure in which a
At this time, the
Example
First, a raw material for forming an active layer was prepared by the following method.
ZnO nanoparticles were selected as nanoparticles to store charge, and dopamine was chemically bonded to the ZnO nanoparticles.
ZnO nanoparticles are commercially available and have a particle size of 14 nm. Dopamine is a hormone present in mammals, including humans, and is one of the neurotransmitters. 3,4-Dihydroxyphenethylamine (3,4-dihydroxyphenethylamine,
In order to chemically bond the dopamine to the ZnO nanoparticles, the ZnO nanoparticles are surface-treated with H 2 O 2 to generate a hydroxyl group (-OH) on the surface of the ZnO nanoparticles as shown in FIG. Next, as shown in FIG. 3, a carboxyl group (-COOH) is formed on the surface of ZnO nanoparticles by reacting with succinic anhydride. At this time, glutaldehyde can be used to generate a carboxyl group.
Finally, as shown in FIG. 4, the EDC / NHS treatment of ZnO nanoparticles with carboxyl groups was carried out to temporarily attach EDC (1-ethyl-3- (3dimethylaminopropyl) carbodiimide) to the carboxyl group, Chemically bonded ZnO nanoparticles were synthesized.
The doped ZnO nanoparticles prepared by the above process were dissolved in THF (tetrahydrofuran) as a solvent together with PVP. In this case, a small amount of coupling agent (1,6-Bis (trichlorosilyl) hexane) was added to connect the doped ZnO nanoparticles with PVP. The PVP contained in the solution was 2.0% by weight and the doped ZnO nanoparticles 0.25 wt%.
Then, a resistance variable memory element having the structure shown in FIG. 1 was manufactured in the following sequence.
First, ITO was coated to a thickness of 200 nm as a
Finally, an Al layer is formed on the surface of the
Electrical characteristics of the memory device manufactured by the above process were measured. At this time, as a comparative example, a memory device manufactured by the same process was fabricated using ZnO nanoparticles not doped with dopamine.
5 is an I-V curve measured for the storage element of this embodiment, and FIG. 6 is an I-V curve measured for the storage element of the comparative example.
As shown in the figure, it can be seen that all of the two kinds of memory elements are resistance change type memory elements which exhibit analog type characteristics in which the resistance gradually changes in accordance with the applied voltage.
The resistance change type memory element of the comparative example exhibited a general tendency that the hysteresis decreases as the voltage increases. On the other hand, the resistance variable memory element of this embodiment shows a unique tendency that the hysteresis increases as the voltage increases. This tendency indicates that the memory element of this embodiment can be applied as a memoryst which is a nonvolatile memory element.
This hysteresis characteristic is similar to the action mechanism of dopamine, which is known to be a kind of happy hormone in the human body, in response to stimulation.
When the memory element of this embodiment is applied to a memristor which is an inactive memory element, it becomes a memristor element having a very simple configuration of a two-terminal structure using only two electrodes.
Further, the non-volatile memory device according to the present embodiment can be applied as a memristor of a neuromorphic device including a memristor, and the non-volatile memory device of the present embodiment can be applied to the remaining components of the brain- Other techniques than those described above can be applied without limitations, so a detailed description thereof will be omitted.
As described above, the hysteresis characteristic of the memory element of the present embodiment is similar to that of dopamine acting as a hormone. Even when applied to a brain nerve simulation element, the hysteresis characteristic exhibits such a characteristic, Can be obtained.
While the present invention has been particularly shown and described with reference to preferred embodiments thereof, it is to be understood that the invention is not limited to the disclosed embodiments, but, on the contrary, is intended to cover various modifications and equivalent arrangements included within the spirit and scope of the appended claims. Those skilled in the art will understand. Therefore, the scope of protection of the present invention should be construed not only in the specific embodiments but also in the scope of claims, and all technical ideas within the scope of the same shall be construed as being included in the scope of the present invention.
100: substrate 200: lower electrode
300: active layer 400: upper electrode
Claims (22)
And the hysteresis increases as the voltage increases.
Composite resistance changes, characterized in that the transition metal oxide is at least one material selected from ZnO, TiO 2, Fe 2 O 3 and NiO.
Wherein the matrix is at least one material selected from PVP, PMMA, PS and PVK.
Wherein transition metal oxide nanoparticles in which the dopamine is chemically bonded are bonded to dopamine through a carboxyl group formed on the surface of the transition metal oxide nanoparticle.
Wherein the resistance-changing composite material exhibits an analog type resistance-changing characteristic among the characteristics of the resistance-change switching element.
Wherein the proportion of the transition metal oxide nanoparticles to which the dopamine is chemically bonded is in the range of 0.05 to 20 wt%.
An active layer formed on the lower electrode and composed of a composite material in which transition metal oxide nanoparticles chemically bonded with dopamine are dispersed in an insulating matrix; And
And an upper electrode formed on the active layer,
And the hysteresis increases as the voltage of the active layer increases.
Wherein the transition metal oxide is at least one material selected from ZnO, TiO 2 , Fe 2 O 3 and NiO.
Wherein the matrix is at least one material selected from PVP, PMMA, PS and PVK.
Wherein the transition metal oxide nanoparticles to which the dopamine is chemically bonded are bonded to the dopamine through a carboxyl group formed on the surface of the transition metal oxide nanoparticle.
Wherein the active layer functions as a resistance variable layer, and the storage element is a resistance variable memory element.
Wherein the memory element is a non-volatile memory element.
Wherein a ratio of transition metal oxide nanoparticles in which dopamine contained in the active layer is chemically bonded is in the range of 0.05 to 20 wt%.
Wherein the active layer has a thickness of 200 nm or more.
Forming an active layer on the surface of the lower electrode; And
And forming an upper electrode on the surface of the active layer,
Wherein forming the active layer comprises:
By forming a hydroxyl group (-OH) on the surface of the transition metal oxide nanoparticles, forming a carboxyl group on the surface of the transition metal oxide nanoparticles using succinic anhydride or glutaraldehyde, and then attaching dopamine to the carboxyl group, Chemically bonding dopamine to the transition metal oxide nanoparticles;
Dissolving the doped transition metal oxide nanoparticles and the insulating matrix material in a solvent;
Applying a solution in which the dopant-bound transition metal oxide nanoparticles and a matrix material are dissolved to the surface of the lower electrode; And
And evaporating the solvent. ≪ RTI ID = 0.0 > 21. < / RTI >
Wherein the step of attaching dopamine to a carboxyl group formed on the surface of the transition metal oxide nanoparticles is performed by EDC / NHS treatment.
Wherein the transition metal oxide is at least one selected from the group consisting of ZnO, TiO 2 , Fe 2 O 3, and NiO.
Wherein the matrix material is at least one material selected from PVP, PMMA, PS and PVK.
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| KR102074942B1 (en) | 2013-07-29 | 2020-02-10 | 삼성전자 주식회사 | Nonvolatile memory transistor and device including the same |
| KR20150094387A (en) | 2014-02-11 | 2015-08-19 | 충북대학교 산학협력단 | Ultra-thin layer based memristor driven by low voltage |
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| Q. Shi et al., ‘Electrical bistable properties of hybrid device based on SiO2 modified-ZnO nanoparticles embedded in poly-4-vinyl-phenol’, Physics Letters A, October 2 2014, 3544~3548 (2014.10.2)* |
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