CN113921711A - Island-shaped low-resistance-path memristor functional layer material, memristor and preparation method - Google Patents
Island-shaped low-resistance-path memristor functional layer material, memristor and preparation method Download PDFInfo
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Abstract
The invention provides an island-shaped low-resistance path memristor functional layer material, a memristor and a preparation method, and belongs to the field of microelectronic devices. The memristor comprises a top electrode, a bottom electrode, a selenide layer, an oxide product layer and a two-dimensional material layer, wherein the bottom electrode is arranged on the selenide layer, the two-dimensional material layer is stacked on the oxide product layer, the top electrode is arranged on the two-dimensional material layer, and the two-dimensional material layer can improve the contact characteristic of the oxide product layer and the top electrode to form ohmic contact. The invention also provides a preparation method of the memristor. The memristor threshold voltage consistency can be improved, and meanwhile, the value of the threshold voltage is reduced.
Description
Technical Field
The invention belongs to the technical field of microelectronic devices, and particularly relates to an island-shaped low-resistance path memristor functional layer material, a memristor and a preparation method.
Background
Memristors are considered a fourth type of passive basic circuit element in addition to resistance, capacitance, inductance. The resistance of the memristor changes along with the amount of charge flowing through the memristor, and the resistance state of the memristor can be kept when current is cut off, so that a nonvolatile information storage function is realized. Through research, the memristor has a nonvolatile information storage function, so that the memristor can be applied to high-density information storage or nonvolatile state logic operation. In addition, part of the memristors have the characteristic that the conductance is continuously adjustable, so that the memristors can be applied to brain-like nerve morphology calculation as synapse devices. Memristors enable the fusion of storage and computation in a single device, making it one of the fundamental devices to build a non-von neumann computing architecture.
At present, the memristor based on the conductive filament theory has the advantages of simple structure, low power consumption, high reading and writing speed and the like, so that the memristor becomes one of the most potential storage technologies. However, the initial research time of memristors is not long, and many problems still need to be solved. On one hand, the migration of ions in the dielectric material in the memristor can form a conductive filament, and the connection and the fracture of the conductive filament change the conductance value of the device. [ see the following two documents: SUN H, LIU Q, LI C, et al direct observer of Conversion Between beer thread Switching and Memory Switching Induced by reducing visual similarity [ J ]. 2014; YANG Y, GAO P, GABAS, et al.Observation of reduction of film growth in nanoscopic reactive media [ J ].2012,3(732.) ].
Due to the randomness of the on-off of the conductive filament of the memristor, most memristors have the problems of discrete distribution of operating voltage, high and low resistance states, which causes the problems of consistency between devices (device to device) and electrical cycle (cycle to cycle) [ LEE S B, CHAE S C, CHANG S H, et al. This severely limits the storage capacity of the memristor memory chip, and also presents a great challenge to large-scale integration and circuit design of the memristor. On the other hand, due to the limitation of the process, the thickness of the functional layer cannot be infinitely reduced, so that the on-off voltage ratio is higher, the control of power consumption is not facilitated, the design of an artificial neural network peripheral circuit is limited, and unnecessary design cost is increased.
Currently, the following work has been applied with respect to improving memristor threshold voltage uniformity:
for example, Gao et Al, using a material design method calculated based on the first principles, showed that a trivalent element such as Al, La, or Ga was doped to HfO2Or ZrO2The formation of oxygen vacancy filaments along doping sites can be effectively controlled in isotetravalent metal oxides, which helps to improve the resistance switching behavior in oxide-Based memristive devices [ GAO B, ZHANG H W, YU S, et al.oxide-Based RRAM: Uniformity Improvement Using A New Material-ordered method; proceedings of the VLSI Technology,2009Symposium on, F,2009[ C ]].]. Bousoulas et al introduced Pt nanoparticles to concentrate the electric field effect between the two electrodes, thereby creating a fine Conductive Filament (CFs) [ BOUSOULAS P, STATHOPOULOS, TSIALOUKIS D, et al, Low-Power and high-level uniformity 3-b Multilevel Switching in Forming Free TiO2-x-Based RRAM With Embedded Pt Nanocrystals [ J].2016,37(7):874-7.]. Fang et al stacked a double layer HfOx/TiOxWith a single layer of HfOxCompared with the prior art, the consistency is improved. According to their theory, this is due to Ti doping effects and confinement of the conductive filaments within the different dielectric layers [ FANG Z, YU H Y, LI X, et al].2011,32(4):566-8.]. Yu et al use an optimized programming strategy to enhance the cycle-to-cycle uniformity and cycling characteristics of a valence-change memristive device (VCM). They attribute this to this New Pulse programming approach that reduces the reset Pulse energy, eliminating the over-reset process [ YU J, XU X, GONG T, et al. uniformity and Enhancement of variable Changed reactive Memory (VCM) by a New Pulse Method; proceedings of the 2019IEEE International Conference on Electron Devices and Solid-State Circuits(EDSSC),F,2019[C].]. It is also noteworthy that the incorporation of metal particles in the functional layer may improve the uniformity of device parameters. Wang et Al embedded Ag nanoparticles to improve device yield and reduce resistance variability [ WANG D T, DAI Y W, XU J, et Al2O3/ZnO/ITO Flexible Devices With Embedded Ag Nanoparticles[J].2016,37(7):878-81.]. Gao et Al found that embedded AgNPs could significantly enhance local electric field and effectively reduce switching voltage, resulting in a sharp increase in OFF/ON ratio, while significantly improving cycling stability due to reduced formation and fracture randomness of conductive filaments [ GAO L W, LI Y H, LI Q, et Al2O3 memory devices by embedded Ag nanoparticles[J].Nanotechnology,2017,28(21):13]。
In the above method, there are problems of complex process, high cost, or unstable performance, so it is necessary to develop a novel low-resistance path memristive functional layer material and memristor.
Disclosure of Invention
Aiming at the defects of the prior art, the invention aims to provide an island-shaped low-resistance path memristor functional layer material, a memristor and a preparation method.
In order to achieve the purpose, the invention provides an island-shaped low-resistance path memristive functional layer material which comprises a selenide layer and an oxidation product layer obtained by in-situ oxidation of selenide on the selenide layer, wherein the selenide layer and the oxidation product layer are tightly laminated to form a whole, selenide in the selenide layer is selenide of metal elements of a fourth subgroup, a fifth subgroup and a sixth subgroup, the oxidation product layer is provided with trigonal crystal clusters of selenium, the trigonal crystal clusters of the selenium are in island-shaped dispersed arrangement in the oxidation product layer, the trigonal crystal clusters of the selenium are positioned on the surface of the oxidation product layer and far away from the unoxidized residual selenide part, and oxygen vacancy conductive filaments are communicated with the trigonal crystal clusters of the selenium and the unoxidized residual selenide part.
Further, selenides of the fourth, fifth, and sixth subgroup metal elements have good metallicity so as to establish ohmic contact between the oxide product layer and an external electrode.
Further, the trigonal crystal clusters of selenium have higher conductivity than the oxidized product layer and the amorphous selenium clusters.
Further, selenides of the fourth, fifth, and sixth subgroup metal elements all form selenium atom clusters during oxidation, and the selenium atom clusters are used as raw materials for forming trigonal crystal clusters of selenium later.
According to a second aspect of the present invention, there is also provided a memristor comprising an island-like low-resistance functional layer material as described above, comprising a top electrode, a bottom electrode, a selenide layer, an oxide product layer, and a two-dimensional material layer, the bottom electrode being disposed on the selenide layer, the two-dimensional material layer being laminated on the oxide product layer, the top electrode being disposed on the two-dimensional material layer, the two-dimensional material layer being for improving a contact characteristic of the oxide product layer with the top electrode to form an ohmic contact.
Furthermore, the material of the two-dimensional material layer is the same as that of the selenide layer, and the two-dimensional material layer is selenide of metal elements of the fourth subgroup, the fifth subgroup and the sixth subgroup.
Further, the thicknesses of the selenide layer, the oxide product layer, and the two-dimensional material layer have a relative size relationship, wherein the selenide layer and the oxide layer are originally an integral body having a slightly thinner total thickness than the upper two-dimensional material layer, while the selenide layer has a thickness in the range of 5 to 10nm, and the oxide layer has a thickness greater than that of the selenide layer, typically about twice as great (depending on the degree of oxidation, in this example, nearly twice as great). The thickness of the two-dimensional material layer is generally slightly greater than the sum of the thicknesses of the underlying selenide layer and the oxide layer.
According to a third aspect of the present invention, there is also provided a method of preparing a memristor as described above, comprising the steps of:
s1: a bottom electrode is prepared on a substrate,
s2: disposing selenide on the bottom electrode prepared in step S1, forming a selenide layer,
s3: performing oxidation annealing on the selenide layer, specifically, annealing at 90-110 ℃ in the atmosphere for 30-60 min, then heating to 180-220 ℃, annealing in the vacuum environment for 8-12 min to obtain an oxide product layer,
s4: a two-dimensional material layer is disposed on the oxidation product layer,
s5: a top electrode is prepared on the two-dimensional material layer.
Further, in step S3, annealing at 90 to 110 ℃ in an atmospheric atmosphere for 30 to 60 minutes, and oxidizing the surface of the selenide layer to obtain an oxide product layer, wherein the oxide product layer contains a selenium atom cluster and oxides of metal elements of the fourth, fifth, and sixth subgroups.
Further, in step S3, the temperature is raised to 180 to 220 ℃, annealing is performed for 8 to 12min in a vacuum environment, the selenium atom clusters near the surface in the oxidation product layer are partially evaporated, and part of the selenium atom clusters in the oxides of the fourth, fifth, and sixth subgroup metal elements are retained.
Generally, compared with the prior art, the above technical solution conceived by the present invention has the following beneficial effects:
1. in the invention, the island-shaped low-resistance passage memristive functional layer material comprises two layers, namely a selenide layer and an oxidation product layer obtained by in-situ oxidation of selenide on the selenide layer, wherein the oxidation product layer is provided with a trigonal crystal cluster of selenium, the trigonal crystal cluster of selenium is in island-shaped dispersed arrangement in the oxidation product layer, the trigonal crystal cluster of selenium is positioned on the surface of the oxidation product layer and is far away from the residual selenide part which is not oxidized, an oxygen vacancy conductive filament is communicated with the trigonal crystal cluster of selenium and the residual selenide part which is not oxidized, the trigonal crystal cluster of selenium has higher conductivity compared with the oxidation product layer and an amorphous selenium cluster, namely, a low-resistance passage is formed in the functional layer material, a plurality of low-resistance passages are gathered in the functional layer material to form a low-resistance passage with stable scale, and the existence of the trigonal crystal cluster of selenium simultaneously reduces the length formed by the conductive filament, the comprehensive effect can improve the consistency of the threshold voltage and reduce the value of the threshold voltage.
2. In the preparation method, the oxidation annealing has two steps, wherein the first step is to oxidize the selenide surface layer transferred to the bottom electrode to obtain a corresponding oxidation product layer with the memristive characteristic. The second step is to evaporate the selenium atom clusters in the oxidized product, which are widely present on the surface and in the van der waals layer, and the annealing under vacuum condition can evaporate the selenium atom clusters, which is not completely performed, and a small part of the selenium atom clusters are still present in the oxidized product layer, and can subsequently form the trigonal crystal clusters of selenium. The method has the advantages of simple process, easy operation, common materials, low cost and popularization and application prospect.
Drawings
FIG. 1 is a diagram of a device structure containing an entire functional layer of island-like crystals, implemented in accordance with the present invention;
FIG. 2 is a sectional view of an HRTEM of an actual device implemented in accordance with the present invention;
FIG. 3 is a flow diagram of a method of making an entire memristor containing island crystals in accordance with the present invention;
FIG. 4 is a diagram of DC cycling characteristics of an island memristive functional layer device implemented in accordance with the present invention;
fig. 5 is a threshold voltage uniformity diagram for an island memristive functional layer device implemented in accordance with the present invention.
The same reference numbers will be used throughout the drawings to refer to the same or like elements or structures, wherein:
the electrode is characterized in that 1 is a bottom electrode, 2 is a selenide layer, 3 is an oxidation product layer, 4 is a trigonal crystal cluster of selenium, 5 is a two-dimensional material layer, 6 is a top electrode, and 7 is an oxygen vacancy conductive filament.
Detailed Description
In order to make the objects, technical solutions and advantages of the present invention more apparent, the present invention is described in further detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention.
The memristor is a microelectronic device with more applications, the requirements of the existing applications on the consistency and synaptic linearity of a memristor storage device are higher and higher, and the problems of higher operating voltage and discrete distribution exist when the on-off of most memristors is random.
In order to solve the problems, the invention provides an island-shaped low-resistance-path memristor functional layer material, a memristor and a preparation method. The following is a more detailed description with reference to specific examples.
Fig. 1 is a structural diagram of a device including an entire functional layer of an island-shaped crystal implemented according to the present invention, and fig. 2 is a sectional diagram of HRTEM of an actual device implemented according to the present invention, which is known from the two diagrams, and includes a top electrode 6, a bottom electrode 1, a selenide layer 2 (the selenide layer is also a first two-dimensional material layer that is peeled and transferred), an oxide product layer 3 (the oxide product layer is also a functional layer with memristive properties formed after an oxidation annealing process), and a two-dimensional material layer 5 (i.e., a second two-dimensional material layer that is peeled and transferred), where the bottom electrode 1 is disposed on the selenide layer, the two-dimensional material layer is stacked on the oxide product layer, the top electrode is disposed on the two-dimensional material layer, and the two-dimensional material layer is used to improve the contact characteristics between the oxide product layer and the top electrode, so as to form ohmic contact. The selenide layer and the oxidation product layer are tightly stacked to form a whole, and the oxidation product layer is obtained by in-situ oxidation of selenide on the selenide layer. The oxidation product layer is provided with selenium trigonal crystal clusters 4, the selenium trigonal crystal clusters 4 are dispersedly arranged in island shapes in the oxidation product layer, the selenium trigonal crystal clusters are located on the surface of the oxidation product layer and are far away from the non-oxidized residual selenide part, and the oxygen vacancy conductive filaments 7 are communicated with the selenium trigonal crystal clusters and the non-oxidized residual selenide part. The thicknesses of the selenide layer, the oxide product layer and the two-dimensional material layer have a relative size relationship, wherein the selenide layer and the oxide layer are originally an integral body, the total thickness of the integral body is slightly thinner than that of the upper two-dimensional material layer, the thickness of the selenide layer is within the range of 5-10 nm, and the thickness of the oxide layer is larger than that of the selenide layer, generally about twice as large (close to twice as large in the example depending on the degree of oxidation). The thickness of the two-dimensional material layer is generally slightly greater than the sum of the thicknesses of the underlying selenide layer and the oxide layer.
In one embodiment of the invention, the selenide in the selenide layer is selenide of a metal element of the fourth, fifth and sixth subgroups, and the selenide of the metal element of the fourth, fifth and sixth subgroups has good metallicity so as to establish ohmic contact between the oxide product layer and an external electrode. Selenides of the fourth, fifth and sixth subgroup metal elements all form selenium atom clusters in the oxidation process, and the selenium atom clusters are used as raw materials for subsequently forming the trigonal crystal clusters of selenium. The trigonal crystalline clusters of selenium have a higher conductivity than the oxidized product layer and the amorphous selenium clusters.
The method comprises five key steps, specifically as follows:
s1: a bottom electrode is prepared on a substrate,
s2: disposing selenide on the bottom electrode prepared in step S1, forming a selenide layer,
s3: and performing oxidation annealing on the selenide layer, specifically, annealing at 90-110 ℃ in the atmosphere for 30-60 min, and oxidizing the surface of the selenide layer to obtain an oxidized product layer, wherein the oxidized product layer contains selenium atom clusters and oxides of metal elements of a fourth, a fifth and a sixth subgroup.
And then, heating to 180-220 ℃, annealing for 8-12 min in a vacuum environment to obtain an oxidation product layer, partially evaporating selenium atom clusters on the surface of the oxidation product layer, and reserving partial selenium atom clusters in the oxides of the fourth, fifth and sixth subgroup metal elements.
S4: a two-dimensional material layer is disposed on the oxidation product layer,
s5: a top electrode is prepared on the two-dimensional material layer.
With respect to the method of making the entire memristor containing island-like crystals, further details are provided below in connection with more specific examples.
Example 1
FIG. 3 is a flow chart of the overall memristor of the crystalline body in the embodiment of the present invention, and it can be seen from the figure that the overall process is roughly divided into five steps, which will be described in turn below.
In the first step, a bottom electrode is prepared on a silicon substrate for subsequent two-dimensional material transfer. Specifically, the substrate is a Si substrate with a 300nm silicon oxide epitaxial layer, and the Si substrate is cleaned by acetone, ethanol and deionized water, and AZ5214 photoresist is dripped on a silicon wafer, spin-coated by a spin coater, and then placed on a 97 ℃ hot plate for pre-baking for two minutes. Then, photolithography was performed, and the electrode pattern on the mask was transferred onto the photoresist, and the pre-exposure time was 1.2 seconds. Then, the silicon wafer subjected to the above treatment was placed on a hot plate at 115 ℃ for post exposure for 2 minutes. The wafer was then placed under a lithography machine for post exposure, taking 12 seconds. Then developing with AZ5214 special developer for 30 seconds to obtain the expected pattern, finally metalizing by electron beam evaporation, and stripping the redundant metal to obtain the bottom electrode. It should be noted that the bottom electrode may not be too thick, generally less than 40nm, and too thick may affect the transfer of the two-dimensional material, which is not favorable for the device fabrication. After this step, a bottom electrode corresponding to number 1 in fig. 1 is formed, which is typically an electrode material containing an adhesion layer to avoid peeling off.
In the second step, a two-dimensional material transfer is performed, the material used in the present invention being 1T-TiSe2，TiSe21T-TiSe with various crystal forms2Is TiSe2The metal oxide selenide obtained by oxidation is regarded as the material system, and actually, selenides of the fourth, fifth and sixth sub-group metal elements form selenium atom clusters in the oxidation process, and oxidation products of the selenides of the fourth, fifth and sixth sub-group metal elements also have the metal property.
Specifically, a purchased two-dimensional material single crystal bulk is mechanically peeled to obtain single crystal TiSe of 20nm or less2Film, then spot-transferring using a metallographic microscope, in order to transfer the filmAnd moving to the position of the bottom electrode prepared previously, namely a 3-micron wide metal strip electrode tip part. Through this step, the first two-dimensional material corresponding to number 2 in fig. 1 is formed, which is also a selenide layer, and the selenide layer two-dimensional material plays two roles, first having good metallic properties to establish ohmic contact between the functional layer and the electrode, and second being oxidized to form TiO2And a functional layer.
The third step is to perform oxidation annealing, specifically, the oxidation annealing conditions used in this embodiment are annealing at 100 ℃ for 45 minutes in an atmospheric environment, then heating to 200 ℃ and annealing for 10 minutes in a vacuum environment. The first step is to oxidize the surface layer of the two-dimensional thin film material transferred to the bottom electrode to obtain a corresponding oxide layer with memristive characteristics, wherein the oxide layer is also a functional layer. The second step is to evaporate the Se clusters of the oxidation product layer, which are widely present in the surface and van der waals layers, and annealing under vacuum conditions can evaporate these Se clusters. However, this process is not completely carried out, and a small fraction of Se clusters is still present in the TiO formed by oxidation2This step is also a preparation for the subsequent formation of island-like crystals. Through this step, an oxide product layer corresponding to the part 3 in FIG. 1, in this example TiO, is formed2The functional layer of (1), but other oxides corresponding to metal selenides with memristive characteristics can be used as the functional layer material.
And fourthly, transferring the two-dimensional film material on the two-dimensional material subjected to the oxidation annealing treatment again, wherein the two-dimensional material layer corresponding to the part 5 in the figure 2 is formed by the transfer preparation method. The step is to improve the contact characteristic of the lower layer functional layer material and the upper electrode, and the step is 1T-TiSe2Is metallic, which forms an ohmic contact and also facilitates the subsequent electrical operation to induce the formation of island-like crystals, in particular as a seed layer for the subsequent trigonal clusters 4 of selenium, i.e. island-like crystals, as can be seen in FIG. 3, which are always in TiO2And 1T-TiSe2Is formed at the contact interface.
And fifthly, manufacturing a top electrode to form a Crossbar structure and form a complete memristor. The steps are the same as the bottom electrode manufacturing steps, and only the thickness of the electrode does not have strict requirements, and the method is suitable. Through this step, the top electrode corresponding to number 6 in fig. 2 is formed.
In the invention, the formation of the trigonal crystal cluster 4 of selenium needs to be induced by electric operation, which is also called as a forming process, and the specific flow is as follows: firstly, applying a positive voltage with a downward electric field direction between a top electrode and a bottom electrode of a device, wherein the voltage intensity is gradually increased from small to large, a common forming voltage range, namely 1.8V-2.5V, is given according to multiple experimental data of a plurality of devices, meanwhile, a forward current limit value is required to be applied to the device, generally 100 muA is given, after the threshold voltage is reached, the current passing through the device is sharply increased, the resistance of the device is sharply reduced, after the phenomenon occurs, the electric induction operation of the device is considered to be successful, and at the moment, a trigonal crystal cluster of selenium is formed in an oxide layer of the device. The formation of oxygen vacancy conducting filaments also requires electrical operation, and the specific flow is as follows: after the electrical induction operation is successfully performed, and when the cyclic operation is performed again, a forward voltage smaller than the forming voltage is applied to the device, the forward voltage value when the device resistance suddenly changes and the current sharply increases is the forward threshold voltage, a common range of forward threshold voltage values is given here based on multiple experimental data for a number of devices, namely 0.7 to 1.2V, after the threshold voltage is reached, oxygen atoms obtain electrons to form oxygen vacancies at the position where the trigonal crystals of the selenium exist in the oxide layer, the oxygen vacancies move towards one end close to the top electrode in a negative charge mode, a conductive path of the oxygen vacancies is formed from top to bottom, that is, the oxygen vacancy conductive filament, when a reverse voltage is applied, the oxygen vacancy is forced to move toward the bottom electrode, and when a threshold voltage is reached, a conductive path formed by the oxygen vacancy is broken, at which time the current of the device is sharply reduced, and the resistance returns to a high-resistance state.
Test example:
fig. 4 is a direct current cycle characteristic diagram of an island-shaped memristive functional layer device implemented according to the present invention, and as shown in fig. 4, the direct current cycle electrical characteristics of the memristive device prepared according to the above process conditions are directly seen, and the consistency of the threshold voltage is good. FIG. 5 is a graph of the threshold voltage uniformity of an island memristive functional layer device implemented according to the present invention, as shown in FIG. 5, the median of the set voltage is 0.84V, the fluctuation range is 0.12V, and the median of the reset voltage is-0.504V, the fluctuation range is 0.144V, which is very small.
Example 2
This example differs from example 1 in that:
the third step: and performing oxidation annealing on the selenide layer, annealing for 30min at 90 ℃ in the atmosphere, then, annealing for 8min at 180 ℃ in a vacuum environment to obtain an oxide product layer.
Example 3
This example differs from example 1 in that:
the third step: and performing oxidation annealing on the selenide layer, annealing for 60min at 90 ℃ in the atmosphere, then, heating to 220 ℃, and annealing for 12min in a vacuum environment to obtain an oxide product layer.
Example 4
The third step: and performing oxidation annealing on the selenide layer, annealing for 46min at 105 ℃ in the atmosphere, then, heating to 201 ℃, and annealing for 10min in a vacuum environment to obtain an oxide product layer.
Example 5
The third step: and performing oxidation annealing on the selenide layer, annealing at 98 ℃ for 39min in the atmosphere, then, heating to 190 ℃, and annealing for 9min in a vacuum environment to obtain an oxide product layer.
The invention prepares the TiSe through a plurality of process steps2-TiO2-TiSe2In the functional layer, the generation of crystalline t-Se, referred to as "islands" for short, is induced, compared with the previous single TiO2The functional layer is introduced with low-resistance crystals, and the formation of the oxygen vacancy low-resistance path can be controlled at fixed points. Mechanistically, it can be understood that TiO is used in the forming process2The amorphous Se cluster in the layer is crystallized into t-Se single crystal and exists as islands in TiO2In the layer, memoryTiSe in which oxygen vacancy conductive filaments in the resistive cycle are formed in place on the islands and underlying layers2Because these islands provide a low resistance path for the formation of the conductive filament, the conductive filament is specifically present at the sites of these islands, exhibiting stability of the threshold voltage. The 'island' of t-Se in the functional layer prepared by the invention has obvious effects on improving the consistency of devices and realizing lower threshold voltage.
It will be understood by those skilled in the art that the foregoing is only a preferred embodiment of the present invention, and is not intended to limit the invention, and that any modification, equivalent replacement, or improvement made within the spirit and principle of the present invention should be included in the scope of the present invention.
Claims (10)
1. An island-shaped low-resistance path memristive functional layer material is characterized by comprising a selenide layer and an oxidation product layer obtained by in-situ oxidation of selenide on the selenide layer, wherein the selenide layer and the oxidation product layer are tightly stacked to form a whole, the selenide in the selenide layer is selenide of metal elements of a fourth subgroup, a fifth subgroup and a sixth subgroup, trigonal crystal clusters of selenium are arranged in the oxidation product layer in an island-shaped dispersing mode, the trigonal crystal clusters of selenium are located on the surface of the oxidation product layer and are far away from the residual selenide part which is not oxidized, and oxygen vacancy conductive filaments are communicated with the trigonal crystal clusters of selenium and the residual selenide part which is not oxidized.
2. An island low resistance channel memristive functional layer material as claimed in claim 1, wherein selenides of metals of fourth, fifth and sixth subgroup have good metallic properties to establish ohmic contact between the oxide product layer and the external electrode.
3. An island low-resistance memristive functional layer material according to claim 2, wherein the trigonal crystalline clusters of selenium have higher conductivity than the oxidized product layer and the amorphous selenium clusters.
4. An island-shaped low-resistance functional layer material as claimed in claim 3, wherein selenides of the metal elements of the fourth, fifth and sixth subgroups form selenium atom clusters during oxidation, and the selenium atom clusters are used as raw materials for forming trigonal crystal clusters of selenium subsequently.
5. A memristor comprising an island-like low-resistance-path memristive functional layer material according to any of claims 1 to 4, comprising a top electrode, a bottom electrode, a selenide layer, an oxide product layer, and a two-dimensional material layer, the bottom electrode being disposed on the selenide layer, the two-dimensional material layer being laminated on the oxide product layer, the top electrode being disposed on the two-dimensional material layer, the two-dimensional material layer being for improving contact characteristics of the oxide product layer with the top electrode to form an ohmic contact.
6. A memristor comprising an island-shaped low-resistance-path memristive functional layer material according to claim 5, wherein the two-dimensional material layer is made of the same material as the selenide layer, and is selenide of metal elements of the fourth, fifth and sixth subgroups.
7. A memristor comprising an island low-resistance-pathway memristive functional layer material according to claim 5, wherein the thicknesses of the selenide layer, the oxide product layer, and the two-dimensional material layer have relative size relationships: the selenide layer and the oxidation product layer are an integral body, the total thickness of the integral body is slightly thinner than that of the two-dimensional material layer, the thickness of the selenide layer is 5 nm-10 nm, and the thickness of the oxidation product layer is larger than that of the selenide layer.
8. A method of making a memristor according to any of claims 5-7, comprising the steps of:
s1: a bottom electrode is prepared on a substrate,
s2: disposing selenide on the bottom electrode prepared in step S1, forming a selenide layer,
s3: performing oxidation annealing on the selenide layer, specifically, annealing at 90-110 ℃ in the atmosphere for 30-60 min, then heating to 180-220 ℃, annealing in the vacuum environment for 8-12 min to obtain an oxide product layer,
s4: a two-dimensional material layer is disposed on the oxidation product layer,
s5: a top electrode is prepared on the two-dimensional material layer.
9. The method for preparing the memristor according to claim 8, wherein in step S3, annealing is performed at 90-110 ℃ in an atmospheric atmosphere for 30-60 min, and the surface of the selenide layer is oxidized to obtain an oxide product layer, wherein the oxide product layer contains selenium atom clusters and oxides of the fourth, fifth and sixth subgroup metal elements.
10. The method for preparing the memristor according to claim 9, wherein in step S3, the temperature is raised to 180 ℃ to 220 ℃, annealing is performed for 8min to 12min in a vacuum environment, the selenium atom clusters adjacent to the surface in the oxidation product layer are partially evaporated, and part of the selenium atom clusters in the oxides of the fourth, fifth and sixth subgroup metal elements are retained.
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