CN114203918B - Novel photoelectric memristor based on PVK/ZnO heterostructure - Google Patents

Abstract

The invention discloses a new photoelectric memristor based on PVK/ZnO heterostructure. The new photoelectric memristor includes from bottom to top: silicon substrate, tungsten electrode layer, zinc oxide layer, polyvinyl carbide azole layer and aluminum electrode. The present invention can introduce a zinc oxide functional layer with high stability and high electron mobility on the basis of the traditional PVK photomemristor to improve the stability and repeatability of the PVK photomemristor.

Description

A new photomemristor based on PVK/ZnO heterostructure

Technical field

The invention belongs to the field of semiconductor technology, and specifically relates to a new photoelectric memristor based on PVK/ZnO heterostructure.

Background technique

Memristor is a nonlinear resistor. The resistance of the device can change with changes in input (current or voltage), and the charge or magnetic flux flowing through the device is memorized through changes in resistance. By introducing light control signals, the pure electronic component memristor can be improved into a photoelectric memristor to better simulate the synapses in the visual system, which will further promote the rapid development of brain-like neural computing in artificial intelligence.

PVK (polyvinylcarbazole) is a common organic material. Compared with other organic materials, it is more suitable for preparing organic photoelectric memristors. However, it is limited by the unclear resistance transformation mechanism of organic substances and poor material stability. Problems such as poor stability and low repeatability. Traditional PVK photomemristors have poor repeatability, unstable high- and low-resistance state transitions, and are sensitive to temperature changes.

Contents of the invention

In order to solve the above problems existing in the prior art, the present invention provides a new photoelectric memristor based on PVK/ZnO heterostructure. The technical problems to be solved by the present invention are achieved through the following technical solutions:

A new photoelectric memristor based on PVK/ZnO heterostructure. The new photoelectric memristor includes from bottom to top: silicon substrate, tungsten electrode layer, zinc oxide layer, polyvinyl carbazole layer and aluminum electrode.

In one embodiment of the present invention, the aluminum electrode includes a first aluminum electrode, a second aluminum electrode and a third aluminum electrode; the first aluminum electrode, the second aluminum electrode and the third aluminum electrode are located in sequence from left to right. The upper surface of the polyvinylcarbazole layer.

In one embodiment of the present invention, the thickness of the zinc oxide layer is 20 nm.

Beneficial effects of the present invention:

Based on the traditional PVK photoelectric memristor, the present invention introduces a zinc oxide functional layer with high stability and high electron mobility, which can improve the memristor performance of the PVK photoelectric memristor.

The present invention will be further described in detail below with reference to the accompanying drawings and examples.

Description of drawings

Figure 1 is a schematic structural diagram of a traditional PVK photomemristor;

Figure 2 is a schematic structural diagram of a new photomemristor with a PVK/ZnO heterostructure provided by an embodiment of the present invention;

Figure 3 is a schematic diagram of the formation and breakage of metal conductive wires in a zinc oxide material provided by an embodiment of the present invention;

Figure 4 is a schematic diagram of the test results of a traditional PVK photomemristor provided by an embodiment of the present invention;

Figure 5 is a schematic diagram of the test results of a new photomemristor with a PVK/ZnO heterostructure provided by an embodiment of the present invention.

Explanation of reference symbols:

Silicon substrate 1, tungsten electrode layer 2, zinc oxide layer 3, polyvinyl carbazole layer 4, first aluminum electrode 51, second aluminum electrode 52, and third aluminum electrode 53.

Detailed ways

The present invention will be described in further detail below with reference to specific examples, but the implementation of the present invention is not limited thereto.

See Figure 1, which is a schematic structural diagram of a traditional PVK photomemristor. Traditional PVK photomemristors have poor repeatability, unstable high- and low-resistance state transitions, and are sensitive to temperature changes. To address this problem, the present invention proposes a new photomemristor based on a PVK/ZnO heterostructure based on the traditional PVK photomemristor.

Embodiment 1

Please refer to Figure 2. Figure 2 is a schematic diagram of a new photomemristor based on PVK/ZnO heterostructure provided by an embodiment of the present invention. The new photomemristor includes from bottom to top:

Silicon substrate 1, tungsten electrode layer 2, zinc oxide layer 3, polyvinyl carbazole layer 4 and aluminum electrode 5.

When the photoelectric memristor is working, in order to ensure that the surface of the photoelectric material is not blocked and to maximize the photoelectric performance of the memristor, the new photoelectric memristor based on the PVK/ZnO heterostructure proposed by the present invention is The PVK layer is provided on top of the zinc oxide layer.

The zinc oxide (ZnO) layer can also be called a zinc oxide functional layer; the polyvinylcarbazole (PVK) layer can also be called a polyvinylcarbazole functional layer. The polyvinyl carbazole layer is a thin film.

It should be noted that the lattice structure of transition metal oxides represented by zinc oxide is dense and uniform, showing extremely strong stability, and its high melting point (melting point of zinc oxide m.p. = 1975°C) indicates that its performance is basically not affected by temperature. Impact of change. As a wide band gap semiconductor, zinc oxide has unipolar resistance switching behavior and high electron mobility. It also has high transparency and excellent room temperature luminescence properties.

During the electrical initialization process of zinc oxide, oxygen ions have a higher mobility than zinc ions. Under the action of external electric field and thermal effect, oxygen ions migrate to the anode, leaving oxygen vacancies. As the applied voltage increases, the oxygen vacancies near the cathode Gradually gather, the electrons provided by the external bias voltage balance the internal charge of the material. When the oxygen vacancy concentration increases to a certain value, the oxygen vacancies near the electrode are rearranged to form an ordered conductive crystalline zinc wire (made of Zn and ZnO _{1- x} together), the metal conductive filament will further enhance the electric field, causing it to grow continuously in the same area. At this time, the material appears in a low-resistance state. When the external bias voltage reaches a certain value, the conductive filament grows to connect the upper and lower electrodes. At this time, the electric field in the zinc oxide begins to decrease, and the migration of oxygen ions caused by the electric field leaves oxygen vacancies. The process is suppressed, and the high temperature near the anode is The concentration of oxygen ions will quickly backfill to the oxygen vacancies. The Joule heat generated by the oxygen ion backfill and the accumulation of external electric field will work together on the conductive filaments, causing the conductive filaments to break and decompose, and the material will show a high resistance state. Please refer to Figure 3. Figure 3 is a schematic diagram of the formation and fracture of metal conductive filaments in a zinc oxide material provided by an embodiment of the present invention. It can be seen from the memristive mechanism of the zinc oxide material that the formation and fracture process of the internal conductive filaments are It is clear that the memristive mechanism is stable. Taking into account the material characteristics and memristor mechanism, zinc oxide memristors have better stability, can be repeated more times, and are less sensitive to temperature changes than organic material memristors.

Based on the above mechanism, the present invention combines PVK with zinc oxide to realize a new photomemristor based on PVK/ZnO heterostructure.

Optionally, the aluminum electrode 5 includes a first aluminum electrode 51 , a second aluminum electrode 52 and a third aluminum electrode 53 .

The first aluminum electrode, the second aluminum electrode and the third aluminum electrode are located on the upper surface of the polyvinylcarbazole layer in order from left to right.

In order to reduce the impact of the aluminum electrode on the optoelectronic material, the aluminum electrode of the present invention needs to be as small as possible without affecting the conductive performance.

Optionally, the thickness of the zinc oxide layer is 20 nm.

It should be noted that the thickness of the zinc oxide layer can be set by those skilled in the art according to business needs. After many experiments and verifications, the thickness of the zinc oxide layer in the present invention is preferably 20 nm.

In summary, the present invention introduces a zinc oxide functional layer with high stability and high electron mobility based on the Al/PVK/W/Si structure photomemristor, which can improve the stability and reliability of the PVK photomemristor. Repeatability, etc.

Further, based on experimental tests, the beneficial effects of the present invention are verified.

Using the I-V test probe station PSM-1000, the top electrode (aluminum electrode) and the bottom electrode (silicon substrate) are energized with probes under a microscope to perform the I-V test. See Figure 4 which is a traditional PVK provided by the embodiment of the present invention. Schematic diagram of photomemristor test results; see Figure 5 which is a schematic diagram of test results of a new photomemristor with a PVK/ZnO heterostructure provided by an embodiment of the present invention.

It can be seen from Figure 4 and Figure 5 that both PVK photoelectric memristors exhibit obvious memristive characteristic curves, and although the introduction of the zinc oxide functional layer will increase the thickness of the functional layer between the electrodes, it does not cause The reduction in operating current in the new PVK photomemristor is due to the high electron mobility of the zinc oxide material. Comparing Figure 4 and Figure 5, it can be seen that the results of five repeated scans show that the repeatability and stability of the new PVK photomemristor proposed by the present invention are greatly improved compared to the traditional PVK photomemristor. The calculation results of the current error value show that the use of zinc oxide functional layer reduces the error current in the memristor by an order of magnitude, which is consistent with our expected results, that is, by introducing zinc oxide with a clear memristor mechanism and high stability The material can solve the problems of traditional organic photomemristors such as poor repeatability, unstable high- and low-resistance state transitions, and sensitivity to temperature changes.

Embodiment 2

The present invention provides a method for preparing a new photoelectric memristor based on PVK/ZnO heterostructure. The preparation method includes:

Step 1: On the upper surface of the silicon substrate layer, obtain a tungsten electrode layer through deposition.

Optionally, step 1 includes:

Using magnetron sputtering equipment, a deposition process is performed on the upper surface of the silicon substrate layer to obtain a tungsten electrode layer.

For example, the magnetron sputtering equipment is MSP-3470x.

Step 2: According to the preset sputtering parameters, obtain a zinc oxide layer on the upper surface of the tungsten electrode layer through sputtering treatment.

Optionally, the preset sputtering parameters include a preset target material, a preset sputtering time, and a preset sputtering power.

Optionally, the preset target material is: a ZnO ceramic target with a purity of 99.99%; the preset sputtering time is 30 minutes; and the preset sputtering power is 77W.

The present invention can flexibly control the internal characteristics of the sputtered film by presetting sputtering parameters. For example, by changing the preset sputtering time, the thickness of the zinc oxide layer can be changed.

Step 3: On the upper surface of the zinc oxide layer, obtain a polyvinylcarbazole layer by baking and annealing.

Optionally, step 3 includes:

Step 3-1: Spin-coat the polyvinylcarbazole solution dissolved in 1,2-dichloroethane on the upper surface of the zinc oxide layer.

Step 3-2: Bake the zinc oxide layer after spin coating.

Step 3-3: Perform annealing treatment on the baked zinc oxide layer to obtain a polyvinylcarbazole layer on the upper surface of the zinc oxide layer.

Step 4: On the upper surface of the polyvinyl carbazole layer, an aluminum electrode is obtained by sputtering with a metal mask to complete the preparation of the memristor.

The new photoelectric memristor based on the PVK/ZnO heterostructure prepared by the present invention can be deposited on a bare silicon substrate using magnetron sputtering equipment MSP-3470x. The zinc oxide functional layer can be deposited on a bare silicon substrate by changing the magnetron sputtering equipment. The target material, sputtering time and sputtering power were prepared on the tungsten electrode, and then the PVK solution dissolved in 1,2-dichloroethane was spin-coated on the upper surface of ZnO, baked to form a film and then annealed. A dense PVK film is obtained. Finally, an aluminum electrode is sputtered and deposited using a metal mask to complete the preparation of the photomemristor.

In summary, the present invention, based on the traditional PVK photomemristor, introduces a zinc oxide functional layer with high stability and high electron mobility, which can improve the memristive performance of the PVK photomemristor.

The above content is a further detailed description of the present invention in combination with specific preferred embodiments, and it cannot be concluded that the specific implementation of the present invention is limited to these descriptions. For those of ordinary skill in the technical field to which the present invention belongs, several simple deductions or substitutions can be made without departing from the concept of the present invention, and all of them should be regarded as belonging to the protection scope of the present invention.

Claims (7)

1. A method for preparing a photomemristor based on PVK/ZnO heterostructure, characterized in that the preparation method includes: Step 1: Obtain a tungsten electrode layer through deposition on the upper surface of the silicon substrate layer; Step 2: According to the preset sputtering parameters, obtain a zinc oxide layer on the upper surface of the tungsten electrode layer through sputtering treatment; Step 3: On the upper surface of the zinc oxide layer, obtain a polyvinylcarbazole layer by baking and annealing; Step 4: On the upper surface of the polyvinyl carbazole layer, obtain an aluminum electrode through sputtering treatment with a metal mask to complete the preparation of the memristor; The step 3 includes: Spin-coat a polyvinylcarbazole solution dissolved in 1,2-dichloroethane on the upper surface of the zinc oxide layer; Baking the zinc oxide layer after spin coating; The baked zinc oxide layer is annealed to obtain a polyvinylcarbazole layer on the upper surface of the zinc oxide layer. 2. The method according to claim 1, characterized in that said step 1 includes: Using magnetron sputtering equipment, a deposition process is performed on the upper surface of the silicon substrate layer to obtain a tungsten electrode layer. 3. The method of claim 1, wherein the preset sputtering parameters include a preset target material, a preset sputtering time, and a preset sputtering power. 4. The method according to claim 3, wherein the preset target material is a ZnO ceramic target with a purity of 99.99%; the preset sputtering time is 30 minutes; and the preset sputtering power is 77W. 5. A photomemristor based on PVK/ZnO heterostructure prepared by the method as claimed in any one of claims 1 to 4, characterized in that the photomemristor includes from bottom to top: Silicon substrate, tungsten electrode layer, zinc oxide layer, polyvinyl carbazole layer and aluminum electrode. 6. The photomemristor according to claim 5, wherein the aluminum electrode includes a first aluminum electrode, a second aluminum electrode and a third aluminum electrode; The first aluminum electrode, the second aluminum electrode and the third aluminum electrode are located on the upper surface of the polyvinylcarbazole layer in order from left to right. 7. The photomemristor according to claim 5, wherein the thickness of the zinc oxide layer is 20 nm.