A Cu-doped Ti x O y thin-film memristor and preparation method

Abstract

The present invention provides a preparation method of a Cu-doped TiO thin film memristor, belonging to the field of semiconductor thin films. The memristor includes a substrate, a lower electrode, a resistive switching layer, and an upper electrode from bottom to top. The material of the resistive switching layer is TiO doped with Cu. x O y The reason for doping Cu into the TiO thin film is that as a transition metal, the ionic radius of Cu is close to that of Ti ions in TiO. After doping Cu into TiO, the energy band of TiO can contain the energy band edge of Cu, which is beneficial to capturing the photo-generated electrons excited by TiO, x O y thus changing the performance of the TiO thin film memristor. The memristor prepared by this method has the advantages of stable performance and good repeatability, and has good application prospects in the future field of semiconductor thin films. x O y -Cu z thin film. x O y In the TiO thin film, doping with Cu is because as a transition metal, the ionic radius of Cu is close to that of Ti ions in TiO. x O y After doping Cu into TiO, x O y the energy band of TiO can contain the energy band edge of Cu, which is beneficial to capturing the photo-generated electrons excited by TiO, x O y thus changing the performance of the TiO thin film memristor. x O y This method of preparing a memristor has the advantages of stable performance and good repeatability, and has good application prospects in the future field of semiconductor thin films. x O y ​

Description

Technical Field

[0001] The present invention relates to the field of semiconductor thin film devices, and particularly to a Cu-doped Ti x O y thin film memristor and a preparation method thereof. Background Art

[0002] Professor Chua first proposed the concept of memristor in 1971. As the fourth basic component, a memristor is a two-terminal element with memory characteristics. In the nearly three decades since Professor Chua proposed the concept of memristor, due to the lack of corresponding physical verification in reality, memristors have not received sufficient attention in the scientific community. It wasn't until 2008 that HP Labs first fabricated a physical model of a memristor, linking the physical device with the concept of memristor for the first time. Since then, due to the potential application value of memristors, it has greatly stimulated researchers' enthusiasm for researching memristors and their applications.

[0003] A memristor is a new type of circuit element with a simple structure, high storage density, low power consumption, and high reading speed. At the same time, memristors can simulate the synaptic characteristics in biological nervous systems, thus being pursued by researchers in various countries. While scientists in various countries have improved the read / write times and the timeliness of information storage of memristors, they have also conducted in-depth research on the working principle of memristors. During the experiment, researchers have made a large number of attempts to find a simpler preparation method and more stable experimental results. Currently, the methods for preparing memristors include: vacuum sputtering, chemical vapor deposition, molecular beam epitaxy, electrodeposition, hydrothermal method, etc. In recent years, memristors have become a new research direction in the fields of materials science, biological science, and physics. When neurons are replaced by memristors, the computing rate of artificial neural networks can be faster and more efficient. Therefore, memristors have more advantages among many neuron synapse simulation devices, laying the foundation for a new generation of computer revolution. The emergence of memristors has provided new alternatives for electronic devices, making them smaller and significantly improving the computing rate of computers. Although the application prospects of memristors are very broad and there is a lot of research on memristors, there are still many problems to be solved to realize the industrialization of memristors, such as high requirements for preparation processes, long preparation cycles, unstable performance, etc. Summary of the Invention

[0004] To solve the above technical problems, the present invention provides a preparation method for a memristor with a simple method and stable performance. The specific content of the invention is as follows: A Cu-doped Ti x O y thin film memristor, which is sequentially provided with a substrate, a lower electrode, a resistive switching layer, and an upper electrode from bottom to top. The material of the resistive switching layer is Cu-doped Ti x O y of Ti x O y-Cu z thin film, in Ti x O y -Cu z where 1 < x < 5, 2 < y < 7, 0.2 < z < 0.6.

[0005] Preferably, the materials of the lower electrode and the upper electrode are any one of a single-layer metal electrode layer, a conductive non-metal layer, and a double-layer composite electrode layer, and the substrate is any one of polished glass, a silicon wafer, and conductive glass.

[0006] Preferably, the single-layer metal electrode material is any one of Cu, Ag, Au, Pt, Al, Ti, and Zn; the conductive non-metal layer material is C; the double-layer composite electrode layer material is any one of Cu / Ti, Au / Ti, C / Au, and Au / Cu.

[0007] Preferably, the lower electrode uses an Au / Ti composite electrode and the upper electrode uses a C / Au composite electrode.

[0008] Preferably, the thickness of the lower electrode is 100 nm to 200 nm, and the thickness of the upper electrode is 20 nm to 100 nm.

[0009] Preferably, the thickness of the resistive switching layer is 100 nm to 700 nm.

[0010] A preparation method of a Cu-doped Ti x O y thin film memristor, characterized by comprising the following steps:

[0011] S1. Clean the substrate: Wash and dry the substrate for later use;

[0012] S2. Grind the Ti target, TiO 2-x target, C target, and Cu target: Grind with sandpaper and set aside;

[0013] S3. Prepare the Au thin film: Use an ion coater and deposit the Au thin film on the substrate with the Au target as the sputtering source;

[0014] S4. Prepare the Au / Ti composite electrode: Adopt the DC sputtering method: Use the Ti target as the sputtering source and sputter-deposit the Ti thin film on the Au thin film to form the Au / Ti composite electrode;

[0015] S5. Prepare the Ti x O y thin film layer: Adopt the RF sputtering method and deposit the Ti 2-x O x thin film on the Au / Ti composite electrode with the TiO y target as the sputtering source;

[0016] S6. Annealing treatment: Prepare Ti x O y After the film is prepared, the pressure in the chamber is not released and it is cooled for 1 hour;

[0017] S7. Prepare Cu-doped Ti x O y film: Use a Cu target as the sputtering source and incorporate the generated Ti x O y film with Cu;

[0018] S8. Prepare C film: Adopt radio frequency sputtering method, use a C target as the sputtering source, and deposit a C film on the Cu-doped Ti x O y film;

[0019] S9. Prepare C / Au composite electrode: Use an ion plating instrument, use an Au target as the sputtering source, deposit an Au film on the C film to form a C / Au composite electrode.

[0020] In the above technical solution, the device of the memristor is (polished glass) / (Au / Ti composite electrode) / Cu-doped Ti x O y film / (C / Au composite electrode) structure.

[0021] Compared with the prior art, the advantages of the present invention are as follows:

[0022] In the present invention, Cu is incorporated into the Ti x O y film because as a transition metal, the ionic radius of Cu is close to that of Ti ions in Ti x O y . After incorporation, the energy band edge of Ti x O y can include the energy band edge of Cu ions, which is beneficial to capturing the photo-generated electrons excited by Ti x O y , thereby changing the performance of the Ti x O y film memristor;

[0023] The present invention provides a preparation method of a Cu-doped Ti x O y film memristor. This memristor has a simple structure, stable performance, good repeatability, and has good application prospects in the fields of computer science, biological science, neural network, electronic engineering, etc. Description of the Drawings

[0024] Figure 1 It is a Cu-doped Ti x O yFlow chart of the preparation method of the thin film memristor;

[0025] Figure 2 is a kind of Cu-doped Ti x O y Structure schematic diagram of the thin film memristor;

[0026] Figure 3 is a kind of Cu-doped Ti x O y Current-voltage (I-V) characteristic curve measured after the preparation of the Cu-doped TiO thin film memristor. Among them, Figure a shows the "8"-shaped curve with a Cu content of 0.2-0.3, Figure b shows the "8"-shaped curve with a Cu content of 0.2-0.3, Figure c shows the "8"-shaped curve with a Cu content of 0.2-0.3, and Figure d shows the "8"-shaped curve with a Cu content of 0.2-0.3.

[0027] In the figure, 1 - substrate; 2 - lower electrode; 3 - resistive switching layer; 4 - upper electrode. Specific implementation manners

[0028] The drawings are only for illustrative purposes; for better explaining this embodiment, some components in the drawings will be omitted, enlarged or reduced, and do not represent the size of the actual product or the actual up and down positions; for those skilled in the art, some well-known structures and their descriptions in the drawings may be omitted; the orientation or positional relationships indicated by the terms "upper", "lower", "top", "bottom", "inner", "outer", etc. are based on the orientation or positional relationships shown in the drawings, and are only for facilitating the description of the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore, should not be construed as a limitation of the present invention.

[0029] The following will be described in detail with reference to the drawings.

[0030] As Figure 1 shown, a flow chart of the preparation method of a Cu-doped TiO thin film memristor. In this embodiment, the substrate is polished glass, the lower electrode is an Au / Ti composite electrode, the resistive switching layer is a Cu-doped TiO x O y thin film; the upper electrode is a C / Au composite electrode. x O y thin film; the upper electrode is a C / Au composite electrode.

[0031] S1. Clean the substrate: Put the polished glass into distilled water, take it out and dry it after ultrasonic cleaning for 5 minutes, then wipe it with absolute ethanol and dry it again for standby.

[0032] S2. Grind the target: First, grind the Ti target and TiO with coarse sandpaper and fine sandpaper 2-xTarget materials, C target material and Cu target material, and then wipe their surfaces with lint-free cloth for standby.

[0033] S3. Prepare Au thin film: Use an ion plating instrument with the Au target material as the sputtering source, adjust the current of the ion plating instrument to be maintained at 6 mA to 9 mA, and sputter to obtain an Au thin film with a thickness of 20 nm to 40 nm.

[0034] S4. Prepare the lower electrode: Adopt the DC sputtering method with the Ti target material as the sputtering source, set the distance from the target material to the substrate to be 8 cm to 12 cm, evacuate the sputtering chamber vacuum to 2×10 -3 Pa, introduce Ar with a purity of 99.999% as the working gas, adjust the DC power to 80 w to 100 w, and the sputtering time to 5 min to 12 min, and deposit a Ti thin film with a thickness of 80 nm to 160 nm on the Au thin film to form an Au / Ti composite electrode.

[0035] S5. Prepare Ti x O y thin film: Adopt the RF sputtering method with the TiO 2-x target material as the sputtering source, set the distance from the target material to the substrate to be 8 cm to 15 cm, evacuate the sputtering chamber vacuum to 2×10 -3 Pa, introduce Ar with a purity of 99.999% as the working gas, adjust the DC power to 80 w to 120 w, and deposit a Ti x O y thin film on the surface of the lower electrode with a thickness of 100 nm to 700 nm.

[0036] S6. Annealing treatment: After S5 is completed, cool for 1 hour before proceeding to the next step. The purpose of this step is to make the generated Ti x O y thin film form better crystals.

[0037] S7. Prepare Cu-doped Ti x O y thin film: Adopt the RF sputtering method with the Cu target material as the sputtering source, set the distance from the target material to the substrate to be 8 cm to 15 cm, evacuate the sputtering chamber vacuum to 2×10 -3 Pa, introduce Ar with a purity of 99.999% as the working gas, adjust the DC power to 20 w to 50 w, and dope Cu into the Ti x O y thin film. Under this condition, when the Cu sputtering time is 35 s to 55 s, the Cu content is 0.2 to 0.3; when the Cu sputtering time is 60 s to 75 s, the Cu content is 0.3 to 0.4; when the Cu sputtering time is 80 s to 100 s, the Cu content is 0.4 to 0.5; when the Cu sputtering time is 120 s to 150 s, the Cu content is 0.5 to 0.6.

[0038] S8. Preparation of C thin film: Using radio frequency sputtering method, with a C target as the sputtering source, set the distance from the target to the substrate to be 8 cm to 15 cm, evacuate the sputtering chamber vacuum to 2×10 -3 Pa, introduce Ar with a purity of 99.999% as the working gas, adjust the DC power to 20 w to 50 w, and deposit a C thin film on the Cu-doped Ti x O y thin film, with a thickness of 10 nm to 20 nm.

[0039] S9. Preparation of C / Au composite electrode: Use an ion plating instrument, with a gold target as the sputtering source, adjust the current of the ion plating instrument to be maintained at 4 mA to 7 mA, sputter for 2 min, deposit an Au thin film on the C thin film, with a thickness of 10 nm to 80 nm, to form a C / Au composite electrode.

[0040] As Figure 2 shown, a structural schematic diagram of a Cu-doped Ti x O y thin film memristor is provided, which is sequentially arranged from bottom to top as a substrate 1, a lower electrode 2, a resistive switching layer 3, and an upper electrode 4. The resistive switching layer material is Ti x O y doped with Cu x O y -Cu z thin film, where 1 < x < 5, 2 < y < 7, and 0.2 < z < 0.6 in Ti x O y -Cu z .

[0041] The materials of the lower electrode and the upper electrode can be any one of a single-layer metal electrode layer, a conductive non-metal layer, and a double-layer composite electrode layer. The substrate can be any one of polished glass, a silicon wafer, and conductive glass.

[0042] The single-layer metal electrode material can be any one of Cu, Ag, Au, Pt, Al, Ti, and Zn; the conductive non-metal layer material can be C; the double-layer composite electrode layer material can be any one of Cu / Ti, Au / Ti, and Au / Cu.

[0043] The prepared Cu-doped Ti x O y thin film memristor has a lower electrode thickness of 100 nm to 200 nm, an upper electrode thickness of 20 nm to 100 nm, and a resistive switching layer thickness of 100 nm to 700 nm.

[0044] As Figure 3 shown is a prepared Cu-doped Ti x Oy The current-voltage (I-V) characteristic curves measured after the preparation of the thin-film memristor, where Figure a shows the figure-eight curve with a Cu content of 0.2 to 0.3, Figure b shows the figure-eight curve with a Cu content of 0.2 to 0.3, Figure c shows the figure-eight curve with a Cu content of 0.2 to 0.3, and Figure d shows the figure-eight curve with a Cu content of 0.2 to 0.3.

[0045] Those of ordinary skill in the art will realize that the embodiments shown here are to assist the reader in understanding the principles of the present invention, and it should be understood that the scope of protection of the present invention is not limited to such specific statements and embodiments. Those of ordinary skill in the art can make various other modifications in various aspects that do not depart from the essence of the present invention based on these technical revelations disclosed in the present invention, and these modifications are still within the scope of protection of the present invention.

Claims

1. A Cu-doped Ti x O y thin-film memristor, characterized in that From bottom to top, it is successively set as a substrate, a lower electrode, a resistive switching layer, and an upper electrode. The resistive switching layer material is Ti x O y Ti doped with Cu x O y -Cu z film. In Ti x O y -Cu z 1 < x < 5, 2 < y < 7, 0.2 < z < 0.6; the thickness of the lower electrode is 100 nm to 200 nm, the thickness of the upper electrode is 20 nm to 100 nm, and the thickness of the resistive switching layer is 100 nm to 700 nm.

2. A Cu-doped Ti x O y thin-film memristor, characterized in that The lower electrode and the upper electrode material can be any one of a single-layer metal electrode layer, a conductive non-metal layer, and a double-layer composite electrode layer, and the substrate can be any one of polished glass, a silicon wafer, and conductive glass.

3. A Cu-doped Ti x O y thin film memristor, characterized in that The single-layer metal electrode material can be any one of Cu, Ag, Au, Pt, Al, Ti, and Zn; the conductive non-metal layer material is C; the double-layer composite electrode layer material can be any one of Cu / Ti, Au / Ti, C / Au, and Au / Cu.

4. A Cu-doped Ti x O y thin film memristor, characterized in that The lower electrode uses an Au / Ti composite electrode, and the upper electrode uses a C / Au composite electrode.

5. A preparation method of a Cu-doped Ti x O y thin film memristor, characterized in that It includes the following steps: S1. Clean the substrate: Wash the substrate and dry it for standby. S2. Polish the Ti target, TiO 2-x Targets: Ti target, C target, and Cu target: Polish with sandpaper and set aside for later use; S3. Prepare the Au film: Use an ion coater, with the Au target as the sputtering source, to deposit the Au film on the substrate. S4. Prepare the Au / Ti composite electrode: Adopt the DC sputtering method: Use the Ti target as the sputtering source to sputter and deposit the Ti film on the Au film to form the Au / Ti composite electrode. S5. Preparation of TiO₂ thin film x O y thin film: Using radio frequency sputtering method, with TiO₂ target as the sputtering source, deposit TiO₂ thin film on the Au / Ti composite electrode 2-x ; x O y thin film S6. Annealing treatment: Prepare Ti x O y After the Ti O film is prepared, do not release the pressure in the cavity and cool for 1 hour; S7. Preparation of Cu-doped TiO₂ thin film: Using a Cu target as the sputtering source, doping the generated TiO₂ thin film with Cu; x O y film: Using a Cu target as the sputtering source, doping the generated TiO x O y film with Cu; S8. Preparation of C thin film: Using radio frequency sputtering method, with a C target as the sputtering source, deposit a C thin film on the Cu-doped Ti x O y thin film; S9. Prepare the C / Au composite electrode: Use an ion coater, with the Au target as the sputtering source, to deposit the Au film on the C film to form the C / Au composite electrode.

Images