Bismuth ferrite photoelectric device with adjustable current polarity and control method
By preparing bismuth ferrate-indium tin ferrate with adjustable current polarity on bismuth ferrate film samples, and regulating photocurrent with laser light sources of different wavelengths, the complexity of current polarity regulation of optoelectronic devices in the prior art and The problem of energy consumption achieves photocurrent polarity regulation with low power consumption and simple structure.
Patent Information
- Application Number
- CN202411110209.3
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- Filing Date
- 2024-08-14
- Publication Date
- 2024-12-24
- Estimated Expiration
- 2044-08-14
AI Technical Summary
Existing reconfigurable visual neural network sensors need to apply gate voltage to the gate dielectric layer or floating gate layer to update positive and negative weights, resulting in complex device structure and additional energy consumption. A new method is urgently needed to regulate the current pole of optoelectronic devices. sex.
By growing ITO electrodes on the surface of bismuth ferrate thin film samples, and undergoing oxygen plasma treatment and photolithography treatment, combined with ion beam etching and wet cleaning, a bismuth ferrate-indium tin oxide device with adjustable current polarity was prepared. A random function generator and laser light source are used to generate pulsed light of different wavelengths to achieve photocurrent regulation under zero bias voltage.
The photocurrent polarity flips and device structure optimization are achieved, reducing power consumption, avoiding additional energy consumption and complex structures, and no need for applied voltage.
Smart Images
Figure CN118647256B_ABST
Abstract
Description
Technical Field
[0001] The invention relates to the field of regulation of photocurrent polarity of ferroelectric devices, and in particular to a bismuth ferrite photoelectric device with adjustable current polarity and a regulation method. Background Art
[0002] Traditional machine vision systems rely on the Von Neumann architecture, where sensors and processing units are separated. After the optical sensor captures visual information, it needs to first transmit the data to the computing processing unit, which results in the transmission of a large amount of redundant data, resulting in high latency and high energy consumption. Neuromorphic visual sensors that use an in-sensor computing architecture can simultaneously realize the perception, storage, and calculation of signals in one device, i.e., the integration of sensing, storage, and computing, reduce data transmission, and significantly reduce energy consumption and latency. In order to truly realize the perception and recognition of images, advanced in-sensor calculations based on matrix-vector multiplication operations are required, and having positive and negative adjustable light responses (i.e., the device has bipolarity) as positive and negative weights is the key to realizing this calculation.
[0003] The reconfigurable visual neural network sensors reported in the literature require applying gate voltage to the gate dielectric layer or floating gate layer to update the positive and negative weights, which makes the device structure complex and requires the construction of peripheral circuits, introducing additional energy consumption. Therefore, it is urgent to find a new method to control the polarity of the current in the photoelectric device. Summary of the invention
[0004] In view of the above-mentioned problems, the purpose of the present invention is to provide a bismuth ferrite photoelectric device with adjustable current polarity and a control method, which introduces new physical means and new physical mechanism for controlling the polarity of photocurrent. The bismuth ferrite photoelectric device optimizes the entire device structure; and during the test process of reading the photocurrent, no external voltage is required, thereby achieving low power consumption.
[0005] To achieve the above purpose, the technical solution adopted by the present invention is as follows:
[0006] A bismuth ferrite photoelectric device with adjustable current polarity is prepared by the following steps:
[0007] (1) Growing an ITO electrode on the surface of a bismuth ferrite thin film sample by magnetron sputtering; the thickness of the ITO electrode is 30-80 nm;
[0008] (2) The surface of the bismuth ferrite film sample with the ITO electrode was treated with oxygen plasma and then spin-coated with 0.5 μm AZ601 glue;
[0009] (3) continuing to perform photolithography on the sample obtained in step (2) under a UV photolithography machine;
[0010] (4) Etching the area without photoresist by using an ion beam etcher;
[0011] (5) Finally, the residual photoresist on the device surface is removed by wet cleaning and etching to obtain a bismuth ferrite-indium tin oxide device with adjustable current polarity.
[0012] Furthermore, the electrodes of the bismuth ferrite photoelectric device are rectangular, with a size of 50 micrometers, and the spacing between different electrodes is 150 micrometers.
[0013] Furthermore, the bismuth ferrite film is based on dysprosium scandate and is controllably prepared by a pulsed laser deposition method, and the thickness of the film is 30-200 nm.
[0014] Furthermore, the band gap of the bismuth ferrite thin film sample is 2.0-2.8 eV.
[0015] Furthermore, the bismuth ferrite thin film sample has excellent ferroelectric properties, and the ferroelectric domain structure will be flipped under the excitation of a specific wavelength.
[0016] Furthermore, the bismuth ferrite thin film device has no bottom electrode, and the indium tin oxide of the top electrode material can be replaced by gold to obtain a bismuth ferrite-gold device, and its preparation process includes the following steps:
[0017] (6.1) Spin-coat 1.4 μm AZ5214 glue and perform photolithography using a UV photolithography machine;
[0018] (6.2) Ti / Au electrode is grown by electron beam evaporation, where the thickness of Ti is 10 nm and the thickness of Au is 50 nm;
[0019] (6.3) Remove the residual photoresist on the device surface by wet etching in acetone, isopropanol and deionized water.
[0020] The present invention also provides a method for regulating a bismuth ferrite photoelectric device with adjustable current polarity, the method comprising the following steps:
[0021] (7.1) Generate 520nm and 405nm pulse photocurrents respectively through an arbitrary function generator and a laser light source device, and irradiate the corresponding areas of the bismuth ferrite photoelectric device;
[0022] (7.2) Study the photogenerated short-circuit current of bismuth ferrite photoelectric devices under zero bias using a semiconductor test analyzer;
[0023] (7.3) By changing the incident wavelength of the excitation light, the direction of the photocurrent in the bismuth ferrite photoelectric device can be controlled.
[0024] Specifically, the test temperature of the device in step (7.1) is 25°C-55°C.
[0025] Specifically, the incident laser wavelength used in the semiconductor test in step (7.2) is 405 nm or 520 nm.
[0026] Specifically, the power of the incident laser is 0.1-5 mW.
[0027] The beneficial effects of the present invention are as follows:
[0028] 1. The present invention achieves the reversal of the photocurrent polarity by changing the wavelength, and introduces a new physical means for regulating the photocurrent polarity.
[0029] 2. The present invention achieves the reversal of the photocurrent polarity by regulating the ferroelectric domain structure, and introduces a new physical mechanism for regulating the photocurrent polarity.
[0030] 3. In the test process of reading the photocurrent, the present invention does not require any external voltage, thus achieving low power consumption.
[0031] 4. The present invention does not require additional gate voltage, the device structure is simple, and there is no additional energy consumption. BRIEF DESCRIPTION OF THE DRAWINGS
[0032] The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments consistent with the present application and, together with the description, serve to explain the principles of the present application.
[0033] Figure 1 This is a photoluminescence spectrum of the bismuth ferrite film sample of the present invention;
[0034] Figure 2 This is a micrograph of the bismuth ferrite-indium tin oxide array in Example 1 of the present invention;
[0035] Figure 3 The photocurrent curves of the bismuth ferrite-indium tin oxide device under two pulse laser excitations of Example 2 of the present invention; (a) is a photocurrent curve under 520nm pulse laser excitation, and (b) is a photocurrent curve under 405nm pulse laser excitation;
[0036] Figure 4 The photocurrent curves of the bismuth ferrite-indium tin oxide device in Example 2 of the present invention under 520nm and 405nm laser excitation at different powers are shown;
[0037] Figure 5 This is a micrograph of the bismuth ferrite-gold array in Example 3 of the present invention;
[0038] Figure 6The graphs are photocurrent curves of the bismuth ferrite-gold device in Example 3 of the present invention under two pulsed laser excitations; wherein (a) is a photocurrent curve under 520nm pulsed laser excitation, and (b) is a photocurrent curve under 405nm pulsed laser excitation;
[0039] Figure 7 These are the out-of-plane phase images of the bismuth ferrite film sample of Example 4 of the present invention under three types of laser excitation; wherein (a) is the out-of-plane phase image in the dark, (b) is the out-of-plane phase image under 520nm laser excitation, and (c) is the out-of-plane phase image under 405nm laser excitation. DETAILED DESCRIPTION
[0040] Here, exemplary embodiments are described in detail, and examples thereof are shown in the accompanying drawings. When the following description refers to the drawings, unless otherwise indicated, the same numbers in different drawings represent the same or similar elements. The implementations described in the following exemplary embodiments do not represent all implementations consistent with the present application.
[0041] The terms used in this application are for the purpose of describing specific embodiments only and are not intended to limit this application. The singular forms of "a", "said" and "the" used in this application and the appended claims are also intended to include plural forms unless the context clearly indicates other meanings. It should also be understood that the term "and / or" used herein refers to and includes any or all possible combinations of one or more associated listed items.
[0042] The present invention is described in detail below with reference to the accompanying drawings and embodiments.
[0043] Figure 1 The photoluminescence spectrum of the bismuth ferrite film sample in this embodiment has a significant photoresponse peak with a central wavelength at 575 nanometers. This peak corresponds to the band-band recombination center of the photogenerated carriers in the bismuth ferrite film sample, and its energy is equal to the band gap energy ~2.15 eV. This shows that when the excitation wavelength is less than 575 nanometers, the bismuth ferrite film sample will have a certain photoresponse.
[0044] Example 1: In this example, a bismuth ferrite-indium tin oxide device was prepared, and the specific process was as follows:
[0045] (1) ITO electrodes with a thickness of 30-80 nm were grown on the surface of bismuth ferrite thin film samples by magnetron sputtering; (2) the surface of the bismuth ferrite thin film samples with ITO electrodes were treated with oxygen plasma (with a power of 100 W and a treatment time of 30 s) to increase the affinity between the substrate and the photoresist and remove surface contaminants such as particles, so that the photoresist can better bond with the substrate; (3) 0.5 μm AZ601 glue was spin-coated and photolithography was performed under a UV lithography machine; (4) ion beam etching was performed on the area without photoresist; (5) residual photoresist on the device surface was removed by wet cleaning and etching.
[0046] Figure 2 This is a micrograph of a bismuth ferrite-indium tin oxide array. As can be seen from the figure, the electrodes of the device are rectangular, with a size of 50 microns, and the spacing between different electrodes is 150 microns.
[0047] Example 2: This example studies the photoelectric properties of bismuth ferrite-indium tin oxide devices under laser excitation of different wavelengths. The specific process is as follows:
[0048] The arbitrary function generator and laser light source equipment were used to generate pulse photocurrents of 520nm and 405nm respectively and irradiate the corresponding areas of the device. The photogenerated short-circuit current of the bismuth ferrite-indium tin oxide device under zero bias was studied using a semiconductor test analyzer. Figure 3 (a) and Figure 3 (b) in the figure are the photocurrent curves of the bismuth ferrite-indium tin oxide device under 520nm and 405nm pulse laser excitation, respectively. It can be seen from the figure that the photocurrent directions of the bismuth ferrite-ITO thin film device under 520nm and 405nm pulse laser excitation are opposite.
[0049] Subsequently, by changing the light intensities of the 520nm laser and the 405nm laser respectively, the variation of the photogenerated short-circuit current of the bismuth ferrite-indium tin oxide device with the light power was detected under zero bias. Figure 4 The photocurrent curves of the bismuth ferrite-indium tin oxide device under 520nm and 405nm laser excitation at different powers are shown below. Under 520nm laser excitation, the photogenerated short-circuit current increases linearly in a negative direction with the increase of light power. Under 405nm laser excitation, the photogenerated short-circuit current increases linearly with the increase of light power. In addition, the directions of the photocurrents generated by 405nm and 520nm laser excitation are always opposite, indicating that the photocurrent direction of the bismuth ferrite-indium tin oxide device can be changed by selecting different laser wavelengths, and it is not affected by light power.
[0050] Example 3: In this example, a bismuth ferrite-gold device was prepared, and the photoelectric properties of the device under pulsed laser excitation of different wavelengths were studied. The specific process is as follows:
[0051] The preparation process of bismuth ferrite-gold device is as follows: (1) spin coating 1.4 μm AZ5214 glue and performing photolithography with UV photolithography machine; (2) growing Ti / Au electrode by electron beam evaporation method, where the thickness of Ti is 10 nm and the thickness of Au is 50 nm; (3) removing the residual photoresist on the surface of the device by wet etching in acetone, isopropanol and deionized water in turn. Figure 5 This is a micrograph of a bismuth ferrite-gold array. The electrodes of the device are rectangular, 50 microns in size, and the spacing between different electrodes is 150 microns.
[0052] The test process of the photoelectric characteristics of the bismuth ferrite-gold device is as follows: through the arbitrary function generator and laser light source equipment, 520nm and 405nm pulse photocurrents are generated respectively and irradiated on the corresponding areas of the device, and the photogenerated short-circuit current of the bismuth ferrite-gold device under zero bias is studied through the semiconductor test analyzer. Figure 6 (a) and Figure 6 (b) in the figure are the photocurrent curves of the bismuth ferrite-gold device under 520nm and 405nm pulsed laser excitation, respectively. As can be seen from the figure, the photocurrent direction of the bismuth ferrite-gold thin film device under 520nm and 405nm pulsed laser excitation is also opposite, indicating that the photocurrent direction of the bismuth ferrite-gold device can be changed by selecting different laser wavelengths. This means that the intrinsic mechanism of wavelength changing the direction of photocurrent comes from the bismuth ferrite thin film sample itself and has nothing to do with the electrode material.
[0053] Example 4: This example studies the out-of-plane phase structure of bismuth ferrite film samples in darkness, under 520nm and 405nm laser excitation, respectively. The specific process is as follows: (1) Observe the out-of-plane phase structure of the bismuth ferrite film sample without laser excitation; (2) Observe the out-of-plane phase structure of the bismuth ferrite film sample after 10 minutes of 520nm laser excitation; (3) Observe the out-of-plane phase structure of the bismuth ferrite film sample after 10 minutes of 405nm laser excitation.
[0054] Figure 7 (a) Figure 7 (b) and Figure 7 (c) in the figure are the out-of-plane phase images of the bismuth ferrite film samples in this embodiment in the dark, under 520nm and 405nm laser excitation respectively. As can be seen from the figure, compared with the sample in the dark, the out-of-plane domain structure of the sample did not change after 520nm laser excitation; the out-of-plane domain structure of 405nm was flipped. The above results show that the intrinsic mechanism of adjusting the polarity of the photocurrent of the device by changing the wavelength may be due to the different flipping characteristics of the out-of-plane ferroelectric domain structure of the bismuth ferrite film sample under laser excitation of different wavelengths.
[0055] The present invention also provides a method for regulating a bismuth ferrite photoelectric device with adjustable current polarity, the method comprising the following steps:
[0056] (1) Generate 520nm and 405nm pulse photocurrents through an arbitrary function generator and a laser light source, respectively, and irradiate the corresponding areas of the bismuth ferrite photoelectric device;
[0057] (2) Study the photogenerated short-circuit current of bismuth ferrite photoelectric devices under zero bias using a semiconductor test analyzer;
[0058] (3) By changing the incident wavelength of the excitation light, the direction of the photocurrent of the bismuth ferrite photoelectric device can be controlled.
[0059] Wherein, the test temperature of the device in step (1) is 25°C-55°C.
[0060] The incident laser wavelength used in the semiconductor test in step (2) is 405 nm or 520 nm, and the incident laser power is 0.1-5 mW.
[0061] Regarding the device in the above embodiment, the specific manner in which each module performs operations has been described in detail in the embodiment of the method, and will not be elaborated here.
[0062] For the device embodiment, since it basically corresponds to the method embodiment, the relevant parts can refer to the partial description of the method embodiment. The device embodiment described above is only schematic, wherein the units described as separate components may or may not be physically separated, and the components displayed as units may or may not be physical units, that is, they may be located in one place, or they may be distributed on multiple network units. Some or all of the modules may be selected according to actual needs to achieve the purpose of the present application scheme. A person of ordinary skill in the art can understand and implement it without paying any creative work.
[0063] Those skilled in the art will readily appreciate other embodiments of the present application after considering the specification and practicing the contents disclosed herein. The present application is intended to cover any variations, uses or adaptations of the present application, which follow the general principles of the present application and include common knowledge or customary technical means in the art that are not disclosed in the present application.
[0064] It should be understood that the present application is not limited to the exact construction that has been described above and shown in the drawings, and that various modifications and changes may be made without departing from the scope thereof.
Claims
1. A bismuth ferrite photoelectric device with adjustable current polarity, characterized in that: The bismuth ferrite photoelectric device is prepared by the following steps: (1) Growing an ITO electrode on the surface of a bismuth ferrite thin film sample by magnetron sputtering; the thickness of the ITO electrode is 30-80 nm; (2) The surface of the bismuth ferrite film sample on which the ITO electrode is grown is treated with oxygen plasma, and 0.5 micron AZ601 glue is spin-coated; the bismuth ferrite film sample has excellent ferroelectric properties, and the ferroelectric domain structure will be flipped under the excitation of the incident laser wavelength of 405 nm or 520 nm; (3) continuing to perform photolithography on the sample obtained in step (2) under a UV photolithography machine; (4) Etching the area without photoresist by using an ion beam etcher; (5) Finally, the residual photoresist on the device surface is removed by wet cleaning and etching to obtain a bismuth ferrite-indium tin oxide device with adjustable current polarity.
2. The bismuth ferrite photoelectric device with adjustable current polarity according to claim 1, characterized in that: The electrodes of the bismuth ferrite photoelectric device are rectangular, with a size of 50 micrometers, and the spacing between different electrodes is 150 micrometers.
3. The bismuth ferrite photoelectric device with adjustable current polarity according to claim 1, characterized in that: The bismuth ferrite film is based on dysprosium scandate and is controllably prepared by a pulse laser deposition method. The thickness of the film is 30-200nm.
4. The bismuth ferrite photoelectric device with adjustable current polarity according to claim 1, characterized in that: The band gap width of the bismuth ferrite film sample is 2.0-2.8 eV.
5. The bismuth ferrite photoelectric device with adjustable current polarity according to claim 1, characterized in that: The bismuth ferrite thin film device has no bottom electrode, and the indium tin oxide of the top electrode material can be replaced by gold to obtain a bismuth ferrite-gold device, and the preparation process thereof includes the following steps: (5.1) Spin-coat 1.4 μm AZ5214 glue and perform photolithography using a UV photolithography machine; (5.2) Growing Ti / Au electrodes by electron beam evaporation, where the thickness of Ti is 10 nm and the thickness of Au is 50 nm; (5.3) Remove the residual photoresist on the device surface by wet etching in acetone, isopropanol and deionized water.
6. A method for controlling a bismuth ferrite photoelectric device with adjustable current polarity as claimed in any one of claims 1 to 5, characterized in that: The method comprises the following steps: (6.1) Generate 520nm and 405nm pulse photocurrents respectively through an arbitrary function generator and a laser light source device, and irradiate the corresponding areas of the bismuth ferrite photoelectric device; (6.2) Study the photogenerated short-circuit current of bismuth ferrite photoelectric devices under zero bias using a semiconductor test analyzer; (6.3) By changing the incident wavelength of the excitation light, the direction of the photocurrent in the bismuth ferrite photoelectric device can be controlled.
7. The method for controlling the bismuth ferrite photoelectric device with adjustable current polarity according to claim 6, characterized in that: The test temperature of the device in the step (7.1) is 25°C-55°C.
8. The method for controlling the bismuth ferrite photoelectric device with adjustable current polarity according to claim 6, characterized in that: The incident laser wavelength used in the semiconductor test in step (7.2) is 405 nm or 520 nm.
9. The method for controlling the bismuth ferrite photoelectric device with adjustable current polarity according to claim 8, characterized in that: The incident laser has a power of 0.1-5 mW.