Efficient preparation method of femtosecond laser induced flexible carbon-based field effect transistor array

Abstract

The invention discloses an efficient preparation method of a femtosecond laser-induced flexible carbon-based field effect transistor array, which comprises the following steps: mixing BaTiO3 nanoparticles and a polyimide solution according to a mass ratio of 1: 100, uniformly stirring to prepare a BaTiO3 / PI mixed solution, forming a thin film with the thickness of 50 microns through a spin-coating technology, and drying to obtain the femtosecond laser-induced flexible carbon-based field effect transistor array. Carrying out pre-curing to form a flexible substrate; femtosecond laser is focused to the surface of the flexible substrate through a galvanometer system, the scanning path and parameters of the femtosecond laser are regulated and controlled, and graphene of different structures is induced in a channel region, an electrode region and a back gate region. According to the high-efficiency preparation method, integrated processing of the electrode, the channel and the insulating layer is realized, so that the manufacturing precision and efficiency of the flexible carbon-based field effect transistor are improved.

Description

Technical Field

[0001] The present invention relates to the field of flexible carbon-based field effect tubes, and in particular to a method for efficiently preparing a flexible carbon-based field effect tube array induced by a femtosecond laser. Background Art

[0002] Flexible carbon-based field-effect transistor (FET) arrays are core components for the next generation of wearable electronics and intelligent sensing systems. All-carbon FET fabrication methods suffer from low process efficiency, limited integration, and poor environmental compatibility. Electron beam lithography or chemical vapor deposition (CVD) processes for single devices take hours to process, and wet processes rely on strong acids or organic solvents that pollute the environment. Traditional flexible FET fabrication relies on photolithography and vacuum coating, resulting in interfacial delamination caused by a mismatch in the thermal expansion coefficients of the metal electrodes and the flexible substrate. The non-all-carbon structure results in high contact resistance and insufficient flexibility, and point-by-point processing is inefficient.

[0003] Flexible all-carbon-based field-effect transistor arrays provide a solution for the next generation of flexible electronic devices that combines excellent performance, durability, and large-scale production. They play a vital role in the development of smart wearable technology, biomedical devices, and electromagnetic wave control and detection devices. The demand for preparing flexible all-carbon-based field-effect transistor arrays stems from their unique material properties and wide application adaptability. All-carbon-based materials (such as graphene and carbon nanotubes) have high electrical conductivity (σ>10 4 S / cm), excellent mechanical flexibility (fracture strain> 20%) and good chemical stability, overcoming the brittle defects of traditional silicon-based or ITO materials. These properties make all-carbon-based materials perform well in electronic devices. 2 / g) and interfacial charge storage capacity (EDL capacitance can reach 20μF / cm 2 ) significantly improves device performance, especially response speed. Currently, the fabrication of flexible all-carbon-based field-effect transistor arrays often faces two major challenges: first, high-precision patterning is difficult to achieve. Conventional photolithography techniques struggle to position carbon materials at the micro- and nanoscale on flexible substrates; second, interface engineering requires a low-damage integration process for the electrode-channel-dielectric all-carbon heterojunction. Therefore, new fabrication methods are urgently needed to address these challenges.

[0004] To address current challenges, a series of research efforts have been conducted both domestically and internationally. On the one hand, new patterning techniques are being investigated to overcome the limitations of traditional photolithography on flexible substrates; on the other, interfacial engineering challenges are being addressed, which are crucial for achieving good integration between the electrodes, channel, and dielectric in all-carbon heterojunctions, and thus improving device performance. To achieve high-precision patterning and low-damage integration processes, researchers at home and abroad are actively exploring new approaches. Moshe David-Pur et al. at the University of California, Berkeley, used CVD to grow a CNT film on a Ni catalyst layer, then transferred it to a PDMS substrate and combined it with a double-layer PDMS passivation technique to create an electrode array. The elastic modulus of PDMS is 0.05 MPa, requiring strict control of the effective electrode surface area, and the CNT conductivity depends on film continuity. Shuangxi Xie et al. at the Shenyang Institute of Automation, Chinese Academy of Sciences, used AFM to cut nanogaps in graphene to serve as electrodes and then assembled SWCNTs into a channel via dielectrophoresis. The resulting SWCNT-graphene FET exhibited p-type characteristics with a nanogaps precision of approximately 50 nm. Chen Wei and others from the National University of Defense Technology used focused electron beam exposure combined with oxygen plasma etching to prepare a full-carbon graphene field-effect transistor; the conductivity of its nanographene electrode is 4.8×10 -3 S / cm, CVD graphene mobility reaches 3500 cm 2 / Vs, with an overlay accuracy of 50nm. Jungwook Choi and others at Seoul National University in South Korea used a nano-template mask combined with CVD to synthesize CNT arrays with controllable position and number. By regulating the pore size to control the catalyst deposition thickness, they achieved the fabrication of carbon-based field-effect transistor arrays. Overall, these current research and related technologies for carbon-based devices are still in the exploratory stage and are still some distance away from mature applications.

[0005] Conventional flexible field-effect transistor (FET) manufacturing relies heavily on photolithography and vacuum deposition processes, whose inherent flaws impose multiple constraints on device performance and industrialization. The process complexity stems from the multi-step, meticulous processing involving repetitive mask manipulation and high-precision metal coating. The specialized equipment required contributes to high manufacturing costs, making it difficult for small and medium-sized R&D institutions and innovative flexible electronics applications to overcome these technical barriers. The conflicting physical properties of the material systems is particularly pronounced between the flexible substrate and the metal electrode. Interfacial stress accumulation caused by temperature fluctuations or mechanical deformation leads to microstructural damage and electrical performance degradation, severely challenging device stability under dynamic bending. Energy barriers formed at the heterogeneous material interface significantly hinder carrier transport efficiency, and the difference in mechanical properties between the rigid electrode and the flexible channel further weakens the device's overall deformability, making it difficult to meet the requirements of high-curvature surface integration or stretchable electronic systems. Furthermore, the reliance on point-by-point patterning severely limits manufacturing efficiency. A process gap exists between the orderly arrangement of microstructures and the scalability of macroscopic devices, making it impossible to balance high-density functional unit design with large-area uniformity control, hindering the commercialization and expansion of flexible electronics. Summary of the Invention

[0006] In response to the problems in the existing technology such as cumbersome photolithography process steps, low efficiency of electron beam lithography, and complex electrode and channel integration process, the present invention provides a femtosecond laser induced flexible carbon-based field effect transistor array efficient preparation method. Through the femtosecond laser direct writing technology, graphene is induced directly on the flexible substrate PI film in one step to prepare a full carbon electrode-channel-insulating layer integrated structure, realizing submicron precision processing and high-density array rapid manufacturing, breaking through the bottleneck of high cost, high pollution and difficulty in scalability of traditional processes.

[0007] In order to achieve the above-mentioned purpose, the present invention adopts the following technical solutions:

[0008] In one embodiment of the present invention, a method for efficiently preparing a femtosecond laser-induced flexible carbon-based field-effect transistor array is proposed. The method comprises:

[0009] BaTiO3 nanoparticles and polyimide solution were mixed at a mass ratio of 1:100 and stirred to form a BaTiO3 / PI mixed solution. A 50 μm thick film was formed by spin coating and pre-cured to form a flexible substrate.

[0010] A femtosecond laser is used to focus on the surface of a flexible substrate through a galvanometer system, and the scanning path and parameters of the femtosecond laser are controlled to induce graphene with different structures in the channel region, electrode region and back gate region.

[0011] Furthermore, in the channel region, the power of the femtosecond laser was adjusted to 20 W and the scanning speed was adjusted to 100 mm / s to generate highly conductive LIG with a sheet resistance of less than 30 Ω / sq.

[0012] Furthermore, in the electrode area, the power of the femtosecond laser was adjusted to 15W and the scanning speed was adjusted to 500mm / s to generate a dense LIG electrode with a square resistance of less than 10Ω / sq.

[0013] Furthermore, in the back gate region, the power of the femtosecond laser was adjusted to 10W, combined with cross scanning, to generate a porous LIG gate with a specific surface area of >500m 2 / g.

[0014] Furthermore, the femtosecond laser is combined with the parallel scanning technology of the galvanometer system to achieve efficient preparation of field effect transistor arrays.

[0015] Beneficial effects:

[0016] The method of the University of California, Berkeley, uses a photolithography template that limits the pattern resolution (>1μm), and polymer penetration can also lead to uneven electrode morphology; the Shenyang Institute of Automation of the Chinese Academy of Sciences uses AFM with low processing efficiency, takes several hours for a single device, and dielectric electrophoresis assembly is difficult to array on a large scale; the National University of Defense Technology is limited by the resolution of traditional photolithography, the channel length is greater than 100μm, and the low gate capacitance results in insufficient driving capability; the template preparation of Seoul National University in South Korea is complex, and dynamic pattern adjustment cannot be achieved. In contrast, the present invention has achieved a major breakthrough using femtosecond laser technology. In terms of precision, it has high-precision performance at the micron level, and has processing efficiency that is unmatched by photolithography and electron beam exposure. It can meet the processing requirements of small sizes and fine structures, and lay the processing foundation for the preparation of smaller and higher-performance carbon-based devices. From the perspective of thermal damage, the ultrashort pulses (10 -15 s) characteristics inhibit thermal diffusion and will not cause damage to the lattice of the carbon material during processing, thereby effectively maintaining the stability of the electrical conductivity of the carbon material and ensuring the reliability and consistency of the electrical performance of carbon-based devices. In terms of patterning processing, femtosecond laser technology can achieve direct patterning without the need for cumbersome masks or catalysts. The morphology of the channel / electrode can be dynamically controlled by simply adjusting the laser parameters such as energy and scanning speed. This feature not only simplifies the preparation process and reduces the number of process steps, but also greatly improves the flexibility and controllability of the processing, and can quickly respond to different design requirements and prepare a variety of carbon-based device structures. In the optimization of heterojunction interfaces, femtosecond-induced localized carbonization generates a gradient interface, which helps to improve the performance of carbon-based devices in practical applications, such as playing a better role in signal transmission, energy storage, etc. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 This is a schematic diagram of the structure of a femtosecond laser-induced flexible carbon-based field-effect transistor of the present invention;

[0018] Figure 2It is a schematic diagram of a femtosecond laser processed field effect tube array according to the present invention. DETAILED DESCRIPTION

[0019] The principles and spirit of the present invention will be described below with reference to several exemplary embodiments. It should be understood that these embodiments are provided solely to enable those skilled in the art to better understand and design the present invention, and are not intended to limit the scope of the present invention in any way. Rather, these embodiments are provided to make this disclosure more thorough and complete, and to fully convey the scope of the present disclosure to those skilled in the art.

[0020] Those skilled in the art will appreciate that embodiments of the present invention may be designed as a structure, apparatus, preparation method, or computer program product. Therefore, the present disclosure may be specifically designed in the following forms: entirely in hardware, entirely in software (including firmware, resident software, microcode, etc.), or a combination of hardware and software.

[0021] According to an embodiment of the present invention, a femtosecond laser-induced efficient preparation method for a flexible carbon-based field-effect transistor array is proposed. By using femtosecond laser direct writing technology, graphene is induced in one step on a flexible substrate PI film to prepare a full-carbon electrode-channel-insulating layer integrated structure, achieving submicron precision processing and high-density array rapid manufacturing, breaking through the bottlenecks of high cost, high pollution and difficulty in scalability of traditional processes.

[0022] The principles and spirit of the present invention are explained in detail below with reference to several representative embodiments of the present invention.

[0023] The present invention provides an efficient preparation method of a femtosecond laser-induced flexible carbon-based field-effect transistor array, comprising:

[0024] Prepare the BaTiO3 / PI mixed solution: Add 0.1g of weighed barium titanate (BaTiO3) powder to 10g of polyimide solution. Stir using the stirring platform of a stirring rotor for a recommended 30 minutes to ensure uniform dispersion of the barium titanate in the polyimide solution. After stirring, transfer the mixed solution to an ultrasonic cleaner and sonicate for 10 minutes to further promote dispersion of the barium titanate and reduce particle aggregation. After sonication, observe the solution to ensure no noticeable precipitation or stratification.

[0025] A 50 μm thick film was formed by spin coating and pre-cured to form a flexible substrate. Figure 1 Insulator in order to provide good mechanical and electrical properties.

[0026] like Figure 1As shown in the figure, the entire field-effect transistor structure includes the LIG source, drain, channel and back gate, all of which are generated by femtosecond laser.

[0027] like Figure 2 As shown, a femtosecond laser 1 (wavelength of 1030nm, pulse width of 200fs, power range of 10-20W) is focused onto the surface of a flexible substrate 3 through a galvanometer system 2. The host computer in the galvanometer system 2 controls the scanning path and parameters of the femtosecond laser 1, thereby inducing graphene with different structures in different areas.

[0028] In the channel region, a combination of high power (20W) and low scan speed (100mm / s) was used. This generated more heat in the material, promoting graphene formation and ultimately producing highly conductive LIG (square resistance <30Ω / sq), suitable for the channel and achieving good current conduction characteristics. In the electrode region (LIG source and drain), medium power (15W) and high scan speed (500mm / s) were used. This combination facilitated the formation of dense LIG electrodes (square resistance <10Ω / sq), ensuring low resistance and good contact between the electrodes, thereby improving overall device performance.

[0029] In the back gate region, low power (10 W) and cross scanning were selected to generate a porous LIG gate (with a specific surface area greater than 500 m 2 This porous structure provides a larger surface area, which helps to improve the gate's response to the electric field and enhance the device's controllability and sensitivity.

[0030] The entire fabrication method involves substrate preparation, laser parameter programming, and galvanometer scanning, and the entire process requires no masks or post-processing, simplifying the manufacturing process and reducing production costs. By properly selecting laser parameters, LIG structures with specific electrical properties can be generated for different functional areas, thereby optimizing device performance. Combined with the parallel scanning technology of the galvanometer system, the efficient fabrication capability of FET arrays is significantly improved, and the three-dimensional structural design of all-carbon-based FETs is realized.

[0031] It should be noted that although the operations of the preparation method of the present invention are described in a specific order in the above embodiments and drawings, this does not require or imply that these operations must be performed in this specific order, or that all illustrated operations must be performed to achieve the desired results. Additionally or alternatively, certain steps may be omitted, multiple steps may be combined into one step, and / or one step may be broken down into multiple steps.

[0032] The present invention proposes a method for efficiently preparing a femtosecond laser-induced flexible carbon-based field-effect transistor array, which has the following advantages:

[0033] The method of the University of California, Berkeley, uses a photolithography template that limits the pattern resolution (>1μm), and polymer penetration can also lead to uneven electrode morphology; the Shenyang Institute of Automation of the Chinese Academy of Sciences uses AFM with low processing efficiency, takes several hours for a single device, and dielectric electrophoresis assembly is difficult to array on a large scale; the National University of Defense Technology is limited by the resolution of traditional photolithography, the channel length is greater than 100μm, and the low gate capacitance results in insufficient driving capability; the template preparation of Seoul National University in South Korea is complex, and dynamic pattern adjustment cannot be achieved. In contrast, the present invention has achieved a major breakthrough using femtosecond laser technology. In terms of precision, it has high-precision performance at the micron level, and has processing efficiency that is unmatched by photolithography and electron beam exposure. It can meet the processing requirements of small sizes and fine structures, and lay the processing foundation for the preparation of smaller and higher-performance carbon-based devices. From the perspective of thermal damage, the ultrashort pulses (10 -15 s) characteristics inhibit thermal diffusion and will not cause damage to the lattice of the carbon material during processing, thereby effectively maintaining the stability of the electrical conductivity of the carbon material and ensuring the reliability and consistency of the electrical performance of carbon-based devices. In terms of patterning processing, femtosecond laser technology can achieve direct patterning without the need for cumbersome masks or catalysts. The morphology of the channel / electrode can be dynamically controlled by simply adjusting the laser parameters such as energy and scanning speed. This feature not only simplifies the preparation process and reduces the number of process steps, but also greatly improves the flexibility and controllability of the processing, and can quickly respond to different design requirements and prepare a variety of carbon-based device structures. In the optimization of heterojunction interfaces, femtosecond-induced localized carbonization generates a gradient interface, which helps to improve the performance of carbon-based devices in practical applications, such as playing a better role in signal transmission, energy storage, etc.

[0034] Although the spirit and principles of the present invention have been described with reference to several specific embodiments, it should be understood that the present invention is not limited to the specific embodiments disclosed, and the division into various aspects does not mean that the features of these aspects cannot be combined to benefit. Such division is only for the convenience of expression. The present invention is intended to cover various modifications and equivalent arrangements included within the spirit and scope of the appended claims.

[0035] Regarding the limitation of the protection scope of the present invention, those skilled in the art should understand that, based on the technical solution of the present invention, various modifications or variations that can be made by those skilled in the art without creative work are still within the protection scope of the present invention.

Claims

1. A method for efficiently preparing a femtosecond laser-induced flexible carbon-based field-effect transistor array, characterized in that: The efficient preparation method comprises: BaTiO3 nanoparticles and polyimide solution were mixed at a mass ratio of 1:100 and stirred to form a BaTiO3 / PI mixed solution. A 50 μm thick film was formed by spin coating and pre-cured to form a flexible substrate. A femtosecond laser is used to focus on the surface of a flexible substrate through a galvanometer system, and the scanning path and parameters of the femtosecond laser are controlled to induce graphene with different structures in the channel region, electrode region and back gate region.

2. The method for efficiently preparing a femtosecond laser-induced flexible carbon-based field effect transistor array according to claim 1, characterized in that: In the channel region, the power of the femtosecond laser was adjusted to 20W and the scanning speed was adjusted to 100mm / s to generate highly conductive LIG with a sheet resistance of less than 30Ω / sq.

3. The method for efficiently preparing a femtosecond laser-induced flexible carbon-based field effect transistor array according to claim 1, characterized in that: In the electrode area, the power of the femtosecond laser was adjusted to 15W and the scanning speed was adjusted to 500mm / s to generate a dense LIG electrode with a square resistance of less than 10Ω / sq.

4. The method for efficiently preparing a femtosecond laser-induced flexible carbon-based field effect transistor array according to claim 1, characterized in that: In the back gate region, the power of the femtosecond laser was adjusted to 10W, combined with cross scanning to generate a porous LIG gate with a specific surface area of >500m 2 / g.

5. The method for efficiently preparing a femtosecond laser-induced flexible carbon-based field effect transistor array according to claim 1, characterized in that: The femtosecond laser is combined with the parallel scanning technology of the galvanometer system to achieve efficient preparation of the field effect tube array.

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