A low-cost, easily formed silicon-based epitaxial magneto-optical thin film, its preparation method, and its application.

Abstract

This invention discloses a low-cost, easily formable silicon-based epitaxial magneto-optical thin film, its preparation method, and its applications. The method employs an in-situ co-creation technique to uniformly disperse ZnFe₂O₄ nanoparticles, which exhibit strong magneto-optical effects but are prone to aggregation, within ZIF-8 with fixed pores. PgC₅Cu is used as a bridging agent to modify the surface of ZIF-8. The ZIF-8 is then uniformly dispersed in a UV-curing adhesive to form a solution, which is then uniformly coated onto a silicon substrate. After UV curing, a silicon-based epitaxial thin film material with excellent magneto-optical properties is successfully constructed. The preparation method of this invention is relatively simple and highly operable. The resulting thin film material exhibits outstanding magneto-optical properties and shows good application potential in various fields such as magneto-optical storage, magneto-optical sensors, optoelectronic integration, and micro / nano optical devices. This provides a highly valuable new material for magneto-optical thin film research and device development.

Description

Technical Field

[0001] This invention belongs to the field of optoelectronic information materials technology, specifically relating to a low-cost, easily formed silicon-based epitaxial magneto-optical thin film, its preparation method, and its application. Background Technology

[0002] With the development of emerging technologies such as 5G communication, interplanetary communication, and big data centers, data networks need to carry massive amounts of information communication and processing, urgently requiring high-performance, highly integrated information processing devices. Silicon-based magneto-optical isolators are one of the key challenges in next-generation information technology—integrated silicon photonics. For example, in the field of optical communication, to achieve high-speed, high-capacity data transmission, devices such as magneto-optical isolators are needed to ensure stable signal transmission, thus promoting the widespread application of silicon-based integrated magneto-optical materials. Common silicon-based integrated magneto-optical materials include yttrium iron garnet (YIG) and doped YIG, bismuth-doped rare-earth iron garnet (Bi:YIG), indium antimonide (InSb), bismuth ferrite (BiFeO3), and rare-earth iron garnet. Among these, YIG and its doped materials have high Faraday rotation and low loss characteristics, making them widely used magneto-optical materials. Bi:YIG further optimizes its magneto-optical performance through bismuth doping. InSb exhibits significant magneto-optical effects in the terahertz band. BiFeO3 possesses unique magnetoelectric coupling characteristics and certain magneto-optical effects.

[0003] Currently, common methods for integrating magneto-optical materials on silicon substrates include heteroepitaxial growth, ion implantation, direct bonding, and micro / nano fabrication. However, in this integration process, significant differences in physical and chemical properties between magneto-optical materials and silicon-based materials often lead to problems such as lattice mismatch and thermal expansion coefficient mismatch, which adversely affect material quality and device performance. Furthermore, the fabrication process for integrating magneto-optical materials on silicon is extremely complex, requiring not only high-precision equipment but also advanced technologies, significantly increasing production costs and difficulty. Crucially, when designing integrated optical systems, the physical properties and processing techniques of traditional crystal materials limit the integration of optical components at very small scales. However, if magnetic unit particles are prepared to be sufficiently small and highly uniformly dispersed in transparent polymers, it is possible to obtain highly transparent and strong magneto-optical materials. Summary of the Invention

[0004] To address the problems of long preparation cycles, high costs, difficult molding, and limited ability to form irregularly shaped devices and integrate optically associated traditional crystal and glass magneto-optical materials, this invention provides a low-cost, easily moldable silicon-based epitaxial magneto-optical thin film and its preparation method. The method utilizes a ZIF-8 framework structure to encapsulate ZnFe2O4 nanoparticles with strong magneto-optical effects. PgC5Cu metal-organic nanocapsules are then used as a bridging agent between the MOF and the polymer, enabling the uniform dispersion of the strongly magneto-optical nanoparticles in a transparent UV-curable adhesive. UV curing is then performed to achieve the epitaxial fabrication of a magneto-optical thin film on a silicon substrate. The resulting silicon-based epitaxial magneto-optical thin film is expected to find practical applications in fiber optic communication, integrated optical devices, miniaturization, and novel irregularly shaped magneto-optical devices.

[0005] To achieve the above objectives, the present invention adopts the following technical solution:

[0006] A silicon-based epitaxial magneto-optical thin film is prepared by first encapsulating ZnFe2O4 nanoparticles in ZIF-8, thereby uniformly dispersing the ZnFe2O4 nanoparticles in ZIF-8 with fixed pores to obtain ZnFe2O4-ZIF-8. Then, pentyl-o-phenylene aromatic copper (PgC5Cu) is used as a bridging agent to modify the surface of ZIF-8 to obtain ZnFe2O4-ZIF-8@PgC5Cu. The ZIF-8 is then dispersed in ultraviolet light adhesive (UCA) to prepare an adhesive solution, and the resulting adhesive solution is uniformly coated on a silicon substrate and cured under ultraviolet light.

[0007] The method for preparing the silicon-based epitaxial magneto-optical thin film includes the following steps:

[0008] 1) Preparation of ZnFe2O4-ZIF-8: FeSO4·7H2O and (CH3COO)2Zn·2H2O were added to deionized water and mixed evenly to obtain solution A; 2-methylimidazole was added to deionized water and mixed evenly to obtain solution B; solution B was quickly poured into solution A, stirred for 30 min and then transferred to a reaction vessel for reaction. After the reaction, the mixture was cooled to room temperature, and the resulting product was washed three times each with water, methanol and dichloromethane (DCM) to obtain ZnFe2O4-ZIF-8.

[0009] 2) Preparation of ZnFe2O4-ZIF-8@PgC5Cu: Pentyl-o-phenylene aromatic copper (PgC5Cu) and the prepared ZnFe2O4-ZIF-8 were weighed into centrifuge tubes A and B, respectively. Then, dichloromethane was added to centrifuge tubes A and B, respectively. After PgC5Cu dissolved, the two solutions were mixed and reacted by sonication for 3 min. After centrifugation, the mixture was washed three times with DCM to obtain ZnFe2O4-ZIF-8@PgC5Cu.

[0010] 3) Preparation of magneto-optical thin film: The obtained ZnFe2O4-ZIF-8@PgC5Cu was mixed with UV adhesive and ultrasonicated until completely dispersed. The resulting dispersion was coated onto a silicon substrate by spin coating or inkjet printing. The silicon substrate surface was then irradiated with a UV lamp to obtain a silicon-based polymer magneto-optical thin film with uniform thickness.

[0011] Furthermore, the molar ratio of FeSO4·7H2O, (CH3COO)2Zn·2H2O and 2-methylimidazole used in step 1) is 0.43:0.765:5.5.

[0012] Furthermore, the reaction in step 1) is carried out at a temperature of 120°C for 2 hours.

[0013] Furthermore, in step 2), the mass ratio of pentyl-o-phenylene aromatic copper to ZnFe2O4-ZIF-8 is 1:20.

[0014] Further, the UV adhesive described in step 3) is made by mixing polyurethane acrylate, 1,6-hexanediol diacrylate (HDDA) and 2,4,6-trimethylbenzoyl-diphenylphosphine oxide in a weight ratio of 7:2:1.

[0015] Furthermore, in step 3), the mass ratio of ZnFe2O4-ZIF-8@PgC5Cu to the UV adhesive is 1:50~1:200.

[0016] Furthermore, the amount of dispersion described in step 3) coated on the silicon substrate is 20 μL / cm. 2 .

[0017] Furthermore, the UV lamp used in step 3) has a power of 6 W.

[0018] Furthermore, the irradiation treatment time in step 3) is 10 minutes.

[0019] Using the aforementioned method for preparing silicon-based epitaxial magneto-optical thin films, magneto-optical elements with special shapes can also be prepared by using irregularly shaped silicon substrates to meet the requirements of irregularly shaped magneto-optical devices.

[0020] The prepared magneto-optical thin film or magneto-optical element can be used to further fabricate magneto-optical devices, including magneto-optical isolators, miniaturized or integrated optical integrated devices, optical circulators, magneto-optical modulators, magneto-optical memories, etc.

[0021] This invention presents, for the first time, a method for preparing silicon-based epitaxial magneto-optical thin films. It employs an in-situ co-creation technique to uniformly disperse ZnFe₂O₄ nanoparticles, which exhibit strong magneto-optical effects but are prone to aggregation, within a porous MOF (metal-organic framework ZIF-8). The ZIF-8 surface is then modified with PgC₅Cu (a copper complex with a specific configuration), ensuring uniform dispersion within a UV-sensitive adhesive, thus successfully constructing a composite material with excellent magneto-optical properties. Within the field of optical integration, this innovative design exhibits numerous significant advantages. Firstly, it effectively preserves the material's structural stability and optical transparency, providing a fundamental guarantee for maintaining precise optical transmission and signal processing in optical integration systems. Secondly, this design endows the material with unprecedented flexibility and processability, greatly expanding the feasibility of constructing complex structures and device layouts in optical integration, creating key conditions for achieving lightweight, portable, and flexible magneto-optical devices. Compared to traditional pure inorganic magneto-optical crystals and magneto-optical glasses, this invention demonstrates multiple advantages in optical integration applications. From a manufacturing process perspective, its method is simpler, effectively shortening the production cycle and significantly reducing energy consumption and cost. This has extremely important economic and efficiency significance for large-scale optical integration manufacturing and industrialization. Simultaneously, its ease of molding and high flexibility allow for more flexible adaptation to various special spatial constraints and functional requirements during the design and implementation of optical integration. This enables it to be widely matched with different optical integration application scenarios, greatly enriching the potential application value and development potential of optical integration technology in multiple fields.

[0022] The significant advantages of this invention are:

[0023] (1) The magneto-optical thin film prepared by the present invention has an optical transmittance of up to 60% in the 1200~2600 nm band without the anti-reflection coating on the surface of the thin film.

[0024] (2) The process of preparing magneto-optical thin films in this invention is simple and efficient. It only requires ultraviolet light irradiation and can be directly formed without additional processing steps. Its preparation cost is low and the cycle is short. It exhibits excellent self-assembly performance and material forming convenience. Moreover, the resulting magneto-optical thin films exhibit excellent magnetic and optical properties, providing high-performance and low-cost new materials for fields such as magneto-optics and optical integration.

[0025] (3) The preparation method of the present invention can endow silicon-based optoelectronic devices with more novel functional characteristics. For example, by utilizing the characteristics of magneto-optical composite materials, it is possible to flexibly control parameters such as the polarization state and intensity of light, and develop optical modulators, optical switches and other devices with special functions, enriching the functional types of silicon-based optoelectronic devices and providing basic support for the development of cutting-edge fields such as optical computing and quantum communication. Attached Figure Description

[0026] Figure 1 The X-ray diffraction pattern of ZnFe2O4-ZIF-8 prepared in the examples is shown.

[0027] Figure 2 The VSM spectra of the ZnFe2O4-ZIF-8 and ZnFe2O4-ZIF-8@PgC5Cu powders prepared in the examples are shown at room temperature.

[0028] Figure 3 The transmission spectra of magneto-optical films prepared by mixing ZnFe2O4-ZIF-8@PgC5Cu with UV photoresist at different mass ratios (1:50, 1:100, 1:200) in the examples are shown.

[0029] Figure 4 The VSM spectra of magneto-optical films prepared by mixing ZnFe2O4-ZIF-8@PgC5Cu with UV photoresist at different mass ratios (1:50, 1:100) in the examples are shown at room temperature.

[0030] Figure 5 The magnetic circular dichroism chromatograms at 200-800 nm are shown for magneto-optical films prepared by mixing ZnFe2O4-ZIF-8@PgC5Cu with UV photoresist at different mass ratios (1:50, 1:100, 1:200) in the examples. Detailed Implementation

[0031] A magneto-optical thin film prepared by silicon-based epitaxy includes the following steps:

[0032] 1) Preparation of ZnFe2O4-ZIF-8: FeSO4·7H2O and (CH3COO)2Zn·2H2O were added to deionized water and mixed evenly to obtain solution A; 2-methylimidazole was added to deionized water and mixed evenly to obtain solution B; solution B was quickly poured into solution A, stirred for 30 min and then transferred to a reaction vessel with a polytetrafluoroethylene liner, heated at 120℃ for 2 h, cooled to room temperature, and the obtained product was washed three times each with water, methanol and dichloromethane (DCM) to obtain ZnFe2O4-ZIF-8, which was then sealed with dichloromethane;

[0033] 2) Preparation of ZnFe2O4-ZIF-8@PgC5Cu: Pentyl-o-phenylene aromatic copper (PgC5Cu) and the prepared ZnFe2O4-ZIF-8 were weighed at a mass ratio of 1:20 and placed in centrifuge tubes A and B respectively. Then, dichloromethane was added to centrifuge tube B and ultrasonically mixed. Dichloromethane was added to centrifuge tube A. After PgC5Cu was dissolved, it was added to centrifuge tube B. After ultrasonic reaction for 3 min, centrifugation was performed and the mixture was washed three times with DCM to obtain ZnFe2O4-ZIF-8@PgC5Cu.

[0034] 3) Preparation of magneto-optical thin film: The obtained ZnFe2O4-ZIF-8@PgC5Cu was mixed with UV photoresist at a mass ratio of 1:50~1:200. After ultrasonication until complete dispersion, the resulting dispersion was coated onto a silicon substrate by spin coating or inkjet printing, with a coating amount of 20 μL / cm. 2 Then, the silicon-based surface was irradiated with an ultraviolet lamp (6 W) for 10 minutes to obtain a silicon-based polymer magneto-optical thin film ZnFe2O4-ZIF-8@PgC5Cu / UCA with uniform thickness.

[0035] In step 1), the molar ratio of FeSO4·7H2O, (CH3COO)2Zn·2H2O and 2-methylimidazole is 0.43:0.765:5.5.

[0036] The UV adhesive described in step 2) is made by mixing polyurethane acrylate, 1,6-hexanediol diacrylate (HDDA) and 2,4,6-trimethylbenzoyl-diphenylphosphine oxide in a weight ratio of 7:2:1.

[0037] To make the content of this invention easier to understand, the technical solution of this invention will be further described below with reference to specific embodiments, but this invention is not limited thereto.

[0038] The pentyl-o-phenylene aromatic copper PgC5Cu used in the examples was synthesized according to the literature (Engineering Plasticization Resistant Gas Separation Membranes Using Metal-Organic Nanocapsules. DOI: 10.1039 / d0sc01498b). Example

[0039] The specific steps for preparing a silicon-based epitaxial magneto-optical thin film are as follows:

[0040] (1) Preparation of ZnFe2O4-ZIF-8: 0.43 mmol FeSO4·7H2O and 0.765 mmol (CH3COO)2Zn·2H2O were added to 5 mL of deionized water and mixed evenly to obtain solution A; 5.5 mmol 2-methylimidazole (C4H6N2) was added to 10 mL of deionized water and mixed evenly to obtain solution B; solution B was quickly poured into solution A and stirred for 30 min, then transferred to a reaction vessel with a polytetrafluoroethylene liner, heated at 120℃ for 2 h, cooled to room temperature, and the obtained product was washed three times each with water, methanol, and dichloromethane (DCM) to obtain ZnFe2O4-ZIF-8, which was then sealed with DCM;

[0041] (2) Preparation of ZnFe2O4-ZIF-8@PgC5Cu: PgC5Cu and ZnFe2O4-ZIF-8 were weighed at a mass ratio of 1:20 and placed in centrifuge tubes A and B respectively. DCM was added to centrifuge tube B at a mass ratio of 1:10 and ultrasonically mixed. DCM was added to centrifuge tube A at a mass ratio of 1:5. After PgC5Cu was dissolved, it was added to centrifuge tube B. After ultrasonic reaction for 3 min, centrifugation was performed. After washing with DCM 3 times, ZnFe2O4-ZIF-8@PgC5Cu was obtained and sealed with DCM.

[0042] (3) Preparation of magneto-optical thin film: ZnFe2O4-ZIF-8@PgC5Cu was mixed with UV photoresist at a mass ratio of 1:50 to 1:200. After ultrasonication until complete dispersion, the resulting dispersion was coated onto a silicon substrate by spin coating or inkjet printing. The coating amount was 20 μL / cm. 2 Then, the silicon-based surface was irradiated with an ultraviolet lamp (6 W) for 10 minutes to obtain ZnFe2O4-ZIF-8@PgC5Cu / UCA with uniform thickness.

[0043] The phase composition of the prepared ZnFe2O4-ZIF-8 was characterized by X-ray diffraction, and the results are shown in the figure. Figure 1 .Depend on Figure 1 As can be seen, the XRD spectrum of ZnFe2O4-ZIF-8 shows characteristic peaks of ZIF-8 and cubic ZnFe2O4, indicating that the composite material Fe3O4 and ZIF-8 was successfully combined.

[0044] Figure 2 The VSM spectra of the prepared ZnFe2O4-ZIF-8 and ZnFe2O4-ZIF-8@PgC5Cu are shown in the figure. As shown, the saturation magnetization of PgC5Cu-modified ZnFe2O4-ZIF-8 is 11 emμ / g, which is 69.23% higher than that of ZnFe2O4-ZIF-8.

[0045] Figure 3 The transmission spectra of magneto-optical thin films prepared by mixing ZnFe2O4-ZIF-8@PgC5Cu with UV photoresist at different mass ratios (1:50, 1:100, 1:200) are shown. As can be seen from the figures, the magneto-optical thin film prepared by mixing ZnFe2O4-ZIF-8@PgC5Cu with UV photoresist at a mass ratio of 1:200 exhibits an optical transmittance as high as 60% in the 1100–2600 nm wavelength range.

[0046] Figure 4The VSM spectra of magneto-optical thin films prepared by mixing ZnFe2O4-ZIF-8@PgC5Cu with UV photoresist at different mass ratios (1:50, 1:100, 1:200) at room temperature are shown in the figures. As can be seen from the figures, the magnetic properties of the material change after adding ZnFe2O4-ZIF-8@PgC5Cu to the UV photoresist, transforming from paramagnetism to ferromagnetism.

[0047] Figure 5 The figures show the magnetic circular dichroism (MBD) spectra of magneto-optical films prepared by mixing ZnFe₂O₄-ZIF-8@PgC₅Cu with UV photoresist at different mass ratios (1:50, 1:100, and 1:200) in the 200-800 nm range. As can be seen from the figures, the ellipticities of the magneto-optical films prepared by mixing ZnFe₂O₄-ZIF-8@PgC₅Cu with UV photoresist at mass ratios of 1:50, 1:100, and 1:200 are -2300 mdeg / cm, -1310.69 mdeg / cm, and -565.93 mdeg / cm, respectively.

[0048] The above description is only a preferred embodiment of the present invention. All equivalent changes and modifications made within the scope of the claims of the present invention should be included in the scope of the present invention.

Claims

1. A method for preparing a silicon-based epitaxial magneto-optical thin film, characterized in that: ZnFe2O4 nanoparticles were first encapsulated with ZIF-8 to obtain ZnFe2O4-ZIF-8. Then, the surface of the nanoparticles was modified with pentyl-o-phenylene aromatic copper to obtain ZnFe2O4-ZIF-8@PgC5Cu. The obtained ZnFe2O4-ZIF-8@PgC5Cu was then mixed with UV adhesive to prepare a glue solution. The glue solution was uniformly coated on a silicon substrate and cured under UV light to obtain a silicon-based polymer magneto-optical film with uniform thickness. The preparation of ZnFe2O4-ZIF-8 includes the following steps: 1) Add FeSO4·7H2O and (CH3COO)2Zn·2H2O to deionized water and mix well to obtain solution A; 2) Add 2-methylimidazole to deionized water and mix well to obtain solution B; 3) Quickly pour solution B into solution A, stir for 30 min, then transfer to a reaction vessel for reaction. After the reaction, cool to room temperature, and then wash the resulting product. The mass ratio of ZnFe2O4-ZIF-8@PgC5Cu to UV adhesive is 1:50~1:200; the UV adhesive is prepared by mixing polyurethane acrylate, 1,6-hexanediol diacrylate and 2,4,6-trimethylbenzoyl-diphenylphosphine oxide in a weight ratio of 7:2:

1.

2. The method for preparing a silicon-based epitaxial magneto-optical thin film according to claim 1, characterized in that, The molar ratio of FeSO4·7H2O, (CH3COO)2Zn·2H2O and 2-methylimidazole used was 0.43:0.765:5.

5.

3. The method for preparing the magneto-optical thin film according to claim 1, characterized in that, The reaction was carried out at a temperature of 120°C for 2 hours.

4. The method for preparing a silicon-based epitaxial magneto-optical thin film according to claim 1, characterized in that, The ZnFe2O4-ZIF-8@PgC5Cu is prepared by mixing pentyl-o-phenylene aromatic copper and ZnFe2O4-ZIF-8 in dichloromethane at a mass ratio of 1:20, reacting with ultrasound for 3 minutes, followed by centrifugation and washing.

5. The method for preparing a silicon-based epitaxial magneto-optical thin film according to claim 1, characterized in that, The coating amount of the adhesive on the silicon substrate is 20 μL / cm. 2 .

6. The method for preparing a silicon-based epitaxial magneto-optical thin film according to claim 1, characterized in that, The UV curing time was 10 min, and the UV lamp power was 6 W.

7. A silicon-based epitaxial magneto-optical thin film prepared by the method of claim 1.

8. A magneto-optical device fabricated using the silicon-based epitaxial magneto-optical thin film of claim 7.

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