chương 1 để làm rõ hơn mục tiêu của luận văn. • Chỉnh sửa lại ký hiệu, thang đo các hình 3. • Chỉnh sửa nội dung phần chương 3 để tăng tính gắn kết giữa chương 2 và chương 3. Ngày tháng năm Giáo viên hướng dẫn Tác giả luận văn CHỦ TỊCH HỘI ĐỒNG 2 ĐỀ TÀI LUẬN VĂN Biểu mẫu của Đề tài/Luận văn tốt nghiệp theo qui định của Trường/Viện/Khoa, tuy nhiên cần đảm bảo giáo viên giao đề tài ký và ghi rõ họ và tên.
Trường hợp có 2 giáo viên hướng dẫn thì sẽ cùng ký tên. Giáo viên hướng dẫn Ký và ghi rõ họ tên 3 Lời cảm ơn Luận văn được thực hiện dưới sự hướng dẫn của thầy giáo Chu Mạnh Hoàng, với những định hướng về mặt chuyên môn và động viên tinh thần, em xin gửi đến thầy lòng biết ơn sâu sắc. Cảm ơn cô giáo Lưu Thị Lan Anh đã luôn quan tâm và giúp đỡ em trong qua trình làm luận văn. Con xin cảm ơn gia đình, bố, mẹ, anh, chị, 2 cháu Tôm, Cá đã luôn là chỗ dựa tinh thần, là nguồn động lực to lớn nhất để con có thể vững bước trên con đường đã chọn.
Tôi xin cảm ơn các bạn Mai Lý, Quốc Trọng, Phạm Khải, Đức Phụng, Vân Đoàn đã luôn bên cạnh, chia sẻ những khó khăn và giúp tôi vượt qua những khó khăn đó, trước trong và sau quá trình làm luận văn. Xin cảm ơn các học viên cao học và các sinh viên 2 nhóm MEMS và Gas Sensor: bạn T. Chính, em N. Vân, …đã giúp đỡ nhiệt tình trong quá trình học thạc sĩ của anh.
Cảm ơn cô giáo Hoàng Linh Giang đã tận tình giúp đỡ, động viên và chia sẻ những khó khăn trong quá trình hoàn thiện luận văn. Quá trình học tập ở viện ITIMS thực sự mang lại cho em nhiều kiến thức và kỹ năng bổ ích. Em sẽ luôn ghi nhớ và trân trọng, thay lời cảm ơn đến các thầy cô, bạn bè và anh chị trong viện. Luận văn có thể còn nhiều thiếu sót vì phải tiếp nhận kiến thức mới, kính mong nhận được sự góp ý từ thầy cô giáo để em hoàn thiện hơn.
Em xin chân thành cảm ơn. Abstract of thesis In terms of structure, the thesis comprises three chapters: Chapter 1 provides an overview of plasmonic substrates, their applications, and various fabrication methods. Chapter 2 designs, simulates, and calculates a microactuator structure for application in the nanoimprinting process. Model a plasmonic substrates to identify optimal parameters for the hotspot.
Chapter 3 details the experimental process of fabricating plasmonic substrates using the mold imprinting method, presenting experimental results; and the resonant properties of the manufactured plasmonic substrates. HỌC VIÊN Ký và ghi rõ họ tên 4 Table of Contents Chapter 1. OVERVIEW OF PLASMONIC SUBSTRATE .2 Applications of plasmonic substrate .1 Surface-Enhanced Raman Spectroscopy (SERS).3 Plasmonic Photovoltaics and Plasmonic Solar Cells .3 Material and structure of plasmonic substrate .1 Material of plasmonic substrate .2 Type of structure of plasmonic substrate .5 Microactuator for controlling the stamp .6 The research situation in Viet Nam and the objectives of the thesis. DESIGN AND SIMULATION OF A MICROACTUATOR FOR CONTROLLING IMPRINTING PROCESS AND A PLASMONIC STRUCTURE 29 2.1 Microactuator for controlling the mold .2 Operation characteristics of a serpentine spring system .3 Calculation of capacitor type actuator .2 A model of plasmonic nanostructure based on the imprinting process.2 Operation characteristics based on FEM simulation.
STUDY AND FABRICATION OF PLASMONIC SUBSTRATES BASED ON IMPRINTING METHOD .1 Process of the imprinting method .1 Process of fabricating imprinting mold .2 Process of fabricating plasmonic substrate .2 Results and Discussion .1 Results of the fabricating mold .2 Result of fabricating plasmonic substrate. 57 Conclussions of the thesis. 60 6 Figure Index Figure Figure 1.1: Localized surface plasmonic .2: Schema of the surface-enhanced Raman scattering (SERS) effect originated by the localized plasmon resonance of metallic inter-nanoparticles (NPs).3: Normalized extinction cross-sectional area for spherical gold nanoparticles of diameters ranging from 20–100 nm[12].4: Three plasmonic approaches to enhance light absorption a) Metal nanoparticles at the front surface of a solar cell. b) Metal nanoparticles embedded inside the cell.
c) Metal corrugations at the back surface of a cell [21].5: New plasmonic solar cell designs: a) tandem, b) plasmonic quantum dots, c) optical antenna array, d) coaxial hole array.6: Representative images of electron microscopy of synthesized Ag nanostructures, demonstrating that diverse sizes and morphologies are made possible by controlling the reaction chemistry.7: Fabrication process of plasmonic nanostructures using electron beam lithography: (a) Substrate, (b) Electron-sensitive polymer coating, (c) Etching and visualization, (d) Metal coating and (e ) Remove the polymer layer.8: The process of fabricating plamonic structure using FIB .9: The process of the nanoimprinting method .11: Principle of the piezoelectric actuators .13: An electrostatic actuator structure .1: The model of the proposed microactuator.2: The microstructure with: 2 (a); 4 (b); 6 serpentine springs (c).3: Parameters of the structure.4: The structure comprises four beams after grid division.5: The simulated images of the behavior in the z-mode and the closest mode of the following structures: 2 springs (a-b); 4 springs (c-d); 6 springs (e-f).6: The operation frequency of three spring types with: w from 2-20 μm, in which t and α are fixed at 10 μm and 50°, respectively (a); t from 2- 20 μm, in which w and α are fixed at 10 μm and 50°, respectively (b); α from 5° - 50°, in which w and t are both 10 µm.7: The difference between the operating frequencies of the z-mode and the nearest mode of all three structures with: w from 2-20 μm, t and α are fixed at 10 μm and 50° (a); t from 2-20 μm, w and α are fixed at 10 μm and 50°(b); α from 5° - 50°, w and t are both 10µm (c).8: Cylindrical capacitor array.9: The displacement along the z-axis depends on the velocity V with structure 1 (a-b) and structure 2 (c-d).10: The plasmonic substrate in the form of hole.11: Images of 2D and 3D structures.12: Grid-Partitioned Structure.13: Distribution of electric field intensity with a plasmonic substrate of 200nm height at various opening angles α: 10° (a); 30° (b); 50° (c); 70° (d); 90° (e); and 110° (f) at a wavelength of 600nm.14: Determination of Electric Field Intensity Location.15: The electric field intensity at the selected location in structures at angles α: 10° (a); 30° (b); 50° (c); 70° (d); 90° (e); 110° (f).1: Fabrication process of imprinting mold using photolithography combined with anisotropic wet chemical etching: (a) oxidation; (b) photolithography; (c) SiO2 etching; (d) remove resist; (e) Silicon etching; (f) remove SiO2.2: Process of photolithography .3: Design of mask .4: Imprinting process: (a) coating polymer; (b) mold-substrate contacted; (c) removing mold; (d) sputtering silver.5: Mask printed with diameter: 20 µm (a), 30 µm (b), 40 µm (c), 50 µm (d), 60 µm (e), 70 µm (f).6: The substrate after photolithography process (a); The substrate etched in solution BHF (b).7: Substrate after 30 mins (a); 35 mins (b) and 40 mins etching in KOH solution.8: The SEM image of the substrate after 30 mins (a); 35 mins (b) and 40 mins etching in KOH solution.9: Silicon nanotip after 35mins etching, .10: Shape of the etch profiles of a <100> oriented silicon substrate after immersion in an anisotropic wet etchant solution.11: Pyrex substrates coated with a polymer blend after the imprinting process with contact times of 20 minutes (a), 30 minutes (b), and 40 minutes (c), respectively.12: The surface of the plasmonic substrate use PDMS.13: The plasmonic substrate after sputtering (a); the thickness of PDMS layer (b); the thickness of Ag layer (c).14: The depth of the hole structure after sputtering.15: The substrate after sputtering (a); the thickness of MAP- 1215 layer (b); the thickness of Ag layer (c).16: The depth of the hole structure after sputtering.17: Raman shift of various poisitions with Methalmin Blue reagent:the silicon substrate (black line); the flat position on substrate 1 (red dash); the hole position on 8 substrate 1 (blue dot); the flat position on substrate 2(green dash) and the hole position on substrate 2(purple dot).18: Raman shift of various poisitions wit RhB reagent:the silicon substrate (black line); the hole position on substrate 1 (red dot); the flat position on substrate 1 (blue line); the flat position on substrate 2(green dot) and the hole position on substrate 2(purple line). 56 Table Table 2-1: Microstructure parameters. 31 Table 2-2: Parameters of the Capacitor Structure. 36 Table 2-3: Simulation structural parameters.
OVERVIEW OF PLASMONIC SUBSTRATE 1.1 Plasmonic effect Surface plasmon (SP) is the collective oscillation of conduction electrons stimulated by light at the interface between two media with opposite dielectric constants, such as dielectric and metal, or strongly mixed semiconductor materials. Light can couple with SP when satisfying the conditions of energy and momentum conservation, and the electric field near the interface of metal-dielectric is enhanced [1]. Surface plasmons are divided into two types: localized surface plasmons (LSPs) and propagating surface plasmons (PSPs) [2]. Localized surface plasmons (LSPs) are a phenomenon that occurs at the nanoscale, primarily on the surfaces of metal nanoparticles or nanostructures.
When incident light, usually in the visible or near-infrared range, interacts with these structures, it induces a coherent oscillation of the free electrons in the metal (Fig 1. This collective oscillation of electrons results in a resonant response, characterized by strong absorption and scattering of light. The resonant frequency of this oscillation is highly dependent on the size, shape, and material properties of the nanoparticle, as well as the surrounding dielectric environment. This tunability makes LSPs a valuable tool for controlling and manipulating light at the nanoscale [3].1: Localized surface plasmonic The electric field associated with the LSPs is highly localized to the vicinity of the nanoparticle, typically within a few nanometers, hence the term "localized." This localization allows for a dramatic enhancement of the electromagnetic field intensity, which is exploited in various applications [4].2 Applications of plasmonic substrate Plasmonic substrates, which typically involve surfaces or structures that support plasmonic excitations, have a wide range of applications across various fields due to their unique optical properties.1 Surface-Enhanced Raman Spectroscopy (SERS) Surface-enhanced Raman Spectroscopy (SERS) is a powerful analytical technique used for detecting and characterizing molecules at extremely low concentrations.
It is based on the principle of enhancing the Raman scattering signal by several orders of 10 magnitude through the interaction of molecules with plasmonic nanostructures or substrates [5].2: Schema of the surface-enhanced Raman scattering (SERS) effect originated by the localized plasmon resonance of metallic inter-nanoparticles (NPs). When light is incident on the substrate containing metal nanoparticles of suitable dimensions, plasmonic effects will occur. When molecules (analytes) are in close proximity to or adsorbed onto the surface of these plasmonic nanoparticles, their electromagnetic fields are significantly enhanced (fig 1. This enhancement arises from the intense electromagnetic field produced by the collective oscillation of electrons (plasmons) at the nanoparticle's surface.
The electromagnetic field is highly localized in the immediate vicinity of the nanoparticle, leading to enormous enhancements in the Raman scattering signal of the adjacent molecules [6]. The enhancement in SERS is typically described in terms of enhancement factors (EF), which quantitatively represent the increase in Raman scattering intensity due to the presence of plasmonic substrates. Enhancement factors can range from 106 to 1014 [7], making SERS an incredibly sensitive technique for molecular detection. The shape, size (fig 1.3), composition, and arrangement of the plasmonic nanostructures significantly influence the enhancement in SERS[8-12].
Nanoparticles with sharp edges or tips exhibit higher enhancement due to stronger electric field localization. Aggregates of nanoparticles can also create hotspots with exceptionally high electric field intensities, further amplifying the enhancement. Plasmonic substrates used in SERS are typically composed of metal nanoparticles or nanostructures, often made of silver, gold, or other noble metals.