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NANOTECHNOLOGY AND PRECISION ENGINEERING 2024年第3期7卷 71-78页

作者： Zhao, Wei xu, zongwei Wang, Pengfei Chen, Hanyi Tianjin Univ State Key Lab Precis Measuring Technol & Instrumen Tianjin 300072 Peoples R China Univ Sci & Technol China Dept Modern Phys Hefei 230026 Peoples R China

Nitrogen vacancy (NV) color centers in diamond have useful applications in quantum sensing and fluorescent marking. They can be generated experimentally by ion implantation, femtosecond lasers, and chemical vapor deposition. However, there is a lack of studies of the yield of NV color centers at the atomic scale. In the molecular dynamics simulations described in this paper, NV color centers are prepared by ion implantation in diamond with pre-doped nitrogen and subsequent annealing. The differences between the yields of NV color centers produced by implantation of carbon (C) and nitrogen (N) ions, respectively, are investigated. It is found that C-ion implantation gives a greater yield of NV color centers and superior location accuracy. The effects of different pre-doping concentrations (400-1500 ppm) and implantation energies (1.0-3.0 keV) on the NV color center yield are analyzed, and it is shown that a pre-doping concentration of 1000 ppm with 2 keV C-ion implantation can produce a 13% yield of NV color centers after 1600 K annealing for 7.4 ns. Finally, a brief comparison of the NV color center identification methods is presented, and it is found that the error rate of an analysis utilizing the identify diamond structure + coordination analysis method is reduced by about 7% compared with conventional identification methods.

关键词： NV color center Ion implantation Molecular dynamics (MD) simulation Yield enhancement NV CENTERS

Fabrication of Superhydrophobic–Hydrophilic Patterned Cu@Ag Composite SERS Substrate via Femtosecond Laser

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Nanomanufacturing and Metrology 2024年第1期7卷 1-14页

作者： Yuheng Zhang zongwei xu Kun Zhang Ying Song Bing Dong Jianshi Wang Mengzhi Yan Qingqing Sun State Key Laboratory of Precision Measuring Technology and Instruments Laboratory of Micro/Nano Manufacturing TechnologyTianjin UniversityTianjin 300072China Shandong Agricultural Equipment Intelligent Engineering Laboratory Shandong Provincial Key Laboratory of Horticultural Machinery and EquipmentCollege of Mechanical and Electronic EngineeringShandong Agricultural UniversityTai’an 827101China

Ultralow concentration molecular detection is critical in various fields,e.g.,food safety,environmental monitoring,and dis-ease *** sensitive surface-enhanced Raman scattering(SERS)based on ultra-wettable surfaces has attracted attention due to its unique ability to detect trace ***,the complexity and cost associated with the preparation of traditional SERS substrates restrict their practical ***,an efficient SERS substrate preparation with high sensitivity,a simplified process,and controllable cost is *** this study,a superhydrophobic–hydrophilic patterned Cu@Ag composite SERS substrate was fabricated using femtosecond laser processing technology combined with silver plating and surface modification *** inducing periodic stripe structures through femtosecond laser processing,the developed substrate achieves uniform distribution *** the surface wettability difference,the object to be measured can be confined in the hydrophilic region and the edge of the hydrophilic region,where the analyte is enriched by the coffee ring effect,can be quickly located by surface morphology difference of micro-nanostructures;thus,greatly improving detec-tion *** fabricated SERS substrate can detect Rhodamine 6G(R6G)at an extraordinarily low concentration of 10^(−15)mol/L,corresponding to an enhancement factor of 1.53×10^(8).This substrate has an ultralow detection limit,incurs low processing costs and is simple to prepare;thus,the substrate has significant application potential in the trace analysis field.

关键词： Femtosecond laser Surface-enhanced Raman scattering Coffee ring effect Superhydrophobic–hydrophilic surface

Foreword to the special issue on wide-bandgap(WBG)semiconductors:from fundamentals to applications

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Nanotechnology and Precision Engineering 2020年第4期3卷 187-188页

作者： zongwei xu Yidan Tang Mathias Rommel Tianjin University China Institute of Microelectronics of Chinese Academy of Sciences China Fraunhofer Institute for Integrated Systems and Device Technology(IISB) Germany

The development of new kinds of semiconductor material is a very attractive topic of scientific research and *** is considered as one of the most impressive 2D materials for many applications,like graphene-reinforced metal matrix nanocomposites.1 Widebandgap(WBG)semiconductors have received widespread attention in recent years because of their superior physical properties such as large band gap,high carrier mobility,and high thermal *** by silicon carbide(SiC)and gallium nitride(GaN),WBG semiconductor materials,therefore,can be operated in extreme working environments or conditions such as high temperature,high frequency,and high power.

关键词： carbide attractive extreme

IMPROVED FABRICATION METHOD FOR CARBON NANOTUBE PROBE OF ATOMIC FORCE MICROSCOPY(AFM)

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Chinese Journal of Mechanical Engineering 2006年第3期19卷 373-375页

作者： xu zongwei DONG Shen GUO Liqiu ZHAO Qingliang Precision Engineering Research Institute Harbin Institute of Technology Harbin150001 China School of Mechanical Engineering Tsinghua University Beijing 100084 China Precision Engineenng Research Institute Harbin Institute of Technology Harbin 150001 China

An improved arc discharge method is developed to fabricate carbon nanotube probe of atomic force microscopy （AFM） here. First, silicon probe and carbon nanotube are manipulated under an optical microscope by two high precision microtranslators. When silicon probe and carbon nanotube are very close, several tens voltage is applied between them. And carbon nanotube is divided and attached to the end of silicon probe, which mainly due to the arc welding function. Comparing with the arc discharge method before, the new method here needs no coat silicon probe with metal film in advance, which can greatly reduce the fabrication＇s difficulty. The fabricated carbon nanotube probe shows good property of higher aspect ratio and can more accurately reflect the true topography of silicon grating than silicon probe. Under the same image drive force, carbon nanotube probe had less indentation depth on soft triblock copolymer sample than silicon probe. This showed that carbon nanotube probe has lower spring constant and less damage to the scan sample than silicon probe.

关键词： Carbon nanotube (CNT) Atomic force microscope (AFM) Probe Fabrication

THEORETICAL ANALYSIS AND EXPERIMENTAL STUDY OF CARBON NANOTUBE PROBE AND CONVENTIONAL ATOMIC FORCE MICROSCOPY PROBE ON SURFACE ROUGHNESS

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Chinese Journal of Mechanical Engineering 2008年第5期21卷 62-64页

作者： WANG Jinghe WANG Hongxiang xu zongwei DONG Shen WANG Shiqian ZHANG Huali Center for Precision Engineering Harbin Institute of Technology Harbin 150001. China

In this paper, three different tips are employed, i.e., the carbon nanotube tip, monocrystalline silicon tip and silicon nitride tip. Resorting to atomic force microscope （AFM）, they are used for measuring the surface roughness of indium tin oxide （ITO） film and the immunoglobulin G （IgG） proteins within the scanning area of 10 μm×10 μm and 0.5 μm×0.5 μm, respectively. Subsequently, the scanned surface of the ITO film and IgG proteins are analyzed by using fractal dimension. The results show that the ffactal dimension measured by carbon nanotube tip is biggest with the highest frequency components and the most microscopic information. Therefore, the carbon nanotube tip is the ideal measuring tool for measuring super-smooth surface, which will play a more and more important role in the high-resolution imaging field.

关键词： Atomic force microscope Carbon nanotube probes Fractal dimension

Generalized design of tunable 3D polarized optical multi-focal spots array

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Optoelectronics Letters 2022年第12期18卷 705-711页

作者： SHI Changkun XIA Zebin LüPeng ZHANG Zengqi xu zongwei State Key Laboratory of Precision Measuring Technology&Instruments Tianjin UniversityTianjin300072China

We report a generally designed optical modulation method to garner the tunable three-dimensional(3D) polarized optical multi-focal spots arrays in the focusing system of high numerical aperture(NA) objective lens, and it has good compatibility with vector beams of different polarization states. Based on the vector angular spectrum theory and Fourier transform, the vector light fields of Gaussian beam, Bessel-Gaussian(BG) beam and Laguerre-Gaussian(LG) beam are modulated with the generally designed multi-focal spots phase filter(MSPF). Meanwhile, a generally designed sidelobe suppression transmission(SST) function is employed to reduce the interference effect of the adjacent focal spots in the arrays. Thus, the one-dimensional(1D) axial multi-focal spots array and the 3D multi-focal spots arrays with high spatial resolution can be generated. The MSPF is flexible and reliable in modulating various vector beams, and exhibiting high tunability for the number(3, 12, 21), spacing(4λ—11.3λ) and spatial distribution(1D—3D) of focal spots in the array. With the generally designed MSPF, the generation of multi-focus array is promoted to be more universal and flexible and shows potential application prospects in femtosecond laser multi-beam parallel processing, particle capture, as well as high-density data storage.

关键词： tunable optical polarization

Density functional theory calculation of the properties of carbon vacancy defects in silicon carbide

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Nanotechnology and Precision Engineering 2020年第4期3卷 211-217页

作者： XiuhongWang Junlei Zhao zongwei xu Flyura Djurabekova Mathias Rommel Ying Song Fengzhou Fanga State Key Laboratory of Precision Measuring Technology&Instruments Centre of MicroNano Manufacturing TechnologyTianjin UniversityTianjin 300072China Department of Physics and Helsinki Institute of Physics University of HelsinkiP.O.Box 43FI-00014 HelsinkiFinland Department of Electrical and Electronic Engineering Southern University of Science and TechnologyShenzhen 518055China Fraunhofer Institute for Integrated Systems and Device Technology IISB Schottkystrasse 1091058 ErlangenGermany

As a promisingmaterial for quantumtechnology,silicon carbide(SiC)has attracted great interest inmaterials *** vacancy is a dominant defect in ***,understanding the properties of this defect is critical to its application,and the atomic and electronic structures of the defects needs to be *** this study,density functional theorywas used to characterize the carbon vacancy defects in hexagonal(h)and cubic(k)lattice *** zero-phonon line energies,hyperfine tensors,and formation energies of carbon vacancies with different charge states(2−,−,0,+and 2+)in different supercells(72,128,400 and 576 atoms)were calculated using standard Perdew-Burke-Ernzerhof and Heyd-Scuseria-Ernzerhof *** show that the zero-phonon line energies of carbon vacancy defects are much lower than those of divacancy defects,indicating that the former is more likely to reach the excited state than the *** hyperfine tensors of VC+(h)and VC+(k)were *** of the calculated hyperfine tensor with the experimental results indicates the existence of carbon vacancies in SiC *** calculation of formation energy shows that the most stable carbon vacancy defects in the material are VC 2+(k),VC+(k),VC(k),VC−(k)and VC 2−(k)as the electronic chemical potential increases.

关键词： Density functional theory Silicon carbide Carbon vacancy

Generation of longitudinally polarized multi-segment optical needles by tightly focusing RPBG beam

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光电子快报:英文版 2023年第7期19卷 399-404页

作者： SHI Changkun SONG Yiding DONG Bing ZHOU Zhanqi ZHANG Zengqi xu zongwei State Key Laboratory of Precision Measuring Technology&Instruments Tianjin UniversityTianjin 300072China School of Optical-Electrical and Computer Engineering University of Shanghai for Science and TechnologyShanghai 200093China

In this paper,an effective method to garner sub-wavelength longitudinally polarized multi-segment optical needle sequence by using a specially designed hybrid filter(HF) in a high numerical aperture(NA) objective focusing system is *** HF is coupled by a binary phase transmission function and a multi-segment modulation function,and the binary phase filter is designed by the particle swarm optimization(PSO) algorithm and acts on the radially polarized Bessel Gaussian(RPBG) beam to obtain a longitudinally polarized optical needle with long depth of focus(DOF,6λ) and a sub-wavelength transverse spot size(0.430λ).The optical needle is with high uniformity of 98% and high beam quality of 96%,and the negligible sidelobe is 15%.On this basis,the multi-segment optical needle sequence with tunable spacing or number can be realized by the multi-segment modulation *** is found that the HF makes the generation of multi-segment optical needle sequence more flexible and *** research has broad application prospects in material processing,particle acceleration,particle capture and other fields.

关键词： function polarized beam

Surface-enhanced Raman scattering on nanodiamond-derived carbon onions

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Nanotechnology and Precision Engineering 2019年第1期2卷 35-39页

作者： Ying Song zongwei xu Andreas Rosenkranz Mathias Rommel Changkun Shi Fengzhou Fang State Key Laboratory of Precision Measuring Technology & Instruments Centre of MicroNano Manufacturing Technology Tianjin University Department of Chemical Engineering Biotechnology and Materials Universidad de Chile Fraunhofer Institute for Integrated Systems and Device Technology (IISB)

Annealing nanodiamonds(ND) at high temperatures up to 1700 ℃ is a common method to synthesize carbon onions. The transformation from NDs to carbon onions is particularly interesting because of carbon onions' potential in the field of tribology and their application in ultra-charge/discharge devices. In this paper, a novel surface-enhanced Raman scattering technique that involves coating the sample with nanoscopic gold particles is proposed to characterize the NDs after different annealing treatments. Conventional Raman and surfaceenhanced Raman spectra were obtained, and the changes of peak parameters as the function of annealing temperature were evaluated. It was found that the widths of the D and the G peaks decreased with increasing annealing temperature, reflecting an improved order in the sp^2-hybridized carbon during the transformation from NDs to carbon onions. After annealing at 1700 ℃, the sp^2?carbon was highly ordered, indicating desirable electrical conductivity and lubricity. With increasing annealing temperature, the D peak showed a blue shift of almost30 cm^(-1), while the G peak merely shifted by 5 cm^(-1). For annealing temperatures above 1100 ℃, an increase of intensity ratio ID/IGwas observed. Compared to the uncoated area, red shifts of 0.5-2 cm^(-1) and of 5-9 cm^(-1) for the G and D peaks, respectively, were detected for the gold-coated area, which was due to the coupling of the plasmons and the phonons of the samples.

关键词： Nanodiamonds Carbon onions Surface-enhanced Raman scattering LOPC mode

Molecular dynamics simulation on the effect of dislocation structures on the retention and distribution of helium ions implanted into silicon

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Nanotechnology and Precision Engineering 2020年第2期3卷 81-87页

作者： Li Ji Lei Liu zongwei xu Ying Song Jintong Wu Rongrong Li Fengzhou Fang Key Laboratory of Precision Measuring Technology&Instruments Tianjin UniversityTianjin 300072China State Key Laboratory for Mesoscopic Physics and Electron Microscopy Laboratory School of PhysicsPeking UniversityBeijing 100871China

To investigate the effect of dislocation structures on the initial formation stage of helium bubbles, molecular dynamics(MD) simulations were used in this study. The retention rate and distribution of helium ions with 2 ke V energy implanted into silicon with dislocation structures were studied via MD simulation. Results show that the dislocation structures and their positions in the sample affect the helium ion retention rate. The analysis on the three-dimensional distribution of helium ions show that the implanted helium ions tend to accumulate near the dislocation structures. Raman spectroscopy results show that the silicon substrate surface after helium ion implantation displayed tensile stress as indicated by the blue shift of Raman peaks.

关键词： Helium ion implantation Molecular dynamics simulation Silicon Dislocation Raman spectroscopy