Molecular dynamics(MD) simulations are performed to study the composition-dependent elastic modulus and thermal conductivity for carbon/silicon core/shell nanowires(NWs).For each concerned carbon/silicon core/shell NW...Molecular dynamics(MD) simulations are performed to study the composition-dependent elastic modulus and thermal conductivity for carbon/silicon core/shell nanowires(NWs).For each concerned carbon/silicon core/shell NW with a specified diameter,it is found that elastic modulus is reduced with a linear dependence on cross-sectional area ratio.The fact matches well with the results of theoretical model.Analysis based on the cross-sectional stress distribution indicates that the core region of core/shell NW is capable of functioning as a mechanical support.On the other hand,thermal conductivity also relies on the cross-sectional area ratio of amorphous silicon shell.The core/shell interface plays a considerable influence on the thermal transport property. The decreasing rate of thermal conductivity is gradually decreased as the composition of amorphous silicon shell increases.In addition,by calculating the phonon density of state,we demonstrate that the reduction in thermal conductivity of the core/shell NW stems from the increase of the low frequency modes and the depression of high-frequency nonpropagating diffusion modes.These results provide an effective way to modify the properties of core/shell NWs for related application.展开更多
CW-CO2 laser nitriding technique was applied to improve the properties （such as aging property and the core loss） of grain oriented silicon steel. The samples were nitrided with regular space. Laser power density an...CW-CO2 laser nitriding technique was applied to improve the properties （such as aging property and the core loss） of grain oriented silicon steel. The samples were nitrided with regular space. Laser power density and scanning speed were chosen as 7.8×10^5W·cm^-2 and 100mm·min^-1. By some laser irradiation, Fe4N and Fe3N were formed in the nitrided zone. The nitrided samples were annealed at the temperatures ranged from 100 to 90℃. The core loss of some interested samples was tested. The results show that the core loss of the nitrided samples with different thickness of 0.23 and 0.30mm decreased by 14.9% and 9.4% respectively, and the aging property were improved up to 800℃. The mechanism of laser nitriding to improve the properties of grain oriented silicon steel is discussed.展开更多
Large-size electronic-grade polycrystalline silicon is an important material in the semiconductor industry with broad application prospects.However,electronic-grade polycrystalline silicon has extremely high requireme...Large-size electronic-grade polycrystalline silicon is an important material in the semiconductor industry with broad application prospects.However,electronic-grade polycrystalline silicon has extremely high requirements for production technology and currently faces challenges such as carbon impurity breakdown,microstructure and composition nonuniformity and a lack of methods for preparing large-size mirror-like polycrystalline silicon samples.This paper innovatively uses physical methods such as wire cutting,mechanical grinding and ion thinning polishing to prepare large-size polycrystalline silicon samples that are clean,smooth,free from wear and have clear crystal defects.The material was characterized at both macroscopic and microscopic levels using metallographic microscopy,scanning electron microscopy(SEM)with backscattered electron diffraction(EBSD)techniques and scanning transmission electron microscopy(STEM).The crystal structure changes from single crystal silicon core to the surface of the bulk in the large-size polycrystalline silicon samples were revealed,providing a technical basis for optimizing and improving production processes.展开更多
This paper focuses on the problems encountered in the production process of electronic-grade polycrystalline silicon.It points out that the characterization of electronic-grade polycrystalline silicon is mainly concen...This paper focuses on the problems encountered in the production process of electronic-grade polycrystalline silicon.It points out that the characterization of electronic-grade polycrystalline silicon is mainly concentrated at the macroscopic scale,with relatively less research at the mesoscopic and microscopic scales.Therefore,we utilize the method of physical polishing to obtain polysilicon characterization samples and then the paper utilizes metallographic microscopy,scanning electron microscopy-electron backscatter diffraction technology,and aberration-corrected transmission electron microscopy technology to observe and characterize the interface region between silicon core and matrix in the deposition process of electronic-grade polycrystalline silicon,providing a full-scale characterization of the interface morphology,grain structure,and orientation distribution from macro to micro.Finally,the paper illustrates the current uncertainties regarding polycrystalline silicon.展开更多
The state-of-the-art multi-core computer systems are based on Very Large Scale three Dimensional (3D) Integrated circuits (VLSI). In order to provide high-speed vertical data transmission in such 3D systems, efficient...The state-of-the-art multi-core computer systems are based on Very Large Scale three Dimensional (3D) Integrated circuits (VLSI). In order to provide high-speed vertical data transmission in such 3D systems, efficient Through-Silicon Via (TSV) technology is critically important. In this paper, various Radio Frequency (RF) TSV designs and models are proposed. Specifically, the Cu-plug TSV with surrounding ground TSVs is used as the baseline structure. For further improvement, the dielectric coaxial and novel air-gap coaxial TSVs are introduced. Using the empirical parameters of these coaxial TSVs, the simulation results are obtained demonstrating that these coaxial RF-TSVs can provide two-order higher of cut-off frequencies than the Cu-plug TSVs. Based on these new RF-TSV technologies, we propose a novel 3D multi-core computer system as well as new architectures for manipulating the interfaces between RF and baseband circuit. Taking into consideration the scaling down of IC manufacture technologies, predictions for the performance of future generations of circuits are made. With simulation results indicating energy per bit and area per bit being reduced by 7% and 11% respectively, we can conclude that the proposed method is a worthwhile guideline for the design of future multi-core computer ICs.展开更多
基金the China Postdoctoral Science Foundation and Fundamental Research Funds for the Central Universities(No.HIT NSRIF 2013031)
文摘Molecular dynamics(MD) simulations are performed to study the composition-dependent elastic modulus and thermal conductivity for carbon/silicon core/shell nanowires(NWs).For each concerned carbon/silicon core/shell NW with a specified diameter,it is found that elastic modulus is reduced with a linear dependence on cross-sectional area ratio.The fact matches well with the results of theoretical model.Analysis based on the cross-sectional stress distribution indicates that the core region of core/shell NW is capable of functioning as a mechanical support.On the other hand,thermal conductivity also relies on the cross-sectional area ratio of amorphous silicon shell.The core/shell interface plays a considerable influence on the thermal transport property. The decreasing rate of thermal conductivity is gradually decreased as the composition of amorphous silicon shell increases.In addition,by calculating the phonon density of state,we demonstrate that the reduction in thermal conductivity of the core/shell NW stems from the increase of the low frequency modes and the depression of high-frequency nonpropagating diffusion modes.These results provide an effective way to modify the properties of core/shell NWs for related application.
基金supported by the National Natural Science Foundation of China(No.50174020).
文摘CW-CO2 laser nitriding technique was applied to improve the properties （such as aging property and the core loss） of grain oriented silicon steel. The samples were nitrided with regular space. Laser power density and scanning speed were chosen as 7.8×10^5W·cm^-2 and 100mm·min^-1. By some laser irradiation, Fe4N and Fe3N were formed in the nitrided zone. The nitrided samples were annealed at the temperatures ranged from 100 to 90℃. The core loss of some interested samples was tested. The results show that the core loss of the nitrided samples with different thickness of 0.23 and 0.30mm decreased by 14.9% and 9.4% respectively, and the aging property were improved up to 800℃. The mechanism of laser nitriding to improve the properties of grain oriented silicon steel is discussed.
基金support from the unveiling project by Qinghai Xince Technology Co.,Ltd.,Huanghe Hydropower Development Co.,Ltd.,Project No.XCKJ-FY(2024)No.1(total No.25).
文摘Large-size electronic-grade polycrystalline silicon is an important material in the semiconductor industry with broad application prospects.However,electronic-grade polycrystalline silicon has extremely high requirements for production technology and currently faces challenges such as carbon impurity breakdown,microstructure and composition nonuniformity and a lack of methods for preparing large-size mirror-like polycrystalline silicon samples.This paper innovatively uses physical methods such as wire cutting,mechanical grinding and ion thinning polishing to prepare large-size polycrystalline silicon samples that are clean,smooth,free from wear and have clear crystal defects.The material was characterized at both macroscopic and microscopic levels using metallographic microscopy,scanning electron microscopy(SEM)with backscattered electron diffraction(EBSD)techniques and scanning transmission electron microscopy(STEM).The crystal structure changes from single crystal silicon core to the surface of the bulk in the large-size polycrystalline silicon samples were revealed,providing a technical basis for optimizing and improving production processes.
基金support of the unveiling project of“Application Research on Carbon and Other Trace Impurities and Microstructure Characterization Technology on the Surface of Electronic Grade Polysilicon”by Qinghai Xince Technology Co.,Ltd.of the Huanghe Hydropower Development Co.,Ltd.,project number:XCKJ-FY(2024)No.1(total No.25).
文摘This paper focuses on the problems encountered in the production process of electronic-grade polycrystalline silicon.It points out that the characterization of electronic-grade polycrystalline silicon is mainly concentrated at the macroscopic scale,with relatively less research at the mesoscopic and microscopic scales.Therefore,we utilize the method of physical polishing to obtain polysilicon characterization samples and then the paper utilizes metallographic microscopy,scanning electron microscopy-electron backscatter diffraction technology,and aberration-corrected transmission electron microscopy technology to observe and characterize the interface region between silicon core and matrix in the deposition process of electronic-grade polycrystalline silicon,providing a full-scale characterization of the interface morphology,grain structure,and orientation distribution from macro to micro.Finally,the paper illustrates the current uncertainties regarding polycrystalline silicon.
文摘The state-of-the-art multi-core computer systems are based on Very Large Scale three Dimensional (3D) Integrated circuits (VLSI). In order to provide high-speed vertical data transmission in such 3D systems, efficient Through-Silicon Via (TSV) technology is critically important. In this paper, various Radio Frequency (RF) TSV designs and models are proposed. Specifically, the Cu-plug TSV with surrounding ground TSVs is used as the baseline structure. For further improvement, the dielectric coaxial and novel air-gap coaxial TSVs are introduced. Using the empirical parameters of these coaxial TSVs, the simulation results are obtained demonstrating that these coaxial RF-TSVs can provide two-order higher of cut-off frequencies than the Cu-plug TSVs. Based on these new RF-TSV technologies, we propose a novel 3D multi-core computer system as well as new architectures for manipulating the interfaces between RF and baseband circuit. Taking into consideration the scaling down of IC manufacture technologies, predictions for the performance of future generations of circuits are made. With simulation results indicating energy per bit and area per bit being reduced by 7% and 11% respectively, we can conclude that the proposed method is a worthwhile guideline for the design of future multi-core computer ICs.
