The fast and convenient demultiplex of optical vortex(OV) mode is crucial for its further application. We propose a novel approach that combines classic Young's doublet with an OV source to effectively identify th...The fast and convenient demultiplex of optical vortex(OV) mode is crucial for its further application. We propose a novel approach that combines classic Young's doublet with an OV source to effectively identify the OV mode through the analysis of interference patterns. The interference patterns of the OV source incident on the double slits can be perfectly illustrated by using both the classical double-slit interference method and the Huygens–Fresnel principle. The interference fringes will twist along the negative or positive direction of x axis when topological charge(TC)l>0 or l<0, and the degree of the movement varies with the TC, allowing for a quantitative display of the OV characteristics through the interference patterns. Additionally, we deduce analytically that the zeroth-order interference fringe has a linear relationship with the TC and the vertical position. These findings highlight the ability to identify the OV mode by analyzing the interference patterns produced by Young's doublet.展开更多
Thermal interface materials(TIMs)with high through-plane thermal conductivity are urgently desired to avoid overheating of high-power density electronics.Introducing and aligning fillers in polymer matrixes via magnet...Thermal interface materials(TIMs)with high through-plane thermal conductivity are urgently desired to avoid overheating of high-power density electronics.Introducing and aligning fillers in polymer matrixes via magnetic field is a promising method to improve the thermal conductivity of the polymer.However,either the fillers need to be modified with magnetic particles or a strong magnetic field is needed for good alignment in high filler content.This prevents further improvement of the through-plane thermal conductivity.Herein,mesophase pitch-based carbon fibers(MPCFs)with a content as high as 76 wt.%are aligned vertically in water-soluble polyvinyl alcohol(PVA)under a low magnetic field(~0.4 T),forming a vertically aligned MPCF(VAMPCF)/PVA composite with an extraordinary through-plane thermal conductivity of 86 W/(m·K),which is higher than that of many alloys.In addition,both theoretical and experimental results demonstrate that the critical intensity of the magnetic field needed for good alignment of the fillers depends on their size and magnetic susceptibility.Furthermore,the water solubility of PVA makes it easy to recycle MPCFs.This study offers an inspired venue to develop excellent and eco-friendly TIMs to meet ever increasing demand in heat dissipation for electronics.展开更多
A 4H-SiC trench gate metal-oxide-semiconductor field-effect transistor(UMOSFET)with semi-super-junction shiel-ded structure(SS-UMOS)is proposed and compared with conventional trench MOSFET(CT-UMOS)in this work.The adv...A 4H-SiC trench gate metal-oxide-semiconductor field-effect transistor(UMOSFET)with semi-super-junction shiel-ded structure(SS-UMOS)is proposed and compared with conventional trench MOSFET(CT-UMOS)in this work.The advantage of the proposed structure is given by comprehensive study of the mechanism of the local semi-super-junction structure at the bottom of the trench MOSFET.In particular,the influence of the bias condition of the p-pillar at the bottom of the trench on the static and dynamic performances of the device is compared and revealed.The on-resistance of SS-UMOS with grounded(G)and ungrounded(NG)p-pillar is reduced by 52%(G)and 71%(NG)compared to CT-UMOS,respectively.Additionally,gate ox-ide in the GSS-UMOS is fully protected by the p-shield layer as well as semi-super-junction structure under the trench and p-base regions.Thus,a reduced electric-field of 2 MV/cm can be achieved at the corner of the p-shield layer.However,the quasi-intrinsic protective layer cannot be formed in NGSS-UMOS due to the charge storage effect in the floating p-pillar,resulting in a large electric field of 2.7 MV/cm at the gate oxide layer.Moreover,the total switching loss of GSS-UMOS is 1.95 mJ/cm2 and is reduced by 18%compared with CT-UMOS.On the contrary,the NGSS-UMOS has the slowest overall switching speed due to the weakened shielding effect of the p-pillar and the largest gate-to-drain capacitance among the three.The proposed GSS-UMOS plays an important role in high-voltage and high-frequency applications,and will provide a valuable idea for device design and circuit applications.展开更多
With the packing density growing continuously in integrated electronic devices,sufficient heat dissipation becomes a serious challenge.Recently,dielectric materials with high thermal conductivity have brought insight ...With the packing density growing continuously in integrated electronic devices,sufficient heat dissipation becomes a serious challenge.Recently,dielectric materials with high thermal conductivity have brought insight into effective dissipation of waste heat in electronic devices to prevent them from overheating and guarantee the performance stability.Layered CrOCl,an antiferromagnetic insulator with low-symmetry crystal structure and atomic level flatness,might be a promising solution to the thermal challenge.Herein,we have systematically studied the thermal transport of suspended few-layer CrOCl flakes by microRaman thermometry.The CrOCl flakes exhibit high thermal conductivities along zigzag direction,from~392±33 to~1,017±46 W·m^(−1)·K^(−1) with flake thickness from 2 to 50 nm.Besides,pronounced thickness-dependent thermal conductivity ratio(/from~2.8±0.24 to~4.3±0.25)has been observed in the CrOCl flakes,attributed to the discrepancy of phonon dispersion and phonon surface scattering.As a demonstration to the heat sink application of layered CrOCl,we then investigate the energy dissipation in graphene devices on CrOCl,SiO_(2) and hexagonal boron nitride(h-BN)substrates,respectively.The graphene device temperature rise on CrOCl is only 15.4%of that on SiO_(2) and 30%on h-BN upon the same electric power density,indicating the efficient heat dissipation of graphene device on CrOCl.Our study provides new insights into two-dimentional(2D)dielectric material with high thermal conductivity and strong anisotropy for the application of thermal management in electronic devices.展开更多
Energy dissipation has always been an attention-getting issue in modern electronics and the emerging low-symmetry two-dimensional(2D)materials are considered to have broad prospects in solving the energy dissipation p...Energy dissipation has always been an attention-getting issue in modern electronics and the emerging low-symmetry two-dimensional(2D)materials are considered to have broad prospects in solving the energy dissipation problem.Herein the thermal transport of a typical 2D ternary chalcogenide Ta_(2)NiS_(5) is investigated.For the first time we have observed strongly anisotropic in-plane thermal conductivity towards armchair and zigzag axes of suspended few-layer Ta_(2)NiS_(5) flakes through Raman thermometry.For 7-nm-thick Ta_(2)NiS_(5) flakes,theκz i g z a g is 4.76 W·m^(−1)·K^(−1) andκa r m c h a i r is 7.79 W·m^(−1)·K^(−1),with a large anisotropic ratio(κa r m c h a i r/κz i g z a g)of 1.64 mainly ascribed to different phonon mean-free-paths along armchair and zigzag axes.Moreover,the thickness dependence of thermal anisotropy is also discussed.As the flake thickness increases,theκa r m c h a i r/κz i g z a g reduces sharply from 1.64 to 1.07.This could be attributed to the diversity in phonon boundary scattering,which decreases faster in zigzag direction than in armchair direction.Such anisotropic property enables heat flow manipulation in Ta_(2)NiS_(5) based devices to improve thermal management and device performance.Our work helps reveal the anisotropy physics of ternary transition metal chalcogenides,along with significant guidance to develop energy-efficient next generation nanodevices.展开更多
基金Project supported by the National Key Research and Development Program of China (Grant Nos.2020YFA0710100 and 2023YFA1407100)the National Natural Science Foundation of China (Grant Nos.92050102 and 12374410)+2 种基金the Jiangxi Provincial Natural Science Foundation (Grant No.20224ACB201005)the Fundamental Research Funds for the Central Universities (Grant Nos.20720230102 and 20720220033)China Scholarship Council (Grant No.202206310009)。
文摘The fast and convenient demultiplex of optical vortex(OV) mode is crucial for its further application. We propose a novel approach that combines classic Young's doublet with an OV source to effectively identify the OV mode through the analysis of interference patterns. The interference patterns of the OV source incident on the double slits can be perfectly illustrated by using both the classical double-slit interference method and the Huygens–Fresnel principle. The interference fringes will twist along the negative or positive direction of x axis when topological charge(TC)l>0 or l<0, and the degree of the movement varies with the TC, allowing for a quantitative display of the OV characteristics through the interference patterns. Additionally, we deduce analytically that the zeroth-order interference fringe has a linear relationship with the TC and the vertical position. These findings highlight the ability to identify the OV mode by analyzing the interference patterns produced by Young's doublet.
基金the National Natural Science Foundation of China(Nos.11874423 and 12174321)the Fundamental Research Funds for the Central Universities(No.20720190050).
文摘Thermal interface materials(TIMs)with high through-plane thermal conductivity are urgently desired to avoid overheating of high-power density electronics.Introducing and aligning fillers in polymer matrixes via magnetic field is a promising method to improve the thermal conductivity of the polymer.However,either the fillers need to be modified with magnetic particles or a strong magnetic field is needed for good alignment in high filler content.This prevents further improvement of the through-plane thermal conductivity.Herein,mesophase pitch-based carbon fibers(MPCFs)with a content as high as 76 wt.%are aligned vertically in water-soluble polyvinyl alcohol(PVA)under a low magnetic field(~0.4 T),forming a vertically aligned MPCF(VAMPCF)/PVA composite with an extraordinary through-plane thermal conductivity of 86 W/(m·K),which is higher than that of many alloys.In addition,both theoretical and experimental results demonstrate that the critical intensity of the magnetic field needed for good alignment of the fillers depends on their size and magnetic susceptibility.Furthermore,the water solubility of PVA makes it easy to recycle MPCFs.This study offers an inspired venue to develop excellent and eco-friendly TIMs to meet ever increasing demand in heat dissipation for electronics.
基金supported by the National Natural Science Foundation of China(Grant No.62104222)the Natural Science Foundation of Fujian Province of China for Distinguished Young Scholars(Grant No.2020J06002)+3 种基金the Science and Technology Project of Fujian Province of China(Grant No.2020I0001)the Science and Technology Key Projects of Xiamen(Grant No.3502ZCQ20191001)Shenzhen Science and Technology Program(Grant No.JSGG20201102-155800003)Jiangxi Provincial Natural Science Foundation(Grant No.20212ACB212005).
文摘A 4H-SiC trench gate metal-oxide-semiconductor field-effect transistor(UMOSFET)with semi-super-junction shiel-ded structure(SS-UMOS)is proposed and compared with conventional trench MOSFET(CT-UMOS)in this work.The advantage of the proposed structure is given by comprehensive study of the mechanism of the local semi-super-junction structure at the bottom of the trench MOSFET.In particular,the influence of the bias condition of the p-pillar at the bottom of the trench on the static and dynamic performances of the device is compared and revealed.The on-resistance of SS-UMOS with grounded(G)and ungrounded(NG)p-pillar is reduced by 52%(G)and 71%(NG)compared to CT-UMOS,respectively.Additionally,gate ox-ide in the GSS-UMOS is fully protected by the p-shield layer as well as semi-super-junction structure under the trench and p-base regions.Thus,a reduced electric-field of 2 MV/cm can be achieved at the corner of the p-shield layer.However,the quasi-intrinsic protective layer cannot be formed in NGSS-UMOS due to the charge storage effect in the floating p-pillar,resulting in a large electric field of 2.7 MV/cm at the gate oxide layer.Moreover,the total switching loss of GSS-UMOS is 1.95 mJ/cm2 and is reduced by 18%compared with CT-UMOS.On the contrary,the NGSS-UMOS has the slowest overall switching speed due to the weakened shielding effect of the p-pillar and the largest gate-to-drain capacitance among the three.The proposed GSS-UMOS plays an important role in high-voltage and high-frequency applications,and will provide a valuable idea for device design and circuit applications.
基金supported by the National Natural Science Foundation of China(No.11874423).
文摘With the packing density growing continuously in integrated electronic devices,sufficient heat dissipation becomes a serious challenge.Recently,dielectric materials with high thermal conductivity have brought insight into effective dissipation of waste heat in electronic devices to prevent them from overheating and guarantee the performance stability.Layered CrOCl,an antiferromagnetic insulator with low-symmetry crystal structure and atomic level flatness,might be a promising solution to the thermal challenge.Herein,we have systematically studied the thermal transport of suspended few-layer CrOCl flakes by microRaman thermometry.The CrOCl flakes exhibit high thermal conductivities along zigzag direction,from~392±33 to~1,017±46 W·m^(−1)·K^(−1) with flake thickness from 2 to 50 nm.Besides,pronounced thickness-dependent thermal conductivity ratio(/from~2.8±0.24 to~4.3±0.25)has been observed in the CrOCl flakes,attributed to the discrepancy of phonon dispersion and phonon surface scattering.As a demonstration to the heat sink application of layered CrOCl,we then investigate the energy dissipation in graphene devices on CrOCl,SiO_(2) and hexagonal boron nitride(h-BN)substrates,respectively.The graphene device temperature rise on CrOCl is only 15.4%of that on SiO_(2) and 30%on h-BN upon the same electric power density,indicating the efficient heat dissipation of graphene device on CrOCl.Our study provides new insights into two-dimentional(2D)dielectric material with high thermal conductivity and strong anisotropy for the application of thermal management in electronic devices.
基金supported by the National Natural Science Foundation of China(NSFC,Nos.11874423 and 11404399)the National Defense Science and Technology Innovation Zone,and the Scientific Researches Foundation of National University of Defense Technology(Nos.ZK20-16 and ZZKY-YX-08-06).
文摘Energy dissipation has always been an attention-getting issue in modern electronics and the emerging low-symmetry two-dimensional(2D)materials are considered to have broad prospects in solving the energy dissipation problem.Herein the thermal transport of a typical 2D ternary chalcogenide Ta_(2)NiS_(5) is investigated.For the first time we have observed strongly anisotropic in-plane thermal conductivity towards armchair and zigzag axes of suspended few-layer Ta_(2)NiS_(5) flakes through Raman thermometry.For 7-nm-thick Ta_(2)NiS_(5) flakes,theκz i g z a g is 4.76 W·m^(−1)·K^(−1) andκa r m c h a i r is 7.79 W·m^(−1)·K^(−1),with a large anisotropic ratio(κa r m c h a i r/κz i g z a g)of 1.64 mainly ascribed to different phonon mean-free-paths along armchair and zigzag axes.Moreover,the thickness dependence of thermal anisotropy is also discussed.As the flake thickness increases,theκa r m c h a i r/κz i g z a g reduces sharply from 1.64 to 1.07.This could be attributed to the diversity in phonon boundary scattering,which decreases faster in zigzag direction than in armchair direction.Such anisotropic property enables heat flow manipulation in Ta_(2)NiS_(5) based devices to improve thermal management and device performance.Our work helps reveal the anisotropy physics of ternary transition metal chalcogenides,along with significant guidance to develop energy-efficient next generation nanodevices.
