A silicon carbide (SiC) vertical channel junction field effect transistor (VJFET) was fabricated based on in-house SiC epitaxial wafer with trenched and implanted method. Its forward drain current is in excess of 3.12...A silicon carbide (SiC) vertical channel junction field effect transistor (VJFET) was fabricated based on in-house SiC epitaxial wafer with trenched and implanted method. Its forward drain current is in excess of 3.12 A (170 W/cm2) with a current gain of ID/IG = 19746 at gate bias VG = 3 V and drain bias VD = 5.5 V. The SiC VJFET device’s related specific on-resistance 54 mΩ·cm2. The BV gain is 250 V with Vg from -10 V to -4 V and is 350 V with Vg from -4 V to -2 V. Self-aligned floating guard rings provide edge termination that blocks 3180V at a gate bias of ?14 V and a drain-current density of 1.53 mA/cm2.展开更多
To maximize the turbine thermal efficiency, modern gas turbine’s inlet temperature is significantly augmented within the past few decades. To prolong the lifespan of gas turbines, many efficient cooling techniques ha...To maximize the turbine thermal efficiency, modern gas turbine’s inlet temperature is significantly augmented within the past few decades. To prolong the lifespan of gas turbines, many efficient cooling techniques have been proposed and applied in the endwall cooling schemes. However, conventional discrete film hole does not take effect at the leading edge nearby region. In this research, how the trenched film hole configurations affects the endwall cooling and phantom cooling characteristics were deeply studied by using a verified approach. Steady 3D Reynolds-averaged Navier-Stokes(RANS) governing equations together with the shear stress transport(SST) k-w turbulence model have been solved. Firstly, results indicate that trenched film holes greatly influence the cooling effectiveness at leading edge nearby region compared to normal case. Nevertheless, suction side phantom cooling is hardly influenced by the trenched film holes. Secondly, the case with a smaller trench width obtains higher endwall cooling effectiveness, particularly at upstream region. More importantly, the cases with W=3D achieve large cooling effectiveness at leading edge nearby region with little influence by trench depth. Additionally, majority of trenched film holes coolant flow is driven towards middle passage. Therefore, the suction side phantom cooling is unaffected by the trenched film holes.展开更多
A new silicon-on-insulator(SOI) high-voltage MOSFET structure with a compensation layer on the trenched buried oxide layer(CL T-LDMOS) is proposed.The high density inverse interface charges at the top surface of the b...A new silicon-on-insulator(SOI) high-voltage MOSFET structure with a compensation layer on the trenched buried oxide layer(CL T-LDMOS) is proposed.The high density inverse interface charges at the top surface of the buried oxide layer(BOX) enhance the electric field in the BOX and a uniform surface electric field profile is obtained,which results in the enhancement of the breakdown voltage(BV).The compensation layer can provide additional P-type charges,and the optimal drift region concentration is increased in order to satisfy the reduced surface electric field(RESURF) condition.The numerical simulation results indicate that the vertical electric field in the BOX increases to 6 MV/cm and the B V of the proposed device increases by 300%in comparison to a conventional SOI LDMOS,while maintaining low on-resistance.展开更多
In 1875,the HMS(皇家海军舰艇)Challenger stopped in the middle of the Pacific Ocean,southwest of the Mariana Islands,to conduct a routine depth sounding.As they'd done countless times before,the British scientists ...In 1875,the HMS(皇家海军舰艇)Challenger stopped in the middle of the Pacific Ocean,southwest of the Mariana Islands,to conduct a routine depth sounding.As they'd done countless times before,the British scientists and sailors on board lowered a weighted rope into the water.Unlike those other times,however,the rope kept falling,seemingly without an end.After nearly 8,230 meters,it finally hit the bottom—the first human attempt at what became known as the Mariana Trench.展开更多
Traffic-induced ground vibrations cause significant problems for residents and nearby structures.Reducing the effect of these vibrations on the neighboring environment is a key challenge,particularly in urban areas.Th...Traffic-induced ground vibrations cause significant problems for residents and nearby structures.Reducing the effect of these vibrations on the neighboring environment is a key challenge,particularly in urban areas.This study presents both numerical and experimental investigations of the performance of mass scatters for screening ground vibrations.A three-dimensional numerical model is validated and extended to conduct a comparative study on the efficiency of three geotechnical methods of isolation.These methods include trench barriers,waveimpeding blocks(WIBs),and mass scatters.The results showed that mass scatters represent an efficient way of scattering ground vibrations,and their efficiency is mainly related to the weights of mass scatters and their natural frequency,which control the dynamic soil response in the frequency domain.Rigid trench barriers are less effective than soft ones,and their efficiency is more pronounced regarding the WIB.Soft barriers with a depth of an order of half of the wavelength can decrease the vibration levels by up to 50%,which is comparable to the performance of enormous mass scatters.The dimensions of WIBs must be chosen according to the wavelength of incident waves and the cutoff frequency of the topsoil layer.Considering the significant wavelength of traffic-induced vibration,the use of trench barriers or WIBs becomes impractical and expensive;therefore,mass scatters appear to be an efficient and practical solution.展开更多
Amino acids are widely present as intermediates in marine nitrogen cycle.However,amino acid distributions in deep-sea seawater,especially in abyssal and hadal zones,are very limited.This study investigated the occurre...Amino acids are widely present as intermediates in marine nitrogen cycle.However,amino acid distributions in deep-sea seawater,especially in abyssal and hadal zones,are very limited.This study investigated the occurrence,vertical variations,and degradation behavior of dissolved free amino acids(DFAA),dissolved combined amino acids(DCAA),and total hydrolyzable amino acids(THAA)in seawater from the sea surface to the hadal zone of the northern Yap Trench.The results showed that concentrations ofΣDFAA,ΣDCAA andΣTHAA ranged from 0.09 to 1.78,0.99 to 17.69 and 1.18 to 18.01μmol/L in the study area,respectively.In the seawater from the trench,glycine was the predominant DFAA,while the DCAA and THAA was dominated by threonine.Mean concentrations of DFAA,DCAA and THAA in different water layers were in the order of:mesopelagic>euphotic>abyssal>bathyal.The concentrations of DCAA and THAA in the sediment-seawater interface were higher than those from the euphotic to abyssal layer.The organic matter(OM)in the seawater of the stations near the Yap Islands were older,while the OM in the stations near the Yap Trench axis was relatively fresh above 1000-m depth.The OM in the sediment-seawater interface is older,especially on the west side of the trench.This is the first systematic survey of DCAA and THAA in the Yap Trench,providing insights into the vertical variations and degradation behaviors of amino acids from the sea surface to the hadal environment.展开更多
The conventional view suggests that the subduction of the South China Sea plate beneath Luzon occurred due to the oceanic lithosphere’s high density,facilitating subduction initiation.However,before the South China S...The conventional view suggests that the subduction of the South China Sea plate beneath Luzon occurred due to the oceanic lithosphere’s high density,facilitating subduction initiation.However,before the South China Sea opened,a continental margin likely existed,meaning that Luzon was directly adjacent to the continental margin rather than the oceanic basin.This would make subduction initiation more challenging.Here,we propose a new model suggesting that during the formation of the South China Sea,extensive mafic magmatic underplating occurred along its continental margin.The high-density magmatic additions may have increased the overall density of the continental margin,potentially exceeding that of Luzon,thereby enabling subduction to proceed.展开更多
The hadal zone-Earth’s deepest oceanic trenches below 6,000 meters-has long been considered a lifeless abyss.Researchers from the Institute of Hydrobiology(IHB)and the Institute of Deep-Sea Science and Engineering(ID...The hadal zone-Earth’s deepest oceanic trenches below 6,000 meters-has long been considered a lifeless abyss.Researchers from the Institute of Hydrobiology(IHB)and the Institute of Deep-Sea Science and Engineering(IDSSE),both under the Chinese Academy of Sciences,together with collaborators from Northwestern Polytechnical University,recently decoded how fish thrive in this extreme realm through two evolutionary pathways while uncovering alarming traces of human pollution in these pristine ecosystems.Their discovery was published in Cell on March 6,2025.展开更多
Partitioning the respiratory components of soil surface CO2 efflux is important in understanding carbon turnover and in identifying the soil carbon sink/source function in response to land-use change. The sensitivitie...Partitioning the respiratory components of soil surface CO2 efflux is important in understanding carbon turnover and in identifying the soil carbon sink/source function in response to land-use change. The sensitivities of soil respiration components on changing climate patterns are currently not fully understood. We used trench and isotopic methods to separate total soil respiration into autotrophic （RA） and heterotrophic components （RH）. This study was undertaken on a Robinia pseudoacacia L. plantation in the southern Taihang Mountains, China. The fractionation of soil ^13CO2 was analyzed by comparing the δ^13C of soil CO2 extracted from buried steel tubes with results from Gas Vapor Probe Kits at a depth of 50 cm.at the preliminary test （2.03‰）. The results showed that the contribution of autotrophic respiration （fRA） increased with increasing soil depth.The contribution of heterotrophic respiration （fR/4） declined with increasing soil depth. The contribution of autotrophic respiration was similar whether estimated by the trench method （fRA, 23.50%） or by the isotopic method in which a difference in value of ^13C between soil and plant prevailed in the natural state （RC, 21.03%）. The experimental error produced by the trench method was insignificant as compared with that produced by the isotopic method, providing a technical basis for further investigations.展开更多
The paper takes a new campus project site of Shanxi university town for example, tests the influence of dynamic com- paction vibration and vibration isolation effect of isolation trench on this ground, and compares th...The paper takes a new campus project site of Shanxi university town for example, tests the influence of dynamic com- paction vibration and vibration isolation effect of isolation trench on this ground, and compares the influences of the dynamic compaction vibration on surrounding buildings with isolation trench and without it. Furthermore, the attenuation law of dy- namic compaction vibration in fill foundation of the loess area under different tamping energy and how to determine safe distance of dynamic compaction construction are studied. And then the quantitative relationship between acceleration and vibration source in new campus project site is presented. We derive the evaluation method that dynamic compaction construction affects adjacent buildings by contrasting with the existing standards and norms. The monitoring results show that isolation trench makes the amplitude attenuation of the horizontal velocity of dynamic compaction vibration reach above 75%, and the safe dis- tance be 30 m under the tamping energy of 6 000 kN · m. Therefore, isolation trench is better for vibration reduction under dynamic compaction construction.展开更多
A new structure of power MOS-gated thyristor named Trench MOS Controlled Thyristor (TMCT) is presented.The MOSFETs used to turn on and turn off the thrysitor are formed with UMOS technology.No parasitic transistors ex...A new structure of power MOS-gated thyristor named Trench MOS Controlled Thyristor (TMCT) is presented.The MOSFETs used to turn on and turn off the thrysitor are formed with UMOS technology.No parasitic transistors exist in this structure,so the problems created by the parasitic transistors can be eliminated.So,the TMCT is expected to be of better performance.The experimental results of the multicellular 600V TMCT with the active area of 02mm2 show that the on-state drop is 125V at 300A/cm2,and the maximum controllable current reaches 296A/cm2 at the gate voltage of -20V and with an inductive load.展开更多
A novel technique to fabricate ultra deep high aspect ratio electrical isolation trenches with DRIE and dielectric refill is presented.The relationship between trench profile and DRIE parameters is discussed.By optimi...A novel technique to fabricate ultra deep high aspect ratio electrical isolation trenches with DRIE and dielectric refill is presented.The relationship between trench profile and DRIE parameters is discussed.By optimizing DRIE parameters and RIE etching the trenches’ opening,the ideal trench profile is obtained to ensure that the trenches are fully refilled without voids.The electrical isolation trenches are 5μm wide and 92μm deep with 0.5μm thick oxide layers on the sidewall as isolation material.The measured I-V result shows that the trench structure has good electrical isolation performance:the average resistance in the range of 0～100V is more than 10 11Ω and no breakdown appears under 100V.This isolation trench structure has been used in fabrication of the bulk integrated micromachined gyroscope,which shows high performance.展开更多
A vertical sandwich deep trench with a field limiting ring is proposed to improve the breakdown voltage of power devices and high voltage devices.Simulation result shows that nearly 100% breakdown voltage of the plane...A vertical sandwich deep trench with a field limiting ring is proposed to improve the breakdown voltage of power devices and high voltage devices.Simulation result shows that nearly 100% breakdown voltage of the plane junction can be realized.展开更多
文摘A silicon carbide (SiC) vertical channel junction field effect transistor (VJFET) was fabricated based on in-house SiC epitaxial wafer with trenched and implanted method. Its forward drain current is in excess of 3.12 A (170 W/cm2) with a current gain of ID/IG = 19746 at gate bias VG = 3 V and drain bias VD = 5.5 V. The SiC VJFET device’s related specific on-resistance 54 mΩ·cm2. The BV gain is 250 V with Vg from -10 V to -4 V and is 350 V with Vg from -4 V to -2 V. Self-aligned floating guard rings provide edge termination that blocks 3180V at a gate bias of ?14 V and a drain-current density of 1.53 mA/cm2.
基金support of the National Natural Science Foundation (No. 51776151 No.51936008+1 种基金 No. 51776173) of Chinasupported by “the Fundamental Research Funds for the Central Universities” No. 3102019OQD702
文摘To maximize the turbine thermal efficiency, modern gas turbine’s inlet temperature is significantly augmented within the past few decades. To prolong the lifespan of gas turbines, many efficient cooling techniques have been proposed and applied in the endwall cooling schemes. However, conventional discrete film hole does not take effect at the leading edge nearby region. In this research, how the trenched film hole configurations affects the endwall cooling and phantom cooling characteristics were deeply studied by using a verified approach. Steady 3D Reynolds-averaged Navier-Stokes(RANS) governing equations together with the shear stress transport(SST) k-w turbulence model have been solved. Firstly, results indicate that trenched film holes greatly influence the cooling effectiveness at leading edge nearby region compared to normal case. Nevertheless, suction side phantom cooling is hardly influenced by the trenched film holes. Secondly, the case with a smaller trench width obtains higher endwall cooling effectiveness, particularly at upstream region. More importantly, the cases with W=3D achieve large cooling effectiveness at leading edge nearby region with little influence by trench depth. Additionally, majority of trenched film holes coolant flow is driven towards middle passage. Therefore, the suction side phantom cooling is unaffected by the trenched film holes.
基金supported by the Guangxi Natural Science Foundation of China(No.2010GXNSFB013054)the Guangxi Key Science and Technology Program ofChina(No.11107001-20)
文摘A new silicon-on-insulator(SOI) high-voltage MOSFET structure with a compensation layer on the trenched buried oxide layer(CL T-LDMOS) is proposed.The high density inverse interface charges at the top surface of the buried oxide layer(BOX) enhance the electric field in the BOX and a uniform surface electric field profile is obtained,which results in the enhancement of the breakdown voltage(BV).The compensation layer can provide additional P-type charges,and the optimal drift region concentration is increased in order to satisfy the reduced surface electric field(RESURF) condition.The numerical simulation results indicate that the vertical electric field in the BOX increases to 6 MV/cm and the B V of the proposed device increases by 300%in comparison to a conventional SOI LDMOS,while maintaining low on-resistance.
文摘In 1875,the HMS(皇家海军舰艇)Challenger stopped in the middle of the Pacific Ocean,southwest of the Mariana Islands,to conduct a routine depth sounding.As they'd done countless times before,the British scientists and sailors on board lowered a weighted rope into the water.Unlike those other times,however,the rope kept falling,seemingly without an end.After nearly 8,230 meters,it finally hit the bottom—the first human attempt at what became known as the Mariana Trench.
文摘Traffic-induced ground vibrations cause significant problems for residents and nearby structures.Reducing the effect of these vibrations on the neighboring environment is a key challenge,particularly in urban areas.This study presents both numerical and experimental investigations of the performance of mass scatters for screening ground vibrations.A three-dimensional numerical model is validated and extended to conduct a comparative study on the efficiency of three geotechnical methods of isolation.These methods include trench barriers,waveimpeding blocks(WIBs),and mass scatters.The results showed that mass scatters represent an efficient way of scattering ground vibrations,and their efficiency is mainly related to the weights of mass scatters and their natural frequency,which control the dynamic soil response in the frequency domain.Rigid trench barriers are less effective than soft ones,and their efficiency is more pronounced regarding the WIB.Soft barriers with a depth of an order of half of the wavelength can decrease the vibration levels by up to 50%,which is comparable to the performance of enormous mass scatters.The dimensions of WIBs must be chosen according to the wavelength of incident waves and the cutoff frequency of the topsoil layer.Considering the significant wavelength of traffic-induced vibration,the use of trench barriers or WIBs becomes impractical and expensive;therefore,mass scatters appear to be an efficient and practical solution.
基金the National Key Research and Development Program of China(No.2022YFC2803803)the National Natural Science Foundation of China(No.42076040)the 111 Project(No.B13030)。
文摘Amino acids are widely present as intermediates in marine nitrogen cycle.However,amino acid distributions in deep-sea seawater,especially in abyssal and hadal zones,are very limited.This study investigated the occurrence,vertical variations,and degradation behavior of dissolved free amino acids(DFAA),dissolved combined amino acids(DCAA),and total hydrolyzable amino acids(THAA)in seawater from the sea surface to the hadal zone of the northern Yap Trench.The results showed that concentrations ofΣDFAA,ΣDCAA andΣTHAA ranged from 0.09 to 1.78,0.99 to 17.69 and 1.18 to 18.01μmol/L in the study area,respectively.In the seawater from the trench,glycine was the predominant DFAA,while the DCAA and THAA was dominated by threonine.Mean concentrations of DFAA,DCAA and THAA in different water layers were in the order of:mesopelagic>euphotic>abyssal>bathyal.The concentrations of DCAA and THAA in the sediment-seawater interface were higher than those from the euphotic to abyssal layer.The organic matter(OM)in the seawater of the stations near the Yap Islands were older,while the OM in the stations near the Yap Trench axis was relatively fresh above 1000-m depth.The OM in the sediment-seawater interface is older,especially on the west side of the trench.This is the first systematic survey of DCAA and THAA in the Yap Trench,providing insights into the vertical variations and degradation behaviors of amino acids from the sea surface to the hadal environment.
基金support from the National Natural Science Foundation of China (Grant No. 42276049)。
文摘The conventional view suggests that the subduction of the South China Sea plate beneath Luzon occurred due to the oceanic lithosphere’s high density,facilitating subduction initiation.However,before the South China Sea opened,a continental margin likely existed,meaning that Luzon was directly adjacent to the continental margin rather than the oceanic basin.This would make subduction initiation more challenging.Here,we propose a new model suggesting that during the formation of the South China Sea,extensive mafic magmatic underplating occurred along its continental margin.The high-density magmatic additions may have increased the overall density of the continental margin,potentially exceeding that of Luzon,thereby enabling subduction to proceed.
文摘The hadal zone-Earth’s deepest oceanic trenches below 6,000 meters-has long been considered a lifeless abyss.Researchers from the Institute of Hydrobiology(IHB)and the Institute of Deep-Sea Science and Engineering(IDSSE),both under the Chinese Academy of Sciences,together with collaborators from Northwestern Polytechnical University,recently decoded how fish thrive in this extreme realm through two evolutionary pathways while uncovering alarming traces of human pollution in these pristine ecosystems.Their discovery was published in Cell on March 6,2025.
基金supported by the National Natural Science Foundation of China(41430747)grant from the Beijing Municipal Education Commission(CEFF-PXM2016_014207_000038)
文摘Partitioning the respiratory components of soil surface CO2 efflux is important in understanding carbon turnover and in identifying the soil carbon sink/source function in response to land-use change. The sensitivities of soil respiration components on changing climate patterns are currently not fully understood. We used trench and isotopic methods to separate total soil respiration into autotrophic （RA） and heterotrophic components （RH）. This study was undertaken on a Robinia pseudoacacia L. plantation in the southern Taihang Mountains, China. The fractionation of soil ^13CO2 was analyzed by comparing the δ^13C of soil CO2 extracted from buried steel tubes with results from Gas Vapor Probe Kits at a depth of 50 cm.at the preliminary test （2.03‰）. The results showed that the contribution of autotrophic respiration （fRA） increased with increasing soil depth.The contribution of heterotrophic respiration （fR/4） declined with increasing soil depth. The contribution of autotrophic respiration was similar whether estimated by the trench method （fRA, 23.50%） or by the isotopic method in which a difference in value of ^13C between soil and plant prevailed in the natural state （RC, 21.03%）. The experimental error produced by the trench method was insignificant as compared with that produced by the isotopic method, providing a technical basis for further investigations.
基金Project of National Natural Science Fund for the Youth,China(No.51208473)The Key Project for Science and Technology of Shanxi,China(No.20130313010-3)
文摘The paper takes a new campus project site of Shanxi university town for example, tests the influence of dynamic com- paction vibration and vibration isolation effect of isolation trench on this ground, and compares the influences of the dynamic compaction vibration on surrounding buildings with isolation trench and without it. Furthermore, the attenuation law of dy- namic compaction vibration in fill foundation of the loess area under different tamping energy and how to determine safe distance of dynamic compaction construction are studied. And then the quantitative relationship between acceleration and vibration source in new campus project site is presented. We derive the evaluation method that dynamic compaction construction affects adjacent buildings by contrasting with the existing standards and norms. The monitoring results show that isolation trench makes the amplitude attenuation of the horizontal velocity of dynamic compaction vibration reach above 75%, and the safe dis- tance be 30 m under the tamping energy of 6 000 kN · m. Therefore, isolation trench is better for vibration reduction under dynamic compaction construction.
文摘A new structure of power MOS-gated thyristor named Trench MOS Controlled Thyristor (TMCT) is presented.The MOSFETs used to turn on and turn off the thrysitor are formed with UMOS technology.No parasitic transistors exist in this structure,so the problems created by the parasitic transistors can be eliminated.So,the TMCT is expected to be of better performance.The experimental results of the multicellular 600V TMCT with the active area of 02mm2 show that the on-state drop is 125V at 300A/cm2,and the maximum controllable current reaches 296A/cm2 at the gate voltage of -20V and with an inductive load.
文摘A novel technique to fabricate ultra deep high aspect ratio electrical isolation trenches with DRIE and dielectric refill is presented.The relationship between trench profile and DRIE parameters is discussed.By optimizing DRIE parameters and RIE etching the trenches’ opening,the ideal trench profile is obtained to ensure that the trenches are fully refilled without voids.The electrical isolation trenches are 5μm wide and 92μm deep with 0.5μm thick oxide layers on the sidewall as isolation material.The measured I-V result shows that the trench structure has good electrical isolation performance:the average resistance in the range of 0～100V is more than 10 11Ω and no breakdown appears under 100V.This isolation trench structure has been used in fabrication of the bulk integrated micromachined gyroscope,which shows high performance.
文摘A vertical sandwich deep trench with a field limiting ring is proposed to improve the breakdown voltage of power devices and high voltage devices.Simulation result shows that nearly 100% breakdown voltage of the plane junction can be realized.
