A novel SiC double-trench metal-oxide-semiconductor field effect transistor(MOSFET) with integrated MOS-channel diode is proposed and investigated by Sentaurus TCAD simulation. The new SiC MOSFET has a trench gate and...A novel SiC double-trench metal-oxide-semiconductor field effect transistor(MOSFET) with integrated MOS-channel diode is proposed and investigated by Sentaurus TCAD simulation. The new SiC MOSFET has a trench gate and a stepped-trench source, and features an integrated MOS-channel diode on the top sidewall of the source trench(MT MOS). In the reverse conduction state, the MOS-channel diode turns on firstly to prevent the internal parasitic body diode being activated, and thus reduces the turn-on voltage VFand suppresses the bipolar degradation phenomena. The VFof1.70 V(@Ids=-100 A/cm^(2)) for the SiC MT MOS is 38.2% lower than that of SiC double-trench MOSFET(DT MOS).Meanwhile, the reverse recovery charge Qrrof the MT MOS is 58.7% lower than that of the DT MOS at Iload= 700 A/cm^(2),and thus the reverse recovery loss is reduced. Furthermore, owing to the modulation effect induced by the double trenches,the MT MOS preserves the same superior forward conduction and blocking performance as those of DT MOS, with 22.9% and 18.2% improvement on breakdown voltage and RON,spcompared to the trench gate MOSFET with planar integrated SBD(ST MOS).展开更多
A novel normally-off double channel reverse conducting(DCRC)HEMT with an integrated MOS-channel diode(MCD)is proposed and investigated by TCAD simulation.The proposed structure has two features:one is double heterojun...A novel normally-off double channel reverse conducting(DCRC)HEMT with an integrated MOS-channel diode(MCD)is proposed and investigated by TCAD simulation.The proposed structure has two features:one is double heterojunctions to form dual 2DEG channels named the 1^(st)path and the 2^(nd)path for reverse conduction,and the other is the MCD forming by the trench source metal,source dielectric,and Ga N.At the initial reverse conduction stage,the MCD acts as a switch to control the 1^(st)path which would be turned on prior to the 2^(nd)path.Because of the introduction of the 1^(st)path,the DCRC-HEMT has an additional reverse conducting channel to help enhance the reverse conduction performance.Compared with the conventional HEMT(Conv.HEMT),the DCRC-HEMT can obtain a low reverse turn-on voltage(VRT)and its VRTis independent of the gate-source bias(VGS)at the same time.The DCRC-HEMT achieves the VRTof 0.62 V,which is 59.7%and 75.9%lower than that of the Conv.HEMT at VGS=0 V and-1 V,respectively.In addition,the forward conduction capability and blocking characteristics almost remain unchanged.In the end,the key fabrication flows of DCRC-HEMT are presented.展开更多
A NiO/β-Ga_(2)O_(3) heterojunction-gate field effect transistor(HJ-FET)is fabricated and it_(s)instability mechanisms are exper-imentally investigated under different gate stress voltage(V_(G,s))and stress times(t_(s...A NiO/β-Ga_(2)O_(3) heterojunction-gate field effect transistor(HJ-FET)is fabricated and it_(s)instability mechanisms are exper-imentally investigated under different gate stress voltage(V_(G,s))and stress times(t_(s)).Two different degradation mechanisms of the devices under negative bias stress(NBS)are identified.At low V_(G,s)for a short t_(s),NiO bulk traps trapping/de-trapping elec-trons are responsible for decrease/recovery of the leakage current,respectively.At higher V_(G,s)or long t_(s),the device transfer char-acteristic curves and threshold voltage(V_(TH))are almost permanently negatively shifted.This is because the interface dipoles are almost permanently ionized and neutralize the ionized charges in the space charge region(SCR)across the heterojunction inter-face,resulting in a narrowing SCR.This provides an important theoretical guide to study the reliability of NiO/β-Ga_(2)O_(3) hetero-junction devices in power electronic applications.展开更多
A new ultralow gate–drain charge(Q_(GD)) 4 H-SiC trench MOSFET is presented and its mechanism is investigated by simulation. The novel MOSFET features double shielding structures(DS-MOS): one is the grounded split ga...A new ultralow gate–drain charge(Q_(GD)) 4 H-SiC trench MOSFET is presented and its mechanism is investigated by simulation. The novel MOSFET features double shielding structures(DS-MOS): one is the grounded split gate(SG), the other is the P+shielding region(PSR). Both the SG and the PSR reduce the coupling effect between the gate and the drain, and transform the most part of the gate–drain capacitance(C_(GD)) into the gate–source capacitance(C_(GS)) and drain–source capacitance(C_(DS)) in series.Thus the C_(GD) is reduced and the proposed DS-MOS obtains ultralow Q_(GD). Compared with the double-trench MOSFET(DT-MOS)and the conventional trench MOSFET(CT-MOS), the proposed DS-MOS decreases the Q_(GD) by 85% and 81%, respectively.Moreover, the figure of merit(FOM), defined as the product of specific on-resistance(R_(on, sp)) and Q_(GD)(R_(on, sp)Q_(GD)), is reduced by 84% and 81%, respectively.展开更多
A novel 4H-SiC trench MOSFET is presented and investigated by simulation in this paper.The device features an integrated Schottky barrier diode and an L-shaped P^+shielding region beneath the gate trench and aside one...A novel 4H-SiC trench MOSFET is presented and investigated by simulation in this paper.The device features an integrated Schottky barrier diode and an L-shaped P^+shielding region beneath the gate trench and aside one wall of the gate trench(S-TMOS).The integrated Schottky barrier diode works as a free-wheeling diode in reverse recovery and reverse conduction,which significantly reduces reverse recovery charge(Q_(rr))and reverse turn-on voltage(VF).The L-shaped P^+region effectively shields the coupling of gate and drain,resulting in a lower gate–drain capacitance(C_(gd))and date–drain charge(Q_(gd)).Compared with that of conventional SiC trench MOSFET(C-TMOS),the V_F and Q_(rr)of S-TMOS has reduced by 44%and 75%,respectively,with almost the same forward output current and reverse breakdown voltage.Moreover,the S-TMOS reduces Q_(gd)and C_(gd)by 32%and 22%,respectively,in comparison with C-TMOS.展开更多
A novel 600 V snapback-free high-speed silicon-on-insulator lateral insulated gate bipolar transistor is proposed and investigated by simulation.The proposed device features an embedded NPN structure at the anode side...A novel 600 V snapback-free high-speed silicon-on-insulator lateral insulated gate bipolar transistor is proposed and investigated by simulation.The proposed device features an embedded NPN structure at the anode side,and double trenches together with an N-type carrier storage(N-CS)layer at the cathode side,named DT-NPN LIGBT.The NPN structure not only acts as an electron barrier to eliminate the snapback effect in the on-state within a smaller cell pitch but also provides an extra electron extracting path during the turn-off stage to decrease the turnoff loss(E_(off)).The double cathode trenches and N-CS layer hinder the hole from being extracted by the cathode quickly.They then enhance carrier storing effect and lead to a reduced on-state voltage drop(V_(on)).The latch-up immunity is improved by the double cathode trenches.Hence,the DT-NPN LIGBT obtains a superior tradeoff between the V_(on)and E_(off).Additionally,the DT-NPN LIGBT exhibits an improved blocking capability and weak dependence of breakdown voltage(BV)on the P+anode doping concentration because the NPN structure suppresses triggering the PNP transistor.The proposed LIGBT reduces the E_(off)by 55%at the same V_(on),and improves the BV by 7.3%compared to the conventional LIGBT.展开更多
Financial distribution to compensate grain production reflects governmental macro-control on grain production and supply. With the reference of agricultural basic theory,agricultural multi-function theory,economic ext...Financial distribution to compensate grain production reflects governmental macro-control on grain production and supply. With the reference of agricultural basic theory,agricultural multi-function theory,economic externality theory,public finance and other theories,this article points out that direct subsidies for grain production is reasonable and necessary with six main theoretical basis,namely fundamentality,multi-function,positive externality of grain production,particularity of grain supply and demand,grain safety being closely linked with national security and basic function of service-oriented government.展开更多
Psoriasis is a common chronic inflammatory skin disease driven by the aberrant activation of dendritic cells(DCs)and T cells,ultimately leading to increased production of cytokines such as interleukin(IL)-23 and IL-17...Psoriasis is a common chronic inflammatory skin disease driven by the aberrant activation of dendritic cells(DCs)and T cells,ultimately leading to increased production of cytokines such as interleukin(IL)-23 and IL-17A.It is established that the cGAS-STING pathway is essential for psoriatic inflammation,however,the specific role of cGAS-STING signaling in DCs within this context remains unclear.In this study,we demonstrated the upregulation of cGAS-STING signaling in psoriatic lesions by analyzing samples from both clinical patients and imiquimod(IMQ)-treated mice.Using a conditional Sting-knockout transgenic mouse model,we elucidated the impact of cGAS-STING signaling in DCs on the activation of IL-17-and IFN-γ-producing T cells in psoriatic inflammation.Ablation of the Sting hampers DC activation leads to decreased numbers of IL-17-producing T cells and Th1 cells,and thus subsequently attenuates psoriatic inflammation in the IMQ-induced mouse model.Furthermore,we explored the therapeutic potential of the STING inhibitor C-176,which reduces psoriatic inflammation and enhances the anti-IL-17A therapeutic response.Our results underscore the critical role of cGAS-STING signaling in DCs in driving psoriatic inflammation and highlight a promising psoriasis treatment.展开更多
Wettability is an essential property of reservoirs that is of great importance for enhancing oil recovery(EOR)and oil migration.The wettability of reservoirs is generally believed to be strongly affected by mineral co...Wettability is an essential property of reservoirs that is of great importance for enhancing oil recovery(EOR)and oil migration.The wettability of reservoirs is generally believed to be strongly affected by mineral compositions but it is not always the case.An integrated study of petrography and wettability was carried out to determine the impact of chlorite minerals on the wettability of the sandstone reservoirs in the Upper Triassic Yanchang Formation.Chlorites are found to be commonly present in the reservoir sandstones as detrital grains,rim-shaped cements,and biotite-chloritized forms with the pore peripheries being largely coated by chlorite,which is the main mineral in direct contact with pores.At pore scale,the wetting state of chlorites can either be oil-wet or water-wet in the tight sandstone reservoirs depending on wettability alteration by oil charge.Chlorites in contact with pores occupy a large of proportions of oil-wet pore walls and are crucial for the formation of oil-wetting state of reservoir sandstones.At core scale,the contents of chlorites in direct contact with pores do not correlate well with the AmottHarvey index due to other factors such as heterogeneity,oil-bearing degrees of samples.展开更多
基金the support by the Science & Technology Program (High voltage and high power SiC material, devices and the application demonstration in power electronic transformers) of the State Grid Corporation of China Co. Ltd.supported by the National Key Research and Development Program of China (Grant No. 2016YFB0400502)。
文摘A novel SiC double-trench metal-oxide-semiconductor field effect transistor(MOSFET) with integrated MOS-channel diode is proposed and investigated by Sentaurus TCAD simulation. The new SiC MOSFET has a trench gate and a stepped-trench source, and features an integrated MOS-channel diode on the top sidewall of the source trench(MT MOS). In the reverse conduction state, the MOS-channel diode turns on firstly to prevent the internal parasitic body diode being activated, and thus reduces the turn-on voltage VFand suppresses the bipolar degradation phenomena. The VFof1.70 V(@Ids=-100 A/cm^(2)) for the SiC MT MOS is 38.2% lower than that of SiC double-trench MOSFET(DT MOS).Meanwhile, the reverse recovery charge Qrrof the MT MOS is 58.7% lower than that of the DT MOS at Iload= 700 A/cm^(2),and thus the reverse recovery loss is reduced. Furthermore, owing to the modulation effect induced by the double trenches,the MT MOS preserves the same superior forward conduction and blocking performance as those of DT MOS, with 22.9% and 18.2% improvement on breakdown voltage and RON,spcompared to the trench gate MOSFET with planar integrated SBD(ST MOS).
基金the National Natural Science Foundations of China(Grant Nos.61874149 and U20A20208)the Outstanding Youth Science and Technology Foundation of China(Grant No.2018-JCJQ-ZQ-060)。
文摘A novel normally-off double channel reverse conducting(DCRC)HEMT with an integrated MOS-channel diode(MCD)is proposed and investigated by TCAD simulation.The proposed structure has two features:one is double heterojunctions to form dual 2DEG channels named the 1^(st)path and the 2^(nd)path for reverse conduction,and the other is the MCD forming by the trench source metal,source dielectric,and Ga N.At the initial reverse conduction stage,the MCD acts as a switch to control the 1^(st)path which would be turned on prior to the 2^(nd)path.Because of the introduction of the 1^(st)path,the DCRC-HEMT has an additional reverse conducting channel to help enhance the reverse conduction performance.Compared with the conventional HEMT(Conv.HEMT),the DCRC-HEMT can obtain a low reverse turn-on voltage(VRT)and its VRTis independent of the gate-source bias(VGS)at the same time.The DCRC-HEMT achieves the VRTof 0.62 V,which is 59.7%and 75.9%lower than that of the Conv.HEMT at VGS=0 V and-1 V,respectively.In addition,the forward conduction capability and blocking characteristics almost remain unchanged.In the end,the key fabrication flows of DCRC-HEMT are presented.
基金supported by the Fundamental Strengthening Program Key Basic Research Project(Grant No.2021-173ZD-057).
文摘A NiO/β-Ga_(2)O_(3) heterojunction-gate field effect transistor(HJ-FET)is fabricated and it_(s)instability mechanisms are exper-imentally investigated under different gate stress voltage(V_(G,s))and stress times(t_(s)).Two different degradation mechanisms of the devices under negative bias stress(NBS)are identified.At low V_(G,s)for a short t_(s),NiO bulk traps trapping/de-trapping elec-trons are responsible for decrease/recovery of the leakage current,respectively.At higher V_(G,s)or long t_(s),the device transfer char-acteristic curves and threshold voltage(V_(TH))are almost permanently negatively shifted.This is because the interface dipoles are almost permanently ionized and neutralize the ionized charges in the space charge region(SCR)across the heterojunction inter-face,resulting in a narrowing SCR.This provides an important theoretical guide to study the reliability of NiO/β-Ga_(2)O_(3) hetero-junction devices in power electronic applications.
基金supported by the National Key Research and Development Program of China(No.2016YFB0400502)
文摘A new ultralow gate–drain charge(Q_(GD)) 4 H-SiC trench MOSFET is presented and its mechanism is investigated by simulation. The novel MOSFET features double shielding structures(DS-MOS): one is the grounded split gate(SG), the other is the P+shielding region(PSR). Both the SG and the PSR reduce the coupling effect between the gate and the drain, and transform the most part of the gate–drain capacitance(C_(GD)) into the gate–source capacitance(C_(GS)) and drain–source capacitance(C_(DS)) in series.Thus the C_(GD) is reduced and the proposed DS-MOS obtains ultralow Q_(GD). Compared with the double-trench MOSFET(DT-MOS)and the conventional trench MOSFET(CT-MOS), the proposed DS-MOS decreases the Q_(GD) by 85% and 81%, respectively.Moreover, the figure of merit(FOM), defined as the product of specific on-resistance(R_(on, sp)) and Q_(GD)(R_(on, sp)Q_(GD)), is reduced by 84% and 81%, respectively.
基金supported by the National Key Research and Development Program of China(No.2016YFB0400502)。
文摘A novel 4H-SiC trench MOSFET is presented and investigated by simulation in this paper.The device features an integrated Schottky barrier diode and an L-shaped P^+shielding region beneath the gate trench and aside one wall of the gate trench(S-TMOS).The integrated Schottky barrier diode works as a free-wheeling diode in reverse recovery and reverse conduction,which significantly reduces reverse recovery charge(Q_(rr))and reverse turn-on voltage(VF).The L-shaped P^+region effectively shields the coupling of gate and drain,resulting in a lower gate–drain capacitance(C_(gd))and date–drain charge(Q_(gd)).Compared with that of conventional SiC trench MOSFET(C-TMOS),the V_F and Q_(rr)of S-TMOS has reduced by 44%and 75%,respectively,with almost the same forward output current and reverse breakdown voltage.Moreover,the S-TMOS reduces Q_(gd)and C_(gd)by 32%and 22%,respectively,in comparison with C-TMOS.
基金supported by Postdoctoral Innovative Talent Support Program under Grant BX20190059the China Postdoctoral Science Foundation under Grant 2019M660235+1 种基金the Sichuan Science and Technology Program under Project 2018JY0555the Science and Technology on Analog Integrated Circuit Laboratory under Project 6142802180509。
文摘A novel 600 V snapback-free high-speed silicon-on-insulator lateral insulated gate bipolar transistor is proposed and investigated by simulation.The proposed device features an embedded NPN structure at the anode side,and double trenches together with an N-type carrier storage(N-CS)layer at the cathode side,named DT-NPN LIGBT.The NPN structure not only acts as an electron barrier to eliminate the snapback effect in the on-state within a smaller cell pitch but also provides an extra electron extracting path during the turn-off stage to decrease the turnoff loss(E_(off)).The double cathode trenches and N-CS layer hinder the hole from being extracted by the cathode quickly.They then enhance carrier storing effect and lead to a reduced on-state voltage drop(V_(on)).The latch-up immunity is improved by the double cathode trenches.Hence,the DT-NPN LIGBT obtains a superior tradeoff between the V_(on)and E_(off).Additionally,the DT-NPN LIGBT exhibits an improved blocking capability and weak dependence of breakdown voltage(BV)on the P+anode doping concentration because the NPN structure suppresses triggering the PNP transistor.The proposed LIGBT reduces the E_(off)by 55%at the same V_(on),and improves the BV by 7.3%compared to the conventional LIGBT.
基金Supported by Subsidized Project Launched by Scientific Research Funds of Southwest University:Study on the Performance of Direct Subsidies for Grain Production(SWU10306)Fundamental Research Funds for the Central Universities:Study on Standards of Direct Subsidies for Grain Production(SWU1109039)
文摘Financial distribution to compensate grain production reflects governmental macro-control on grain production and supply. With the reference of agricultural basic theory,agricultural multi-function theory,economic externality theory,public finance and other theories,this article points out that direct subsidies for grain production is reasonable and necessary with six main theoretical basis,namely fundamentality,multi-function,positive externality of grain production,particularity of grain supply and demand,grain safety being closely linked with national security and basic function of service-oriented government.
基金supported by China National Natural Science Foundation(grant nos.82374445,82303061,82305233 and 82373179)Shanghai Shuguang Scholar(grant no.22SG42)+3 种基金Scientific research project of Shanghai Municipal Health Commission(grant no.20224Z0019)Key Discipline Construction Project of Shanghai Three Year Action Plan for Strengthening the Construction of Public Health System(grant no.GWVI-11.1-24)High-level Chinese Medicine Key Discipline Construction Project(Integrative Chinese and Western Medicine Clinic)of National Administration of TCM(grant no.zyyzdxk-2023065)Evidence-based dermatology base sponsored by state Administration of Traditional Chinese medicine.
文摘Psoriasis is a common chronic inflammatory skin disease driven by the aberrant activation of dendritic cells(DCs)and T cells,ultimately leading to increased production of cytokines such as interleukin(IL)-23 and IL-17A.It is established that the cGAS-STING pathway is essential for psoriatic inflammation,however,the specific role of cGAS-STING signaling in DCs within this context remains unclear.In this study,we demonstrated the upregulation of cGAS-STING signaling in psoriatic lesions by analyzing samples from both clinical patients and imiquimod(IMQ)-treated mice.Using a conditional Sting-knockout transgenic mouse model,we elucidated the impact of cGAS-STING signaling in DCs on the activation of IL-17-and IFN-γ-producing T cells in psoriatic inflammation.Ablation of the Sting hampers DC activation leads to decreased numbers of IL-17-producing T cells and Th1 cells,and thus subsequently attenuates psoriatic inflammation in the IMQ-induced mouse model.Furthermore,we explored the therapeutic potential of the STING inhibitor C-176,which reduces psoriatic inflammation and enhances the anti-IL-17A therapeutic response.Our results underscore the critical role of cGAS-STING signaling in DCs in driving psoriatic inflammation and highlight a promising psoriasis treatment.
基金supported by the Strategic Priority Research Program of the Chinese Academy of Sciences(Grant Nos.XDA14010202,XDA14010401)the National Natural Science Foundation of China(Grant No.41821002)。
文摘Wettability is an essential property of reservoirs that is of great importance for enhancing oil recovery(EOR)and oil migration.The wettability of reservoirs is generally believed to be strongly affected by mineral compositions but it is not always the case.An integrated study of petrography and wettability was carried out to determine the impact of chlorite minerals on the wettability of the sandstone reservoirs in the Upper Triassic Yanchang Formation.Chlorites are found to be commonly present in the reservoir sandstones as detrital grains,rim-shaped cements,and biotite-chloritized forms with the pore peripheries being largely coated by chlorite,which is the main mineral in direct contact with pores.At pore scale,the wetting state of chlorites can either be oil-wet or water-wet in the tight sandstone reservoirs depending on wettability alteration by oil charge.Chlorites in contact with pores occupy a large of proportions of oil-wet pore walls and are crucial for the formation of oil-wetting state of reservoir sandstones.At core scale,the contents of chlorites in direct contact with pores do not correlate well with the AmottHarvey index due to other factors such as heterogeneity,oil-bearing degrees of samples.
