The interface reaction between the SiC particles （ SiCp ） and Fe was stndicd during sintering the SiCp reinforced Fe matrix composites at 1423 K for 1 h. In the composite having 3wt% （weight ratio） SiCp （the 3SiC...The interface reaction between the SiC particles （ SiCp ） and Fe was stndicd during sintering the SiCp reinforced Fe matrix composites at 1423 K for 1 h. In the composite having 3wt% （weight ratio） SiCp （the 3SiCp/ Fe composite）, the interface reaction products of Fe3 Si, the carbon precipitates, and Fe3 C or pearlite were generated. Fe3 Si coustructs the bright matrix of the reaction zone in the original situation of the SiCp. The carbon precipitates are randondy embedded in the reaction zone. Fe3 C or pearlite exists at the grain boundaries of the Fe matrix. As increasing the SiCp concentration in the SiCp/ Fe composite, the inteusity of the interface reaction between SiCp and Fe iacreases. After the 10SiCp/ Fe composite （ having 10wt .% SiCp ） sintered at 1423 K for 1 h, all of SiCp are decomposed, and replaced by the reaction zone composed of Fe3 Si and the carbon precipitates. No Fe3 C or pearlite was genertaed during the reaction. The effects of the techniques of oxidizing of SiCp , coating SiCp by interaction with the Cr powder, and alloying the Fe matrix by adding the Cr element on the interface stability of the SiCp/ Fe composite system were also investigated, respectitely. The oxide membrane and the coating layer on SiCp can inhibit the interface reaction between SiCp and Fe by isolating SiCp from the Fe matrix during sintering. The interface reaction does not occur in the 3 SiCp/ Fe- 10 Cr composite but in the 3 SiCp/ Fe-5 Cr composite. In the SiCp/ Fe-Cr alloy composites, the interface reaction between SiCp and the Fe- Cr alloys is weaker than that between SiCp and Fe . The Cr element behaves as a diluent, it causes a redaction in the interface reaction, which is proportional to the amount of the element added.展开更多
The effect of nitric oxide（NO） annealing on charge traps in the oxide insulator and transition layer in n-type4H–Si C metal–oxide–semiconductor（MOS） devices has been investigated using the time-dependent bias s...The effect of nitric oxide（NO） annealing on charge traps in the oxide insulator and transition layer in n-type4H–Si C metal–oxide–semiconductor（MOS） devices has been investigated using the time-dependent bias stress（TDBS）,capacitance–voltage（C–V）,and secondary ion mass spectroscopy（SIMS）.It is revealed that two main categories of charge traps,near interface oxide traps（Nniot） and oxide traps（Not）,have different responses to the TDBS and C–V characteristics in NO-annealed and Ar-annealed samples.The Nniotare mainly responsible for the hysteresis occurring in the bidirectional C–V characteristics,which are very close to the semiconductor interface and can readily exchange charges with the inner semiconductor.However,Not is mainly responsible for the TDBS induced C–V shifts.Electrons tunneling into the Not are hardly released quickly when suffering TDBS,resulting in the problem of the threshold voltage stability.Compared with the Ar-annealed sample,Nniotcan be significantly suppressed by the NO annealing,but there is little improvement of Not.SIMS results demonstrate that the Nniotare distributed within the transition layer,which correlated with the existence of the excess silicon.During the NO annealing process,the excess Si atoms incorporate into nitrogen in the transition layer,allowing better relaxation of the interface strain and effectively reducing the width of the transition layer and the density of Nniot.展开更多
Radiation effects of silicon carbide metal–oxide–semiconductor field-effect transistors(SiC MOSFETs)induced by 20 MeV proton under drain bias(V_(D)=800 V,V_(G)=0 V),gate bias(V_(D)=0 V,V_(G)=10 V),turn-on bias(V_(D)...Radiation effects of silicon carbide metal–oxide–semiconductor field-effect transistors(SiC MOSFETs)induced by 20 MeV proton under drain bias(V_(D)=800 V,V_(G)=0 V),gate bias(V_(D)=0 V,V_(G)=10 V),turn-on bias(V_(D)=0.5 V,V_(G)=4 V)and static bias(V_(D)=0 V,V_(G)=0 V)are investigated.The drain current of SiC MOSFET under turn-on bias increases linearly with the increase of proton fluence during the proton irradiation.When the cumulative proton fluence reaches 2×10^(11)p·cm^(-2),the threshold voltage of SiC MOSFETs with four bias conditions shifts to the left,and the degradation of electrical characteristics of SiC MOSFETs with gate bias is the most serious.In the deep level transient spectrum test,it is found that the defect energy level of SiC MOSFET is mainly the ON2(E_(c)-1.1 eV)defect center,and the defect concentration and defect capture cross section of SiC MOSFET with proton radiation under gate bias increase most.By comparing the degradation of SiC MOSFET under proton cumulative irradiation,equivalent 1 MeV neutron irradiation and gamma irradiation,and combining with the defect change of SiC MOSFET under gamma irradiation and the non-ionizing energy loss induced by equivalent 1 MeV neutron in SiC MOSFET,the degradation of SiC MOSFET induced by proton is mainly caused by ionizing radiation damage.The results of TCAD analysis show that the ionizing radiation damage of SiC MOSFET is affected by the intensity and direction of the electric field in the oxide layer and epitaxial layer.展开更多
Experiments and simulation studies on 283 MeV I ion induced single event effects of silicon carbide(SiC) metal–oxide–semiconductor field-effect transistors(MOSFETs) were carried out. When the cumulative irradiation ...Experiments and simulation studies on 283 MeV I ion induced single event effects of silicon carbide(SiC) metal–oxide–semiconductor field-effect transistors(MOSFETs) were carried out. When the cumulative irradiation fluence of the SiC MOSFET reached 5×10^(6)ion·cm^(-2), the drain–gate channel current increased under 200 V drain voltage, the drain–gate channel current and the drain–source channel current increased under 350 V drain voltage. The device occurred single event burnout under 800 V drain voltage, resulting in a complete loss of breakdown voltage. Combined with emission microscope, scanning electron microscope and focused ion beam analysis, the device with increased drain–gate channel current and drain–source channel current was found to have drain–gate channel current leakage point and local source metal melt, and the device with single event burnout was found to have local melting of its gate, source, epitaxial layer and substrate. Combining with Monte Carlo simulation and TCAD electrothermal simulation, it was found that the initial area of single event burnout might occur at the source–gate corner or the substrate–epitaxial interface, electric field and current density both affected the lattice temperature peak. The excessive lattice temperature during the irradiation process appeared at the local source contact, which led to the drain–source channel damage. And the excessive electric field appeared in the gate oxide layer, resulting in drain–gate channel damage.展开更多
This paper presents a high-power-density solid-state transformer(SST)designed for 25 kV alternative current railway applications,delivering a 3 kV direct current output to traction inverters.The SST is composed of sub...This paper presents a high-power-density solid-state transformer(SST)designed for 25 kV alternative current railway applications,delivering a 3 kV direct current output to traction inverters.The SST is composed of sub-modules with the adoption of 1.7 kV insulated gate bipolar transistor and SiC metal oxide field effect transistor(MOSFET)in an input-series-output-series structure,providing higher power density than conventional topologies that rely on high-voltage switches(>1.7 kV).Because these high-voltage SiC MOSFETs are still expensive and not fully commercialised,the proposed approach offers a more cost-effective alternative.A total of 42 converter cells ensure a highly modular and scalable design,with precise synchronisation and high-speed control achieved through an EtherCAT-based communication network.Additionally,a distributed control algorithm is introduced,mitigating excessive dependence on the communication link for module-level operations.The effectiveness of the entire system-including the design and control schemes-has been experimentally verified,ranging from individual converter cells to a reduced SST prototype of up to three sub-modules.These results confirm the feasibility and advantages of the proposed SST in terms of power density,cost efficiency and reliability for railway traction applications.展开更多
基金Funded by the Natural Science Foundation of Anhui Province(No.050440704)
文摘The interface reaction between the SiC particles （ SiCp ） and Fe was stndicd during sintering the SiCp reinforced Fe matrix composites at 1423 K for 1 h. In the composite having 3wt% （weight ratio） SiCp （the 3SiCp/ Fe composite）, the interface reaction products of Fe3 Si, the carbon precipitates, and Fe3 C or pearlite were generated. Fe3 Si coustructs the bright matrix of the reaction zone in the original situation of the SiCp. The carbon precipitates are randondy embedded in the reaction zone. Fe3 C or pearlite exists at the grain boundaries of the Fe matrix. As increasing the SiCp concentration in the SiCp/ Fe composite, the inteusity of the interface reaction between SiCp and Fe iacreases. After the 10SiCp/ Fe composite （ having 10wt .% SiCp ） sintered at 1423 K for 1 h, all of SiCp are decomposed, and replaced by the reaction zone composed of Fe3 Si and the carbon precipitates. No Fe3 C or pearlite was genertaed during the reaction. The effects of the techniques of oxidizing of SiCp , coating SiCp by interaction with the Cr powder, and alloying the Fe matrix by adding the Cr element on the interface stability of the SiCp/ Fe composite system were also investigated, respectitely. The oxide membrane and the coating layer on SiCp can inhibit the interface reaction between SiCp and Fe by isolating SiCp from the Fe matrix during sintering. The interface reaction does not occur in the 3 SiCp/ Fe- 10 Cr composite but in the 3 SiCp/ Fe-5 Cr composite. In the SiCp/ Fe-Cr alloy composites, the interface reaction between SiCp and the Fe- Cr alloys is weaker than that between SiCp and Fe . The Cr element behaves as a diluent, it causes a redaction in the interface reaction, which is proportional to the amount of the element added.
基金Project supported by the National Natural Science Foundation of China(Grant Nos.61404098 and 61274079)the Doctoral Fund of Ministry of Education of China(Grant No.20130203120017)+2 种基金the National Key Basic Research Program of China(Grant No.2015CB759600)the National Grid Science&Technology Project,China(Grant No.SGRI-WD-71-14-018)the Key Specific Project in the National Science&Technology Program,China(Grant Nos.2013ZX02305002-002 and 2015CB759600)
文摘The effect of nitric oxide（NO） annealing on charge traps in the oxide insulator and transition layer in n-type4H–Si C metal–oxide–semiconductor（MOS） devices has been investigated using the time-dependent bias stress（TDBS）,capacitance–voltage（C–V）,and secondary ion mass spectroscopy（SIMS）.It is revealed that two main categories of charge traps,near interface oxide traps（Nniot） and oxide traps（Not）,have different responses to the TDBS and C–V characteristics in NO-annealed and Ar-annealed samples.The Nniotare mainly responsible for the hysteresis occurring in the bidirectional C–V characteristics,which are very close to the semiconductor interface and can readily exchange charges with the inner semiconductor.However,Not is mainly responsible for the TDBS induced C–V shifts.Electrons tunneling into the Not are hardly released quickly when suffering TDBS,resulting in the problem of the threshold voltage stability.Compared with the Ar-annealed sample,Nniotcan be significantly suppressed by the NO annealing,but there is little improvement of Not.SIMS results demonstrate that the Nniotare distributed within the transition layer,which correlated with the existence of the excess silicon.During the NO annealing process,the excess Si atoms incorporate into nitrogen in the transition layer,allowing better relaxation of the interface strain and effectively reducing the width of the transition layer and the density of Nniot.
基金Project supported by the National Natural Science Foundation of China(Grant No.12075065)。
文摘Radiation effects of silicon carbide metal–oxide–semiconductor field-effect transistors(SiC MOSFETs)induced by 20 MeV proton under drain bias(V_(D)=800 V,V_(G)=0 V),gate bias(V_(D)=0 V,V_(G)=10 V),turn-on bias(V_(D)=0.5 V,V_(G)=4 V)and static bias(V_(D)=0 V,V_(G)=0 V)are investigated.The drain current of SiC MOSFET under turn-on bias increases linearly with the increase of proton fluence during the proton irradiation.When the cumulative proton fluence reaches 2×10^(11)p·cm^(-2),the threshold voltage of SiC MOSFETs with four bias conditions shifts to the left,and the degradation of electrical characteristics of SiC MOSFETs with gate bias is the most serious.In the deep level transient spectrum test,it is found that the defect energy level of SiC MOSFET is mainly the ON2(E_(c)-1.1 eV)defect center,and the defect concentration and defect capture cross section of SiC MOSFET with proton radiation under gate bias increase most.By comparing the degradation of SiC MOSFET under proton cumulative irradiation,equivalent 1 MeV neutron irradiation and gamma irradiation,and combining with the defect change of SiC MOSFET under gamma irradiation and the non-ionizing energy loss induced by equivalent 1 MeV neutron in SiC MOSFET,the degradation of SiC MOSFET induced by proton is mainly caused by ionizing radiation damage.The results of TCAD analysis show that the ionizing radiation damage of SiC MOSFET is affected by the intensity and direction of the electric field in the oxide layer and epitaxial layer.
基金supported by the National Natural Science Foundation of China (Grant No. 12075065)。
文摘Experiments and simulation studies on 283 MeV I ion induced single event effects of silicon carbide(SiC) metal–oxide–semiconductor field-effect transistors(MOSFETs) were carried out. When the cumulative irradiation fluence of the SiC MOSFET reached 5×10^(6)ion·cm^(-2), the drain–gate channel current increased under 200 V drain voltage, the drain–gate channel current and the drain–source channel current increased under 350 V drain voltage. The device occurred single event burnout under 800 V drain voltage, resulting in a complete loss of breakdown voltage. Combined with emission microscope, scanning electron microscope and focused ion beam analysis, the device with increased drain–gate channel current and drain–source channel current was found to have drain–gate channel current leakage point and local source metal melt, and the device with single event burnout was found to have local melting of its gate, source, epitaxial layer and substrate. Combining with Monte Carlo simulation and TCAD electrothermal simulation, it was found that the initial area of single event burnout might occur at the source–gate corner or the substrate–epitaxial interface, electric field and current density both affected the lattice temperature peak. The excessive lattice temperature during the irradiation process appeared at the local source contact, which led to the drain–source channel damage. And the excessive electric field appeared in the gate oxide layer, resulting in drain–gate channel damage.
基金Korea Institute of Energy Technology Evaluation and Planning funded by the Korea Government,Grant/Award Number:20224000000160Korea Agency for Infrastructure Technology Advancement,Grant/Award Number:RS 2021-KA163337。
文摘This paper presents a high-power-density solid-state transformer(SST)designed for 25 kV alternative current railway applications,delivering a 3 kV direct current output to traction inverters.The SST is composed of sub-modules with the adoption of 1.7 kV insulated gate bipolar transistor and SiC metal oxide field effect transistor(MOSFET)in an input-series-output-series structure,providing higher power density than conventional topologies that rely on high-voltage switches(>1.7 kV).Because these high-voltage SiC MOSFETs are still expensive and not fully commercialised,the proposed approach offers a more cost-effective alternative.A total of 42 converter cells ensure a highly modular and scalable design,with precise synchronisation and high-speed control achieved through an EtherCAT-based communication network.Additionally,a distributed control algorithm is introduced,mitigating excessive dependence on the communication link for module-level operations.The effectiveness of the entire system-including the design and control schemes-has been experimentally verified,ranging from individual converter cells to a reduced SST prototype of up to three sub-modules.These results confirm the feasibility and advantages of the proposed SST in terms of power density,cost efficiency and reliability for railway traction applications.
