This paper describes the successful fabrication of 4H-SiC junction barrier Schottky （JBS） rectifiers with a linearly graded field limiting ring （LG-FLR）. Linearly variable ring spacings for the FLR termination are...This paper describes the successful fabrication of 4H-SiC junction barrier Schottky （JBS） rectifiers with a linearly graded field limiting ring （LG-FLR）. Linearly variable ring spacings for the FLR termination are applied to improve the blocking voltage by reducing the peak surface electric field at the edge termination region, which acts like a variable lateral doping profile resulting in a gradual field distribution. The experimental results demonstrate a breakdown voltage of 5 kV at the reverse leakage current density of 2 mA/cm2 （about 80% of the theoretical value）. Detailed numerical simulations show that the proposed termination structure provides a uniform electric field profile compared to the conventional FLR termi- nation, which is responsible for 45% improvement in the reverse blocking voltage despite a 3.7% longer total termination length.展开更多
A method of ascertaining grade length limitation of freeways in mountain terrain is presented. The relationship models between 15 th percentile speeds and grades were built through the surveys and analyses of operatio...A method of ascertaining grade length limitation of freeways in mountain terrain is presented. The relationship models between 15 th percentile speeds and grades were built through the surveys and analyses of operation speeds on 7 typical sections of 3 freeways in mountain terrain. Using 15 thpercentile and 85 th percentile as speed limitations, the methods of determining admitted velocities were put forward according to the grades. Deceleration distances of longitudinal slopeways were analyzed utilizing the theories of vehicle. According to the results of analysis, grade length limitation was loosed. Finally the values of grade length limitation for freeways were put forward. The results could be used as references for freeway design.展开更多
基金Project supported by the State Key Program of the National Natural Science Foundation of China(Grant No.61234006)
文摘This paper describes the successful fabrication of 4H-SiC junction barrier Schottky （JBS） rectifiers with a linearly graded field limiting ring （LG-FLR）. Linearly variable ring spacings for the FLR termination are applied to improve the blocking voltage by reducing the peak surface electric field at the edge termination region, which acts like a variable lateral doping profile resulting in a gradual field distribution. The experimental results demonstrate a breakdown voltage of 5 kV at the reverse leakage current density of 2 mA/cm2 （about 80% of the theoretical value）. Detailed numerical simulations show that the proposed termination structure provides a uniform electric field profile compared to the conventional FLR termi- nation, which is responsible for 45% improvement in the reverse blocking voltage despite a 3.7% longer total termination length.
基金Sponsored by the Specialized Research Fund for the Doctoral Program of High Education(Grant No.20030213030)
文摘A method of ascertaining grade length limitation of freeways in mountain terrain is presented. The relationship models between 15 th percentile speeds and grades were built through the surveys and analyses of operation speeds on 7 typical sections of 3 freeways in mountain terrain. Using 15 thpercentile and 85 th percentile as speed limitations, the methods of determining admitted velocities were put forward according to the grades. Deceleration distances of longitudinal slopeways were analyzed utilizing the theories of vehicle. According to the results of analysis, grade length limitation was loosed. Finally the values of grade length limitation for freeways were put forward. The results could be used as references for freeway design.
