In the modern society,there is a strong demand for semiconductor chips,and the 4H polytype silicon carbide(4H-SiC)power device is a promising candidate for the next generation semiconductor chip,which can be used in v...In the modern society,there is a strong demand for semiconductor chips,and the 4H polytype silicon carbide(4H-SiC)power device is a promising candidate for the next generation semiconductor chip,which can be used in various power electronic systems.In order to improve the performance of the 4H-SiC power device,a novel ultrahigh-voltage(UHV)4H-SiC merged p-type/intrinsic/n-type(PiN)Schottky(MPS)diode with three-dimensional(3D)p-type buried layers(PBL)(3D-PBL MPS)is proposed and investigated by numerical simulation.The static forward conduction characteristics of the 3D-PBL MPS are similar to those of the conventional 4H-SiC MPS diode without the PBL(PBL-free MPS).However,when the 3D-PBL MPS is in the reverse blocking state,the 3D PBL can transfer the peak electric field(E_(peak))into a deeper position in the body of the epitaxial layer,and enhance the ability of the device to shield the high electric field at the Schottky contact interface(E_(S)),so that the reverse leakage current of the 3D-PBL MPS at 10 kV is only 0.002%of that of the PBL-free MPS.Meanwhile,the novel 3D-PBL MPS has overcome the disadvantage in the 4H-SiC MPS diode with the two-dimensional PBL(2D-PBL MPS),and the forward conduction characteristic of the 3D-PBL MPS will not get degenerated after the device converts from the reverse blocking state to the forward conduction state because of the special depletion layer variation mechanism depending on the 3D PBL.All the simulation results show that the novel UHV 3D-PBL MPS has excellent device performance.展开更多
A coupled-mode method for three-dimensional acoustic propagation and scattering in two-dimensional waveguides is presented.This method synthesizes the three-dimensional field solution by using Fourier transform techni...A coupled-mode method for three-dimensional acoustic propagation and scattering in two-dimensional waveguides is presented.This method synthesizes the three-dimensional field solution by using Fourier transform techniques based on a sequence of two-dimensional problems,each of which is solved by a numerical model recently developed by Luo et al.[Chin.Phys.Lett.29(2012)014302].Numerical results indicate that the present model is remarkably accurate,and thus can serve as benchmark against other numerical models.In addition,this model can be applied to realistic problems,and can also be used to analyze horizontal refraction in some range-dependent waveguides in reality,such as the continental shelf environment,ridge-like bathymetry,and underwater trenches.展开更多
The direct global matrix approach can be applied to modeling of range-dependent sound propagation in order to achieve numerically stable and accurate solutions.By solving the global system directly,this method feature...The direct global matrix approach can be applied to modeling of range-dependent sound propagation in order to achieve numerically stable and accurate solutions.By solving the global system directly,this method features high efficiency as well as accuracy by avoiding error accumulation.It is an important issue to solve linear systems numerically in the direct global matrix approach,especially for the large-scale problems.An efficient and memory-saving algorithm is developed for solving the global system,in which the global coefficient matrix is treated as a block pentadiagonal matrix.As a result,this numerical model has the ability to solve large-scale problems on regular computers.Numerical examples are also presented to demonstrate the accuracy and efficiency of this method.展开更多
Sound propagation in a wedge with perfectly reflecting boundaries is one of the few range-dependent problems with an analytical solution.Since sound propagation towards the wedge apex will be completely backscattered ...Sound propagation in a wedge with perfectly reflecting boundaries is one of the few range-dependent problems with an analytical solution.Since sound propagation towards the wedge apex will be completely backscattered due to the perfectly reflecting boundaries,this test problem is an ideal benchmark for a full two-way solution to the wave equation.An analytical solution for sound propagation in a wedge with a pressure-release sea surface and a pressure-release bottom was presented by Buckingham et al.[J.Acoust.Soc.Am.87(1990)1511].The ideal wedge problem with a rigid bottom is also of great importance in underwater acoustics.We present an analytical solution to the problem with a wedge bounded above by a pressure-release sea surface and below by a rigid bottom,which may be used to provide informative means of investigating the sound field in depth-varying channels,and to establish the accuracy of numerical propagation models for which it is difficult to treat problems with a pressure-release bottom.A comparison of the analytical solution and the numerical solution recently proposed by Luo et al.[Chin.Phys.Lett.29(2012)014302]is also presented,indicating that this numerical propagation model provides high accuracy.展开更多
An accurate and numerically stable method based on the coupled-mode theory is presented.By applying the direct global matrix approach to obtain the modal expansion coefficients,this method is numerically stable.In add...An accurate and numerically stable method based on the coupled-mode theory is presented.By applying the direct global matrix approach to obtain the modal expansion coefficients,this method is numerically stable.In addition,appropriately normalized range solutions are introduced,which resolves the overflow problem entirely.Furthermore,we put forward source conditions appropriate for the line-source problem in plane geometry.As a result,this method is capable of dealing with the scenario where a line source is located inside the region of a deformation.Closed-form expressions for coupling matrices are provided for ideal waveguides.Numerical results indicate that the present method is accurate and numerically stable.Consequently,this model can serve as a benchmark in range-dependent propagation modeling.展开更多
基金Project(F2020210016) supported by the Natural Science Foundation of Hebei,ChinaProject(620004153) supported by the National Natural Science Foundation of China。
文摘In the modern society,there is a strong demand for semiconductor chips,and the 4H polytype silicon carbide(4H-SiC)power device is a promising candidate for the next generation semiconductor chip,which can be used in various power electronic systems.In order to improve the performance of the 4H-SiC power device,a novel ultrahigh-voltage(UHV)4H-SiC merged p-type/intrinsic/n-type(PiN)Schottky(MPS)diode with three-dimensional(3D)p-type buried layers(PBL)(3D-PBL MPS)is proposed and investigated by numerical simulation.The static forward conduction characteristics of the 3D-PBL MPS are similar to those of the conventional 4H-SiC MPS diode without the PBL(PBL-free MPS).However,when the 3D-PBL MPS is in the reverse blocking state,the 3D PBL can transfer the peak electric field(E_(peak))into a deeper position in the body of the epitaxial layer,and enhance the ability of the device to shield the high electric field at the Schottky contact interface(E_(S)),so that the reverse leakage current of the 3D-PBL MPS at 10 kV is only 0.002%of that of the PBL-free MPS.Meanwhile,the novel 3D-PBL MPS has overcome the disadvantage in the 4H-SiC MPS diode with the two-dimensional PBL(2D-PBL MPS),and the forward conduction characteristic of the 3D-PBL MPS will not get degenerated after the device converts from the reverse blocking state to the forward conduction state because of the special depletion layer variation mechanism depending on the 3D PBL.All the simulation results show that the novel UHV 3D-PBL MPS has excellent device performance.
基金Supported by the National Natural Science Foundation of China under Grant Nos 11125420 and 11174312the Knowledge Innovation Project of the Chinese Academy of Sciences.
文摘A coupled-mode method for three-dimensional acoustic propagation and scattering in two-dimensional waveguides is presented.This method synthesizes the three-dimensional field solution by using Fourier transform techniques based on a sequence of two-dimensional problems,each of which is solved by a numerical model recently developed by Luo et al.[Chin.Phys.Lett.29(2012)014302].Numerical results indicate that the present model is remarkably accurate,and thus can serve as benchmark against other numerical models.In addition,this model can be applied to realistic problems,and can also be used to analyze horizontal refraction in some range-dependent waveguides in reality,such as the continental shelf environment,ridge-like bathymetry,and underwater trenches.
基金Supported by the National Natural Science Foundation of China under Grant Nos 11125420 and 11104312the Knowledge Innovation Project of the Chinese Academy of Sciences.
文摘The direct global matrix approach can be applied to modeling of range-dependent sound propagation in order to achieve numerically stable and accurate solutions.By solving the global system directly,this method features high efficiency as well as accuracy by avoiding error accumulation.It is an important issue to solve linear systems numerically in the direct global matrix approach,especially for the large-scale problems.An efficient and memory-saving algorithm is developed for solving the global system,in which the global coefficient matrix is treated as a block pentadiagonal matrix.As a result,this numerical model has the ability to solve large-scale problems on regular computers.Numerical examples are also presented to demonstrate the accuracy and efficiency of this method.
基金Supported by the National Natural Science Foundation of China under Grant Nos 11125420,10734100the Knowledge Innovation Program of Chinese Academy of Sciences.
文摘Sound propagation in a wedge with perfectly reflecting boundaries is one of the few range-dependent problems with an analytical solution.Since sound propagation towards the wedge apex will be completely backscattered due to the perfectly reflecting boundaries,this test problem is an ideal benchmark for a full two-way solution to the wave equation.An analytical solution for sound propagation in a wedge with a pressure-release sea surface and a pressure-release bottom was presented by Buckingham et al.[J.Acoust.Soc.Am.87(1990)1511].The ideal wedge problem with a rigid bottom is also of great importance in underwater acoustics.We present an analytical solution to the problem with a wedge bounded above by a pressure-release sea surface and below by a rigid bottom,which may be used to provide informative means of investigating the sound field in depth-varying channels,and to establish the accuracy of numerical propagation models for which it is difficult to treat problems with a pressure-release bottom.A comparison of the analytical solution and the numerical solution recently proposed by Luo et al.[Chin.Phys.Lett.29(2012)014302]is also presented,indicating that this numerical propagation model provides high accuracy.
基金Supported by the Knowledge Innovation Program of Chinese Academy of Sciences.
文摘An accurate and numerically stable method based on the coupled-mode theory is presented.By applying the direct global matrix approach to obtain the modal expansion coefficients,this method is numerically stable.In addition,appropriately normalized range solutions are introduced,which resolves the overflow problem entirely.Furthermore,we put forward source conditions appropriate for the line-source problem in plane geometry.As a result,this method is capable of dealing with the scenario where a line source is located inside the region of a deformation.Closed-form expressions for coupling matrices are provided for ideal waveguides.Numerical results indicate that the present method is accurate and numerically stable.Consequently,this model can serve as a benchmark in range-dependent propagation modeling.
