Improvement of Electrical Performance of SOI-LIGBT by Resistive Field Plate

The electrical performance including breakdown voltage and turn-off speed of SOI-LIGBT is improved by incorporating a resistive field plate (RFP) and a p-MOSFET.The p-MOSFET is controlled by a signal detected from a point of the RFP.During the turning-off of the IGBT,the p-MOSFET is turned on,which provides a channel for the excessive carriers to flow out of the drift region and prevents the carriers from being injected into the drift region.At the same time,the electric field affected by the RFP makes the excessive carriers flow through a wider region,which almost eliminates the second phase of the turning-off of the SOI-LIGBT caused by the substrate bias.Faster turn-off speed is achieved by above two factors.During the on state of the IGBT,the p-MOSFET is off,which leads to an on-state performance like normal one.At least,the increase of the breakdown voltage for 25% and the decrease of the turn-off time for 65% can be achieved by this structure as can be verified by the numerical simulation results.

Magnetoelastic combined resonance and stability analysis of a ferromagnetic circular plate in alternating magnetic field

The nonlinear combined resonance problem of a ferromagnetic circular plate in a transverse alternating magnetic field is investigated. On the basis of the deformation potential energy, the strain potential energy, and the kinetic energy of the circular plate, the Hamilton principle is used to induce the magnetoelastic coupling transverse vibration dynamical equation of the ferromagnetic circular plate. Based on the basic electromagnetic theory, the expressions of the magnet force and the Lorenz force of the circular plate are presented. A displacement function satisfying clamped-edge combined with the Galerkin method is used to derive the Duffing vibration differential equation of the circular plate. The amplitude-frequency response equations of the system under various combined resonance forms are obtained by means of the multi-scale method, and the stability of the steady-state solutions is analyzed according to the Lyapunov theory. Through examples, the amplitude-frequency characteristic curves with different parameters, the amplitude of resonance varying with magnetic field intensity and excitation force, and the time-course response diagram, phase diagram, Poincar′e diagram of the system vibration are plotted, respectively. The effects of different parameters on the amplitude and stability of the system are discussed. The results show that the electromagnetic parameters have a significant effect on the multi-valued attribute and stability of the resonance solutions, and the system may exhibit complex nonlinear dynamical behavior including multi-period and quasi-periodic motion.

Numerical simulation of 80 ℃ temperature field distribution of thick plate multi-pass welding with SYSWELD

The PPG PITT-CHAR XP flame retardant system has been used by COOEC to preventing the thermal softening of steel in the high temperature,whose degradation temperature is 80 ℃.To prevent damage to PPG PITT-CHAR XP fire retardant paint from excessive heat during welding,it is necessary to get accurately reserved area near the welding joints prior to welding. For the foregoing reasons,the 80 ℃ temperature field distribution of thick plate multi-pass welding was analyzed with SYSWELD.The influence of welding groove form and time interval on welding temperature field was also analyzed. Results showed that the range of 80 ℃ welding temperature field increased with the increasing of weld layers at first and then it inclined to stable value. Interpass time setting was crucial to control the range of 80 ℃ welding temperature field. It was also found that double V groove had better thermal diffusivity than double-bevel groove.And double-bevel groove was better than single V groove.

A low specific on-resistance SOI LDMOS with a novel junction field plate

A low specific on-resistance SO1 LDMOS with a novel junction field plate （JFP） is proposed and investigated theo- retically. The most significant feature of the JFP LDMOS is a PP-N junction field plate instead of a metal field plate. The unique structure not only yields charge compensation between the JFP and the drift region, but also modulates the surface electric field. In addition, a trench gate extends to the buffed oxide layer （BOX） and thus widens the vertical conduction area. As a result, the breakdown voltage （BV） is improved and the specific on-resistance （Ron,sp） is decreased significantly. It is demonstrated that the BV of 306 V and the Ron,sp of 7.43 mΩ.cm2 are obtained for the JFP LDMOS. Compared with those of the conventional LDMOS with the same dimensional parameters, the BV is improved by 34.8%, and the Ron,sp is decreased by 56.6% simultaneously. The proposed JFP LDMOS exhibits significant superiority in terms of the trade-off between BV and Ron,sp. The novel JFP technique offers an alternative technique to achieve high blocking voltage and large current capacity for power devices.

BASIC CURVILINEAR COORDINATE EQUATIONS OF ELECTROELASTIC PLATES UNDER BIASING FIELDS WITH APPLICATIONS IN BUCKLING ANALYSIS

The authors have developed a two-dimensional model for the extension and flexure response of electroelastic plates under biasing fields in a curvilinear coordinate system. Applications of the model in analyzing buckling of two circular piezoelectric plates, one single-layered and the other double-layered, are included. The analysis indicates that the piezoelectric coupling has a strengthening effect against buckling.

Reverse blocking characteristics and mechanisms in Schottky-drain AlGaN/GaN HEMT with a drain field plate and floating field plates

In this paper, a novel A1GaN/GaN HEMT with a Schottky drain and a compound field plate （SD-CFP HEMT） is presented for the purpose of better reverse blocking capability. The compound field plate （CFP） consists of a drain field plate （DFP） and several floating field plates （FFPs）. The physical mechanisms of the CFP to improve the reverse breakdown voltage and to modulate the distributions of channel electric field and potential are investigated by two-dimensional numer- ical simulations with Silvaco-ATLAS. Compared with the HEMT with a Schottky drain （SD HEMT） and the HEMT with a Schottky drain and a DFP （SD-FP HEMT）, the superiorities of SD-CFP HEMT lie in the continuous improvement of the reverse breakdown voltage by increasing the number of FFPs and in the same fabrication procedure as the SD-FP HEMT. Two useful optimization laws for the SD-CFP HEMTs are found and extracted from simulation results. The relationship between the number of the FFPs and the reverse breakdown voltage as well as the FP efficiency in SD-CFP HEMTs are discussed. The results in this paper demonstrate a great potential of CFP for enhancing the reverse blocking ability in A1GaN/GaN HEMT and may be of great value and significance in the design and actual manufacture of SD-CFP HEMTs.

MULTI-FIELD COUPLING BEHAVIOR OF SIMPLY-SUPPORTED CONDUCTIVE PLATE UNDER THE CONDITION OF A TRANSVERSE STRONG IMPULSIVE MAGNETIC FIELD

In order to study the multi-field coupling mechanical behavior of the simply-supported conductive rectangular thin plate under the condition of an externally lateral strong impulsive magnetic field, that is the dynamic buckling phenomenon of the thin plates in the effect of the magnetic volume forces produced by the interaction between the eddy current and the magnetic fields, a FEM analysis program is developed to characterize the phenomena of magnetoelastic buckling and instability of the plates. The critical values of magnetic field for the three different initial vibrating modes are obtained, with a detailed discussion made on the effects of the lengththickness ratio a/h of the plate and the length-width ratio a/b as well as the impulse parameter on the critical value BOcr of the applied magnetic field.

Numerical Analysis of the Flow Field in a Sloshing Tank with a Horizontal Perforated Plate

Liquid sloshing is a type of free surface flow inside a partially filled water tank.Sloshing exerts a significant effect on the safety of liquid transport systems;in particular,it may cause large hydrodynamic loads when the frequency of the tank motion is close to the natural frequency of the tank.Perforated plates have recently been used to suppress the violent movement of liquids in a sloshing tank at resonant conditions.In this study,a numerical model based on OpenF OAM(Open Source Field Operation and Manipulation),an open source computed fluid dynamic code,is used to investigate resonant sloshing in a swaying tank with a submerged horizontal perforated plate.The numerical results of the free surface elevations are first verified using experimental data,and then the flow characteristics around the perforated plate and the fluid velocity distribution in the entire tank are examined using numerical examples.The results clearly show differences in sloshing motions under first-order and third-order resonant frequencies.This study provides a better understanding of the energy dissipation mechanism of a horizontal perforated plate in a swaying tank.

Breakdown voltage model and structure realization of a thin silicon layer with linear variable doping on a silicon on insulator high voltage device with multiple step field plates

Based on the theoretical and experimental investigation of a thin silicon layer（TSL） with linear variable doping（LVD） and further research on the TSL LVD with a multiple step field plate（MSFP）,a breakdown voltage（BV） model is proposed and experimentally verified in this paper.With the two-dimensional Poisson equation of the silicon on insulator（SOI） device,the lateral electric field in drift region of the thin silicon layer is assumed to be constant.For the SOI device with LVD in the thin silicon layer,the dependence of the BV on impurity concentration under the drain is investigated by an enhanced dielectric layer field（ENDIF）,from which the reduced surface field（RESURF） condition is deduced.The drain in the centre of the device has a good self-isolation effect,but the problem of the high voltage interconnection（HVI） line will become serious.The two step field plates including the source field plate and gate field plate can be adopted to shield the HVI adverse effect on the device.Based on this model,the TSL LVD SOI n-channel lateral double-diffused MOSFET（nLDMOS） with MSFP is realized.The experimental breakdown voltage（BV） and specific on-resistance（R on,sp） of the TSL LVD SOI device are 694 V and 21.3 ·mm 2 with a drift region length of 60 μm,buried oxide layer of 3 μm,and silicon layer of 0.15 μm,respectively.

A simulation study of field plate termination in Ga2O3 Schottky barrier diodes

In this work, the field plate termination is studied for Ga2O3Schottky barrier diodes(SBDs) by simulation. The influence of field plate overlap, dielectric material and thickness on the termination electric field distribution are demonstrated.It is found that the optimal thickness increases with reverse bias increasing for all the three dielectrics of SiO2, Al2O3, and HfO2. As the thickness increases, the maximum electric field intensity decreases in SiO2and Al2O3, but increases in HfO2.Furthermore, it is found that SiO2and HfO2are suitable for the 600 V rate Ga2O3SBD, and Al2O3is suitable for both600 V and 1200 V rate Ga2O3SBD. In addition, the comparison of Ga2O3SBDs between the SiC and GaN counterpart reveals that for Ga2O3, the breakdown voltage bottleneck is the dielectric. While, for SiC and GaN, the bottleneck is mainly the semiconductor itself.

Calculation and experimental study on heating temperature field of super-high strength aluminum alloy thick plate

Stepped heating treatment has been applied to aluminum alloy thick plate to improve the mechanical performance and corrosion resistance.Accurate temperature control of the plate is the difficulty in engineering application.The heating process,the calculation of surface heat transfer coefficient and the accurate temperature control method were studied based on measured heating temperature for the large-size thick plate.The results show that,the temperature difference between the surface and center of the thick plate is small.Based on the temperature uniformity,the surface heat transfer coefficient was calculated,and it is constant below300°C,but grows greatly over300°C.Consequently,a lumped parameter method(LPM)was developed to predict the plate temperature.A stepped solution treatment was designed by using LPM,and verified by finite element method(FEM)and experiments.Temperature curves calculated by LPM and FEM agree well with the experimental data,and the LPM is more convenient in engineering application.

Flow Field Analysis of Submerged Horizontal Plate Type Breakwater

Submerged horizontal plate can be considered as a new concept breakwater. In order to reveal the wave elimination mechanism of this type breakwater, boundary element method is utilized to investigate the velocity field around plate carefully. The flow field analysis shows that the interaction between incident wave and reverse flow caused by submerged plate will lead to the formation of wave elimination area around both sides of the plate. The velocity magnitude of flow field has been reduced and this is the main reason of wave elimination.

Inverse problem of pulsed eddy current field of ferromagnetic plates

To determine the wall thickness, conductivity and permeability of a ferromagnetic plate, an inverse problem is established with measured values and calculated values of time-domain induced voltage in pulsed eddy current testing on the plate. From time-domain analytical expressions of the partial derivatives of induced voltage with respect to parameters,it is deduced that the partial derivatives are approximately linearly dependent. Then the constraints of these parameters are obtained by solving a partial linear differential equation. It is indicated that only the product of conductivity and wall thickness, and the product of relative permeability and wall thickness can be determined accurately through the inverse problem with time-domain induced voltage. In the practical testing, supposing the conductivity of the ferromagnetic plate under test is a fixed value, and then the relative variation of wall thickness between two testing points can be calculated via the ratio of the corresponding inversion results of the product of conductivity and wall thickness. Finally, this method for wall thickness measurement is verified by the experiment results of a carbon steel plate.

Regional characteristics of stress field in the southern part of the north－south seismic belt in China and its relation with plate movement

The regional characteristics of stress field in the southern part of the northusouth seismic belt (NSB) have beenanalyzed in detail based on the mechanism solutions of 134 medium and large earthquakes from 1933 to 1991.The results show that the southern part of the NSB is a shallow earthquake zone where most earthquakes arecaused by the strike-slip faulting. There is a systematic distribution of the directions of P-and T-axes in thewestern and the eastern regions of the southern part of the NSB. P-and T-axes in the western region are in theNE-SW direction and in the NW-SE direction. P-and T-axes in the eastern region are oriented in NW-SE andNE-SW, respectively. The directions of p-axes in the western and the eastern regions show a pattern of a reversal 'V' as a whole. The boundary between the eastern and western regions coincides with that between the Tibetan Plateau and the Yangtze crustal block. Based on a lot of mechanism solutions, the result indicates that thedirection of P-axes roughly shows the consistent distributions from the Himalayan collision zone to the easternregion and from the eastern coast collision zone in Taiwan to the eastern region of southern part of the NSB, respectively. It is suggested that the tectonic force due to relative movement between the indo-Australian and theEurasian plates is transmitted from the Himalayan collision zone to the western region of the southern part ofNSB, simultaneously, the tectonic force due to the relative movement between the Philippine Sea and theEurasian plates is transmitted from the eastern region coast in Taiwan to the eastern region of the southern partof NSB, and control the stress field there, respectively.

Sheltering effect of punched steel plate sand fences for controlling blown sand hazards along the Golmud-Korla Railway:Field observation and numerical simulation studies

Sand fences made of punched steel plate(PSP)have recently been applied to control wind-blown sand in desertified and Gobi areas due to their strong wind resistance and convenient in situ construction.However,few studies have assessed the protective effect of PSP sand fences,especially through field observations.This study analyzes the effects of double-row PSP sand fences on wind and sand resistance using field observations and a computational fluid dynamics(CFD)numerical simulation.The results of field observations showed that the average windproof efficiencies of the first-row and second-row sand fences were 79.8%and 70.8%,respectively.Moreover,the average windproof efficiencies of the numerical simulation behind the first-row and second-row sand fences were 89.8%and 81.1%,respectively.The sand-resistance efficiency of the double-row PSP sand fences was 65.4%.Sand deposition occurred close to the first-row sand fence;however,there was relatively little sand on the leeward side of the second-row sand fence.The length of sand accumulation near PSP sand fences obtained by numerical simulation was basically consistent with that through field observations,indicating that field observations combined with numerical simulation can provide insight into the complex wind-blown sand field over PSP sand fences.This study indicates that the protection efficiency of the double-row PSP sand fences is sufficient for effective control of sand hazards associated with extremely strong wind in the Gobi areas.The output of this work is expected to improve the future application of PSP sand fences.

Influence of a drain field plate on the forward blocking characteristics of an AlGaN/GaN high electron mobility transistor

In this paper, the influence of a drain field plate （FP） on the forward blocking characteristics of an AlGaN/GaN high electron mobility transistor （HEMT） is investigated. The HEMT with only a gate FP is optimized, and breakdown voltage VBR is saturated at 1085 V for gate–drain spacing LGD ≥ 8 μm. On the basis of the HEMT with a gate FP, a drain FP is added with LGD=10 μm. For the length of the drain FP LDF ≤ 2 μm, VBR is almost kept at 1085 V, showing no degradation. When LDF exceeds 2 μm, VBR decreases obviously as LDF increases. Moreover, the larger the LDF, the larger the decrease of VBR. It is concluded that the distance between the gate edge and the drain FP edge should be larger than a certain value to prevent the drain FP from affecting the forward blocking voltage and the value should be equal to the LGD at which VBR begins to saturate in the first structure. The electric field and potential distribution are simulated and analyzed to account for the decrease of VBR.

Field plate structural optimization for enhancing the power gain of GaN-based HEMTs

A novel source-connected field plate structure, featuring the same photolithography mask as the gate electrode, is proposed as an improvement over the conventional field plate （FP） techniques to enhance the frequency performance in GaN-based HEMTs. The influences of the field plate on frequency and breakdown performance are investigated simul- taneously by using a two-dimensional physics-based simulation. Compared with the conventional T-gate structures with a field plate length of 1.2 gm, this field plate structure can induce the small signal power gain at 10 GHz to increase by 5-9.5 dB, which depends on the distance between source FP and dramatically shortened gate FE This technique minimizes the parasitic capacitances, especially the gate-to-drain capacitance, showing a substantial potential for millimeter-wave, high power applications.

A Lateral Regulator Diode with Field Plates for Light-Emitting-Diode Lighting

A lateral current regulator diode （CRD） with field plates is proposed and experimentally demonstrated. The proposed CFtD is based on the junction field-effect transistor （JFET） structure. A cathode field plate is adopted to alleviate the channel-length modulation effect and to improve the saturated I-V characteristics. An anode field plate is induced to achieve a high breakdown voltage VB of the CRD. The influence of the key device parameters on the I-V characteristics of the lateral CRD are discussed. Experimental results show that the proposed CRD presents good I-V characteristics with a high VB about 180 V and a low knee voltage （Vk） below 3 V. Furthermore, the proposed CRD has a negative temperature coefficient. The well characteristic of the proposed CRD makes it a cost-effective solution for light-emitting-diode lighting.

Simultaneous resonance of an axially moving ferromagnetic thin plate under a line load in a time-varying magnetic field

In this paper,the simultaneous resonance of a ferromagnetic thin plate in a time-varying magnetic field,having axial speed and being subjected to a periodic line load,is studied.Based on the large deflection theory of thin plates and electromagnetic field theory,the nonlinear vibration differential equation of the plate is obtained by using the Hamilton′s principle and the Galerkin method.Then the boundary condition in which the longer opposite sides are clamped and hinged is considered.The dimensionless nonlinear differential equations are solved by using the method of multiple scales,and the analytical solution is given.In addition,the stability analysis is also carried out by using Lyapunov stability theory.Through numerical analysis,the variation curves of system resonance amplitude with frequency tuning parameter,magnetic field strength and external excitation amplitude are obtained.Different parameters that have significant effects on the response of the system,such as the thickness,the axial velocity,the magnetic field intensity,the position,and the frequency of external excitation,are considered and analyzed.The results show that the system has multiple solution regions and obvious nonlinear coupled characteristics.

Evaluation of Large Amplitude Free Vibration Behavior of Moderately Thick Square Plates Using Coupled Displacememt Field Method

A simple and efficient coupled displacement field method is developed to study the large amplitude free vibration behavior of the moderately thick square plates.A single term trigonometric admissible displacement field is assumed for one of the variables,say,the total rotations(in both X,Y directions).Making use of the coupling equation,the spatial variation for the lateral displacement field is derived in terms of the total rotations.The coupled displacement field method makes the energy formulation to contain half the number of unknown independent coefficients,in the case of a square plate,contrary to the conventional RayleighRitz method.The lesser number of undetermined coefficients significantly simplifies the vibration problem.The expressions for the linear and nonlinear fundamental frequency parameters for the all edges simply supported moderately thick square plates are derived.The numerical results obtained from the present formulation are in very good agreement with those obtained from the existing literature.