A novel super-junction lateral double-diffused metal-oxide semiconductor (SJ-LDMOS) with a partial lightly doped P pillar (PD) is proposed. Firstly, the reduction in the partial P pillar charges ensures the charge...A novel super-junction lateral double-diffused metal-oxide semiconductor (SJ-LDMOS) with a partial lightly doped P pillar (PD) is proposed. Firstly, the reduction in the partial P pillar charges ensures the charge balance and suppresses the substrate-assisted depletion effect. Secondly, the new electric field peak produced by the P/P junction modulates the surface electric field distribution. Both of these result in a high breakdown voltage (BV). In addition, due to the same conduction paths, the specific on-resistance (Ron,sp) of the PD SJ-LDMOS is approximately identical to the conventional SJ-LDMOS. Simulation results indicate that the average value of the surface lateral electric field of the PD SJ-LDMOS reaches 20 V/μm at a 15 μm drift length, resulting in a BV of 300 V.展开更多
A stacked lateral double-diffused metal–oxide–semiconductor field-effect transistor(LDMOS) with enhanced depletion effect by surface substrate is proposed(ST-LDMOS), which is compatible with the traditional CMOS pro...A stacked lateral double-diffused metal–oxide–semiconductor field-effect transistor(LDMOS) with enhanced depletion effect by surface substrate is proposed(ST-LDMOS), which is compatible with the traditional CMOS processes. The new stacked structure is characterized by double substrates and surface dielectric trenches(SDT). The drift region is separated by the P-buried layer to form two vertically parallel devices. The doping concentration of the drift region is increased benefiting from the enhanced auxiliary depletion effect of the double substrates, leading to a lower specific on-resistance(Ron,sp). Multiple electric field peaks appear at the corners of the SDT, which improves the lateral electric field distribution and the breakdown voltage(BV). Compared to a conventional LDMOS(C-LDMOS), the BV in the ST-LDMOS increases from 259 V to 459 V, an improvement of 77.22%. The Ron,sp decreases from 39.62 m?·cm^2 to 23.24 m?·cm^2 and the Baliga's figure of merit(FOM) of is 9.07 MW/cm^2.展开更多
A novel low specific on-resistance (Ron,sp) lateral double-diffused metal oxide semiconductor (LDMOS) with a buried improved super-junction (BISJ) layer is proposed. A super-junction layer is buried in the drift...A novel low specific on-resistance (Ron,sp) lateral double-diffused metal oxide semiconductor (LDMOS) with a buried improved super-junction (BISJ) layer is proposed. A super-junction layer is buried in the drift region and the P pillar is split into two parts with different doping concentrations. Firstly, the buried super-junction layer causes the multiple-direction assisted depletion effect. The drift region doping concentration of the BISJ LDMOS is therefore much higher than that of the conventional LDMOS. Secondly, the buried super-junction layer provides a bulk low on-resistance path. Both of them reduce Ron,sp greatly. Thirdly, the electric field modulation effect of the new electric field peak introduced by the step doped P pillar improves the breakdown voltage (BV). The BISJ LDMOS exhibits a BV of 300 V and Ron,sp of 8.08 mΩ·cm2 which increases BV by 35% and reduces Ron,sp by 60% compared with those of a conventional LDMOS with a drift length of 15 μm, respectively.展开更多
Double-diffusive stationary and oscillatory instabilities at the marginal state in a saturated porous horizontal fluid layer heated and salted from above are investigated theoretically under the Darcy's framework for...Double-diffusive stationary and oscillatory instabilities at the marginal state in a saturated porous horizontal fluid layer heated and salted from above are investigated theoretically under the Darcy's framework for a porous medium. The contributions of Soret and Dufour coefficients are taken into account in the analysis. Linear stability analysis shows that the critical value of the Darcy-Rayleigh number depends on cross-diffusive parameters at marginally stationary convec- tion, while the marginal state characterized by oscillatory convection does not depend on the cross-diffusion terms even if the condition and frequency of oscillatory convection depends on the cross-diffusive parameters. The critical value of the Darcy-Rayleigh number increases with increasing value of the solutal Darcy-Rayleigh number in the absence of cross- diffusive parameters. The critical Darcy-Rayleigh number decreases with increasing Soret number, resulting in destabiliza- tion of the system, while its value increases with increasing Dufour number, resulting in stabilization of the system at the marginal state characterized by stationary convection. The analysis reveals that the Dufour and Soret parameters as well as the porosity parameter play an important role in deciding the type of instability at the onset. This analysis also indicates that the stationary convection is followed by the oscillatory convection for certain fluid mixtures. It is interesting to note that the roles of cross-diffusive parameters on the double-diffusive system heated and salted from above are reciprocal to the double-diffusive system heated and salted from below.展开更多
This paper describes experimental results on the solidification process over the vertically positioned circular cylinder, placed in an aqueous solution of sodium nitrate, where the aqueous solution in the vessel is he...This paper describes experimental results on the solidification process over the vertically positioned circular cylinder, placed in an aqueous solution of sodium nitrate, where the aqueous solution in the vessel is heated from the bottom. After the initiation of solidification by cooling the cylinder below the liquidus temperature, the pure ice formation on the cylinder causes the rejection of solute into the surrounding aqueous solution. The solute enriched vertical fluid layer over the ice then falls on the bottom of the vessel due to its higher density, and accumulates there. This process results in the formation of solute rich and hot horizontal layer (heavy layer), underlying the relatively cold but less concentrated fluid layer (light layer). As this process advances, however, because of the continuing influx of solute rich fluid, the lower heavy layer occupies more space, and the interface of the two layers rises slowly. The pH indicator method has been successfully employed in order to visualize the flows during this process. In this report, we document the evolution of both temperature and flow fields in the aqueous solution quantitatively, as the solidification progresses and the density discontinuity of the two layers rises.展开更多
This study is devoted to the analysis of a one-dimensional time-dependent double-diffusive flow over a semi-infinite vertical plate, under a convective surface boundary condition. Using similarity variable, the govern...This study is devoted to the analysis of a one-dimensional time-dependent double-diffusive flow over a semi-infinite vertical plate, under a convective surface boundary condition. Using similarity variable, the governing nonlinear partial differential equations have been transformed into a set of coupled nonlinear ordinary differential equations, which are solved numerically by using shooting method alongside with Runge-Kutta integration scheme as embedded in Maple software programme. The numerical results of the skin-friction coefficient, the Nusselt and Sherwood numbers are discussed and depicted graphically.展开更多
A numerical analysis has been carried out to study the problem of plane stagnation double-diffusive MHD convective flow with convective boundary condition in a porous media. The governing nonlinear partial differentia...A numerical analysis has been carried out to study the problem of plane stagnation double-diffusive MHD convective flow with convective boundary condition in a porous media. The governing nonlinear partial differential equations have been reduced to systems of nonlinear ordinary differential equations by the similarity transformations. The transformed equations are solved numerically by using the classical fourth order Runge-Kutta method together with the shooting technique implemented on a computer program. The effects of the physical parameters are examined on the velocity, temperature and concentration profiles. Numerical data for the skin-friction coefficients, Nusselt and Sherwood numbers have been tabulated for various parametric conditions and are also shown graphically and discussed.展开更多
In this study we investigate the dynamic recovery effects in IRF9520 commercial p-channel power vertical double diffused metal-oxide semiconductor field-effect transistors(VDMOSFETs) subjected to negative bias tempe...In this study we investigate the dynamic recovery effects in IRF9520 commercial p-channel power vertical double diffused metal-oxide semiconductor field-effect transistors(VDMOSFETs) subjected to negative bias temperature(NBT)stressing under the particular pulsed bias. Particular values of the pulsed stress voltage frequency and duty cycle are chosen in order to analyze the recoverable and permanent components of stress-induced threshold voltage shift in detail. The results are discussed in terms of the mechanisms responsible for buildup of oxide charge and interface traps. The partial recovery during the low level of pulsed gate voltage is ascribed to the removal of recoverable component of degradation, i.e., to passivation/neutralization of shallow oxide traps that are not transformed into the deeper traps(permanent component).Considering the value of characteristic time constant associated with complete removal of the recoverable component of degradation, it is shown that by selecting an appropriate combination of the frequency and duty cycle, the threshold voltage shifts induced under the pulsed negative bias temperature stress conditions can be significantly reduced, which may be utilized for improving the device lifetime in real application circuits.展开更多
A novel terminal-optimized triple RESURF LDMOS(TOTR-LDMOS) is proposed and verified in a 0.25-μm bipolarCMOS-DMOS(BCD) process. By introducing a low concentration region to the terminal region, the surface electric f...A novel terminal-optimized triple RESURF LDMOS(TOTR-LDMOS) is proposed and verified in a 0.25-μm bipolarCMOS-DMOS(BCD) process. By introducing a low concentration region to the terminal region, the surface electric field of the TOTR-LDMOS decreases, helping to improve the breakdown voltage(BV) and electrostatic discharge(ESD) robustness. Both traditional LDMOS and TOTR-LDMOS are fabricated and investigated by transmission line pulse(TLP) tests,direct current(DC) tests, and TCAD simulations. The results show that comparing with the traditional LDMOS, the BV of the TOTR-LDMOS increases from 755 V to 817 V without affecting the specific on-resistance(R_(on,sp)) of 6.99Ω·mm^(2).Meanwhile, the ESD robustness of the TOTR-LDMOS increases by 147%. The TOTR-LDMOS exhibits an excellent performance among the present 700-V LDMOS devices.展开更多
A new analytical model for the surface electric field distribution and breakdown voltage of the silicon oil insulator (SOI) trench lateral double-diffused metal-oxide-semiconductor (LDMOS) is presented. Based on t...A new analytical model for the surface electric field distribution and breakdown voltage of the silicon oil insulator (SOI) trench lateral double-diffused metal-oxide-semiconductor (LDMOS) is presented. Based on the two-dimensional Laplace solution and Poisson solution, the model considers the influence of structure parameters such as the doping concentration of the drift region, and the depth and width of the trench on the surface electric field. Further, a simple analytical expression of the breakdown voltage is obtained, which offers an effective way to gain an optimal high voltage. All the analytical results are in good agreement with the simulation results.展开更多
The Dufour and Soret effects on the unsteady twodimensional magnetonyaro dynamics (MHD) doublediffusive free convective flow of an electrically conducting fluid past a vertical plate embedded in a nonDarcy porous me...The Dufour and Soret effects on the unsteady twodimensional magnetonyaro dynamics (MHD) doublediffusive free convective flow of an electrically conducting fluid past a vertical plate embedded in a nonDarcy porous medium are investigated numeri cally. The governing nonlinear dimensionless equations are solved by an implicit finite difference scheme of the CrankNicolson type with a tridiagonal matrix manipulation. The effects of various parameters entering into the problem on the unsteady dimension less velocity, temperature, and concentration profiles are studied in detail. Furthermore, the time variation of the skin friction coefficient, the Nusselt number, and the Sherwood number is presented and analyzed. The results show that the unsteady velocity, tem perature, and concentration profiles are substantially influenced by the Dufour and Soret effects. When the Dufour number increases or the Soret number decreases, both the skin friction and the Sherwood number decrease, while the Nusselt number increases. It is found that, when the magnetic parameter increases, the velocity and the temperature decrease in the boundary layer.展开更多
Zoning in ore bodies, ore deposits and ore regions are recognized as temporal-spatial structures generated by the dynamics of ore- forming processes. Viewed from the theory of dissipative structures, ore zoning is a k...Zoning in ore bodies, ore deposits and ore regions are recognized as temporal-spatial structures generated by the dynamics of ore- forming processes. Viewed from the theory of dissipative structures, ore zoning is a kind of self-organization phenomenon occurring in far from-equilibrium geochemical dynamic systems. Therefore,kinetic and dynamic approaches must be taken to reveal the mechanisms of ore zoning. Two dominant coupling processes leading to ore zoning——reaction-transport feedbacks and double-diffusive convection——are discussed.展开更多
A shortout analytic method of stability in Strong nonlinear autonomous system is introduced into stability analysis of the themohaline double-diffusive system.Using perturbation technique obtains conditions of existen...A shortout analytic method of stability in Strong nonlinear autonomous system is introduced into stability analysis of the themohaline double-diffusive system.Using perturbation technique obtains conditions of existence and stability for linear and nonlinear periodic solutions.For linear periodic solution in infinitesimeal motion the existence range of monotomic branch and oscillatory branch are outilined.The oscillatory branch of nonlinear periodic solution in finite-amplitude motion has unstable periodic solution when μ is smaller than critical value μc in this case of 0<rs-rsc<<1The stability conclusions under different direction of vortex are drawn out .展开更多
The water column structure of the ice shelf cavity outflow from under Pine Island Glacier and its temporal variability were investigated using a hourly time series of yo-yo CTD and LADCP data collected over -24 h at t...The water column structure of the ice shelf cavity outflow from under Pine Island Glacier and its temporal variability were investigated using a hourly time series of yo-yo CTD and LADCP data collected over -24 h at the southern end of the ice shelf front. The primary water types present over the continental shelf off Pine Island Bay were Circumpolar Deep Water (CDW), modified Circumpolar Deep Water (mCDW), Shelf Water (SW), and Ice Shelf Water (ISW). As CDW transited the shelf, it transitioned into cooler, mCDW. In the upper 200 m, ISW dominated within 100 km of the ice shelf and SW further offshore. Within Pine Island Bay, the water column was partitioned into two primary layers based on their behavior: an upper outflowing layer from 100 m to 450 m composed of ISW with a significant meltwater component, 1%-2%, over an inflowing layer from -550 m to the sea bed composed of mCDW. Due to the small cavity extent, the outflowing water was warmer than the seawater freezing point. The upper ISW layer was further split into upper ISW layer #1 (100-300 m) and upper ISW layer #2 (320450 m) with the transition coinciding with the ice shelf draft. Small step-like features with heights from 1-50 m existed within both the ISW layers and were more prominent in upper ISW layer #1. A baroclinic signal at the semidiurnal frequency existed within both primary layers with the strongest signal, - 10 cm·s^-1, propagating vertically in the upper ISW layer.展开更多
A straightforward analytic method of stability in strong nonlinear autonomous system is introduced into the stability analysis of the themohaline double-diffusive system. The perturbation technique is used to obtain c...A straightforward analytic method of stability in strong nonlinear autonomous system is introduced into the stability analysis of the themohaline double-diffusive system. The perturbation technique is used to obtain conditions of existence and stability for linear and nonlinear periodic solutions. For linear periodic solution in infinitesimal motion, the existence range of monotonic branch and oscillatory branch are outlined. The oscillatory branch of nonlinear periodic solution in finite-amplitude motion has unstable periodic solution when μis smaller than critical value μc in this case of 0 < Rs-R12<<1. The stability conclusions under different direction of vortex are drawn out.展开更多
The impedance and output power measurements of LDMOS transistors are always a problem due to their low impedance and lead widths.An improved thru-reflect-line(TRL) calibration algorithm for measuring the characteristi...The impedance and output power measurements of LDMOS transistors are always a problem due to their low impedance and lead widths.An improved thru-reflect-line(TRL) calibration algorithm for measuring the characteristics of L-band high power LDMOS transistors is presented.According to the TRL algorithm,the individual two-port S parameters of each fixture half can be obtained.By de-embedding these S parameters of the test fixture,an accurate calibration can be made.The improved TRL calibration algorithm is successfully utilized to measure the characteristics of an L-band LDMOS transistor with a 90 mm gate width.The impedance of the transistor is obtained,and output power at 1 dB compression point can reach as much as 109.4 W at 1.2 GHz, achieving 1.2 W/mm power density.From the results,it is seen that the presented TRL calibration algorithm works well.展开更多
The physical mechanisms triggering electrostatic discharge (ESD) in high voltage LDMOS power transistors (〉 160 V) under transmission line pulsing (TLP) and very fast transmission line pulsing (VFTLP) stress ...The physical mechanisms triggering electrostatic discharge (ESD) in high voltage LDMOS power transistors (〉 160 V) under transmission line pulsing (TLP) and very fast transmission line pulsing (VFTLP) stress are investigated by TCAD simulations using a set of macroscopic physical models related to previous studies implemented in Sentaurus Device. Under VFTLP stress, it is observed that the triggering voltage of the high voltage LDMOS obviously increases, which is a unique phenomenon compared with the low voltage ESD protection devices like NMOS and SCR. The relationship between the triggering voltage increase and the parasitic capacitances is also analyzed in detail. A compact equivalent circuit schematic is presented according to the investigated phenomena. An improved structure to alleviate this effect is also proposed and confirmed by the experiments.展开更多
A novel buffer super-junction (S J) lateral double-diffused MOSFET (LDMOS) with an N-type buried layer (NB) is proposed. An N- buffer layer is implemented under the SJ region and an N-type layer is buried in the...A novel buffer super-junction (S J) lateral double-diffused MOSFET (LDMOS) with an N-type buried layer (NB) is proposed. An N- buffer layer is implemented under the SJ region and an N-type layer is buried in the P substrate. Firstly, the new electric field peak introduced by the p-n junction of the P substrate and the N-type buried layer modulates the surface electric field distribution. Secondly, the N-buffer layer suppresses the substrate assisted depletion effect. Both of them improve the breakdown voltage (BV). Finally, because of the shallow depth of the SJ region, the NB buffer SJ-LDMOS is compatible with Bi-CMOS technology. Simulation results indicate that the average value of the surface lateral electric field strength of the NB buffer SJ-LDMOS reaches 23 V/μm at 15/μm drift length which results in a BV of 350 V and a specific on-resistance of 21 mΩ·cm2.展开更多
基金supported by the National Science and Technology Major Project of the Ministry of Science and Technology of China (Grant No. 2010ZX02201)the National Natural Science Foundation of China (Grant No. 61176069)the National Defense Pre-Research of China (Grant No. 51308020304)
文摘A novel super-junction lateral double-diffused metal-oxide semiconductor (SJ-LDMOS) with a partial lightly doped P pillar (PD) is proposed. Firstly, the reduction in the partial P pillar charges ensures the charge balance and suppresses the substrate-assisted depletion effect. Secondly, the new electric field peak produced by the P/P junction modulates the surface electric field distribution. Both of these result in a high breakdown voltage (BV). In addition, due to the same conduction paths, the specific on-resistance (Ron,sp) of the PD SJ-LDMOS is approximately identical to the conventional SJ-LDMOS. Simulation results indicate that the average value of the surface lateral electric field of the PD SJ-LDMOS reaches 20 V/μm at a 15 μm drift length, resulting in a BV of 300 V.
基金supported by the National Natural Science Foundation of China(Grant No.61464003)the Guangxi Natural Science Foundation,China(Grant Nos.2015GXNSFAA139300 and 2018JJA170010)
文摘A stacked lateral double-diffused metal–oxide–semiconductor field-effect transistor(LDMOS) with enhanced depletion effect by surface substrate is proposed(ST-LDMOS), which is compatible with the traditional CMOS processes. The new stacked structure is characterized by double substrates and surface dielectric trenches(SDT). The drift region is separated by the P-buried layer to form two vertically parallel devices. The doping concentration of the drift region is increased benefiting from the enhanced auxiliary depletion effect of the double substrates, leading to a lower specific on-resistance(Ron,sp). Multiple electric field peaks appear at the corners of the SDT, which improves the lateral electric field distribution and the breakdown voltage(BV). Compared to a conventional LDMOS(C-LDMOS), the BV in the ST-LDMOS increases from 259 V to 459 V, an improvement of 77.22%. The Ron,sp decreases from 39.62 m?·cm^2 to 23.24 m?·cm^2 and the Baliga's figure of merit(FOM) of is 9.07 MW/cm^2.
基金Project supported by the National Science and Technology Project of the Ministry of Science and Technology of China(Grant No.2010ZX02201)the National Natural Science Foundation of China(Grant No.61176069)the National Defense Pre-Research of China(Grant No.51308020304)
文摘A novel low specific on-resistance (Ron,sp) lateral double-diffused metal oxide semiconductor (LDMOS) with a buried improved super-junction (BISJ) layer is proposed. A super-junction layer is buried in the drift region and the P pillar is split into two parts with different doping concentrations. Firstly, the buried super-junction layer causes the multiple-direction assisted depletion effect. The drift region doping concentration of the BISJ LDMOS is therefore much higher than that of the conventional LDMOS. Secondly, the buried super-junction layer provides a bulk low on-resistance path. Both of them reduce Ron,sp greatly. Thirdly, the electric field modulation effect of the new electric field peak introduced by the step doped P pillar improves the breakdown voltage (BV). The BISJ LDMOS exhibits a BV of 300 V and Ron,sp of 8.08 mΩ·cm2 which increases BV by 35% and reduces Ron,sp by 60% compared with those of a conventional LDMOS with a drift length of 15 μm, respectively.
基金support received from UGC, DSA-I in the Department of Mathematics, the University of Burdwan
文摘Double-diffusive stationary and oscillatory instabilities at the marginal state in a saturated porous horizontal fluid layer heated and salted from above are investigated theoretically under the Darcy's framework for a porous medium. The contributions of Soret and Dufour coefficients are taken into account in the analysis. Linear stability analysis shows that the critical value of the Darcy-Rayleigh number depends on cross-diffusive parameters at marginally stationary convec- tion, while the marginal state characterized by oscillatory convection does not depend on the cross-diffusion terms even if the condition and frequency of oscillatory convection depends on the cross-diffusive parameters. The critical value of the Darcy-Rayleigh number increases with increasing value of the solutal Darcy-Rayleigh number in the absence of cross- diffusive parameters. The critical Darcy-Rayleigh number decreases with increasing Soret number, resulting in destabiliza- tion of the system, while its value increases with increasing Dufour number, resulting in stabilization of the system at the marginal state characterized by stationary convection. The analysis reveals that the Dufour and Soret parameters as well as the porosity parameter play an important role in deciding the type of instability at the onset. This analysis also indicates that the stationary convection is followed by the oscillatory convection for certain fluid mixtures. It is interesting to note that the roles of cross-diffusive parameters on the double-diffusive system heated and salted from above are reciprocal to the double-diffusive system heated and salted from below.
文摘This paper describes experimental results on the solidification process over the vertically positioned circular cylinder, placed in an aqueous solution of sodium nitrate, where the aqueous solution in the vessel is heated from the bottom. After the initiation of solidification by cooling the cylinder below the liquidus temperature, the pure ice formation on the cylinder causes the rejection of solute into the surrounding aqueous solution. The solute enriched vertical fluid layer over the ice then falls on the bottom of the vessel due to its higher density, and accumulates there. This process results in the formation of solute rich and hot horizontal layer (heavy layer), underlying the relatively cold but less concentrated fluid layer (light layer). As this process advances, however, because of the continuing influx of solute rich fluid, the lower heavy layer occupies more space, and the interface of the two layers rises slowly. The pH indicator method has been successfully employed in order to visualize the flows during this process. In this report, we document the evolution of both temperature and flow fields in the aqueous solution quantitatively, as the solidification progresses and the density discontinuity of the two layers rises.
文摘This study is devoted to the analysis of a one-dimensional time-dependent double-diffusive flow over a semi-infinite vertical plate, under a convective surface boundary condition. Using similarity variable, the governing nonlinear partial differential equations have been transformed into a set of coupled nonlinear ordinary differential equations, which are solved numerically by using shooting method alongside with Runge-Kutta integration scheme as embedded in Maple software programme. The numerical results of the skin-friction coefficient, the Nusselt and Sherwood numbers are discussed and depicted graphically.
文摘A numerical analysis has been carried out to study the problem of plane stagnation double-diffusive MHD convective flow with convective boundary condition in a porous media. The governing nonlinear partial differential equations have been reduced to systems of nonlinear ordinary differential equations by the similarity transformations. The transformed equations are solved numerically by using the classical fourth order Runge-Kutta method together with the shooting technique implemented on a computer program. The effects of the physical parameters are examined on the velocity, temperature and concentration profiles. Numerical data for the skin-friction coefficients, Nusselt and Sherwood numbers have been tabulated for various parametric conditions and are also shown graphically and discussed.
基金Project supported by the Fund from the Ministry of Education,Science and Technological Development of the Republic of Serbia(Grant Nos.OI-171026 and TR-32026)the Ei PCB Factory,Ni
文摘In this study we investigate the dynamic recovery effects in IRF9520 commercial p-channel power vertical double diffused metal-oxide semiconductor field-effect transistors(VDMOSFETs) subjected to negative bias temperature(NBT)stressing under the particular pulsed bias. Particular values of the pulsed stress voltage frequency and duty cycle are chosen in order to analyze the recoverable and permanent components of stress-induced threshold voltage shift in detail. The results are discussed in terms of the mechanisms responsible for buildup of oxide charge and interface traps. The partial recovery during the low level of pulsed gate voltage is ascribed to the removal of recoverable component of degradation, i.e., to passivation/neutralization of shallow oxide traps that are not transformed into the deeper traps(permanent component).Considering the value of characteristic time constant associated with complete removal of the recoverable component of degradation, it is shown that by selecting an appropriate combination of the frequency and duty cycle, the threshold voltage shifts induced under the pulsed negative bias temperature stress conditions can be significantly reduced, which may be utilized for improving the device lifetime in real application circuits.
基金supported by the National Natural Science Foundation of China (Grant No. 61504049)the China Postdoctoral Science Foundation (Grant No. 2016M600361)the Fundamental Research Funds for the Central Universities,China (Grant No. JUSRP51510)。
文摘A novel terminal-optimized triple RESURF LDMOS(TOTR-LDMOS) is proposed and verified in a 0.25-μm bipolarCMOS-DMOS(BCD) process. By introducing a low concentration region to the terminal region, the surface electric field of the TOTR-LDMOS decreases, helping to improve the breakdown voltage(BV) and electrostatic discharge(ESD) robustness. Both traditional LDMOS and TOTR-LDMOS are fabricated and investigated by transmission line pulse(TLP) tests,direct current(DC) tests, and TCAD simulations. The results show that comparing with the traditional LDMOS, the BV of the TOTR-LDMOS increases from 755 V to 817 V without affecting the specific on-resistance(R_(on,sp)) of 6.99Ω·mm^(2).Meanwhile, the ESD robustness of the TOTR-LDMOS increases by 147%. The TOTR-LDMOS exhibits an excellent performance among the present 700-V LDMOS devices.
基金Project supported by the National Natural Science Foundation of China (Grant Nos. 61176069 and 60976060)the National Key Laboratory of Analogue Integrated Circuit, China (Grant No. 9140C090304110C0905)
文摘A new analytical model for the surface electric field distribution and breakdown voltage of the silicon oil insulator (SOI) trench lateral double-diffused metal-oxide-semiconductor (LDMOS) is presented. Based on the two-dimensional Laplace solution and Poisson solution, the model considers the influence of structure parameters such as the doping concentration of the drift region, and the depth and width of the trench on the surface electric field. Further, a simple analytical expression of the breakdown voltage is obtained, which offers an effective way to gain an optimal high voltage. All the analytical results are in good agreement with the simulation results.
文摘The Dufour and Soret effects on the unsteady twodimensional magnetonyaro dynamics (MHD) doublediffusive free convective flow of an electrically conducting fluid past a vertical plate embedded in a nonDarcy porous medium are investigated numeri cally. The governing nonlinear dimensionless equations are solved by an implicit finite difference scheme of the CrankNicolson type with a tridiagonal matrix manipulation. The effects of various parameters entering into the problem on the unsteady dimension less velocity, temperature, and concentration profiles are studied in detail. Furthermore, the time variation of the skin friction coefficient, the Nusselt number, and the Sherwood number is presented and analyzed. The results show that the unsteady velocity, tem perature, and concentration profiles are substantially influenced by the Dufour and Soret effects. When the Dufour number increases or the Soret number decreases, both the skin friction and the Sherwood number decrease, while the Nusselt number increases. It is found that, when the magnetic parameter increases, the velocity and the temperature decrease in the boundary layer.
文摘Zoning in ore bodies, ore deposits and ore regions are recognized as temporal-spatial structures generated by the dynamics of ore- forming processes. Viewed from the theory of dissipative structures, ore zoning is a kind of self-organization phenomenon occurring in far from-equilibrium geochemical dynamic systems. Therefore,kinetic and dynamic approaches must be taken to reveal the mechanisms of ore zoning. Two dominant coupling processes leading to ore zoning——reaction-transport feedbacks and double-diffusive convection——are discussed.
文摘A shortout analytic method of stability in Strong nonlinear autonomous system is introduced into stability analysis of the themohaline double-diffusive system.Using perturbation technique obtains conditions of existence and stability for linear and nonlinear periodic solutions.For linear periodic solution in infinitesimeal motion the existence range of monotomic branch and oscillatory branch are outilined.The oscillatory branch of nonlinear periodic solution in finite-amplitude motion has unstable periodic solution when μ is smaller than critical value μc in this case of 0<rs-rsc<<1The stability conclusions under different direction of vortex are drawn out .
基金support personnel on the RVIB Nathaniel B.Palmer during NPB0901funded partially by both the Australian Antarctic Division,project 2944
文摘The water column structure of the ice shelf cavity outflow from under Pine Island Glacier and its temporal variability were investigated using a hourly time series of yo-yo CTD and LADCP data collected over -24 h at the southern end of the ice shelf front. The primary water types present over the continental shelf off Pine Island Bay were Circumpolar Deep Water (CDW), modified Circumpolar Deep Water (mCDW), Shelf Water (SW), and Ice Shelf Water (ISW). As CDW transited the shelf, it transitioned into cooler, mCDW. In the upper 200 m, ISW dominated within 100 km of the ice shelf and SW further offshore. Within Pine Island Bay, the water column was partitioned into two primary layers based on their behavior: an upper outflowing layer from 100 m to 450 m composed of ISW with a significant meltwater component, 1%-2%, over an inflowing layer from -550 m to the sea bed composed of mCDW. Due to the small cavity extent, the outflowing water was warmer than the seawater freezing point. The upper ISW layer was further split into upper ISW layer #1 (100-300 m) and upper ISW layer #2 (320450 m) with the transition coinciding with the ice shelf draft. Small step-like features with heights from 1-50 m existed within both the ISW layers and were more prominent in upper ISW layer #1. A baroclinic signal at the semidiurnal frequency existed within both primary layers with the strongest signal, - 10 cm·s^-1, propagating vertically in the upper ISW layer.
基金National Natural Science Foundation of China and Zhonggahan University Science Foundation.
文摘A straightforward analytic method of stability in strong nonlinear autonomous system is introduced into the stability analysis of the themohaline double-diffusive system. The perturbation technique is used to obtain conditions of existence and stability for linear and nonlinear periodic solutions. For linear periodic solution in infinitesimal motion, the existence range of monotonic branch and oscillatory branch are outlined. The oscillatory branch of nonlinear periodic solution in finite-amplitude motion has unstable periodic solution when μis smaller than critical value μc in this case of 0 < Rs-R12<<1. The stability conclusions under different direction of vortex are drawn out.
文摘The impedance and output power measurements of LDMOS transistors are always a problem due to their low impedance and lead widths.An improved thru-reflect-line(TRL) calibration algorithm for measuring the characteristics of L-band high power LDMOS transistors is presented.According to the TRL algorithm,the individual two-port S parameters of each fixture half can be obtained.By de-embedding these S parameters of the test fixture,an accurate calibration can be made.The improved TRL calibration algorithm is successfully utilized to measure the characteristics of an L-band LDMOS transistor with a 90 mm gate width.The impedance of the transistor is obtained,and output power at 1 dB compression point can reach as much as 109.4 W at 1.2 GHz, achieving 1.2 W/mm power density.From the results,it is seen that the presented TRL calibration algorithm works well.
文摘The physical mechanisms triggering electrostatic discharge (ESD) in high voltage LDMOS power transistors (〉 160 V) under transmission line pulsing (TLP) and very fast transmission line pulsing (VFTLP) stress are investigated by TCAD simulations using a set of macroscopic physical models related to previous studies implemented in Sentaurus Device. Under VFTLP stress, it is observed that the triggering voltage of the high voltage LDMOS obviously increases, which is a unique phenomenon compared with the low voltage ESD protection devices like NMOS and SCR. The relationship between the triggering voltage increase and the parasitic capacitances is also analyzed in detail. A compact equivalent circuit schematic is presented according to the investigated phenomena. An improved structure to alleviate this effect is also proposed and confirmed by the experiments.
基金supported by the National Science and Technology Major Project of the Ministry of Science and Technology of China(No.2010ZX02201)the National Natural Science Foundation of China(No.61176069)the National Defense Pre-Research of China(No.51308020304)
文摘A novel buffer super-junction (S J) lateral double-diffused MOSFET (LDMOS) with an N-type buried layer (NB) is proposed. An N- buffer layer is implemented under the SJ region and an N-type layer is buried in the P substrate. Firstly, the new electric field peak introduced by the p-n junction of the P substrate and the N-type buried layer modulates the surface electric field distribution. Secondly, the N-buffer layer suppresses the substrate assisted depletion effect. Both of them improve the breakdown voltage (BV). Finally, because of the shallow depth of the SJ region, the NB buffer SJ-LDMOS is compatible with Bi-CMOS technology. Simulation results indicate that the average value of the surface lateral electric field strength of the NB buffer SJ-LDMOS reaches 23 V/μm at 15/μm drift length which results in a BV of 350 V and a specific on-resistance of 21 mΩ·cm2.