Stress intensities at the triple junction of a multilevel thin film package

Stress intensities of a singular near-tip field around the vertex of a triple junction wedge in multilevel thin film packages are calculated using the two-state M-integral. For this calculation the existence of a simple auxiliary field in the sense of the M-integral associated with every eigenfunction for the triple junction vertex is first verified numerically. The auxiliary field is then employed for superposition with the elastic field under consideration, and the associated two-state M-integral is computed via the domain integral technique. This enables us to extract the stress intensity of each singular eigenfunction for the triple junction vertex at three different junction angles,  = 45°, 90° and 135°.     

Vortex motion modulated by a self field in a large Josephson junction

Motion of a vortex array (flux flow) in a large Josephson junction is studied both theoretically and experimentally. An expression for dc current-voltage (I-V) characteristics of a large junction in a flux-flow state, which is caused by the external dc magnetic field and current, is obtained by taking account of the self field due to the dc current through the junction as well as the large loss due to the surface resistance of junction electrodes. It is shown that the spacially uniform flux flow is crucially modulated by the self field in a high-velocity region of the flux flow. As a result, the magnitude of the current peak inI-Vcurves decreases significantly and saturates with respect to both the length and the quality factor of the junction, which is confirmed by experiments with large Pb-PbxOy-Pb junctions.     

A concise analytical approach for predicting the voltage and edge peak field profiles of the planar junction with a single floating field limiting ring

A concise analytical approach for predicting the voltage and edge peak field profiles of the planar junction with a single floating field limiting ring is proposed in this paper. From this analysis, the effects of the background doping concentration, junction depth and reversed voltage on the voltage and edge peak field profiles are analysed. The optimal distance between the main junction and the ring junction is also obtained. The analytical results are in excellent agreement with that of the two-dimensional semiconductor device simulator DESSIS-ISE, showing the validity of the approach presented.     

Influence of nonuniform magnetic field on a ferrite junctioncirculator

We have analytically formulated the problem that a ferrite circulator junction is biased by a nonuniform magnetic field. Interport impedances of the junction can, therefore, be solved numerically. Nonuniform-bias field will reduce the transmission bandwidth, and the circulation condition is apt to be altered if the bias field shows nonuniformity near the center of the junction. Our calculation compares very well with measurements     

Diffraction by a planar junction between a perfectly conducting anda periodically loaded impedance surface

By using a perturbative method, an integral representation for the field scattered by a planar junction between a perfectly conducting and a periodically loaded impedance surface is determined, when the junction is illuminated by a plane wave perpendicularly incident on its edge. Both a uniform, asymptotic expression and a series representation are presented for the first-order perturbative correction to the field scattered by the junction. The series representation is expressed in terms of Bessel functions of integer order and is suitable for field calculations at small distances from the edge. Several numerical results are presented to demonstrate the applicability of the proposed technique     

Breakdown voltage enhancement of the p-n junction by self-aligneddouble diffusion process through a tapered SiO2 implant mask

The low doping region extension at the edge of the junction curvature is implemented with the self-aligned double diffusion process using a tapered SiO₂ implant mask. The p⁺-p-n diodes fabricated with the proposed double diffusion process have relaxed the surface electric field at the junction curvature and increased the breakdown voltage by 140 V, compared with the cylindrical p-n junction. It is also found that the breakdown voltage of the p⁺ -p-n diodes having the field plate (FP) over the tapered oxide is 500 V, while that of the conventional p-n junction with the FP is 280 V     

EMF Induced in a p–n Junction under a Strong Microwave Field and Light

Semiconductors - The effect of a strong electromagnetic field on currents and electromotive forces in a p–n junction is considered. It is shown that a p–n junction upon exposure to an...     

单场限环结构的表面电场分布及环间距的优化

基于横向扩散与纵向扩散构成的冶金结边界为椭圆形这一特点,讨论单场限环结构表面电场强度的分布,给出表面电场强度、主结及环结分担电压的解析表达式。在纵向结深和掺杂浓度一定的条件下,根据临界电场击穿理论,讨论环间距的优化设计方法。单场限环结构主结环结间表面电场强度的绝对值曲线近似呈抛物线,最大电场位于主结处。随着环间距的增大,最大电场变大;随着横向扩散深度的增大,最大电场变小。环右侧最大电场也出现在结处,随着环间距和横向扩散深度的增加,最大电场均减小。在场限环结构中,当主结和环结在表面处的最大电场强度均等于临界电场强度时,击穿电压达到最大值,此时所对应的环间距为最佳环间距。     

An analytic approach for optimal field ring spacing of a diode under punchthrough operation

The use of floating field limiting ring (FFRL) reduces the surface field due to junction curvature effect, and the breakdown voltage in planar devices can be increased. In this paper, a new analytic method is developed based on the combination of plane junction in the bulk and cylindrical junction at the surface. From these analysis, optimal space between main diffusion and FFLR can be obtained. The influences of concentration and width of lightly doped collector region and base diffusion junction depth are also investigated. The results are in good agreement with the two-dimensional numerical ones.     

The influence of a current on the magnetization dynamics in a ferromagnet-antiferromagnet structure: Simulation

A ferromagnet-antiferromagnet junction in the presence of an in-plane magnetostatic field and a spin-polarized current flowing perpendicularly to the junction layers is considered. In the macrospin approximation, the system of nonlinear equations describing the dynamics of magnetization of the antiferromagnet layer in such a junction is numerically solved with allowance for the spin torque transfer and the spin equilibrium disturbance caused by spins injected by the current into the antiferromagnet. It is shown that, when the current exceeds a certain threshold, the magnetization becomes instable and that, beyond the instability region, the results are in complete agreement with the theory using linearization in small deviations from the equilibrium. It is found that the development of instability causes switching from the antiparallel configuration to the parallel one and that, in the instability region, nondecaying oscillations of the longitudinal and transverse components of the antiferromagnet magnetization are formed.     

Eddy currents in the <Emphasis Type="Italic">p–n</Emphasis> junction in a microwave field

The formation of eddy currents in the p–n junction in a microwave field is investigated. It is shown that the eddy currents decrease the thermopower of hot carriers in the diode. The formula, which takes into account the sample sizes in calculating the currents in a p–n junction in the microwave field, is derived.     

An analytical model for the internal electric field insubmicrometer MOSFETs

A pseudo-two-dimensional analytical MOSFET model is presented. The channel is divided into source, drain, and junction regions. The source region includes an expression for the carrier-velocity saturation based on the Scharfetter-Gummel formula. The drain region includes an expression for the spread of the lateral field into the bulk. The bulk field in the drain region is described by the radial field from a semicircular drain junction. The junction region describes the voltage drop across a diffused doping profile given an exponential approximation at the junction. The saturation condition is evaluated for both the validity of the gradual channel approximation (GCA) in the source region and carrier-velocity saturation in the drain region. The model elucidates the dependence of the surface field on substrate bias, drain junction depth, and diffusion profile. The model is compared to MINIMOS calculations and found to correlate within 10% for all bias and device combinations of interest for modeling EPROM devices. The computation time of the model is two to three orders of magnitude shorter than full two-dimensional MINIMOS simulations     

An efficient method to analyze the H-plane waveguide junctioncirculator with a ferrite sphere

This paper presents an approximate, but efficient field treatment of the new easy-to-fabricate ferrite-sphere-based H-plane waveguide circulator for potentially low-cost millimeter-wave communication systems. A new three-dimensional modeling strategy using a self-inconsistent mixed-coordinates-based mode-matching technique is developed, i.e., the solutions of the Helmholtz wave equations in the ferrite sphere and in the surrounding areas are deduced in the form of infinite summation of spherical, cylindrical, and general Cartesian modes, respectively. The point-matching method is then used on the interface between the ferrite sphere and air within the cylindrical junction, as well as the interface between the junction and waveguides to numerically obtain the coefficients of different orders of basis functions of the field. Therefore, the field distributions, as well as the characteristics of the circulator, are numerically calculated and good agreement is observed between the numerical results and measured data     

Voltage dependence of the differential capacitance of a p +-n junction

The dependences of the differential capacitance and current of a p ⁺-n junction with a uniformly doped n region on the voltage in the junction region are calculated. The p ⁺-n junction capacitance controls the charge change in the junction region taking into account a change in the electric field of the quasi-neutral n region and a change in its bipolar drift mobility with increasing excess charge-carrier concentration. It is shown that the change in the sign of the p ⁺-n junction capacitance with increasing injection level is caused by a decrease in the bipolar drift mobility as the electron-hole pair concentration in the n region increases. It is shown that the p ⁺-n junction capacitance decreases with increasing reverse voltage and tends to a constant positive value.     

一种沟槽-场限环复合终端结构的设计

为了改善硅功率器件击穿电压性能以及改善IGBT电流的流动方向,提出了一种沟槽-场限环复合终端结构。分别在主结处引入浮空多晶硅沟槽,在场限环的左侧引入带介质的沟槽,沟槽右侧与场限环左侧横向扩展界面刚好交接。结果表明,这一结构改善了IGBT主结电流丝分布,将一部分电流路径改为纵向流动,改变了碰撞电离路径,在提高主结电势的同时也提高器件终端结构的可靠性;带介质槽的场限环结构进一步缩短了终端长度,其横纵耗尽比为3.79,较传统设计的场限环结构横纵耗尽比减少了1.48%,硅片利用率提高,进而减小芯片面积,节约制造成本。此方法在场限环终端设计中非常有效。     

圆柱突变结击穿电压及电场沿结边的分布

基于横向侧扩散与纵向体扩散结深构成椭圆形冶金结外形这一与工艺实际相符合的假设 ,通过圆柱对称解的归一化 ,提出了平面结击穿电场沿结边分布的解析解。理论结果阐述了不同结深及结边形状对边缘区击穿电压的影响规律 ,说明了表面击穿电压总是小于体内击穿电压的原因。     

A Large Magnetoresistance Effect in p–n Junction Devices by the Space‐Charge Effect

The finding of an extremely large magnetoresistance effect on silicon based p–n junction with vertical geometry over a wide range of temperatures and magnetic fields is reported. A 2500% magnetoresistance ratio of the Si p–n junction is observed at room temperature with a magnetic field of 5 T and the applied bias voltage of only 6 V, while a magnetoresistance ratio of 25 000% is achieved at 100 K. The current‐voltage (I–V) behaviors under various external magnetic fields obey an exponential relationship, and the magnetoresistance effect is significantly enhanced by both contributions of the electric field inhomogeneity and carrier concentrations variation. Theoretical analysis using classical p–n junction transport equation is adapted to describe the I–V curves of the p–n junction at different magnetic fields and reveals that the large magnetoresistance effect origins from a change of space‐charge region in the p–n junction induced by external magnetic field. The results indicate that the conventional p–n junction is proposed to be used as a multifunctional material based on the interplay between electronic and magnetic response, which is significant for future magneto‐electronics in the semiconductor industry.     

The implementation of a reduced-field profile design forhigh-performance bipolar transistors

The first realization of a reduced-field design concept for advanced bipolar devices using the low-temperature epitaxial (LTE) technique to form the base layer is described. By inserting a lightly doped collector (LDC) spacer layer between the heavily doped base and collector regions, it is successfully demonstrated that the collector-base (CB) junction avalanche multiplication can be reduced substantially while maintaining high collector doping for current density consideration. Similar applications of the LDS technique to the emitter-base (EB) junction also results in a lower electric field, thus less EB junction reverse leakage. The feasibility of the reduced-field profile design concept is demonstrated using a LTE-base device structure