MOSFET substrate current model including energy transport

A new MOSFET substrate current model, incorporating energy transport, is proposed. It was found that a non-steady-state electron transport effect and two effects attributed to electron pressure are essential to calculate the substrate current characteristics accurately. The predictions from the present model compare favorably with the experimental data for MOSFET's with effective channel length down to 0.45 µm.     

Simulation of deep submicron SOI N-MOSFET considering the velocityovershoot effect

A set of numerical simulations were performed on 0.22 μm SOI MOSFET's with relatively uniform channel field and charge using the hydrodynamic model, the energy transport model, and the drift-diffusion model. The simulation results based on the advanced models (hydrodynamic and energy transport) show nearly identical results for the I-V characteristics and they agreed quite well with the experimental results, while the results from drift-diffusion model do not. Also the simulation results show that both the hydrodynamic and energy transport models handle the effect of velocity overshoot on the I-V characteristic of the 0.12 μm device well     

笛卡尔展开算法高效求解增广电场积分方程

将多层快速笛卡尔展开算法(Multilevel Accelerated Cartesian Expansion Algorithm,MLACEA)用于求解理想导体目标的增广电场积分方程(Augmented Electric Field Integral Equation,AEFIE),详细推导了基于AEFIE-矩量法(Method of Moments,MoM)的MLACEA算法的具体实现过程.计算实例表明,在求解低频电磁散射问题及电路问题时基于AEFIE-MoM矩量法的MLACEA算法既具有非常高的计算精度、又可大幅度降低MoM的计算复杂度,使得其计算量和计算机内存需求可由原来MoM的O(N2)量级降低至MLACEA算法的O(N)量级.     

Delay analysis of BiNMOS driver including high current transients

The BiNMOS gate delay analysis including high current transients has been developed. The modeling equations account for the high electric field effect in the nMOS transistor and emitter crowding, base pushout, and base conductivity modulation in the bipolar transistor. In examining the switching transient of a BiNMOS driver, the base pushout mechanism exhibits a detrimental effect on the gate propagation delay. The circuit modeling methodology provides a fast turn-around design evaluation of sensitivity of process and device parameters into circuit performance. Computer simulation of a BiNMOS driver using the present analysis is compared with PISCES device simulation in support of physical reasoning     

Discretization method for current continuity equation containingmagnetic field

Discretization methods for the current continuity equation in the presence of a magnetic field are studied. To produce a nonoscillatory solution, a novel discretization method is presented. It can eliminate the crosswind effect and has improved stability     

A complete small-signal HBT model including AC current crowding effect

An improved small-signal equivalent circuit of HBT concerning the AC current crowding effect is proposed in this paper.AC current crowding effect is modeled as a parallel RC circuit composed of Cbi and Rbi,with distributed base-collector junction capacitance also taken into account.The intrinsic portion is taken as a whole and extracted directly from the measured S-parameters in the whole frequency range of operation without any special test structures.An HBT device with a 2 × 20 μm2 emitter-area under three different biases were used to demonstrate the extraction and verify the accuracy of the equivalent circuit.     

Transit-time reduction in AlGaAs/GaAs HBTs utilizing velocityovershoot in the p-type collector region

The effect of electron-velocity overshoot in a p-type GaAs collector on the transit-time reduction of AlGaAs/GaAs HBTs (heterojunction bipolar transistors) is investigated. A cutoff frequency improvement of about 30% over the conventional n-type GaAs collector was obtained in p-type collector HBTs for the same collector depletion-layer width. A significant increase in electron velocity in the p-type GaAs collector layer was confirmed by a simple analysis     

HCI degradation model based on the diffusion equation including the MVHR model

This paper presents an improvement of the R-D model explaining analytically the 0.5 exponent observed during HCI stress. An original model based on diffusion equation is proposed where the balance between the hot-hole-induced generation of dangling bonds and the passivation mechanisms via a Multi-Vibrational Hydrogen Release is enlightened. The second and smaller slope observed is explained and modelled with the hot spot displacement along the Si-SiO₂ interface.     

New explicit current/voltage equation for p‐i‐n solar cells including interface potential drops and drift/diffusion transport

Analytical modeling of p‐i‐n solar cells constitutes a practical tool to extract material and device parameters from fits to experimental data, and to establish optimization criteria. This paper proposes a model for p‐i‐n solar cells based on a new approximation, which estimates the electric field taking into account interface potential drops at the intrinsic‐to‐doped interfaces. This leads to a closed‐form current/voltage equation that shows very good agreement with device simulations, revealing that the inclusion of the interface potential drops constitutes a major correction to the classical uniform‐field approach. Furthermore, the model is able to fit experimental current/voltage curves of efficient nanocrystalline Si and microcrystalline Si p‐i‐n solar cells under illumination and in the dark, obtaining material parameters such as mobility‐lifetime product, built‐in voltage, or surface recombination velocity. Copyright © 2012 John Wiley & Sons, Ltd.     

Extremely scaled double-gate CMOS performance projections,including GIDL-controlled off-state current

A simulation-based analysis of extremely scaled double-gate (DG) CMOS, emphasizing the effects of gate-induced drain leakage (GIDL) in DG MOSFETs, is described. Device and ring-oscillator simulations project an enormous performance potential for DG/CMOS, but also show how and why GIDL can be much more detrimental to off-state current in DG devices than in the single-gate counterparts. However, for asymmetrical (n⁺ and p⁺ polysilicon) gates, the analysis further shows that the GIDL effect can be controlled by tailoring the back (p⁺ -gate) oxide thickness, which implies design optimization regarding speed as well as static power in DG/CMOS circuits     

Compact modeling of a flash memory cell including substrate-bias-dependent hot-electron gate current

We propose a compact model for a Flash memory cell that is suitable for circuit simulation. The model includes a hot-electron gate current model that considers not only channel hot electron injection but also channel initiated secondary electron injection to express properly substrate bias dependence of gate current. Tunneling gate current for erasing is expressed by the BSIM4 tunneling gate current model. Good agreement between measured and simulated results of both programming and erasing characteristics for 130-nm technology Flash memory cells indicates that our model is useful in designing and optimizing circuit for Flash memories.     

An accurate analysis of noise in rectangular bipolar transistors including current crowding

An accurate analysis of noise in rectangular bipolar transistors is developed from a distributed model using a collective approach and the transport noise theory. In this model, emitter current crowding effect are taken into account and noise behaviour at intermediate and low values of source impedance is precisely described. The structure of teh equivalent lumped circuit is established, and the analytical relationships characterizing its elements in an extended range of current and frequency are given. It is shown that; (a) the active base region must be represented by a nonlinear impedance with a generalized thermal noise source; (b) for low source impedances the equivalent input voltage shot noise generator is higher than predicted by low injection theories. Furthermore it is found that emitter crowding induces a uniform and important decrease in (a) base impedance (b) thermal noise and (c) the correlation between shot noise generators of the equivalent lumped circuit. Finally it appears that classical low injection theories are valid when crowding occurs in transistors biased with high source impedances.     

Integral equation analysis of vertical current sheets in planarcircuits and antennas

The electric field integral equation (EFIE) for planar circuits and antennas is usually solved with a spectral computation of the Green's functions. The method of moments solution of the EFIE becomes cumbersome for three-dimensional (3D) metallic surfaces in an arbitrary multilayered medium. Here, it is demonstrated how some of the numerical work can be replaced by analytical computations for 3D planar structures by using the closed form expressions for the spectral Green's functions. An example of a two-conductor line short circuited with a vertical metallic plate is presented     

Determination of discharge current equation parameters of ESD using genetic algorithms

In the literature there is an absence of an accurate equation describing the current of the electrostatic discharge (ESD) phenomenon. Reported, is a method that is a genetic algorithm, which having as input data current measurements from ESD generators optimises the parameters of the discharge current's equation.     

The phase-plane for Langmuir's equation for space-charge limited current flow†

We consider the behaviour of the solutions of Langmuir's equation in the phase-plane and in particular we discuss the nature of the singular points and the directions of the asymptotes. It is shown that the isoclines of the equation are a family of conies passing through the singular points.     

Rate equation of current degradation of the Spindt-type field emitter array

The degradation rate of the emission current of the Spindt-type field emitter arrays in the display environment has been measured. The relative degradation rate is found to be a function of the square of emission current and proportional to the anode bias (voltage). A life model is presented that leads to development of an analytical rate equation of emission current degradation. Based on this model, there is a steady-state level at which the emission current is stable. The steady-state emission current depends on anode bias, background pressure in the package and cleanliness of anode and cathode surfaces. Experimental results are consistent with the rate equation derived from the model. Since the model does not include any material and process that make the cathode, it could probably apply to any field emission cathodes.     

An analytical drain current model of short-channel MOSFETs including source/drain resistance effect

In this paper, the DC characteristics of MOSFETs are investigated by means of an analytical approach with considerations of the source/drain parasitic resistance (R _S/R _D). Experimental data of MOS devices for DRAM design and results of TCAD simulation are used to verify the accuracy of theoretical calculation. It is found that both the R _S and R _D can induce a large reduction in the drain current in the linear region, but only the source resistance can cause a large reduction in the drain current in the saturation region. Moreover, the drain current deduction due to the R _S/R _D increases with decreasing channel length and oxide thickness.     

Spectral linewidth of DFB lasers including the effects of spatialholeburning and nonuniform current injection

An analytic expression for the linewidth of distributed-feedback (DFB) lasers is derived. Local fluctuations in carrier density are shown to provide a significant contribution to laser linewidth in the presence of spatial holeburning. In a single-electrode DFB laser the effect can be avoided by careful optimization of the kl-product, but for a multielectrode DFB laser the linewidth can also be reduced by adjusting the injected current profile to compensate for spatial holeburning. Numerical results for a three-electrode λ/4-shifted DFB laser are presented     

A trigonometric approximation to the current in the solution of Hallen's equation

A simple trigonometric expansion for the current in the solution of Hallen's equation gives a good approximation to the impedance of isolated thin cylindrical dipole antennas. For the half-wavelength dipole a two-term representation for the current is found to give an impedance which compares favorably with experimental measurements.     

Multidimensional Polynomial Transform Algorithm For Multidimensional Discrete Hartley Transform

In this paper, we present an index permutation-based fast algorithm for the multidimensional discrete Hartley transform (MD-DHT). By reordering the MD-DHT input sequence, we first convert the MD-DHT into a multiple sum that contains a number of one-dimensional discrete W transforms (1D-DWTs). We then use a combination of the 1D-DWTs and the multidimensional polynomial transform to compute the multiple sum. It is shown that the number of multiplications and additions required for the proposed algorithm are approximately 1/m and 2m+1/3m times that of the commonly used row-column DHT method, respectively. The developed algorithm is also simple in structure and easy to realize in programming.