大功率LED伏安特性模型研究

研究了大功率LED芯片的伏安特性。基于LED 芯片的特殊性,从经典的PN结伏安特性出发,进行理论推导并通过选择不同的基函 数,构建出了大功率LED芯片的伏安特性新 模型和优化模型,模型中的系数采用最小二乘法进行确定。对大功率LED芯片的实测 伏安特性数据表明,本文构建出的优化模型比经典的PN结模型更能准确表征LED的伏安特性 ,与实测的伏安特性数据一致性更高,更具实用价值。     

Approximated analytical model for dark and Jsc—Voccharacteristics of p+-i-n+solar cells

The current-voltage characteristics of p⁺-i-n⁺solar cells is analyzed and an approximated two-exponential model for the dark andJ_{sc}-V_{oc}operation is presented. It is shown that this two-exponential model and the superposition principle can be used as a first approximation and as a means of attaining further insight on the basic mechanisms actually occurring in the cell. However, some care should be taken when trying to determine the physical solar cell parameters from experimental data through fitting techniques. All this facts are illustrated and confirmed with theoretical examples and measured current-voltage characteristics of six different devices.     

Effect of p-base sheet and contact resistances on staticcurrent-voltage characteristics of scaled low-voltage vertical powerDMOSFETs

Static current-voltage characteristics of low-voltage scaled power double-diffused MOSFETs fabricated using selectively formed TiSi₂ films on gate polysilicon and source contact regions are reported. It is shown that considerable modulation of drain-source current-voltage characteristics results from increased p-base sheet and contact resistances. This effect is found to vanish at higher operating temperatures. Increased p-base contact resistance also results in a large forward voltage drop for the body p-n junction diode     

Current-voltage characteristics of a spherical diode

Consideration is given to a stationary process of acceleration of an intense charged-particle beam in a spherical diode. The particle beam is characterized via a self-consistent kinetic approximation with allowance for the thermal straggling of velocities. The results of numerical calculations are presented, namely, the dependences of the potential on the coordinate and the current-voltage characteristics of the spherical diode.     

Application of the superposition principle to solar-cell analysis

The principle of superposition is used to derive from fundamentals the widely used shifting approximation that the current-voltage characteristic of an illuminated solar cell is the dark current-voltage characteristic shifted by the short-circuit photocurrent. Thus the derivation requires the linearity of the boundary-value problems that underlie the electrical characteristics. This focus on linearity defines the conditions that must hold if the shifting approximation is to apply with good accuracy. In this regard, if considerable photocurrent and considerable dark thermal recombination current both occur within the junction space-charge region, then the shifting approximation is invalid. From a rigorous standpoint, it is invalid also if low-injection concentrations of holes and electrons are not maintained throughout the quasi-neutral regions. The presence of sizable series resistance also invalidates the shifting approximation. Methods of analysis are presented to treat these cases for which shifting is not strictly valid. These methods are based on an understanding of the physics of cell operation. This understanding is supported by laboratory experiments and by exact computer solution of the relevant boundary-value problems. For the case of high injection in the base region, the method of analysis employed accurately yields the dependence of the open-circuit voltage on the short-circuit current (or the illumination level).     

Accurate modeling for submicrometer-gate Si and GaAs MESFET's using two-dimensional particle simulation

Device characteristics, including nonstationary carrier-transport effects such as velocity overshoot phenomena in submicrometergate Si and GaAs MESFET's, are presented in detail by two-dimensional full Monte Carlo particle simulation. Accurate current-voltage characteristics and transient current response are successfully obtained without relaxation time approximation. Moreover, the carrier dynamics influence on device operation is clarified in a realistic device model, compared with the conventional simulation. It can be pointed out that such nonstationary carrier transport is acutely important for accurate modeling of submicrometer-gate GaAs MESFET's, but is not as important for that of Si MESFET's.     

Power output and efficiency of voltage controlled negative resistance oscillators

This correspondence summarizes the equations for power output and efficiency of voltage controlled negative resistance oscillators with cubic current-voltage characteristics, and considers the application of these equations to bulk GaAs oscillators.     

Simulation of the superconducting quasiparticle mixer using afive-port model

A harmonic Newton technique has successfully been used in the simulation of superconducting quasiparticle mixers in a five-port model. The steady-state large-signal waveform impressed across the tunnel junction by the incident local oscillator (LO) power is computed in the frequency domain. The three-frequency approximation provides the initial trial solution, which, together with the superlinear convergence property of Newton's method, ensures rapid convergence. A wide range of simulations based on the response function of a real superconductor-insulator-superconductor (SIS) junction is presented. The case of an SIS harmonic mixer (n=2) is also studied. Using a five-port model, the simulation explicitly takes the effect of the first harmonic into account. The algorithm and the principal results obtained for a hypothetical mixer incorporating the measured current-voltage characteristics of a real (SIS) junction are presented. The first results indicate that harmonic quasiparticle mixing may be very attractive in the submillimeter-wave band     

One-carrier space-charge limited currents in solids containing double-level centers

A study of steady-state one-carrier space-charge limited currents in solids containing double-level centers is presented. Using the regional approximation method, asymptotic current-voltage characteristics are derived, as an example, for the case where the thermal equilibrium fermi-level is situated in the lower half of the gap between both defect levels. The results for other energy level schemes are presented. Some considerations related to the information content and to a meaningful interpretation of one-carrier SCLC experiments are given.     

Common emitter breakdown

A theory of the current-voltage characteristics with grounded emitter and open base is developed in a first approximation form. The results show the typical negative resistance region characteristic of theseI-Vcurves, and the theory indicates the important parameters which control this negative resistance. The containment of the emitter current with subsequent development of "hot spots" on the transistor becomes easily understood. Experimental evidence of the importance of localized breakdown spots in common emitter breakdown is presented.     

Current-voltage characteristics of thin-film SOI MOSFET's in strong inversion

A simple analytic model for the steady-state current-voltage characteristics of strongly inverted silicon-on-insulator (SOI) MOSFET's is developed. The model, simplified by a key approximation that the inversion charge density is described well by a linear function of the Surface potential, clearly shows the dependence of the drain current on the device parameters and on the terminal voltages, including the back-gate (substrate) bias. The analysis is supported by measurements of current-voltage characteristics of thin-film (laser-recrystallized) SOI MOSFET's. The dependence of carrier mobility on the terminal voltages, especially the back-gate bias, is analyzed and shown to underlie discrepancies between the theoretical (constant mobility) and experimental results at high gate voltages. The mobility dependence on the back-gate bias enhances the strong influence of the back gate on the drain current, especially when the device is saturated.     

Effect of laser radiation on GaP epitaxial diode structures

The effect of laser radiation on the current-voltage characteristics and intrinsic quantum yield of electroluminescence after irradiation is investigated. As a result of irradiation at supercritical radiant power flux levels (greater than 10⁷ W/cm²) an abrupt drop in the luminescence quantum yield and a steep growth of the leakage currents are observed in the current-voltage characteristics. It is assumed that by exciting the electronic subsystem of the impurity atoms the powerful optical radiation facilitates the occurrence of quasichemical reactions. Fiz. Tekh. Poluprovodn. 33, 499–500 (April 1999)     

Characteristics of a depletion-type IGFET

Recently, the depletion-type IGFET became widely used as a load device in logic circuits. The purpose of this correspondence is to present a development of the current-voltage characteristic of a depletion-type IGFET based on the assumption that the non-linear semiconductor capacitance can be replaced by a constant average capacitance. This approximation is justified in light of the theoretical and experimental results obtained by many authors [1]-[4], indicating that the exact form of the semiconductor capacitance has little effect on the dc characteristics of a field-effect device.     

考虑速度过冲效应的HEMT物理模型

本文提出了一种考虑这冲效应的ＨＥＭＴ器件静态和小信号解析物理模型。通过对栅极下面道中造近源端附近的电场采用弱强梯场近似，提出了一个半经验的速度过冲模型，在非线性电荷控制模型的基础上述导出了基于物理参数的ＨＥＭＴ器件电流－电压特性和小等效电路参数的解析表达式。实际计算结果与测得数据比较表明，本模型具有比较高的精度。     

On mechanism of radiative sensitivity of power diode direct voltage drop

There are carried out experimental researches of dependence of drop of direct voltage of current-voltage characteristics of the silicone power diode on electrons radiation dose. It is stated that dose increase from 2×10¹⁴ to 2×10¹⁵ Φ_e/cm² results in direct voltage drop on the diode increases monotonically, and the lifetime of the minority charge carriers decreases by a factor of ten. It is shown the dominating role of decrease of minority charge carriers density in the base together with majority charge carries lifetime at forming of current-voltage characteristics of after irradiation by electrons.     

电路级热载流子效应仿真研究

随着集成电路制造工艺的不断进步,沟道长度、结深、栅氧厚度等特征尺寸不断减小,而电路的电源电压没有按比例减小,易造成MOSFET的电流-电压特性退化,需要提前在设计阶段加以考虑。对电路长期可靠性问题中的热载流子效应(HCI)进行了仿真研究。     

Using reverse dynamic I-V characteristics of AlGaAs/GaAs optothyristor for pulsed power-switching applications

The reverse dynamic current-voltage (I-V) characteristics of a high performance MBE grown AlGaAs/GaAs based heterostructure optothyristor have been studied for high power pulsed switching applications. Switched current and dissipated energy per switching as a function of the blocking voltage are presented. Possible reverse switching mechanisms are also discussed in terms of the novel device structure.<>     

Simulation of the electrical properties of polycrystalline ceramic semiconductors with submicrometer grain sizes

A numerical model for the calculation of the electrical characteristics of polycrystalline ceramic semiconductors is suggested. The model is applicable in a situation where the average grain size is comparable with the depletion region width near a grain boundary and the double Schottky barriers of neighboring boundaries overlap. The two-dimensional calculation is carried out in the diffusion-drift approximation using the Voronoi grid method. The effect of crystalline grain size on the current-voltage characteristic and specific capacitance of the material is analyzed usingp-SrTiO₃ as an example.     

Nonlinear coupling with silicon tunnel junctions in integrated logic

Most of the logic schemes that are amenable to integrated semiconductor construction utilize resistances to couple transistor stages to a power supply and to other stages. It is shown that the coupling functions ideally require nonlinear rather than linear current-voltage characteristics. Tunnel junctions can provide very attractive nonlinear characteristics for coupling purposes, and this is the main theme of the present paper. Performance advantages are investigated, particularly the improvement in delay-power product, or energy required to process a binary digit. Techniques for fabricating low-capacitance tunnel junctions in integrated fashion with silicon bipolar transistor regions are discussed.