Structure-enhanced MOSFET degradation due to hot-electron injection

Device degradation due to channel hot-electron injection in several nonconventional MOSFET structures including minimum-overlap gate, offset gate, graded drain, and lightly doped drain (LDD) structures are evaluated. In these nonconventional structures the device degradation is much faster than that in conventional devices when biased with the same amount of hot electrons in the channel. This faster degradation rate is proposed to be due to external channel pinchoff at the more lightly doped drain edge. This behavior implies even more severe constraints on the operating regime for these nonconventional device structures at submicrometer gatelengths to maintain adequate reliability margins.     

角度多样性激光散斑抑制方法的比较

根据成像原理推导了运动透镜、运动45直角棱镜,以及旋转反射镜所引起的角度变化公式,并对影响角度变化的参数（透镜的焦距、物距及光源的发散角等）和引入角度多样性的这三种方法进行了分析比较。实验结果与理论分析表明,在相同条件下,将45直角棱镜运动20 m和反射镜旋转0.02就能实现两个完全独立散斑图样,而运动透镜需要更大的位移,这为设计运动方案引入角度多样性激光散斑抑制提供参考。     

Hot-carrier degradation mechanism in narrow- and wide-channeln-MOSFETs with recessed LOCOS isolation structure

Narrow-channel n-MOSFETs with recessed LOCOS (R-LOCOS) isolation structure exhibit less hot carrier-induced degradation than wide-channel n-MOSFETs, but the degradation mechanism of both devices is the same. This new finding Is explained by the fact that in deep submicron MOSFETs with ultra-thin gate oxide, the dominant factor deciding the degradation behavior in narrow- and wide-channel devices is the vertical electric field effect rather than the mechanical stress effect     

Hot-carrier damage from high to low voltage using the energy-driven framework

In this work, we confirm that the energy is the driving force of Hot Carrier effects. When the energy is high, the Energy-driven framework allows to retrieve Lucky Electron Model-like equations. But when the energy is lowered, high energy electrons generated by Electron-Electron Scattering become the dominant contribution to the degradation. For even lower energy Multiple Vibrational Excitation mechanism starts taking the lead.     

Nonlinear gain suppression in semiconductor lasers due to carrier heating

A simple model is presented for carrier heating in semiconductor lasers from which the temperature dynamics of the electron and hole distributions can be calculated. Analytical expressions for two new contributions to the nonlinear gain coefficient, in are derived, which reflect carrier heating due to stimulated emission and free carrier absorption. In typical cases, carrier heating and spectral holeburning are found to give comparable contributions to nonlinear gain suppression. The results are in good agreement with recent measurements on InGaAsP laser diodes.<>     

Second breakdown in power transistors due to avalanche injection

Second breakdown in power transistors continues to be an actively discussed subject. Although there is general agreement that the lateral thermal instability model adequately explains forward bias second breakdown, it fails to explain the reverse bias failure mechanism. The thermal initiation and electrical initiation processes have been successful in explaining only some aspects of this phenomena. This paper studies the subject of reverse bias second breakdown both experimentally and analytically. It is seen that there is excellent correlation between theory and experiment. The conclusion of this investigation is that avalanche injection is the triggering mechanism. Further, the filamentary currents that result from this can in most cases result in device failure. It is also concluded that under fixed circuit conditions, the reverse bias second breakdown potential of a transistor is completely specified by the single parameter Vpwhich is the voltage necessary for avalanche injection.     

Noise properties of injection lasers due to reflected waves

This paper describes the theoretical investigation of the origin, qualitative, and quantitative properties of the low frequency noise appearing in the light output of the laser diode, which is strongly coupled to optical fibers. This kind of noise has caused serious problems for reliable optical communications, especially for analog-modulation systems. It is shown that there are two different phenomena which generate such noise. One of them is the double cavity state, and the other is the external light injection state. The cause of our noise considered in the double cavity state is the phase variation due to the variation of the equivalent length between the laser and the reflection point generated by mechanical vibrations. On the other hand, the cause in the external light injection state is the random generations of locking and unlocking states due to the frequency variation (or mode jumping) caused by the variation of the internal temperature of the laser diode. We conclude from our theory that an effective method to reduce such noise is to operate the laser diode at well above the threshold current. The complete elimination will be attained by use of the optical isolator inserted between the laser diode and the transmission lines.     

Degradation of the mode suppression in single-mode laser diodes due to integrated optical amplifiers

We show that the side-mode suppression in single-mode laser diodes, such as DFB or distributed Bragg reflector laser diodes, can be reduced by 10 dB or more if an optical amplifier is integrated with the laser diode. The reduction of the side-mode rejection is due to an increase of spontaneous emission that couples into the side mode, an increase which in turn is due to amplified spontaneous emission originating in the optical amplifier.     

Hot-carrier memory effect in an Al/SiN/SiO2/Si MNOS diode due to electrical stress

An Al/SiN(70 Å)/SiO2(126 Å)/(p)Si MNOS diode was fabricated by using the LOCOS process. The interface trap densities at SiN-SiO2and at the SiO2-Si interface were measured by a CV method. Successive stresses of biasing at -20 V introduces both trap densities. Memory effect of the flat-band shifts was observed. The electron traps were first produced at the SiN-SiO2interface. In addition, the hole traps were also produced owing to the two-step barrier formation in the insulators. Fowler-Nordheim tunneling may be responsible for the trapping in the oxide. The hole traps can be annealed while the electron traps cannot be.     

An empirical model for device degradation due to hot-carrier injection

An empirical model for device degradation due to hot-carrier injection in submicron n-channel MOSFET's is presented. Relationships between device degradation, drain voltage, and substrate current are clarified on the basis of experiments and modeling. The presented model makes it possible to predict the lifetime of submicron devices by determining a certain criterion, such as taking a Vthshift of 10 mV over ten years as being allowable. This could also provide quantitative guiding principles for devising "hot-carrier resistant" device structures.     

Improved performance due to suppression of spontaneous emission in tensile-strain semiconductor lasers

It is shown that application of biaxial tension to the active region of a bulk or quantum well semiconductor laser can significantly enhance TM gain compared to TE gain and reduce the threshold current density, due to suppression of spontaneous emission polarised in the growth plane of the laser structure. The differential gain is enhanced compared to unstrained structures and a larger peak gain can be achieved than in comparable structures under biaxial compression.<>     

Fine structure of microwave cross-polarization due to precipitation

Microwave crosspolarization due to precipitation is generally attributed to the nonspherical shape of particles. In the simplest model [1] one assumes that the precipitation medium has two symmetry planes and only the coherent part of the field is taken into account. A canting of these planes must be assumed to explain the crosspolarization between vertical and horizontal polarizations. Theoretical investigations based on the equation of radiative transfer suggest a certain importance of non coherent scattering effects. This paper reports results of a threeyear experimental work and aims to give a better insight on the crosspolarization mechanisms.     

Comments on "Structure-enhanced MOSFET degradation due to hot-electron injection"

Hsu and Grinolds recently compared channel hot-electron (CHE) stress results of conventional and "extended drain" NMOS FET's. [1]. They observe increasing degradation as the extended drain resistance increases when the drain bias is defined as that which produces a fixed substrate current. A model in which the hot-electron stress induces surface states within the extended drain region is proposed. We argue that the drain bias condition chosen for these measurements does not produce equal numbers of channel hot electrons in all devices as is claimed. Since the ratio of substrate current to source current is a measure of the mean electron energy, we claim that this ratio (and hence the mean electron energy) increases as extended drain resistance increases.     

Calculation of phase distortion due to tunnel injection in heterojunction IMPATTs

A computer simulation method is suggested which uses the microwave negative resistance distribution profile within the depletion layer of an ATT device to calculate the phase distortion due to tunnel injected current. The method has been applied to explain the deterioration of device performance in GaAs/GaInAs heterostructure IMPATTs for high frequency operation.<>     

Low-voltage punchthrough injection structure

Some new results for low-voltage low-current BARITT oscillators are presented. It is shown that an X band oscillator operating with an applied power as low as 0.1 W and an efficiency near 1% is quite feasible.     

Current oscillations due to filamentary double injection in diodes with deep levels

Current oscillations occurring in the positive differential resistance region of the d.c. I–V characteristics of Au-compensated n-type silicon pin diodes have been investigated. The experimental results strongly suggest that the current oscillations are caused by the formation of unstable filaments prior to the occurrence of stable filaments which are connected with the negative differential resistance region typical for double injection diodes with deep levels. On the basis of this model the degree of modulation could be increased up to 30% in our diodes.     

Line narrowing in a single-mode injection laser due to external optical feedback

The effect of external optical feedback on the linewidth of a single-mode injection laser is considered theoretically. A set of three rate equations with Langevin noise sources is used to obtain the power spectrum. If the high-frequency structure in the power spectrum is ignored, the line shape is Lorentzian and exhibits broadening or narrowing depending on the external-cavity phase shift. Particular attention is paid to the line narrowing after including the effect of carrrier-induced index changes.     

Features of the capacitance-voltage characteristics in a MOS structure due to the oxide charge

MOS structures based on p-and n-type silicon and subjected to the effect of voltages of both polarities with a magnitude as large as 70 V are studied. In all cases, an increase in the effective positive charge at the Si/SiO₂ boundary was observed. In the case of structures with p-Si, a steplike increase in the high-frequency capacitance in the inversion region at some value of the threshold voltage was observed. The increase in the capacitance and the threshold voltage were governed by the value of the effective charge and the area of the gate of the structure. The observed effect is accounted for by lateral diffusion of free electrons accumulated in the semiconductor in the vicinity of the gate contact. After completion of the effect of the voltage on the structures, the capacitance-voltage characteristics were recovered to the state close to the initial state in the relaxation time characteristic of reverse drift of ions and emission of charge carriers by tunneling from “slow” traps in the vicinity of the Si/SiO₂ interface.     

单相光伏并网逆变器直流注入问题的成因和抑制

随着非隔离型光伏并网逆变器的广泛应用,直流注入问题也日益受到重视,IEEE Std 929-2000规定直流注入必须小于系统额定电流的0.5%。将直流注入产生的原因分为两种类型:测量器件输入失调导致的平移型直流注入和测量器件的非线性造成的非线性直流注入,并分别提出了应对方法。针对平移型的直流注入问题,提出了通过一个直流分量积分补偿环节来抑制逆变器控制算法中偏移型直流分量,该直流抑制算法无需增加外围硬件电路,且只占用很少的控制芯片资源。针对非线性直流注入问题,做出了定量分析,为测量元器件非线性度指标的选择提供了的参考价值。最后将上述直流抑制算法应用于无差拍并网控制中,并在Matlab/Simulink进行了仿真分析,结果验证了理论分析和算法的正确性。     

由背面工艺导致的3.3-kV NPT-IGBT阳极注入效率降低效应的实验研究

The anode injection efficiency reduction of 3.3-kV-class non-punch-through insulated-gate bipolar transistors (NPT-IGBTs) due to backside processes is experimentally studied through comparing the forward blocking capabilities of the experiments and the theoretical breakdown model in this paper. Wafer lifetimes are measured by a μ-PCD method, and well designed NPT-IGBTs with a final wafer thickness of 500 μm are fabricated. The test results show higher breakdown voltages than the theoretical breakdown model in which anode injection efficiency reduction is not considered. This indicates that anode injection efficiency reduction must be considered in the breakdown model. Furthermore, the parameters related to anode injection efficiency reduction are estimated according to the experimental data.