A new gradual hole injection dual-gate LIGBT

A new shorted-anode lateral insulated gate bipolar transistor (SA-LIGBT), entitled gradual hole injection dual gate LIGBT (GHI-LIGBT), is proposed and fabricated. The new device employs a dual gate and p⁺ injector in order to initiate the hole injection gradually from the anode electrode into the drift region so that the negative differential resistance (NDR) regime may be eliminated. The experimental results show that the NDR regime, which may cause undesirable device characteristics, is completely eliminated in the GHI-LIGBT, and the forward voltage drop is reduced by 1 V at the current density of 200 A/cm² in comparison with the conventional SA-LIGBT     

Charge-control analysis of the COMFET turn-off transient

A quasi-static charge-control analysis of the unique transient turn-off characteristic of the COMFET is developed. The analysis describes the transient behavior in terms of steady ON-state current components that flow in the constituent MOSFET and BJT in the basic COMFET structure. The effects of the expanding depletion region at the cathode and of minority-carrier injection into the anode are properly accounted for. Consequently, the physics underlying the turnoff time is clarified, and device design criteria for shortening it, without considerably degrading the ON-state current conduction capability, are suggested.     

Transient characteristics of n-channel hybrid Schottky injectionFETs

Theoretical transient characteristics of hybrid Schottky injection FETs (HSINFETs) are considered. The theoretical analysis is based on two-dimensional numerical simulations, in which the entire turn-off process and the effects of minority-carrier injection levels on the transient performance of the HSINFET device are analyzed. The analysis shows that the fast turn-off speed in the HSINFET device occurs because (1) only a small number of minority carriers is injected into the drift region, (2) a current path, provided by the Schottky contact, effectively removes electrons from the drift region during turn-off, and (3) Schottky clamping at the anode is effective during turn-off and prevents the p⁺ portion of the hybrid anode from significantly injecting holes. Experimental results compared the DC and transient performance of the lateral double-diffused MOS transistor (LDMOST), lateral insulated-gate transistor (LIGT), Schottky injection field-effect (SINFET), and HSINFET are presented     

Tunneling injection into modulation doping structures: a mechanismfor negative differential resistance three-terminal high-speed devices

A tunneling injection mechanism into the channel of a modulation doping field effect transistor is discussed. In the presaturation regime of the drain current, the source current exhibits negative differential resistance as a result of the charge control by the gate field in the channel. The tunneling three-terminal device promises high-frequency operation     

Hybrid Schottky injection MOS-gated power transistor

A modified Schottky injection field effect transistor (SINFET) which offers lower on-resistance and a switching speed comparable to conventional n-channel LDMOSTs is described. The fabrication process is similar to that of an LDMOS transistor but with the high-low (n+n-) `ohmic? contact at the drain replaced by a parallel combination of a Schottky barrier and a pn junction diode. This hybrid anode injects minority carriers into the n- drift region, which in turn provides conductivity modulation. A current handling capability 3.5 times larger than that of the LDMOST is achieved. With the minority carrier injection level limited by the Schottky barrier, the total amount of minority carriers injected by the hybrid anode is much lower than that injected by the pn junction diode alone. Thus, the device speed is comparable to the conventional n-channel LDMOST. By minimising the shunting resistance in the p-channel region, devices with a latch-up current density of 400 A/cm2 are obtained.     

Gate-controlled negative differential resistance in drain currentcharacteristics of AlGaAs/InGaAs/GaAs pseudomorphic MODFETs

The observation of negative differential resistance (NDR) and negative transconductance at high drain and gate fields in depletion-mode AlGaAs/InGaAs/GaAs MODFETs with gate lengths L _g ~0.25 μm is discussed. It is shown that under high bias voltage conditions, V_ds>2.5 V and V_gs>0 V, the device drain current characteristic switches from a high current state to a low current state, resulting in reflection gain in the drain circuit of the MODFET. The decrease in the drain current of the device corresponds to a sudden increase in the gate current. It is shown that the device can be operated in two regions: (1) standard MODFET operation for V_gs<0 V resulting in f_max values of >120 GHz, and (2) a NDR region which yields operation as a reflection gain amplifier for V_gs >0 V and V_ds>2.5 V, resulting in 2 dB of reflection gain at 26.5 GHz. The NDR is attributed to the redistribution of charge and voltage in the channel caused by electrons crossing the heterobarrier under high-field conditions. The NDR gain regime, which is controllable by gate and drain voltages, is a new operating mode for MODFETs under high bias conditions     

Lateral insulated-gate bipolar transistor (LIGBT) with a segmentedanode structure

A novel lateral insulated-gate bipolar transistor (LIGBT) structure, called the segmented anode LIGBT, is presented. In this structure, the anode, which is responsible for the injection of minority carriers for conductivity modulation, is implemented using segments of p ⁺ and n⁺ diffusions along the device width. This segmented design of the anode structure results in higher switching speed and reduction in device size. Depending on the value of the specific ON resistance, experimental results show that the segmented anode LIGBT has from 20% to 250% reduction in turn-off time as compared to the shorted anode LIGBT     

The degradation of high-intensity BSF solar-cell fill factors due to a loss of base conductivity modulation

The loss of base conductivity modulation in high-intensity back-surface-field silicon solar cells is discussed. It is shown that the loss of conductivity modulation begins in a region immediately in front of the back-surface-field region and spreads toward the front of the device as the current through the cell increases. The effect of this loss of conductivity modulation, in cells which have high base resistivity, is to cause a significant degradation in the fill factor of the device. A computer simulation of the device is presented which shows that the degradation of the fill factor is more severe in n⁺-p-p⁺cells than in p⁺-n-n⁺cells of the equivalent geometry and base resistivity. The origin of this difference is found to lie in the mobility difference between electrons and holes in silicon. The effects of the loss of base conductivity modulation can be reduced either through an increase in the base doping or through a reduction in the base width.     

Electronic Instabilities Leading to Electroformation of Binary Metal Oxide‐based Resistive Switches

Oxide‐based resistive switching devices are a leading contender for the next generation memories. Before use, each device has to go through a conditioning process called electroformation which has been suggested to be initiated by the accumulation of oxygen vacancies. Here, experimental evidence is presented which shows that both Ta₂O_5‐x‐ and TiO_2‐x‐based crossbar devices, exhibit characteristic electronic instability leading to a reversible constriction of the current flow to a narrow filament prior to permanent change. Thus, it is asserted, electroformation is initiated through purely electronic and reversible events, to be followed later by structural changes in the material, like oxygen vacancy redistribution. Furthermore, the electronic instability responsible for electroformation also gives rise to negative differential resistance (NDR) and that this characteristics appears to involve two distinct mechanisms: a thermal one in which Joule heating causes resistance to decrease as current increases and a second electronic mechanism that appears not to require Joule heating for NDR. Using a combination of thermometry and thermal modeling, a self‐consistent temperature and filament radius as a function of power are found for the 5 μm cross‐bar devices. In the thermal NDR regime, the filament appears to be ～500 nm in diameter and has a peak temperature of ～300 °C, while in the adiabatic regime, the estimated filament diameter is much smaller (<50 nm) and the maximum temperature inside it exceeds 800 °C.     

Modeling of electron-hole scattering in semiconductor devices

It is generally assumed in device modeling that the effects of electron-hole scattering can be fully accounted for by a suitable reduction in the electron and hole mobilities with injection level, without modifying the semiconductor device equations themselves. Physical considerations indicate that this is not the case, and that electron-hole collisions introduce a direct coupling between the electron and hole currents. This is determined from first principles, and the results of a Boltzmann calculation are described. The key result is that the impact of an electron-hole scattering event depends on the relative drift velocity between electrons and holes. In low injection, the effective minority-carrier diffusion mobility cannot be assumed to be identical to majority-carrier mobilities or to minority-carrier drift mobilities. In high injection, a reduction in the conductivity mobility does not imply a reduction in the ambipolar diffusion constant. Results for p-i-n diodes are given     

新型恒压控制型负阻HBT的研制进展

研究了HBT产生负阻的可能机制,通过对材料结构和器件结构的特殊设计,采用常规台面HBT工艺,先后研制出3类高电流峰谷比的恒压控制型负阻HBT.超薄基区HBT的负阻特性是由超薄基区串联电阻压降调制效应造成的,在GaAs基InGaP/GaAs和AlGaAs/GaAs体系DHBT中均得到了验证.双基区和电阻栅型负阻HBT均为复合型负阻器件.双基区负阻HBT通过刻断基区,电阻栅负阻HBT通过在集电区制作基极金属形成集电区反型层,构成纵向npn与横向pnp的复合结构,由反馈结构(pnp)的集电极电流来控制主结构(npn)的基极电流从而产生负阻特性.3类负阻HBT与常规HBT在结构和工艺上兼容,兼具HBT的高速高频特性和负阻器件的双稳、自锁、节省器件的优点.     

A new AlGaAs/GaAs/InAlGaP npn bulk-barrier optoelectronic switch

Two-terminal switching performance is observed in a new AlGaAs/GaAs/InAlGaP optoelectronic device. The device shows that the switching action takes place from a low current state to a high current state through a region of negative differential resistance (NDR). The transition from either state to the other may be induced by an appropriate optical or electrical input. It is seen that the effect of illumination increases the switching voltage V/sub S/ and decreases the switching current I/sub S/, which is quite different from other results reported. In addition, it possesses obvious NDR even up to 160/spl deg/C. This high-temperature performance provides the studied device with potential high-temperature applications.     

Optical and electrical oscillations in double-heterojunctionnegative differential resistance devices

The observation of optical and electrical oscillations is reported in a GaAs/AlGaAs digital optoelectronic switch (DOES) structure. The oscillations are correlated to the negative differential resistance (NDR) region typically observed in the current-voltage (I-V ) characteristics of this heterostructure. Plateaulike DC I-V characteristics in the NDR region and an apparent enhancement of the DC luminescence are shown to be a direct result of device oscillations in the NDR regime. External and intrinsic circuit parameters are demonstrated to determine the temporal characteristics of both the electrical and optical oscillations. These oscillations can be of sufficient magnitude to induce lasing at apparently very low DC current levels. It is shown that an external optical pulse can be used to induce the extent of the NDR region and thereby quench optical oscillations. In this manner, an optically controlled free-running optical oscillator is demonstrated     

Unified Breakdown Model of SOI RESURF Device with Uniform/Step/Linear Doping Profile

A unified breakdown model of SOI RESURF device with uniform,step，or linear drift region doping profile is firstly proposed.By the model,the electric field distribution and breakdown voltage are researched in detail for the step numbers from 0 to infinity.The critic electric field as the function of the geometry parameters and doping profile is derived.For the thick film device,linear doping profile can be replaced by a single or two steps doping profile in the drift region due to a considerable uniformly lateral electric field,almost ideal breakdown voltage,and simplified design and fabrication.The availability of the proposed model is verified by the good accordance among the analytical results,numerical simulations,and reported experiments.     

均匀、阶梯和线性掺杂漂移区SOI RESURF器件的统一击穿模型

提出了一个均匀、阶梯和线性掺杂漂移区SOI高压器件的统一击穿模型.基于分区求解二维Poisson方程,得到了不同漂移区杂质分布的横向电场和击穿电压的统一解析表达式.借此模型并对阶梯数从0到无穷时器件结构参数对临界电场和击穿电压的影响进行了深入研究.从理论上揭示了在厚膜SOI器件中用阶梯掺杂取代线性漂移区,不但可以保持较高的耐压,而且降低了设计和工艺难度.解析结果、MEDICI仿真结果和实验结果符合良好.     

Operating principle of dual collector magnetotransistors studied bytwo-dimensional simulation

Dual collector magnetotransistors are magnetic-field-sensitive devices currently developed in several laboratories. Optimized sensor design is often attempted by trial and error rather than by established design rules. This motivated the present comprehensive study of the operation of magnetotransistors by accurate two-dimensional numerical simulations. We model vertical and lateral transistors as obtained by industrial IC technology on the basis of data provided by the chip manufacturer. We consider the entire device structure with the full, complex device geometry, and the physically proper boundary conditions. Our simulations reveal the details, controversial hitherto, of the operating principle of these devices. In particular we find that, in the case of the vertical transistor, it is essentially the emitter injection modulation effect which dominates the sensor response. In the case of the lateral transistor, the magnetic sensitivity is predominantly determined by minority-carrier deflection, although side effects are involved as well. By variation of the doping profile and the device geometry we derive rules for optimized magnetotransistor design     

Operating principle of dual collector magnetotransistors studied bytwo-dimensional simulation

Dual collector magnetotransistors are magnetic-field-sensitive devices currently developed in several laboratories. Optimized sensor design is often attempted by trial and error rather than by established design rules. This motivated the present comprehensive study of the operation of magnetotransistors by accurate two-dimensional numerical simulations. We model vertical and lateral transistors as obtained by industrial IC technology on the basis of data provided by the chip manufacturer. We consider the entire device structure with the full, complex device geometry, and the physically proper boundary conditions. Our simulations reveal the details, controversial hitherto, of the operating principle of these devices. In particular we find that, in the case of the vertical transistor, it is essentially the emitter injection modulation effect which dominates the sensor response. In the case of the lateral transistor, the magnetic sensitivity is predominantly determined by minority-carrier deflection, though side effects are involved as well. By variation of the doping profile and the device geometry we derive rules for optimized magnetotransistor design     

An exclusive-OR logic circuit based on controlled quenching ofseries-connected negative differential resistance devices

An exclusive-OR (XOR) logic circuit with clocked supply voltage based on the controlled quenching of series-connected negative differential resistance (NDR) devices is demonstrated. This controlled quenching process obeys a simple rule: the NDR device with the smallest peak current is always quenched first. In our present work, resonant-tunneling diodes provide the critical NDR feature, while FET's, which are integrated with RTD's in parallel, modulate the peak currents of NDR devices. The modulation of peak currents in different NDR devices directly controls the quenching sequence, and results in certain logic functions, one of which is XOR     

Small signal analysis and optimization of the BARITT diode

Carriers are injected into the delay path of the BARITT structure with zero drift velocity, hence, diffusion can not be neglected in the small signal analysis. The inclusion of a diffusion region adjacent to the injection plane produces a more physically reasonable approach to the small signal analysis. This analysis is accomplished through a regional approximation. The three regions are the diffusion region (where diffusion dominates the conduction process) a low field region (where drift dominates but the carrier velocity has not reached the saturation velocity) and a high field region (where the carriers drift with a saturated velocity). The inclusion of the diffusion region removes the zero-velocity singularity which results in the conventional analysis and accounts for an appreciable delay which has been previously neglected. The device characteristics are optimized for various device parameters. The optimized device length and most probable value of the negative resistance are given, and a qualitative discussion of the physical origin of the behavior of the device characteristics is given.     

90 nm PDSOI MOSFET 热阻研究

对90 nm PDSOI MOSFET的热阻进行了提取与研究.以H型栅MOSFET为研究对象,将源体二极管作为温度敏感器,通过测量源体结电流与器件温度的关系以及源体结电流与器件功率的关系,获得MOS器件功率与器件温度的关系,从而获取MOS器件热阻值.实验结果表明,该工艺下PMOS器件的热阻比NMOS器件大,其原因是PM...