A Closed-Form Model for Position-Dependent Potential across the Channel in DG-MOSFETs

A closed-form model for electrostatic potential distribution in the direction normal to the channel for double-gate （DG） MOSFETs is presented. The effects of doping （NA for nMOS） and minority carriers both are taken into account for the first time, in solving Poisson＇s equation analytically. Excellent agreement between model-predicted results and numerical device simulation is achieved for a wide range of body thickness, light or high channeldoping, under various bias conditions. This complete closed form for position-dependent potential distribution has wide applications for MOS compact modelling and device design.     

Improvement of High Temperature Characteristics for SiGeC p-i-n Diodes with Carbon Incorporation

Temperature-dependent characteristics of SiGeC p-i-n diodes axe analysed and discussed. Based on the ISE data, the temperature-dependent physical models applicable for SiGeC/Si diodes are presented. Due to the addition of carbon into the SiGe system, the thermal stability of SiGeC diodes are improved remarkably. Compared to SiGe diodes, the reverse leakage current of SiGeC diodes is decreased by 97.1% at 400 K and its threshold voltage shift is reduced over 65.3% with an increasing temperature from 300 K to 400 K. Furthermore, the fast and soft reverse recovery characteristics are also obtained at 400 K for SiGeC diodes. As a result, the most remarkable feature of SiGeC diodes is the better high-temperature characteristics and this can be applied to high temperature up to 400 K.     

Synthesis,Characterization of 9, 9＇-Bianthracene and Fabrication of 9, 9＇-Bianthracene Field-Effect Transistors

We synthesize and purify 9, 9＇-bianthracene with the purity up to 96.4%. The electronic and crystallographic structures of 9, 9＇-bianthracene are studied. The results of a joint experimental investigation based on a combination of x-ray diffraction （XRD） spectra, hydrogen nuclear magnetic （HNMR） spectra, infrared absorption （FT-IR） spectra, and mass spectra （MS） of 9, 9＇-bianthracene are obtained. The uniform compact film is observed by an atomic-force microscope （AFM）. Organic field effect transistors （OFETs） with an active layer based on the synthesized 9, 9＇-bianthracene are fabricated for the first time. Its field-effect mobility is as large as 0.067 cm^2 /（V·s） and the on/off ratio is above 5 ×10^4. The result demonstrates that the oligomerization of a small semiconductor molecule is an effective method to develop high-mobility organic semiconductors.     

Numerical Study on a Lateral Double-Gate Tunnelling Field Effect Transistor

A novel lateral double-gate tunnelling field effect transistor （DG-TFET） is studied and its performance is presented by a two-dimensional device simulation with code ISE. The result demonstrates that this new tunnelling transistor allows for the steeper sub-threshold swing below 60mV/dec, the super low supply voltage （operable at VDD 〈 0.3 V） and the rail-to-rail logic （significant on-state current at the drain-source voltage VDS = 50mV） for the aggressive technology assumptions of the availability of high-k/metal stack with equivalent gate oxide thickness EOT =0.24 nm and the work function difference 4.5 eV of materials.     

非对称HALO掺杂栅交叠轻掺杂漏围栅MOSFET的解析模型

为抑制短沟道效应和热载流子效应, 提出了一种非对称HALO掺杂栅交叠轻掺杂漏围栅MOSFET新结构. 通过在圆柱坐标系中精确求解三段连续的泊松方程, 推导出新结构的沟道静电势、阈值电压以及亚阈值电流的解析模型. 结果表明, 新结构可有效抑制短沟道效应和热载流子效应, 并具有较小的关态电流. 此外, 分析还表明栅交叠区的掺杂浓度对器件的亚阈值电流几乎没有影响, 而栅电极功函数对亚阈值电流的影响较大. 解析模型结果和三维数值仿真工具ISE所得结果高度符合.     

Mechanism of Current Oscillations in Gallium ArsenidePhotoconductive Semiconductor Switches

Semi-insulating photoconductive semiconductor switch with an electrode gap of 4 mm, triggered by a laser pulse with energy of 0.5md, and applied bias of 2.5kV, the periodicity current oscillation with a cycle of 12ns is obtained. It is indicated that the current oscillation is one mode of transferred electron effect, namely quenched domain mode. This mode of trans-electron oscillator is obtained when the instantaneous bias electric field drops below the sustaining field （the minimum electric field required to support the domain） before the domain reaches the anode, which leads to the domain disappears somewhere in the bulk of the switch and away from the ohmic contacts. We mainly analyse the time-dependent characteristic of the mode, the theoretical analysis results are in excellent agreement with the experiment.     

对称三材料双栅应变硅金属氧化物半导体场效应晶体管二维解析模型

提出了对称三材料双栅应变硅金属氧化物半导体场效应晶体管器件结构,为该器件结构建立了全耗尽条件下的表面势模型、表面场强和阈值电压解析模型,并分析了应变对表面势、表面场强和阈值电压的影响,讨论了三栅长度比率对阈值电压和漏致势垒降低效应的影响,对该结构器件与单材料双栅结构器件的性能进行了对比研究.结果表明,该结构能进一步提高载流子的输运速率,更好地抑制漏致势垒降低效应.适当优化三材料栅的栅长比率,可以增强器件对短沟道效应和漏致势垒降低效应的抑制能力.     

Quantum-Confined Stark Effects in a Single GaN Quantum Dot

Using analytical expressions for the polarization field in GaN quantum dot, and an approximation by separating the potential into a radial and an axial, we investigate theoretically the quantum-confined Stark effects. The electron and hole energy levels and optical transition energies are calculated in the presence of an electric field in different directions. The results show that the electron and hole energy levels and the optical transition energies can cause redshifts for the lateral electric field and blueshifts for the vertical field. The rotational direction of electric field can also change the energy shift.     

小尺寸应变Si金属氧化物半导体场效应晶体管栅隧穿电流预测模型

小尺寸金属氧化物半导体场效应晶体管(MOSFET)器件由于具有超薄的氧化层、关态栅隧穿漏电流的存在严重地影响了器件的性能,应变硅MOSFET器件也存在同样的问题.为了说明漏电流对新型应变硅器件性能的影响,文中利用积分方法从准二维表面势分析开始,提出了小尺寸应变硅MOSFET栅隧穿电流的理论预测模型,并在此基础上使用二维器件仿真软件ISE进行了仔细的比对研究,定量分析了在不同栅压、栅氧化层厚度下MOSFET器件的性能.仿真结果很好地与理论分析相符合,为超大规模集成电路的设计提供了有价值的参考. 关键词： 应变硅 准二维表面势 栅隧穿电流 预测模型     

Two-dimensional analytical models for asymmetric fully depleted double-gate strained silicon MOSFETs

This paper develops the simple and accurate two-dimensional analytical models for new asymmetric double-gate fully depleted strained-Si MOSFET. The models mainly include the analytical equations of the surface potential, surface electric field and threshold voltage, which are derived by solving two dimensional Poisson equation in strained-Si layer. The models are verified by numerical simulation. Besides offering the physical insight into device physics in the model, the new structure also provides the basic designing guidance for further immunity of short channel effect and drain-induced barrier-lowering of CMOS-based devices in nanometre scale.     

A Novel Kind of Transverse Micro-Stack High-Power Diode Bars

Novel transverse micro-stack semiconductor laser bars are put forward to improve the output optical power of semiconductor laser bars at low injection current. More importantly, the novel laser bars have a coupled large optical cavity, which can overcome the problem of catastrophic optical damage and improve light beam quality due to the coherently coupled emitting along the transverse direction. The micro-stack tunnel regeneration tri-active region laser structure was grown by metal organic chemical vapour deposition. For a weakly coupled uncoated device, the optical power exceeds 60 W under 50 A driving current and the slope efficiency reaches 1.55 W/A. Further experiments show that the perpendicular divergence of 23° is achieved from transverse strongly coupled devices.     

非对称Halo异质栅应变Si SOI MOSFET的二维解析模型

为了进一步提高深亚微米SOI (Silicon-On-Insulator) MOSFET (Metal-Oxide Semiconductor Field Effect Transistor) 的电流驱动能力, 抑制短沟道效应和漏致势垒降低效应, 提出了非对称Halo异质栅应变Si SOI MOSFET. 在沟道源端一侧引入高掺杂Halo结构, 栅极由不同功函数的两种材料组成. 考虑新器件结构特点和应变的影响, 修正了平带电压和内建电势. 为新结构器件建立了全耗尽条件下的表面势和阈值电压二维解析模型. 模型详细分析了应变对表面势、表面场强、阈值电压的影响, 考虑了金属栅长度及功函数差变化的影响. 研究结果表明,提出的新器件结构能进一步提高电流驱动能力, 抑制短沟道效应和抑制漏致势垒降低效应, 为新器件物理参数设计提供了重要参考. 关键词： 非对称Halo 异质栅 应变Si 短沟道效应     

A Physics-Based Compact Direct-Current and Alternating-Current Model for AlGaN/GaN High Electron Mobility Transistors

A set of analytical models for the dc and small signal characteristics of AIGaN/GaN high electron mobility transis- tors （HEMTs） are presented. A modified transferred-electron mobility model is adapted and a phenomenological low-field mobility model is developed. We calculate the channel charge considering the neutralization of donors and the contribution of free electrons in the AlGaN layer. The gate-to-source and gate-to-drain capacitances are obtained analytically, and the cut-off frequency is predicted. The models are implemented into the HSPICE simulator for the dc, ac and transient simulations and verified by experimental data for the first time. A high efficiency class-E GaN HEMT power amplifier is designed and simulated by the HSPICE to verify the applicability of our models.     

Simulation analysis of a novel fully depleted SOI MOSFET: Electrical and thermal performance improvement through trapezoidally doped channel and silicon–nitride buried insulator

In this paper, we present a novel nano-scale fully depleted silicon-on-insulator metal-oxide semiconductor field-effect transistor (SOI MOSFET). On-state current increment, leakage current decrement, and self-heating effect improvement are pursued in our proposed structure. The structure makes use of a buried insulator layer which consists of two materials to reduce the self-heating effect. On the other hand, to modify the sub- and super-threshold drain current, vertical trapezoidal doping distribution and additional side gate technique are employed. Our novel transistor is named dual material buried insulator vertical trapezoidal doping SOI MOSFET (DV-SOI MOSFET). We investigate the electrical performance and thermal behavior of the DV-SOI MOSFET using a commercial device simulator. We demonstrate that the proposed structure increases on–off current ratio by orders of magnitude and considerably improves self-heating effect in comparison with the conventional uniform doping fully depleted silicon-on-insulator MOSFET (C-SOI) which uses side gate for better electrical performance.     

Statistical emission of electrons from nanocrystalline silicon quantum dot memory nodes in a few-electron MOSFET memory device

Operation of a short and narrow channel metal-oxide-semiconductor field-effect transistor (MOSFET) memory device with a few nanocrystalline Si (nc-Si) dots in the active region has been investigated at 300 and 30 K. The discrete shift of the threshold voltage (V_th) in the current-voltage characteristics that arises from the screening effect of the charge stored in the nc-Si dot above the FET channel, suggests memory operation. It is found that the value of V_th changes with temperature whereas the magnitude of the shift in V_th is independent of temperature. The lifetime of the electrons stored in the floating node has also been investigated at different read voltages.     

Investigation of the Imaging Polarization Effect Based on a Pixellated CdZnTe Detector

A pixel array CdZnTe imaging system, employing a 40 × 40× 5 mm^3 pixellated CdZnTe detector, is established. The imaging polarization effect in the CdZnTe pixellated detector for a collimated CS137 Gamma source is investigated in detail. The experimental results for different irradiated fluxes indicate that excessive irradiated flux indeed causes central pixels to be shut off completely. The imaging performance of the polarized detector is severely degraded. Polarized detector counts are simultaneously reduced to one-third of the non-polarized detector counts. A theoretical model of potential distribution is also proposed by solving the Poisson equation and, in turn, the electric potential distortion for high irradiated flux is discussed by comparison with the experimental results.     

Modeling of a Silicon Nanowire pH Sensor with Nanoscale Side Gate Voltage

A silicon nanowire （Si-NW） sensor for pH detection is presented. The conductance of the device is analytically obtained, demonstrating that the conductance increases with decreasing oxide thickness. To calculate the electrical conductance of the sensor, the diffusion-drift model and nonlinear Poisson-Boltzmann equation are applied. To improve the conductance and sensitivity, a Si-NW sensor with nanoscaie side gate voltage is offered and its characteristics are theoretically achieved. It is revealed that the conductance and sensor sensitivity can be enhanced by adding appropriate side gate voltages. This effect is compared to a similar fabricated structure in the literature, which has a wire with a rectangular cross section. Finally, the effect of NW length on sensor performance is investigated and an inverse relation between sensor sensitivity and NW length is achieved.     

Silicon-on-Nothing MOSFETs: An efficient solution for parasitic substrate coupling suppression in SOI devices

With today's technology downscaling, the coupling through the substrate becomes an important limiting factor for the performance of mixed-mode high-frequency integrated circuits, filters, convertors, transmission lines and even single MOSFETs. This paper presents original studies on the coupling through the substrate in SOI devices and on substrate engineering which allows to suppress this effect. Particular attention is paid to the Silicon-on-Nothing (SON) MOSFET architecture as one of the most promising solutions to suppress the effect of parasitic coupling through the substrate on the transistor behavior.     

Stabilization of silicon-based devices in ion-containing media using thin Al2O3 platelets and MoS2 oriented thin films

A simplified analogue to an Ion-Sensitive Field-Effect Transistor (ISFET) was tested in the presence of ions. The gate electrode in an ISFET is an aqueous solution, unlike in a Metal-Oxide Field-Effect Transistor (MOSFET) where the gate is a metal. A problem with the ISFET is that the insulating oxide between the silicon and the solution is slowly penetrated by various ions such as OH^– or Na⁺ causing a change in the characteristics of the device.The application of thin alumina platelets and thin MoS₂ films as a protective insulating layer, when deposited over the insulating silicon oxide, was tested against the penetration of ions. It is shown that there is a significant decrease in the ion penetration through to the silicon oxide layer, depending on the applied bias, when the oxide is covered with thin alumina or MoS2 layers. The effect of different ions and ion concentrations are presented. Suggestions for further improvement are made.     

Small Amplitude Solitons in Bose--Einstein Condensates with External Perturbation

By developing a small amplitude soliton approximation method, we study analytically weak nonlinear excitations in cigar-shaped condensates with repulsive interatomic interaction under consideration of external perturbation potential. It is shown that matter wave solitons may exist and travel over a long distance without attenuation and change in shape by properly adjusting the strength of interatomic interaction to compensate for the effect of external perturbation potential.