Quantum cascade multi-electron injection into Si-quantum-dot floating gates embedded in SiO2 matrices

The use of silicon-quantum-dots (Si-QDs) as floating gates in metal-oxide-semiconductor-field-effect-transistors (MOSFETs) has been attracting great attention. It has been reported that large decreases in drain current are observed within a very short time in Si-QDs memories, indicating that the collective motion of electrons occurs during electron injection into Si-QDs. In this study, we present a theoretical report which indicates that the interaction length between QDs is about 5-10 nm. From these results, we propose a mechanism for “quantum cascade multi-electron injection”.     

HL-1M装置逃逸电子的定标律

使用一维数值模型, 推断了逃逸能量ε_r与逃逸约束时间τ_r的关系。模拟结果给出能量ε_r 和放电参数的定标律。在HL- 1M 装置中不同实验条件下测量了硬X 射线谱, 研究了逃逸电子能量 ε_r模拟的定标律, 并推导出HL- 1M 装置放电的逃逸电子的约束时间与逃逸电子扩散系数。     

Energy relaxation of electrons impacts on channel quantization in nano-MOSFETs

The effects of the rising electron temperature due to the energy relaxation on the quantization of the inversion layer in a nano-metal–oxide–semiconductor field transistor (MOSFET) with p-type silicon substrate have been theoretically investigated via self-consistent solution to the coupled Schrödinger equation with considering quantum coupling effects and Poisson equation. The first quantized energy level in the inversion layer rises from 3.6 to 211.4 %, and the total number of the inversion channel electron decreases from 95.7 to 6.5 % relative to those neglecting energy relaxation of channel electrons when the channel electric field increases from 10 to 55 kV/cm. The output characteristic of MOSFET will be largely affected by the energy relaxation when the channel electric field is higher than 10 kV/cm. All these suggest that the energy relaxation of channel electrons should be considered in the modeling of MOSFETs for higher channel electric field.     

A Novel Fully Depleted Air AlN Silicon-on-Insulator Metal--Oxide--Semiconductor Field Effect Transistor

A novel fully depleted air A1N silicon-on-insulator （SOD metai-oxide-semiconductor field effect transistor （MOS- FET） is presented, which can eliminate the self-heating effect and solve the problem that the off-state current of SOI MOSFETs increases and the threshold voltage characteristics become worse when employing a high thermal conductivity material as a buried layer. The simulation results reveal that the lattice temperature in normal SOI devices is 75K higher than the atmosphere temperature, while the lattice temperature is just 4 K higher than the atmosphere temperature resulting in less severe self-heating effect in air A1N SOI MOSFETs and A1N SOI MOSFETs. The on-state current of air A1N SOI MOSFETs is similar to the A1N SOI structure, and improves 12.3% more than that of normal SOI MOSFETs. The off-state current of A1N SOI is 6. 7 times of normal SOI MOSFETs, while the counterpart of air A1N SOI MOSFETs is lower than that of SOI MOSFETs by two orders of magnitude. The threshold voltage change of air A1N SOl MOSFETs with different drain voltage is much less than that of A1N SOI devices, when the drain voltage is Mased at 0.8 V, this difference is 28mV, so the threshold voltage change induced by employing high thermal conductivity material is cured.     

Quantum-Mechanical Study on Surrounding-Gate Metal-Oxide-SemiconductorField-Effect Transistors

As the channel length of metal-oxide-semiconductor field-effect transistors (MOSFETs) scales into the nanometer regime, quantum mechanical effects arebecoming more and more significant. In this work, a model for thesurrounding-gate (SG) nMOSFET is developed. The Schrödinger equation issolved analytically. Some of the solutions are verified via results obtainedfrom simulations. It is found that the percentage of the electrons withlighter conductivity mass increases as the silicon body radius decreases, oras the gate voltage reduces, or as the temperature decreases. The centroidof inversion-layer is driven away from the silicon-oxide interface towardsthe silicon body, therefore the carriers will suffer less scattering fromthe interface and the electrons effective mobility of the SG nMOSFETs will be enhanced.     

A study on the performance of metal-oxide-semiconductor-field-effect-transistors with asymmetric junction doping structure

Diode currents of MOSFET were studied and characterized in detail for the ion implanted pn junction of short channel MOSFETs with shallow drain junction doping structure. The diode current in MOSFET junctions was analyzed on the point of view of the gate-induced-drain leakage (GIDL) current. We could found the GIDL current is generated by the band-to-band tunneling (BTBT) of electrons through the reverse biased channel-to-drain junction and had good agreement with BTBT equation. The effect of the lateral electric field on the GIDL current according to the body bias voltage is characterized and discussed. We measured the electrical doping profiling of MOSFETs with a short gate length, ultra thin oxide thickness and asymmetric doped drain structure and checked the profile had good agreement with simulation result. An accurate effective mobility of an asymmetric source–drain junction transistor was successfully extracted by using the split C–V technique.     

激光功率密度对Al膜靶后表面快电子发射的影响

 报道了在20 TW皮秒激光器上完成的p偏振激光与等离子体相互作用过程中产生的快电子的角分布和能谱测量结果。实验得到：当激光功率密度小于10¹⁷ W/cm²时,电子发射没有明显定向性,在激光入射面内多峰发射;当激光功率密度大于10¹⁷ W/cm2,小于10¹⁸ W/cm²时,电子主要沿靶面法线方向发射;当激光功率密度达到相对论强度时,电子主要沿激光传播方向发射;激光功率密度未达到相对论强度时,靶后表面法线方向快电子能谱拟合平均温度符合共振吸收温度定标率;激光功率密度达相对论强度以上时,靶后表面法线方向快电子能谱拟合平均温度高于已有的温度定标率。     

飞秒激光-等离子体相互作用中快电子能量分布

 采用不同量程的电子谱仪与LiF热释光探测器相配合,测量了飞秒激光 等离子体相互作用中产生的快电子能量分布。结果显示快电子能量分布的一致性和多个重要特征与国外同类实验和计算机模拟结果相似。快电子能谱在低能处产生凹陷是由于冷电子的回流产生的;几种加速机制共同作用是能谱在100~350 keV范围内出现平台的原因;快电子的有效温度较好地满足共振吸收的温度定标律是由于反射激光加速与共振吸收机制均是通过朗道阻尼或波破对电子进行加速的。     

Electrical characteristics of AlInN/GaN HEMTs under cryogenic operation

Electrical properties of an AlInN/GaN high-electron mobility transistor (HEMT) on a sapphire substrate are investi-gated in a cryogenic temperature range from 295 K down to 50 K. It is shown that drain saturation current and conductance increase as transistor operation temperature decreases. A self-heating effect is observed over the entire range of temperature under high power consumption. The dependence of channel electron mobility on electron density is investigated in detail. It is found that aside from Coulomb scattering, electrons that have been pushed away from the AlInN/GaN interface into the bulk GaN substrate at a large reverse gate voltage are also responsible for the electron mobility drop with the decrease of electron density.     

飞秒激光与等离子体相互作用过程中超热电子能谱的测量

 报道了在3TW飞秒激光器上完成的激光 等离子体相互作用过程中产生的超热电子的能谱测量结果。能谱测量显示：在较低的能段，超热电子能谱先是呈现一个局部的平台，然后迅速衰减，呈现非类麦克斯韦分布，这是由于几种加热机制共同作用，其中占主导地位的是反射激光对电子的加速；在较高的能段，超热电子能谱呈类麦克斯韦分布，拟合的温度远远高于已知的温度定标律给出的温度，其原因在于超热电子分布的高能尾部本身的抬高和激光的自聚焦及成道。     

MOSFET scaling into the 10 nm regime

Scaling limits of the double-gate MOSFET structure are explored. Because short-channel effects can be adequately controlled by thinning the silicon body, the eventual scaling limit will be determined by the ability to control off-state leakage due to quantum mechanical tunneling and thermionic emission between the source and drain. Depending on threshold voltage and the source/drain doping profile, this will restrict gate length scaling to 5–11 nm. As power supplies are scaled down, maintaining on-state drive current may become difficult due to threshold voltage limitations. Series resistance becomes important as the body thickness is reduced, but intrinsic device performance may still be improved.     

GaSb p-channel metal-oxide-semiconductor field-effect transistor and its temperature dependent characteristics

GaSb p-channel metal-oxide-semiconductor field-effect transistors(MOSFETs)with an atomic layer deposited Al2O3gate dielectric and a self-aligned Si-implanted source/drain are experimentally demonstrated.Temperature dependent electrical characteristics are investigated.Different electrical behaviors are observed in two temperature regions,and the underlying mechanisms are discussed.It is found that the reverse-bias pn junction leakage of the drain/substrate is the main component of the off-state drain leakage current,which is generation-current dominated in the low temperature regions and is diffusion-current dominated in the high temperature regions.Methods to further reduce the off-state drain leakage current are given.     

微波击穿大气电子温度与电子密度依存关系

给出了描述高功率微波脉冲大气非线性传输及微波大气等离子体特征演化的方程组,并在以微波群速度运动的局域坐标系下完成程序编制。据此模拟分析了高功率微波大气长程非线性传输及自产生大气等离子体的基本物理过程,给出了在击穿建立过程中,电子数密度增长与电子温度升高之间的关系。模拟结果表明:由于大气层中本底自由电子数密度较低,高功率微波脉冲到达时会迅速地将大气中现有的自由电子加热至平衡温度,与之相比导致电子数密度雪崩式增长的击穿过程要缓慢得多,而且随着击穿过程的开始电子温度会从平衡温度快速下降。     

利用轫致辐射谱回推超热电子温度

超短超强激光打靶产生的超热电子与固体靶相互作用时会产生轫致辐射X射线。利用蒙特卡罗方法,对电子在固体靶中传输产生的轫致辐射X射线进行了模拟。1 MeV电子束与固体靶作用产生的轫致辐射谱模拟结果表明,轫致辐射谱高能段斜率受靶厚度及靶材料的影响不明显。麦克斯韦分布的电子束及单能电子束与30 m铜靶作用的模拟结果显示,两种电子源产生的轫致辐射谱在电子束能量或温度较高时基本一致。给出了一种利用轫致辐射谱斜率反推超热电子温度的定标方法。模拟了不同温度下超热电子产生的轫致辐射光子的能量角分布及光子数角分布,结果显示辐射光子能量通量和光子数随着电子温度的提高越来越向前倾,并给出了另外一种由轫致辐射能量角分布反推超热电子温度的定标关系。     

Photoelectric spectroscopy of oxide states with MOS structures atT=79 K

AtT=79 K illumination effects with visible and UV light on the drain current were studied forn-channel enhancement-type MOS transistors. The results show that the response of photoelectric measurements is due to electron excitation from oxide states into the silicon surface layer (positive changes of drain current). The oxide states lying near the bottom of the silicon dioxide conduction band are distributed in energy. Oxide states having captured a hole can be discharged by electrons excited from the silicon conduction or valence band (negative changes of drain current) in combination with a tunneling process.     

Effects of atomic number Z on the energy distribution of hot electrons generated by femtosecond laser interaction with metallic targets

The effects of atomic number Z on the energy distribution of hot electrons generated by the interaction of 60fs, 130mJ, 800nm, and 7×10^17W/cm^2 laser pulses with metallic targets have been studied experimentally. The results show that the number and the effective temperature of hot electrons increase with the atomic number Z of metallic targets, and the temperature of hot electrons are in the range of 190-230keV, which is consistent with a scaling law of hot electrons temperature.     

Detection of defects binding free polarons in colored alkali halide crystals

The assumption has been made that defects binding free polarons in colored alkali halide crystals are F'-center, i.e., defects that slow down the motion of dislocations (photoplastic effect). This assumption has been confirmed by the experiments performed in this study. Thus, the anion vacancy in alkali halide crystals at a low temperature can capture three electrons: two electrons at a deep level (F'-center) and one electron in a bound polaron state. This electron is retained due to the energy gain in the interaction of a local deformation of the polaron and a local deformation surrounding the F'-center, despite the presence of the Coulomb repulsion.     

An optimized design of 10-nm-scale dual-material surrounded gate MOSFETs for digital circuit applications

In this paper, we have proposed and simulated a new 10-nm Dual-Material Surrounded Gate MOSFETs (DMSG) MOSFETs for nanoscale digital circuit applications. The subthreshold electrical properties such as subthreshold current–voltage characteristics, subthreshold swing factor, threshold voltage and drain induced barrier lowering (DIBL) of the device have been ascertained and mathematical models have been developed. It has been observed that the DM design can effectively suppress short-channel effects as compared to single material gate structure. The proposed analytical expressions are used to formulate the objective functions, which are the pre-requisite of genetic algorithm computation. The problem is then presented as a multi-objective optimization one where the subthreshold electrical parameters are considered simultaneously. Therefore, the proposed technique is used to search of the optimal electrical and geometrical parameters to obtain better electrical performance of the 10-nm-scale transistor. These characteristics make the optimized 10-nm transistors potentially suitable for deep nanoscale logic and memory applications.     

体硅、SOI及DSOI MOSFET器件级电、热分析

利用简化的半导体电学方程,数值模拟获得了各种电学参数的分布,并结合简化电阻模型,模拟了体硅、SOI及DSOI的MOSFET器件的温度场。结果表明MOSFET器件的沟道,特别是靠近漏的区域电场强度及电流密度等各项电、热特性参数在该区域变化剧烈,是最主要的热源区。     

Radiative transfer in the lyman α spectral line with self-consistent electron velocity distribution

Radiative transfer in the Ly α spectral line in a stationary, plane-parallel plasma of constant temperature and electron density is studied using model H-atoms with only two bound levels and a continuum. For this purpose, the equation of radiative transfer is solved simultaneously with the steady-state equations of the atomic levels and the kinetic equation of the electrons. The numerical results indicate that, in hydrogen plasmas with temperatures T ? 12,000°K and electron densities n_e ? 10¹⁶cm^?3, the high-energy tail of the electron velocity distribution deviates from a Maxwell distribution, even in cases of rather large optical thicknesses and that therefore the deviations from local thermodynamic equilibrium are increased compared with estimates based on the assumption of a Maxwellian electron velocity distribution. This qualitative conclusion should hold in spite of some deficiencies of the model which are discussed.