Effect of Halo structure variations on the threshold voltage of a 22 nm gate length NMOS transistor

This paper reports on the effects of the Halo structure variations on threshold voltage (V_th) in a 22 nm gate length high-k/metal gate planar NMOS transistor. Since the V_th is one of the important physical parameter for determining the functionality of complementary metal-oxide–semiconductor device, this experiment will focus on finding the best combination on process parameter to achieve the best value of V_th. The Halo structure variable process parameters are the Halo implantation dose, the Halo implantation tilting angle, the Source/Drain implantation dose and the compensation implantation dose. The design of the planar device consists of a combination of high permittivity material (high-k) and a metal gate. Titanium dioxide was used as the high-k material instead of the traditional SiO₂ dielectric and tungsten silicide was used as the metal gate. The optimization process was executed using Taguchi's L₉ array to obtain a robust design. Taguchi's Nominal-the-Best signal-to-noise ratio was used in an effort to minimize the variance of V_th. The results show that the V_th values have least variance and the mean value can be adjusted to 0.289 V±12.7% which is in line with projections made by the International Technology Roadmap for Semiconductors.     

Red Shift and Broadening of Backward Harmonic Radiation from Electron Oscillations Driven by Femtosecond Laser Pulse

The characteristics of backward harmonic radiation due to electron oscillations driven by a linearly polarized fs laser pulse are analysed considering a single electron model. The spectral distributions of the electron＇s backward harmonic radiation are investigated in detail for different parameters of the driver laser pulse. Higher order harmonic radiations are possible for a sufficiently intense driving laser pulse. We have shown that for a realistic pulsed photon beam, the spectrum of the radiation is red shifted as well as broadened because of changes in the longitudinal velocity of the electrons during the laser pulse. These effects are more pronounced at higher laser intensities giving rise to higher order harmonics that eventually leads to a continuous spectrum. Numerical simulations have further shown that by increasing the laser pulse width the broadening of the high harmonic radiations can be controlled.     

Enhanced mid-IR emission in Yb-Tm co-doped oxyfluoride glass ceramics

Tm³⁺-Yb³⁺ co-doped transparent oxyfluoride glass ceramics were prepared through thermal treatment of the as-prepared glasses. The precipitation of nanocrystals and the incorporation of Tm³⁺ and Yb³⁺ into the nanocrystals were confirmed by X-ray diffraction and absorption spectra. Based on the Judd-Ofelt theory, the J-O parameters Ω_λ (λ = 2, 4, 6), spontaneous radiative transition rates, radiative lifetimes and fluorescence branching ratios of Tm³⁺ in both as-prepared glasses and glass ceramics were calculated. Intense mid-IR emission and upconversion luminescence in the Tm³⁺ and Yb³⁺ co-doped glass ceramics were observed under 980 nm excitation. Especially, compared with that of the as-prepared glasses, mid-IR luminescence intensity of Tm³⁺ in the glass ceramics was greatly enhanced. Desirable spectroscopic characteristics suggest that these oxyfluoride glass ceramics may be promising mid-IR laser active medium.     

玻璃激光内雕技术的最新进展

玻璃激光内雕技术的发展经历了传统的白色激光内雕和现代的着色激光内雕两个阶段.传统的白色激光内雕是通过在激光聚焦点的光强超过玻璃的损伤阈值而产生炸裂形成微裂纹,利用微裂纹对光的散射实现三维白色内雕.现代的着色激光内雕技术包括以下几个方面:空间选择性色心控制,离子价态操控以及纳米粒子析出.本文介绍了各种玻璃激光内雕技术的原...     

Propagation of Intense Femtosecond Laser Pulses in Deuterated Methane and Deuterium Cluster Jets

Propagation of intense femtosecond laser pulses (60 fs, 800 nm, 120 mJ, 6×1017 W cm-2 in vacuum) in supersonic (CD4)N and (D2)N cluster jets at different background pressures was studied. Pump-probe interferometry is employed to investigate the propagation of laser beams in dense cluster jets by examining the electron density distribution of plasma channels. It was found that propagation effects, including ionization-induced defocusing and laser attenuation of incident pulses, are very different in the (CD4)N and (D2)N cluster jets. Different ionization states of CD4 and D2 molecules were observed by analyzing the transverse electron density profiles of the plasma channels and should be considered as a major reason for the differences in the propagation effects. Numerical simulations of the nonlinear propagation of femtosecond laser pulses in (CD4)N and (D2)N cluster jets were performed, and the results indicated a good reproduction of the experimental data.     

激光诱导材料表面着色研究进展

概述了三种激光着色机理:氧化膜干涉着色,以纳秒激光为主要着色方式,具有成本低、工业应用成熟等特点;周期性结构衍射着色,除了传统的超快激光诱导条纹结构着色,近些年发展起来的多光束干涉着色,丰富了周期性结构的种类,又大大提高了着色效率,更加适用于工业应用;等离基元金属纳米结构着色,通过调节纳米结构的间距、纳米结构尺寸等参数,可以对单个纳米结构实现显色控制,因而可以打印出具有纳米尺度像素大小的超高分辨率彩色图案.根据各种着色机理,概述了激光着色在防伪标记、激光隐写、彩色全息图等领域的应用,并提出了激光着色面临的重复性和稳定性的共性问题,提出了下一步的研究方向,包括从理论上对工艺技术进行研究,提高模型与实际效果的一致性,优化工艺方式得到输入和输出的定量关系,提高着色效果和加工效率等.     

EPR study of a-Si structural relaxations

A detailed analysis of the EPR line-shape was performed on amorphous silicon (a-Si) samples obtained by Kr⁺ ion implantation. It is shown that the line has predominantly Lorentzian character, however, a small Gaussian component is present as well. We monitored line-shape behavior during the relaxation and subsequent derelaxation process. A strong, fourfold increase in Gaussian component has been observed upon structural relaxation, suggesting spin homogenization throughout the bulk. Subsequent ion implantation derelaxation caused gradual return of the Lorentzian character, i.e. cluster structure of the amorphous phase.     

Optical measurements and analytical modeling of magnetic field generated in a dieletric target

Polarization rotation of a probe pulse by the target is observed with the Faraday rotation method in the interaction of an intense laser pulse with a solid target.The rotation of the polarization plane of the probe pulse may result from a combined action of fused silica and diffused electrons.After the irradiation of the main pulse,the rotation angle changed significantly and lasted ～2 ps.These phenomena may imply a persistent magnetic field inside the target.An analytical model is developed to explain the experimental observation.The model indicates that a strong toroidal magnetic field is induced by an energetic electron beam.Meanwhile,an ionization channel is observed in the shadowgraph and extends at the speed of light after the irradiation of the main beam.The formation of this ionization channel is complex,and a simple explanation is given.