气压对激光烧蚀Al靶诱导保护气电离的影响

用Nd：YAG脉冲激光烧蚀Al靶获得等离子体，脉冲能量固定在145mJ／pulse。用Ar气作保护气，利用时空分辨技术，采集了100Pa、lkPa、10kPa和100kPa气压下等离子体辐射的时空分辨谱。筒要描述了各气压下等离子体的辐射特征，详细分析了各气压下Ar的特征辐射规律。根据这些气压下Ar特征谱线的分布特征，简要论述了Ar气电离与气压的关系；用量子理论对此给予全面解释。进一步讨论了环境气体电离机制，认为环境气体对等离子体的连续辐射吸收是诱导环境气体电离的主要机制。     

Ar 辅助Al 等离子体辐射谱分析

Nd∶YAG脉冲激光聚焦到Al 靶表面,烧蚀Al 靶,产生Al 等离子体。用Ar 气作保护气 时,将诱发Ar 气电离,产生丰富的Ar + 离子辐射。文中根据Ar + 离子辐射信息,分析了Ar Ⅱ385. 06nm、Ar Ⅱ386. 85nm、Ar Ⅱ404. 29nm等三条谱线的时间分辨行为,计算了Al 等离子体离子辐射时期的电子温度;估算了特征辐射时期的电子密度。结果发现:在Al 等离子体离子辐射时期,电子温度约1. 2～1. 9eV ,随延迟时间增加,单调递减;在特征辐射时期,电子密度大约是2 ×1018 cm- 3 。     

Ar 辅助Al 等离子体辐射谱分析

Nd∶YAG脉冲激光聚焦到Al靶表面,烧蚀Al靶,产生Al等离子体。用Ar气作保护气时,将诱发Ar气电离,产生丰富的Ar 离子辐射。文中根据Ar 离子辐射信息,分析了ArⅡ385.06nm、ArⅡ386.85nm、ArⅡ404.29nm等三条谱线的时间分辨行为,计算了Al等离子体离子辐射时期的电子温度;估算了特征辐射时期的电子密度。结果发现:在Al等离子体离子辐射时期,电子温度约1.2～1.9eV,随延迟时间增加,单调递减;在特征辐射时期,电子密度大约是2×1018cm-3。     

高气压Ar对激光诱导Al等离子体辐射特性的影响

用高能量钕玻璃激光器(0~25J)烧蚀Al靶产生等离子体。实验中测量了Ar气气压在0.1~1.0MPa范围内,等离子体发射光谱的谱线强度、半宽度、信背比以及等离子体的电子温度和电子密度随气压的变化。结果表明,随着环境气体压强的升高,等离子体的空间体积被压缩,电子温度和电子密度增大,辐射强度有明显的增强。     

激光烧蚀Al靶诱导的环境气体电离轴向分布

用Nd:YAG脉冲激光烧蚀Al靶获得等离子体,脉冲能量固定在145mJ/pulse。用Ar作环境气体,压强固定在10kPa。利用时空分辨技术,采集了垂直于靶面方向上,即等离子体轴向,离靶面0．1mm,0.5mm,1.0mm,1.5mm,2.0mm位置处等离子发光光谱。基于各点Ar^2 辐射时间分布,详细分析了Ar^ 辐射轴向分布规律,并对这种分布机制进行了简单的讨论。     

Ar气下激光诱导Cu等离子体电子温度的实验研究

本文从实验上研究了Ar气下激光诱导Cu等离子体的空间分辨发射光谱.在局部热力学平衡(LTE)条件下,根据谱线的相对强度,得到了等离子体的电子温度在104K以上.研究了原子发射谱线强度、电子温度随空间变化的规律.结果表明,通过Cu(Ⅰ)和Ar(Ⅱ)得到的等离子体电子温度随着空间距离的增加都呈下降趋势,具有相同的变化规律.据此,我们可以通过测量背景气体的电子温度来近似判断近靶面未知谱线等离子体的电子温度.     

缓冲气压对CO2激光Al靶等离子体参量的影响

为了研究缓冲气压对激光等离子体参量的影响,利用CO2,激光烧蚀A1靶产生等离子体,缓冲气压变化范围为10-4Pa～2103Pa,激光脉冲能量为180mJ/脉冲,在局域热平衡和光学薄等离子体假设下,采用发射光谱法计算了等离子体的电子温度和电子密度,并研究了缓冲气压对这些参量的影响。结果表明,等离子体的电子温度和电子密度分别在1.05eV～2.47eV与1.951016cm-3～10.5 1016cm-3范围内,Al等离子体的电子温度随气压的增大而减少;低缓冲气压时,电子密度随气压增大而减小,当气压达到600Pa时,激光脉冲会击穿空气形成等离子体,电子密度又开始上升,当气压超过3000Pa时,空气等离子体会屏蔽激光脉冲能量,使到达靶面的激光能量急剧下降,Al原子的特征谱线也随之减弱而几乎消失。这一结果对理解缓冲气压对激光与物质相互作用过程的影响是有帮助的。     

激光诱导Al等离子体中电子密度和温度的实验研究

激光烧蚀等离子体在微量元素分析方面有着重要的应用背景，而缓冲气体的种类及压力对激光等离子体的特性有重要影响。报道了以氦气、氩气、氮气和空气作为缓冲气体，实验测定了不同气压下Nd：YAG激光烧蚀Al靶产生的等离子体中的时间分辨发射光谱，利用发射谱线的Stark展宽和相对强度计算了等离子体中的电子密度和温度，得到了在不同缓冲气体中激光诱导Al等离子体的电子密度随延时、气压的演化规律，同时得到了电子温度的时间演化特性。实验结果表明，电子密度的数量级约为10^17cm^-3，电子温度测量值约为10000K，二者都是在激光脉冲后随时间快速衰减，直到4μs以后达到一个较低的水平并缓慢变化，其中以氩气作为缓冲气体时等离子体中的电子密度最大。     

激光诱导钢靶等离子体时间分辨光谱特性研究

为了改善激光诱导击穿光谱质量,使用具有时间分辨功能的光谱仪采集激光诱导钢靶等离子体光谱,研究了钢靶等离子体辐射光谱随延迟时间的变化特性。结果表明,光谱强度和背景强度随延时皆呈指数衰减,原子谱线强度在前4μs内衰减更快但寿命较长,离子谱线存在寿命较短;采集延时对不同谱线的信噪比影响不同,Mn I403.08nm、Cr I 428.97nm、CrⅡ458.82nm、Fe I 430.79nm和FeⅡ503.57nm谱线得到的最佳延时分别为8,2,0,2,4μs。采用双线法和Boltzmann曲线法计算等离子体温度、Saha-Boltzmann方程计算电子密度,验证了在0~10μs范围内采集到的光谱信号满足局部热平衡状态。     

激光诱导Cu等离子体光谱时间演化特性研究

针对激光诱导Cu等离子体时间演化问题,使用Nd∶YAG脉冲激光器对Cu样品进行烧蚀产生等离子体,采集延迟时间为0.5～10 μs时等离子体时间分辨光谱并对整体谱线进行分析。激光能量调节为142 mJ,在热力学平衡状态下,利用Boltzmann斜率法测得等离子体电子温度。选择独立较好、不受相邻谱线影响的Cu I 521.8 nm作为特征谱线测量其半波宽度,并采用Stark展宽法计算等离子体的电子密度。实验表明:随着延时时间的增加,等离子体内能因不断向外扩展转化为动能而骤减,电子温度整体呈下降趋势,且在延时时间为2 μs时达到最大,延时时间13 μs后下降趋缓。随着延迟时间的增加,等离子体的电子密度降低,电子与发射粒子之间的碰撞程度也相应降低,谱线展宽随之减小。     

Preparation and Characterization of TaN ALD Precursors

High purity organic-tantalum precursors for thin film ALD TaN were synthesized and characterized.Vapor pressure and thermal stability of these precursors were studied.From the vapor pressure analysis,it was found that TBTEMT has a higher vapor pressure than any other published liquid TaN precursor,including TBTDET,TAITMATA,and IPTDET.Thermal stability of the alkyl groups on the precursors was investigated using a 1H NMR technique.The results indicated that the tertbutylimino group is the most stable group on TBTDET and TBTEMT as compared to the dialkylamido groups.Thermal stability of TaN precursors decreased in the following order:TBTDET ＞ PDMAT ＞ TBTEMT.In conclusion,precursor vapor pressure and thermal stability were tuned by making slight variations in the ligand sphere around the metal center.     

Curved crystal spectrometer for the measurement of X-ray lines from laser-produced plasmas

In order to diagnose the laser-produced plasmas, a focusing curved crystal spectrometer has been developed for measuring the X-ray lines radiated from a laser-produced plasmas. The design is based on the fact that the ray emitted from a source located at one focus of an ellipse will converge on the other focus by the reflection of the elliptical surface. The focal length and the eccentricity of the ellipse are 1350 mm and 0.9586, respectively. The spectrometer can be used to measure the X- ray lines in the wavelength range of 0.2-0.37 nm, and a LiF crystal （200） （2d = 0.4027 nm） is used as dispersive element covering Bragg angle from 30° to 67.5°. The spectrometer was tested on Shengnang- Ⅱ which can deliver laser energy of 60-80 J/pulse and the laser wavelength is 0.35 μm. Photographs of spectra including the 1 s2p ^1P1-1s^2 ^1S0 resonance line（w）, the 1s2p ^3P2-1s^2 1S0 magnetic quadrupole line（x）, the 1s2p ^3P1-1 s^2 ^1S0 intercombination lines（y）, the 1 s2p ^3S~1-1 s^2 ^1S0 forbidden line（z） in helium-like Ti Ⅹ Ⅺ and the 1 s2s2p ^2P3/2-1 s622s ^2S1/2 line（q） in lithium-like Ti Ⅹ Ⅹhave been recorded with a X-ray CCD camera. The experimental result shows that the wavelength resolution（λ/△ 2） is above 1000 and the elliptical crystal spectrometer is suitable for X-ray spectroscopy.     

Electronic Structure of Semiconductor Nanocrystals

This paper reviews our recent development of the use of the large-scale pseudopotential method to calculate the electronic structure of semiconductor nanocrystals, such as quantum dots and wires, which often contain tens of thousands of atoms. The calculated size-dependent exciton energies and absorption spectra of quantum dots and wires are in good agreement with experiments. We show that the electronic structure of a nanocrystal can be tuned not only by its size,but also by its shape. Finally,we show that defect properties in quantum dots can be significantly different from those in bulk semiconductors.     

Critical Stage Rule-Based Real Time Dispatch（RTD）System in Highly-Mixed-Products （HMP） FAB

An improving utilization and efficiency of critical equipments in semiconductor wafer fabrication facilities are concerned. Semiconductor manufacturing FAB is one of the most complicated and cost sensitive environments. A good dispatching tool will make big difference in equipment utilization and FAB output as a whole. The equipment in this paper is In-Line DUV Scanner. There are many factors impacting utilization and output on this equipment group. In HMP environment one of the issues is changing of reticule in this area and idle counts due to load unbalance between equipments. Here we'll introduce a rule-based RTD system which aiming at decreasing the number of recipe change and idle counts among a group of scanner equipment in a high-mixed-products FAB.     

GaAsSb/InAlAs PA DHBTs Grown by Production MBE

The epi material growth of GaAsSb based DHBTs with InAlAs emitters are investigated using a 4 × 100mm multi-wafer production Riber 49 MBE reactor fully equipped with real-time in-situ sensors including an absorption band edge spectroscope and an optical-based flux monitor. The state-of-the-art hole mobilities are obtained from 100nm thick carbon-doped GaAsSb. A Sb composition variation of less than ± 0.1 atomic percent across a 4 × 100mm platen configuration has been achieved. The large area InAlAs/GaAsSb/InP DHBT device demonstrates excellent DC characteristics,such as BVCEO＞6V and a DC current gain of 45 at 1kA/cm2 for an emitter size of 50μm × 50μm. The devices have a 40nm thick GaAsSb base with p-doping of 4. 5 × 1019cm-3 . Devices with an emitter size of 4μm × 30μm have a current gain variation less than 2% across the fully processed 100mm wafer. ft and fmax are over 50GHz,with a power efficiency of 50% ,which are comparable to standard power GaAs HBT results. These results demonstrate the potential application of GaAsSb/InP DHBT for power amplifiers and the feasibility of multi-wafer MBE for mass production of GaAsSb-based HBTs.     

Technology innovation and process integrations for sub-100nm gate patterning

This paper presents a brief overview of the Applied Centura(R)DPS(R)system,configured with silicon etch DPS Ⅱ chamber, with emphasis on discussing tuning capability for CD uniformity control. It also presents the studies of etch process chemistry and film integration impact for an overall successful gate patterning development. Discussions will focus on resolutions to key issues, such as CD uniformity, line-edge roughness, and multilayer film etching integration.     

White organic light-emitting devices based on fac tris（2- phenylpyridine） iridium sensitized 5,6,11,12-tetraphenylnap -hthacene

We have fabricated the white organic light-emitting devices （WOLEDs） based on 4,4＇ -bis（2,2 -diphenyl vinyl）-1,1＇ - biphenyl （DPVBi） and phosphorescence sensitized 5,6,11,12,-tetraphenylnaphthacene （rubrene）. The device structure is ITO/2T-NATA （20 nm）/NPBX （20 nm）/CBP： x%Ir（ppy）3：0.5% rubrene （8 nm）/NPBX （5 nm）/DPVBi （30 nm）/Alq（30 nm）/LiF（0.5 nm）/A1. In the devices, DPVBi acts as a blue light-emitting layer, the rubrene is sensitized by a phosphorescent material, fac tris （2-phenylpyridine） iridium [Ir（ppy）3], acts as a yellow light-emitting layer, and N,N＇ -bis- （1-naphthyl）- N,N＇ -diphenyl -1, 1＇ -biphenyl-4,4＇ -diamine （NPBX） acts as a hole transporting and exciton blocker layer, respectively. When the concentration of Ir （PPY）3 is 6wt%, the maximum luminance is 24960 cd/m^2 at an applied voltage of 15 V, and the maximum luminous efficiency is 5.17 cd/A at an applied voltage of 8 V.     

Complete approach to automatic identification and subpixel center location for ellipse feature

To meet the need of automatic image features extraction with high precision in visual inspection, a complete approach to automatic identification and sub-pixel center location for similar-ellipse feature is proposed. In the method, the feature area is identified automatically based on the edge attribute, and the sub-pixel center location is accomplished with the leastsquare algorithm. It shows that the method is valid, practical, and has high precision by experiment. Meanwhile this method can meet the need of instrumentation of visual inspection because of easy realization and without man-machine interaction.     

小角度扩展相关性近似算法分析

本论文提出一种在多天线MIMO信道相关性建模中小角度扩展近似理论算法,并应用于分析MIMO系统性能。分析中分别对三种不同角能量分布情况下的空间相关性研发快速近似计算法,并同时提出双模(Bi-Modal)角能量分布情况下的近似运算。通过分析这些新方法的近似效率,可以得到计算简单、复杂度低、而且符合实际的MIMO相关信道矩阵,对系统级的快速高效计算法的研究和系统级的评估以及误差分析具有重要的意义。     

Noise character analysis and the restraint of self-pulsation laser diodes

We calculate the Langevin noise sources of self-pulsation laser diodes, analyze the effects of active region noise and saturable-absorption region noise on the power fluctuation as well as period fluctuation, and propose a novel method to restrain the noise effects. A visible SIMULINK model is established to simulate the system, The results indicate that the effects of noise in absorption region can be ignored; that with the increase of DC injecting current, the noise effects enhance power jitter, and nevertheless, the period jitter is decreased; and that with external sinusoidal current modulating the self-pulsation laser diode, the noise-induced power jitter and period jitter can be suppressed greatly. This work is valuable for clock recovery in all-optical network.