嵌入在Si衬底上的分子束外延GaAs层的微区喇曼和光致发光分析

对分子束外延生长的嵌入在Si衬底上的边长为20—150μm正方形GaAs层微区进行了微区喇曼和光致发光分析。发现微区GaAs层的喇曼散射谱和光致发光谱与普通平面Si片上生长的GaAs层的基本相同,证实嵌入式生长可以得到与通常平面生长基本相同的质量。仔细的分析表明随着微区尺寸的减小GaAs层的无序程度有少许增长。     

基于MOCVD的InP/GaAs异质外延生长

使用金属有机物气相沉积方法(MOCVD),在GaAs衬底上生长InP外延层.先在GaAs衬底上生长一层低温InP缓冲层,然后再生长InP外延层.通过比较不同缓冲层生长条件下的外延层晶体质量,发现在生长温度为450℃,厚度约15nm的缓冲层上外延所得到的晶体质量最理想;此外,外延层厚度的增加对其晶体质量有明显改善作用.实验在优化生长条件的同时,也考虑了热退火等辅助工艺,最后所获得的外延层的双晶X射线衍射(DCXRD)的ω/2θ扫描外延峰半高全宽(FWHM)值为238.5".     

基于MOCVD的InP/GaAs异质外延生长

使用金属有机物气相沉积方法(MOCVD),在GaAs衬底上生长InP外延层.先在GaAs衬底上生长一层低温InP缓冲层,然后再生长InP外延层.通过比较不同缓冲层生长条件下的外延层晶体质量,发现在生长温度为450℃,厚度约15nm的缓冲层上外延所得到的晶体质量最理想;此外,外延层厚度的增加对其晶体质量有明显改善作用.实验在优化生长条件的同时,也考虑了热退火等辅助工艺,最后所获得的外延层的双晶X射线衍射(DCXRD)的ω/2θ扫描外延峰半高全宽(FWHM)值为238.5".     

利用全固态分子束外延方法在Ge(100)衬底上异质外延GaAs薄膜及相关特性表征

利用全固态分子束外延(MBE)方法在Ge(100)衬底上异质外延GaAs薄膜,并通过高能电子衍射(RHEED)、高分辨X射线衍射(XRD),原子力显微镜等手段研究了不同生长参数对外延层的影响.RHEED显示在较高的生长温度或较低的生长速率下,低温GaAs成核层呈现层状生长模式.同时降低生长温度和生长速率会使GaAs薄膜的XRD摇摆曲线半高宽(FWHM)减小,并降低外延层表面的粗糙度,这主要是由于衬底和外延薄膜之间的晶格失配度减小的结果.     

过渡层对Ge衬底GaAs外延层晶体质量的影响

利用低压金属有机化学汽相淀积(MOCVD)设备在Ge衬底上生长GaAs外延层.通过改变GaAs过渡层的生长温度对GaAs外延层进行了表征,利用扫描电镜(SEM)和X射线衍射仪研究了表面形貌和晶体质量,优化出满足高效太阳能电池要求的高质量GaAs单晶层生长条件.     

GaAs(001)衬底上MOCVD生长的立方相GaN外延薄膜的光学性质研究

本文报道了利用MOCVD方法,在GaAs衬底(001)面制备的立方GaN薄膜的光学性质.利用光致发光(PL)光谱的半高宽确定制备的样品具有不同的晶体质量.利用喇曼散射(RS)光谱研究了立方GaN薄膜中的光学声子模式.横向(TO)和纵向(LO)声子在立方GaN中的散射峰分别位于552cm-1和739cm-1.另外还观察到来自界面无序层的TOB和LOB.根据喇曼频移和选择定则可识别GaN中的相组成.其来自六方相GaN的E2声子模,可作为识别立方GaN中六方相的标志.随着退火温度的升高,样品中的界面层的效应减弱,六方相增加     

GaAs(100)衬底上热壁外延生长的ZnSe薄膜光学声子散射光谱研究

本文给出n型GaAs(100)衬底上热壁外延生长的Znse薄膜室温喇曼散射分析.Znse纵光学(LO)声子喇曼峰的线宽测量表明作者已在GaAs(100)衬底上用封闭式热壁外延法长出了高质量ZnSe单晶膜.较差质量外延膜在背散射喇曼谱中出现的横光学(TO)声子峰被归之于外延膜生长过程中与孪生有关的微观取向错误的出现.首次在意到GaAs表面化学腐蚀处理使n型GaAs的LO声子-等离子激元耦合模喇曼强度有成倍提高,并证明这是因为化学腐蚀使GaAs表面氧化层厚度减小,增加了入射激光束在GaAs基质材料中的穿透深度.     

AlGaN缓冲层结构对Si基GaN材料性能的影响

Si衬底与GaN之间较大的晶格失配和热失配引起的张应力使GaN外延层极易产生裂纹,如何补偿GaN所受到的张应力是进行Si基GaN外延生长面临的首要问题.采用金属有机化合物化学气相沉积(MOCVD)技术在4英寸(1英寸=2.54 cm)Si (111)衬底上制备了GaN外延材料并研究了不同AlGaN缓冲层结构对Si基GaN外延材料性能的影响,并采用高分辨X射线衍射仪(HRXRD)、原子力显微镜(AFM)、喇曼光谱以及光学显微镜对制备的GaN材料的性能进行了表征.采用3层A1GaN缓冲层结构制备了表面光亮、无裂纹的GaN外延材料,其(002)晶面半高宽为428 arcsec,表面粗糙度为0.194 nm.结果表明,采用3层A1GaN缓冲层结构可以有效地降低GaN材料的张应力和位错密度,进而遏制表面裂纹的出现,提高晶体质量.     

In_xGa_(1-x)As/InP混晶的长波长光学声子谱

本文报道In_xGa_(1-x)As/InP混晶的室温喇曼散射测试结果。所用的样品用MOCVD方法生长在〈100〉晶向的InP衬底上,混晶组分x值在0.17-0.5之间。实验结果表明,In_xGa_(1-x)AS混晶的年波长光学声子谱呈现双模行为,具有类GaAs和类InAs两个光学支,同时探索了晶体应力对LO声子模线型的影响。     

物理气相传输法制备层状MoS2薄膜

以化学气相沉积(CVD)方法在蓝宝石衬底上沉积一层较厚的MoS_2膜作为前驱体,使用物理气相传输(PVT)方法制备了层状MoS_2薄膜。用光学显微镜、扫描电子显微镜、喇曼光谱和光致发光光谱对制备的层状MoS_2膜表面形貌、层数、光学特性进行了研究。分析了源和衬底距离对MoS_2薄膜沉积的影响,发现距离较近有利于成核概率增大,形成连续膜,但是易引入不稳定因素导致立体生长的MoS_2纳米片,同时观察到出现树枝状生长,这是由于前驱体质量过剩引起的部分晶面生长速率过高导致的。喇曼光谱测试表明,薄膜大部分为单层膜和双层膜,有少量的多层膜,膜的光致发光光谱强度与层数有关,单层膜光致发光光谱强度最强。     

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。     

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.     

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.     

A Versatile Mixed-Signal Pin Approach for Cost-Effective Test of Automotive ICs

Integrated circuits (ICs) intended for increasingly sophisticated automotive applications bring unique test demands. Advanced ICs for applications such as highly integrated automatic braking system (ABS) and airbag controllers combine high voltage digital channels, significant VI demands and precise timing capability. Along with continued missioncritical reliability concerns, the trend toward higher voltage operation and increased device integration requires specialized test capabilities able to extend across the wide operating ranges found in automotive applications. Among these capabilities, automotive test requirements increasingly dictate a need for a cost-effective versatile mixed-signal pin electronics with very high data rates reaching up to 50MHz with a voltage swing of-2 V to +28 V.     

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.     

Optical vibration and deviation measurement of rotating machine parts

It is of interest to get appropriate information about the dynamic behaviour of rotating machinery parts in service. This paper presents an approach of optical vibration and deviation measurement of such parts. Essential of this method is an image derotator combined with a high speed camera or a laser doppler vibrometer （LDV）.