Amorphization and Solid-Phase Epitaxial Growth of C-Cluster Ion-Implanted Si

Amorphization and solid-phase epitaxial growth were studied in C-cluster ion-implanted Si. C₇H₇ ions were implanted at a C-equivalent energy of 10 keV to C doses of 0.1 × 10¹⁵ cm⁻² to 8.0 × 10¹⁵ cm⁻² into (001) Si wafers. Transmission electron microscopy revealed a C amorphizing dose of ~5.0 ×  10¹⁴ cm⁻². Annealing of amorphized specimens to effect solid-phase epitaxial growth resulted in defect-free growth for C doses of 0.5 × 10¹⁵ cm⁻² to 1.0 × 10¹⁵ cm⁻². At higher doses, growth was defective and eventually polycrystalline due to induced in-plane tensile stress from substitutional C incorporation.     

Analytical Model for Redistribution Profile of Ion-Implanted Impurities During Solid-Phase Epitaxy

We evaluated the redistribution profiles of ion-implanted impurities during solid-phase epitaxy using Rutherford backscattering spectrometry (RBS). RBS data revealed that the As concentration changes only near the moving amorphous/crystal interface. We derived an analytical model for the redistribution profiles using a segregation coefficient m between amorphous and crystalline Si, introduced a parameter of reaction length l that is the distance where impurities were exchanged, and obtained good agreement with experimental data with an m value of 3 and an l value of 1 nm for As. Furthermore, we applied our model to P and B redistribution profiles and obtained good agreement with corresponding m value of 4 and l value of 1 nm for P and m value of 0.3 and l value of 1 nm for B     

非晶硅磷掺杂固相效率的计算

本文介绍一种计算高质量GDa-Si磷掺杂固相效率η(S)的方法。所得的结果是:当掺杂剂气相浓度C(g)等于固相浓度C(S)时,对于C(g)<10~(-4),η(S)是常数,其值为20％,即a-Si薄膜中四配位磷原子密度N(P_4~+)与三配位磷原子密度N(P_3~0)之比是1/4;对于C(g)>10~(-4),、η(S)服从Street定律,其值为10~(-2)～10~(-3)。N(P_4~+)/N(P_3~0)～1/100。P_3~0P_4~0—D之间的热平衡反应常数K～10~(16)cm~(-3)。但是,当C(g)≤10~(-6)时,K可降到10~(16)cm~(-3)。     

外延淀积过程中的自掺杂抑制

外延层杂质浓度是影响器件电学性能的重要参数。文章对外延淀积过程中自掺杂的产生过程进行了分析，提出了在外延淀积过程中可以通过改变气流、温度及采用背封技术、二步外延等方法来解决外延自掺杂，从而改善器件的特性参数。     

Recrystallization of Electrodeposited Copper Thin Films During Annealing

The microstructure evolution of electrodeposited copper thin films was studied at room and elevated temperatures. The effects of isothermal and nonisothermal treatments were investigated. The heating rate in nonisothermal treatment was found to significantly control the recrystallization temperature and time. The Johnson–Mehl–Avrami–Kolmogorov model was applied to describe the fraction recrystallized under isothermal conditions. It was proven that the recrystallization of copper films during nonisothermal annealing can be modeled using the additivity rule. Based on the isothermal results, a model was applied to predict the recrystallization kinetics during nonisothermal heat treatments.     

高浓度磷扩散的模拟

介绍了在SilvacoTCAD软件中最新加入的磷扩散模型──PERCO模型。该模型建立了杂质、空位及自间隙的连续性方程，描述了由于高浓度磷扩衡引起的超平衡点缺陷对磷在硅中分布的影响。已将该模型用于对实际工艺模拟的校正，取得满意的结果，同时，可以体会到模型校正的意义。     

Si~+注入SOS中退火固相外延再生长改善结晶质量

本文研究Si~+室温深注入(150～160keV,1～3×10~15/cm~2)SOS中600+1050℃两步退火固相外延再生长改善SOS膜界面附近结晶质量和Si~+室温浅注入(85keV,3×10~(15)/cm~2)SOS中600+1050℃两步退火固相外延再生长改善SOS膜表面结晶质量的工艺.180keVH~+沟道效应—背散射测量表明,两步Si~+注入和两步退火团相外延再生长工艺能够有效地改善SOS膜结晶质量°表面归一化最小产额x_o、界面最小产额x_i 和退道率dx/dz分别减小到0.06、0.12和0.19/μm.     

重掺磷衬底上外延层生长工艺研究

重掺磷衬底上硅外延片是制作集成电路开关电源的肖特基二极管和场控高频电力电子器件的首选产品。重掺磷衬底外延片可以大幅降低压降中半导体部分引起的压降所占的比例。介绍了重掺磷外延片的一种实用生产技术,在高浓度衬底外延后失配现象、杂质外扩抑制方法、减少外延过程中衬底磷杂质的挥发等方面进行了研究。在研究的基础上使用CSD公司的EpiPro5000型外延设备进行工艺试验,采用盖帽层分层生长、变流量赶气和低温度生长等工艺条件控制磷杂质的扩散和挥发,从而减少自掺杂效应,获得良好的电阻率均匀性和陡峭的外延层过渡区。试验结果已成功应用于大规模生产,得到了用户认可。     

用椭偏光法研究离子注入层的红外辐照再结晶机理

本文用椭偏光法结合阳极氧化剥层技术研究了(31)~P离子注入硅的损伤分布及在红外辐照快速退火中的再结晶机理。结果表明,对于1OOkeV,5×10_(14)cm~(-2)(31)~P离子注入硅,注入区形成了970(?)的隐埋非晶层。将此样品在1100℃源温下辐照30秒,非晶层从与单晶衬底的交界面处向表面固相外延再结晶240(?),外延速率为8(?)/秒。     

Control of Hole Concentration in Liquid-Phase Epitaxial Layers of PbTe by As Doping

Liquid-phase epitaxial layers of PbTe grown at ⋍55O‡C have been doped p-type over the concentration range 5 × 10¹⁶ − 5 × 10¹⁸cm^-3by adding from 0.004 − 10 at.% arsenic to the melts. The hole concentrations of the layers, which were grown on p+ substrates, were obtained from plasma reflectivity and thermoelectric probe measurements. The latter assessment technique is shown to be a reliable and simple method for determining the hole concentration in epitaxial layers with thicknesses greater than ≃ 5ym, provided the damage introduced by the probe is controlled. Damage can cause negative thermoelectric power signals to be obtained from p-type PbTe, showing that dislocations introduce donor centres in this material.     

激光有源欺骗最大干扰距离试验方法探讨

依据激光在大气中的传播规律,结合激光有源欺骗干扰设备的工作原理和使用方法,提出了消光法用于激光有源欺骗最大干扰距离试验的思想,并推导出了理论公式,对试验时应注意的有关问题进行了讨论．     

Cyclic Annealing During Metalorganic Vapor-Phase Epitaxial Growth of (211)B CdTe on (211) Si Substrates

High-quality (211)B CdTe buffer layers on Si substrates are required to enable Hg_1–x Cd _x Te growth and device fabrication on lattice-mismatched Si substrates. Metalorganic vapor-phase epitaxy (MOVPE) of (211)B CdTe on Si substrates using Ge and ZnTe interlayers has been achieved. Cyclic annealing has been used during growth of thick CdTe layers in order to improve crystal quality. The best (211)B CdTe/Si films grown in this study display a low x-ray diffraction (XRD) rocking-curve full-width at half-maximum (FWHM) of 85 arcsec and etch pit density (EPD) of 2 × 10⁶ cm⁻². These values are the best reported for MOVPE-grown (211) CdTe/Si and are comparable to those for state-of-the-art molecular beam epitaxy (MBE)-grown CdTe/Si.     

合肥地区2013年春节期间PM2.5质量浓度演变特征

利用2013年2月8～19日合肥地区获取的大气颗粒物和常规气象观测资料,依据烟花爆竹燃放、降水过程、相对湿度 和风速特点,分析了PM2.5质量浓度在不同气象条件下的变化特征。结果表明:合肥春节期间PM2.5质量浓度平 均值为58.3 μg/m3,仅出现两个PM2.5质量浓度污染日;城市居民集中燃放烟花爆竹引起PM2.5质量浓度 急剧增大,但主要排放PM1;降水过程对PM2.5质量浓度具有湿沉降作用,过程降水量越大, PM2.5质量浓 度湿沉降量越大; PM1、PM1～2.5 和PM2.5～10与相对湿度的相关系数分别为0.45、0.26和－0.07,粒径 尺度越小的颗粒物吸湿增长特性越显著; PM2.5质量浓度演变与风速呈负相关,两者的相关 系数为－0.33,风速越大,越利于颗粒物扩散。     

Effect of Local Hot Spots on the Maximum Dissipation Rates During Flow Boiling in a Microchannel

One of the most promising technologies to replace air-cooling of micro-processor chips is flow boiling in microchannels. The very high heat flux dissipation from micro-processor chips is highly non-uniform due to the presence of multiple localized hot spots usually related to the localization of bridges and gate oxide shorts. Previous studies focused on the performance of microchannels under uniform heating conditions. Recently, Revellin and Thome (see Int. J. Heat Mass Transf., vol 51, no.5-6, p. 1216-25, 2008) have proposed a new theoretical model to predict the critical heat flux (CHF) in microchannels. This model has been modified here to take into account a non-uniform axial heat flux along a microchannel. The model is used here to perform a local hot spot study to investigate the effects of fluid, saturation temperature, mass flux, microchannel diameter, heated length, size, location and number of hot spots as well as the distance between two consecutive hot spots. Based on the present simulations, to best dissipate a hot spot's heat flux, microchannel heat sinks should follow the following recommendations for a channel of fixed length: determine the optimum channel diameter for the fluid (typically either very small or large is best), utilize as high of mass flux as feasible, and design with as low of saturation temperature as possible. Furthermore, the local hot spot size should be as small as possible, the number of local hot spots as few as possible and the distance between two hot spots as large as possible. Utilizing the present numerical method for individual microchannels arranged in parallel in a multi-microchannel cooling element, it is possible to simulate the entire power dissipation profile of a microprocessor die for local limits of CHF.     

The Role of Elastic and Plastic Anisotropy of Sn in Recrystallization and Damage Evolution During Thermal Cycling in SAC305 Solder Joints

Because failures in lead-free solder joints occur at locations other than the most highly shear-strained regions, reliability prediction is challenging. To gain physical understanding of this phenomenon, physically based understanding of how elastic and plastic deformation anisotropy affect microstructural evolution during thermomechanical cycling is necessary. Upon solidification, SAC305 (Sn-3.0Ag-0.5Cu) solder joints are usually single or tricrystals. The evolution of microstructures and properties is characterized statistically using optical and orientation imaging microscopy. In situ synchrotron x-ray measurements during thermal cycling are used to examine how crystal orientation and thermal cycling history change strain history. Extensive characterization of a low-stress plastic ball grid array (PBGA) package design at different stages of cycling history is compared with preliminary experiments using higher-stress package designs. With time and thermal history, microstructural evolution occurs mostly from continuous recrystallization and particle coarsening that is unique to each joint, because of the specific interaction between local thermal and displacement boundary conditions and the strong anisotropic elastic, plastic, expansion, and diffusional properties of Sn crystals. The rate of development of recrystallized microstructures is a strong function of strain and aging. Cracks form at recrystallized (random) boundaries, and then percolate through recrystallized regions. Complications arising from electromigration and corrosion are also considered.     

基于siPLS的强化生物除磷污泥胞内糖原近红外分析

为了快速、准确地测定强化生物除磷（EBPR）过程中污泥胞内糖原的含量,采用4种预处理方法分别对污泥近红外光谱进行预处理,并结合联合区间偏最小二乘（siPLS）进行变量优选,建立光谱吸光度数据与糖原含量的定量分析模型。结果表明,将一阶S-G（Savitzky-Golay）平滑处理后的光谱等分为20个子区间,联合子区间[10131619]建立的siPLS模型预测效果最优,预测集的均方根误差（RMSEP）和相关系数（rp）分别达到0.0048、0.9105,且该模型的交互验证和外部验证相对分析误差（RPD）均大于3.0。一阶平滑处理后的光谱 siPLS 模型预测精度高、建模变量少,可实现糖原含量的快速测定。     

"数字逻辑"课程教学方法探讨

本文从教学的逻辑性与启发性方面，以及师生关系方面论述了教师在授课中引导学生积极思维，创新思维，提高教学效果的一些方法。     

电压骤降下双馈电机撬棒投切时刻对电网的无功功率影响

风力发电机规模和单机容量不断增大,电网对风力发电机之类的可再生能源并网有着极其严格的要求,其中最具挑战性的要求是低电压穿越,即在电网出现跌落时,要求风机在一定时间内不得脱网,直至发电机发出一定的无功功率帮助电网恢复。本文研究在电网出现大幅跌落时,通过控制撬棒投切的不同时刻,来讨论是否其投切时刻影响着系统从电网吸收的无功功功率,最终通过合理的投切时刻来最大程度上减少系统从电网吸收的无功功率,帮助电网更好的恢复。