Comparison of spatial compositional uniformity and dislocation density for organometallic vapor phase epitaxial Hg1−x CdxTe grown by the direct alloy and interdiffused growth processes

Etch pit density and spatial compositional uniformity data are presented for organometallic vapor phase epitaxial Hg_1−x Cd_x Te grown by the direct alloy and interdiffused growth methods. For alloy growth, composition variation is as low as Δx=0.004 and 0.02 over 2- and 3-in diam areas, respectively; while for growth on CdZnTe substrates, etch pit density values lower than 2×10⁵ cm⁻² have been achieved. For interdiffused growth on CdZnTe, etch pit density values lower than 5×10⁵ cm⁻² have been obtained, while the composition variation is usually Δx≤0.004 and 0.014 over 2- and 3-in diam areas, respectively. Data demonstrate that the choice of particular CdZnTe substrate strongly affects the subsequent etch pit density measured in the layer. Reasonably uniform n-type doping over 3-in diam area using the source triethylgallium is also reported for both growth methods.     

Mechanism of defect formation in low-dose oxygen implanted silicon-on-insulator material

The defects and microstructure of low-dose (<0.7 × 10¹⁸ cm⁻²), oxygen-implanted silicon-on-insulator (SIMOX) material were investigated as a function of implant dose and annealing temperature by plan-view and cross-sectional transmission electron microscopy. The threading-dislocations in low-dose (0.2∼0.3×10¹⁸ cm⁻²), annealed SIMOX originate from unfaulting of long (∼10 μm), shallow (0.3 μm), extrinsic stacking faults generated during the ramping stage of annealing. As dose increases, the defect density is reduced and the structure of the buried oxide layer evolves dramatically. It was found that there is a dose window which gives a lower defect density and a continuous buried oxide with a reduced density of Si islands in the buried oxide.     

采用扫描电镜的ECP技术分析人工合成金刚石晶体中的晶体缺陷

本文应用扫描电镜的ＥＣＰ技术对人造金刚石晶体表面的位错密度，进行了实验分析，并同位错蚀坑分析技术的测量结果进行了比较，结果表明，如采用临界束流强度作为描述ＥＣＰ本征衬度的参数，则它同位错密度间存在明显定量的数学关系，因此上述临界束流强度可用来评价晶体中位错密度的相对变化。     

较大直径、低位错锑化铟单晶的研制

本文简要介绍了用ＴＤＫ－３６单晶炉拉制的较大直径（φ＝２５ｍｍ）、低位错（＜１００ｃｍ￣（－２））的锑化铟单晶的理论和实践。通过对晶体生长室内温场，特别是内外坩埚尺寸的调整及对循环水流量的控制，成功地拉制出较大直径、低位错的锑化铟单晶。     

热退火对GaAs半导体晶片均匀性的影响

主要讨论热退火(850℃退火2小时)对GaAs半导体晶片的位错密度和电阻率的影响,阐述了位错密度的分布与电阻率分布之间的关系。通过特殊的实验方法得到的结果证明:适当的退火处理将改善GaAs晶片中缺陷密度、电阻率的大小及分布,从而得到均匀性较好的GaAs材料。     

AlN基板与金属化层界面的分析电镜研究

利用各种分析电镜观察了掺杂助烧剂和未掺杂助烧剂的ＡｌＮ陶瓷的微观结构特征，鉴别了ＡｌＮ中的第二相，研究了ＡｌＮ基板上薄膜（Ａｕ－Ｐｔ－Ｔｉ）和厚膜（Ｍｏ－Ｍｎ）金属化界面的结构。     

Φ200 mm硅单晶的生长工艺特点

在全自动拉晶条件下，讨论了拉制Φ２００ｍｍ硅单晶遇到的新问题。热场配置、工艺参数的选择、石英坩埚的选用等有了更严格的要求。合理的轴向温度梯度和径向温度梯度、低拉速、低晶转及规范的拉晶工艺是拉制大直径单晶的关键。     

影响碲镉汞晶体电子迁移率的主要因素

通过把迁移率的实测值与影响ＨｇＣｄＴｅ晶体电子迁移率的主要散射机构进行对比，得出结论：位错是ＨｇＣｄＴｅ晶体低温电子迁移率降低的主要原因。     

Molecular dynamics simulation of dislocation nucleation and motion at γ/γ′ interface in Ni-based superalloy

Molecular dynamics simulations are conducted on the dislocation behavior at the apices and edges of cuboidal Ni₃Al precipitate in a pure Ni matrix, or the idealized γ/γ′ microstructure in a Ni-based superalloy. A tensile simulation of the [001] direction is implemented with a periodic cell that has eight cubic precipitates in order to investigate the nucleation site of dislocation in the idealized microstructure with no defects other than the γ/γ′ interfaces. The effect of residual internal stresses on the stability of the interfaces is also discussed. Other simulations are conducted on the behavior of edge dislocations nucleated from a free surface and proceeding in the γ matrix toward γ′ precipitates under shear force. Dislocation pinning at γ′ precipitates, bowing-out in the γ channel, pile-up and nucleation of superdislocation in the γ′ precipitate are simulated and inspected in detail. Discussions on the size of the γ/γ′ microstructure and the sharpness of the edge of the γ′ precipitate are also presented.