多孔硅的应用研究进展

多孔硅是一种新型的纳米半导体光电材料,室温下具有优异的光致发光、电致发光等特性,易与现有硅技术兼容,极有可能实现硅基光电器件等多个领域的应用．扼要论述了多孔硅在绝缘材料、敏感元件及传感器、照明材料及太阳能电池、光电器件以及作为合成其它材料的模板等多个领域内的应用进展情况,并对其发展前景作了展望。     

硼离子选择注入制备多孔硅微阵列

根据 p型硅和 n型硅不同的制备多孔硅的工艺条件 ,利用硼离子选择注入 ,在 n型硅片上的局部微区域 ,形成易于腐蚀的 p型硅 ,用电化学腐蚀方法制备出图形化的多孔硅阵列 .省去了传统掩膜腐蚀工艺的掩膜材料的选取与制备以及后道工艺中掩膜材料的清除等工艺 ,克服了掩膜材料掩蔽效果较差以及存在横向钻蚀等缺点 .通过 AFM,SEM测试 ,证明该方法的效果很好     

Ka波段Si基微机械宽带垂直过渡

介绍了一种适用于三维毫米波集成电路的Si基微机械垂直过渡,该垂直过渡是两层0.1mm厚的共面波导传输线通过0.3mm厚中间层,在中间层采用了同轴结构,该同轴结构通过金属化通孔来实现。这一设计原理简单,结构简洁,便于优化设计,具有很宽的带宽和平坦的幅度响应。运用三维电磁场仿真软件对该垂直过渡结构进行了建模,并作了优化设计与仿真计算,运用微机械金属化通孔工艺和多层键合工艺研制了样品。在片测试结果表明该样品性能良好,在26.5～34.0GHz该过渡插入损耗小于3.5dB,带内起伏小于2dB。     

Study of waveguide coupling efficiency in hybrid silicon lasers

This paper presents a new method to increase the waveguide coupling efficiency in hybrid silicon lasers. We find that the propagation constant of the InGaAsP emitting layer can be equal to that of the Si resonant layer through improving the design size of the InP waveguide. The coupling power achieves 42% of the total power in the hybrid lasers when the thickness of the bonding layer is 100 nm. Our result is very close to 50% of the total power reported by Intel when the thickness of the thin bonding layer is less than 5 nm. Therefore, our invariable coupling power technique is simpler than Intel＇s.     

掺杂室沉积本征微晶硅材料及其在太阳能电池中的应用

在掺杂P室采用甚高频等离子体增强化学气相沉积（VHF—PECVD）技术,制备了不同硅烷浓度条件下的本征微晶硅薄膜．对薄膜电学特性和结构特性的测试结果分析表明：随硅烷浓度的增加,材料的光敏性先略微降低后提高,而晶化率的变化趋势与之相反;X射线衍射（xRD）测试表明材料具有（220）择优晶向．在P腔室中用VHF—PECVD方法制备单结微晶硅太阳能电池的i层和p层,其光电转换效率为4．7％,非晶硅／微晶硅叠层电池（底电池的p层和i层在P室沉积）的效率达8．5％．     

基于IBM SiGe BiCMOS工艺5PAe的2GHz功率放大器设计

采用IBM公司刚刚推出试用的0.35μm SiGe BiCMOS开发性工艺5PAe设计并实现了一个2GHz功率放大器. 该放大器采用两级单端结构,除集电极扼流电感外,其余元件全部片上实现,具有集成度高、结构简单的特点. 通过在管子基极和匹配电感中串联电阻,实现了全频段稳定. 键合测试表明,在所有电源电压下电路均能稳定工作. 在VC=3.5V, VB=6V, f=2.0GHz时,小信号增益为20.8dB,输入输出反射系数分别小于-17和-16dB, Pout-2dB约为24dBm. 而在输出功率为25.1dBm时,功率附加效率达到21.5%,二次和三次谐波分别小于-45和-52dBc,因而具有较好的线性度.     

纳米硅/晶体硅异质结电池的暗I-V特性和输运机制

采用HWCVD技术在P型CZ晶体硅衬底上制备了纳米硅／晶体硅异质结太阳电池,测量了晶体硅表面在不同氢处理时间下的异质结的暗I-V特性和相应的电池性能参数．室温下的正向暗I-V特性采用双二极管模型来拟合,可将0～1V的电压范围区分为4个区域：旁路电阻（0～0．15V）、非理想二极管2（0．15～0．3V）、理想二极管1（0．3～0．5V）和串联电阻（〉0．5V）．拟合结果表明,适当的氖处理时间（～30s）可有效降低非理想二极管的理想因子n2,即降低界面复合电流,表明具有好的界面特性．对于282～335K的暗I—V温度特性的研究表明,在0．15～0．3V的低电压范围,暗电流主要由耗尽区的复合电流提供,0．3～0．5V电压范围,对输运起主要作用的是隧穿过程,该过程可用通过界面陷阱能级的隧穿模型来解释．     

Relevance of Thermal Mismatch in Large-Area Composite Substrates for HgCdTe Heteroepitaxy

It is well known that the large lattice mismatch (>14%) associated with CdTe/Si, CdTe/Ge, and CdTe/GaAs composite substrates, is a great contributor to large dislocation densities and other defects that limit the performance of HgCdTe-based infrared detectors. Though thermal expansion mismatch is another possible contributor to material defects, little work has been done towards documenting and understanding its effects in these systems. Here, we perform studies to determine the relative contributions of lattice and thermal mismatch to CdTe film characteristics, including dislocation density and residual stress. Unannealed and thermally cycled films are characterized using x-ray diffraction, defect decoration, and Nomarski and transmission electron microscopy. For CdTe/Si, the residual stress is consistently observed to be tensile, while for CdTe/Ge and CdTe/GaAs, a compressive residual film stress is measured. We show based on theoretically predicted stress levels that the experimental measurements imply the dominance of thermal mismatch in the residual stress characteristics.     

Stress-Induced Grain Boundary Migration in Polycrystalline Copper

We use three-dimensional (3D) grain-continuum models to study grain boundary migration, treating each grain with anisotropic elastic properties. Grain boundary speeds are computed using a finite element method to calculate differences in strain energy density across grain boundaries. Body-fitted finite element meshes are used. An interface tracking program, PLENTE, is used to develop starting structures and move the grain boundaries based on these speeds. We demonstrate this procedure on textured films consisting of 〈100〉 and 〈111〉 fiber textured film. We also apply the model to a short section of a Cu line embedded in oxide. We conclude with a discussion on the relative impact of different driving forces for grain boundary motion.