A Multi-Finger Si_(1-x)Ge_x/Si Heterojunction Bipolar Transistor for Wireless Power Amplifier Applications

A large area multi-finger configuration power SiGe HBT device(with an emitter area of about 880μm~2)was fabricated with 2μm double-mesa technology.The maximum DC current gain β is 214.The BV_(CEO) is up to 10V,and the BV_(CBO) is up to 16V with a collector doping concentration of 1×10~(17)cm~(-3) and collector thickness of 400nm.The device exhibits a maximum oscillation frequency f_(max) of 19.3GHz and a cut-off frequency f_T of 18.0GHz at a DC bias point of I_C=30mA and V_(CE)=3V.MSG(maximum stable gain)is 24.5dB,and U(Mason unilateral gain)is 26.6dB at 1GHz.Due to the novel distribution layout,no notable current gain fall-off or thermal effects are observed in the I-V characteristics at high collector current.

光子晶体在Si基发光器件中的应用

在Si基集成光电子学的发展中,实现高效的Si基光源始终是人们期待的目标.但是Si材料的间接带隙特性导致其发光效率低.目前,已经探索了多种Si基材料体系以提高Si材料的发光效率,但是尚未取得突破性的进展.近年来,光子晶体以其独特的控光能力而备受人们的关注,将光子晶体引入到Si基材料体系中可以显著提高Si基材料的发光效率,这无疑对Si基光电子学的发展起到了重要的贡献.本文简述了利用光子晶体提高Si基材料发光效率的机制,介绍了光子晶体在几种Si基材料中的应用,探索了Si基光子晶体发光器件的潜在应用前景.

DCXRD Investigation of a Ge/Si（001） Island Multilayer Structure

A Ge/Si（001） island multilayer structure is investigated by double crystal X-ray diffraction, transmission electron microscopy,and atomic force microscopy. We fit the satellite peaks in the rocking curve by two Lorentz lineshapes, which originate from the wetting layer region and the island region. Then from the ratio of the thick- nesses of the Si and Ge （GeSi） layers as determined by TEM,tbe Ge compositions of the wetting layer and islands are estimated to be about 0. 51 and 0. 67, respectively,according to the positions of the fitted peaks. This proves to be a relatively simple way to investigate the Ge/Si （001） island multilayer structure.

Uniformity Investigation in 3C-SiC Epitaxial Layers Grown on Si Substrates by Horizontal Hot-Wall CVD

50mm 3C-SiC epilayers are grown on （100） and （111） Si substrates in a newly developed horizontal lowpressure hot-wall CVD reactor under different growth pressures and flow rates of H_2 carrier gas. The structure,electrical properties, and thickness uniformity of the 3C-SiC epilayers are investigated by X-ray diffraction （XRD） ,sheet resistance measurement, and spectroscopic ellipsometry. XRD patterns show that the 3C-SiC films have excellent crystallinity. The narrowest full widths at half maximum of the SIC（200） and （111） peaks are 0.41° and 0.21°, respectively. The best electrical uniformity of the 50mm 3C-SiC films obtained by sheet resistance measurement is 2.15%. A σ/mean value of ± 5.7% in thickness uniformity is obtained.

nc-Ge/Si岛基光子晶体单点缺陷腔的数值模拟与分析

阐述了利用光子晶体单点缺陷微腔来提高Ge/Si纳米岛发光效率的机理.通过3D FDTD方法计算出在平板厚度为300nm时,谐振波长随a和r/a变化的规律,即当给定r/a,h时,波长随晶格常数成次线性增加;当给定a,h时,波长随r/a的增加而减小.并从理论上给予分析.

射频磁控溅射制备掺Al的纳米Si-SiO_2复合薄膜及其光致发光特性

采用射频磁控技术和退火处理制备掺Al的纳米Si-SiO_2复合薄膜.通过X射线衍射(XRD)、X射线光电子能谱(XPS)和傅里叶变换红外光谱(FTIR)表征了薄膜的结构,组分和成键情况.掺Al在SiO_2中造成氧空位,使薄膜光致发光强度增强,并出现新的发光峰.退火温度对掺Al薄膜的光致发光的峰位和峰强有较大影响.

Analysis of Si/GaAs Bonding Stresses with the Finite Element Method

In conjunction with ANSYS, we use the finite element method to analyze the bonding stresses of Si/GaAs. We also apply a numerical model to investigate a contour map and the distribution of normal stress,shearing stress,and peeling stress,taking into full consideration the thermal expansion coefficient as a function of temperature. Novel bonding structures are proposed for reducing the effect of thermal stress as compared with conventional structures. Calculations show the validity of this new structure.

Si／SiGe量子级联激光器研究进展

Si／SiGe量子级联激光器是一种新型的带内跃迁的红外光源，突破了Si基材料间接带隙特性对光跃迁的限制。Si/SiGe量子级联激光器的开发将为实现太赫兹有源器件的硅基集成产生深远影响。文章介绍了Si/SiGe量子级联激光器的工作原理，以及这类激光器在能带设计、材料生长和波导制作方面的最新进展。

双源电子束蒸发制备Si/SiO2光学薄膜的工艺

用双源电子束蒸发的方法,在K9玻璃基片上蒸镀Si和SiO2的混合膜.通过改变两种膜料蒸发速率的比例,得到的各个膜层,其折射率大小在两种膜料折射率之间的范围内变化.从实验上得出了混合膜层的折射率随Si和SiO2蒸发速率比变化的规律,并讨论了这种淀积方法的优越性.

离子束溅射制备Si／Ge多层膜及红外吸收性能研究

采用离子束溅射方法在Si衬底上制备Si／Ge多层膜。通过改变生长温度、溅射速率等因素得到一系列Si／Ge多层膜样品。通过X射线衍射、拉曼散射、原子力显微分析（AFM）等表征方法研究薄膜结构与生长条件的关系。在小束流（10mA）、室温条件下制备出界面清晰、周期完整的Si／Ge多层膜。通过红外吸收谱的测量发现薄膜样品具有较好的红外吸收性能。

InP/Si键合界面热应力分析

从理论上分析了键合热应力产生的原因,在此基础上,采用双层条状金属热应力模型讨论InP/Si键合过程中应力的大小及分布情况.结果表明, 由剪切应力和晶片弯矩决定的界面正应力是晶片中心区域大面积键合失败的主要原因,同时InP/Si键合合适的退火温度应该在250～300 ℃.最后在300 ℃退火条件下很好地实现了InP/Si键合,界面几乎没有气泡,有效键合面积超过90%.

光子晶体对nc-Ge/Si岛发光增强的模拟

在Si基集成光电子学的发展中,高效的Si基光源是人们不懈追求的目标.但是Si材料的间接带隙特性导致其发光效率低,更谈不上受激发射.于是人们探索了多种Si基材料体系来提高Si材料的发光效率,并在不同程度上取得了重要的进展.在众多的Si基发光材料体系中,Ge/Si量子点材料,不仅生长工艺与标准的CMOS工艺有很好的兼容性,而且发光波长能够覆盖重要的光通信波段即1.3～1.55 μm,因此成为实现Si基发光器件的重要途径之一.但是目前这种材料的发光效率仍很低,所以提高其发光效率自然成为人们关注的焦点.如果将光子晶体引入到nc-Ge/Si材料中,它不仅可以改变材料本身的自发发射特性,而且可以改变发射的光子的提取效率,从而使材料的发光效率得到增强.提出了在Ge/Si量子点材料中引入光子晶体结构来提高其发光效率,包括光子晶体点缺陷腔结构和带边模式工作的完整光子晶体结构,并从理论上分析了发光效率提高的原理.针对发光波长在1.5 μm附近的材料结构,模拟出了相应的光子晶体的结构参数.从模拟结果可以看出,对于缺陷腔的光子晶体结构,采用单点缺陷微腔很好地实现了单模运作,但是微腔内有源材料的体积很小,因此得到的发光效率很低.而采用耦合缺陷腔的结构和H2腔都增加了腔内有源区的体积.但是耦合腔与H2腔相比,谐振腔模减少,主谐振模式的峰值强度增加,更容易实现单模发光.因而更适用于提高nc-Ge/Si的发光效率.而带边模式工作的光子晶体结构,尺寸较大,不需引入缺陷,工艺上更容易实现.

Low -temperature preparation of ZnO films on Si substrates by MOCVD

ZnO films were deposited on Si（100） substrates at 300℃ by metal - organic chemical vapor deposition（MOCVD）. The effect of different ratios of DEZn to N2O on crystal quality was analyzed. It is found that the optimum ratio of DEZn to N2O is 2.1. And in this optimum growth condition, X - ray diffraction （XRD） and scanning probe morphology （SPM） images indicate that the films grow along the c - axis orientation. ZnO film exhibits a strong UV optical absorption near 388 nm. And the optical absorbance is close to zero,that indicates nearly 100% optical transparence. Photoluminescence （PL） spectrum shows only strong near - band - edge emissions with little or no deep - level emission related to defects. The full - width at half - maximum （FWHM） of the ultraviolet emission peak is 80meV. The results indicate that better crystal quality can be obtained.

Growth of near planar Si0.5Ge0.5 epitaxial layers directly on Si substrate by UHV/CVD at 500℃

The relationship between Ge content of Si1-xGex layers and growth conditions was investigated via UHV/CVD system at relative low temperature of 500℃. Si1-xGex layers were in a metastable state in this case. 10-period strained 3.0 nm- Si0.5Ge0.5/3.4 nm- Si multi quantum wells were obtained directly on Si substrate. Raman Measurement, high resolution electron microscopy and photoluminescence were used to characterize the structural and optical properties. It is found that such relative thick Si0.5Ge0.5/Si multi quantum wells are still near planar and free of dislocations, that makes it exploit applications to electrical and optical devices.

纳米Si镶嵌SiO2薄膜的发光与非线性光学特性的应用

采用射频磁控溅射技术和热退火处理制备了纳米Si镶嵌SiO2薄膜，在室温下观察到光致发光现象，峰值分别位于360，430和835nm，结合吸收谱、光致发光激发谱和X射线衍射分析讨论了发光机理．利用纳米Si镶嵌SiO2薄膜的非线性光学特性可作为可饱和吸收体，在Nd