SiGe异质结双极晶体管频率特性分析

在分析载流子输运和分布的基础上,建立了物理意义清晰的各时间常数模型．模型体现了时间常数与SiGe异质结双极晶体管结构参数及电流密度之间的关系,并且包含了基区扩展效应．同时对特征频率与上述参数之间的关系进行了模拟分析和讨论．     

多发射极Si/SiGe异质结晶体管

在硅衬底上外延生长一层Si_1-xGe_x合金材料,它的带隙随组分x的增加而变窄,如果用Si_1-xGe_x窄带材料作晶体管基区,利用硅作为集电极和发射极构成双极晶体管,就可以很容易实现器件的高频、高速、大功率。设计了一种以Si/Si_1-xGe_x/Si为纵向结构,梳状10指发射区为横向结构的异质结晶体管,利用双台面工艺方法制造出具有如下参数的器件:电流增益β=26、V_CB=7V、I_CM≥180mA、f_T≤ 2GHz,实现了高频大功率,充分显示出Si/Si_1-xGe_x材料的优越性。     

Si／SiGe腐蚀停止技术的研究及其在SiGe／SiHBT工艺中的应用

对ＳｉＧｅ／Ｓｉ腐蚀停止技术进行了大量的实验研究，分析了腐蚀的化学机理，并在一定的腐蚀液浓度和温度下，获得了Ｓｉ和ＳｉＧｅ的腐蚀速率比大于３０的结果。该技术极宜在ＳｉＧｅ／ＳｉＨＢＴ制作中应用。     

SiGe HBT双端口网络参数模型和模拟

针对等效电路模型中应用频率范围窄、精度低以及在高频器件分析过程中与网络分析法的兼容性差等问题,由交流I-V方程出发,推导得到使用散射参数描述的锗硅异质结双极晶体管(SiGe HBT)的双端口网络参数模型．着重分析了Si／SiGe异质结和基区结构对器件交流性能的作用,并尽量避免省略物理量和对频率上限的限制．与等效电路模型相比,模型的频域精度由半定量提高至优于5％,并将适用频率由特定范围扩展至只计入本征参数时的特征频率fT,涵盖全部SiGe HBT的小信号工作频段,为器件的设计、优化和应用提供了一种宽频带和高精度的定量模拟方法．     

SiGe/Si异质结PIN顶注入电光调制器的数值分析

针对电光调制器的调制效率低造成调制器的驱动电压较高的问题。文中基于等离子色散效应理论,利用计算机辅助设计模拟方法,设计了一种SiGe/Si异质结PIN顶注入硅基电光调制器,分析了不同结构尺寸、掺杂浓度下折射率变化、吸收系数变化和衰减等影响。研究结果表明：该器件有效增大了折射率变化和吸收系数变化,增强了电光调制器的等离子体色散效应,提高了硅基调制器的调制效率。SiGe/Si异质结PIN顶注入电光调制器的20 dB衰减所需的驱动电压从1.24 V降到0.99 V,其调制效率约为硅基调制器的1.25倍,SiGe/Si异质结可以有效增强等离子体色散效应,提高电光调制器的调制效率,改善电光调制器的性能。     

SiGe／Si HBT的直流特性分析

应用＂掺杂工程＂和＂带隙工程＂各自的特点，设计了一种独特的基区双向高速输运的ＳｉＧｅ／Ｓｉ　ＨＢＴ层结构，并利用此结构在３μｍ工艺线上做出了性能良好的ＳｉＧｅ／Ｓｉ　ＨＢＴ。其主要直流参数为：室温共发射极最大电流增益βｍａｘ（３００Ｋ）可达３００，低温βｍａｘ（７７Ｋ）可达８０００，厄利电压３００Ｖ，漏电流在ｎＡ量级，均为国际先进水平。同时，给出了ＳｉＧｅ／ＳｉＨＢＴ的室温（大注入，小注入），低温（大注入，小注入）的输出特性曲线，进行了对比分析，详细讨论了影响室温β，低温β及其它直流参数的主要因素。     

小尺寸应变Si/SiGe PMOSFET阈值电压及其电流电压特性的研究

针对Si/SiGe pMOSFET器件结构求解泊松方程,同时考虑器件尺寸减小所致的物理效应,如漏致势垒降低(DIBL)效应、短沟道效应(SCE)和速度过冲效应,获得了强反型时小尺寸P+多晶SiGe栅应变Si pMOSFET的阈值电压模型和I-V特性模型。运用Matlab对模型进行计算,获得阈值电压随多晶SiGe栅Ge组分、栅长、氧化层厚度、弛豫SiGe虚拟衬底Ge组分、掺杂浓度以及漏源偏压的变化规律,I-V特性计算结果表明MOS器件采用Si基应变技术将有更高的输出特性。用器件仿真软件ISETCAD对模型结构进行仿真,所得结果与Matlab计算结果一致,从而证明了该模型的正确性,为小尺寸应变Si MOS器件的分析设计提供了参考。     

SiC／Si异质生长的研究

在半导体材料中，ＳｉＣ比Ｓｉ具有更优越的物理特性、化学特性和半导体特性，在高温、高频和功率器件制造中有十分广阔的应用前景．但是它的材料制备很困难．文中在理论分析基础上，以Ｓｉ为衬底，用常压化学气相淀积（ＡＰＣＶＤ）技术，在温度为１１００℃下，生长出ＳｉＣ多晶薄膜，样品用ＡＥＳ和Ｘ－射线衍射进行了测试和分析     

Si／SiGe／Si HBT直流特性的解析模型与模拟

在考虑了重掺杂效应、异质结构垒效应、各物理量随温度的变化以及背注入空穴电流、ＢＥ结空间电荷区复合电流、中性基区复合电流对基极电流贡献后,对Ｓｉ／ＳｉＧｅ／Ｓｉ ＨＢＴ的常温和低温直流特性进行了解析模拟。给出了Ｔ＝７７Ｋ和３００Ｋ时的Ｓｉ／ＳｉＧｅ ＨＢＴ Ｇｕｍｍｅｌ图和电流增益β与集电极电流密度ＪＣ的关系。研究了基区少子寿命对β的影响。模拟显示,Ｓｉ／ＳｉＧｅ／Ｓｉ ＨＢＴ在电流和中等电流下有良     

Research of Current Mode Atomic Force Microscopy (C-AFM) for Si/SiC Heterostructures on 6H-SiC(0001)

Si/SiC heterostructures with different growth temperatures were prepared on 6 HSiC(0001) by LPCVD. Current mode atomic force microscopy and transmission electron microscopy were employed to investigate the electrical properties and crystalline structure of Si/SiC heterostructures. Face-centered cubic(FCC) on hexagonal close-packing(HCP) epitaxy of the Si(111)/SiC(0001) heterostructure was realized at 900°C. As the growth temperature increases to1 050°C, the 110 preferred orientation of the Si film is observed. The Si films on 6 H-SiC(0001)with different growth orientations consist of different distinctive crystalline grains: quasi-spherical grains with a general size of 20 μm, and columnar grains with a typical size of 7 μm×20 μm. The electrical properties are greatly influenced by the grain structures. The Si film with 110 orientation on SiC(0001) consists of columnar grains, which is more suitable for the fabrication of Si/SiC devices due to its low current fluctuation and relatively uniform current distribution.     

Crystallization of Fe78Si9B13 Bulk Crystaline/Amorphous (c/a) Composite

A metallic crystalline/amorphous (c/a) bulk composite was prepared by the slow cooling method after remelting the amorphous Fe78Si9B13 ribbon. By X-ray diffraction (XRD),differential scanning calorimetry (DSC) and scanning electron microscope (SEM), the composite consists of the primary dendrite a-Fe (without Si) as well as the amorphous matrix. After being anneal at 800 K, the uniform spheroid particles are formed in the c/a composite, which does not form in the amorphous ribbon under the various annealing process. Energy dispersive analysis of X-rays (EDAX), SEM and XRD were applied to give more detailed information. The formation and evolution of the particle may stimulate the possible application of the Fe-matrix amorphous alloy.     

Structure and internal stress of Au films deposited on Si02/Si(100) and mica by dc sputtering

Au films with a thickness of about 300 nm were deposited on SiO2/Si(100) and mica substrates by dc sputtering. X-ray diffraction spectroscopy and field emission scanning electron microscopy were used to analyze the structure and internal stress of the Au films. The films grown on SiO2/Si(100) show a preferential orientation of [111] in the growth direction. However the films grown on mica have mixture crystalline orientations of [111], [200], [220] and [311] in the growth direction and the orientations of [200]and [311] are slightly more than those of [111] and [2201. An intemal stress in the films grown on SiO2/Si(100) is tensile. For Au films grown on mica the internal stresses in the [111]- and [311]-orientation grains are compressive while those in the [200]- and [220]-orientation grains are tensile. Au films grown SiO2/Si(100) have some very large grains with a size of about 400 nm and have a wider grain size distribution compared with those grown on mica.     

Fabrication of GaN epitaxial films on Al_2O_3/Si (001) substrates

Ｇａｌｌｉｕｍｎｉｔｒｉｄｅｈａｓａｄｉｒｅｃｔｅｎｅｒｇｙｂａｎｄｇａｐｏｆ3.39ｅＶａｔｒｏｏｍｔｅｍｐｅｒａｔｕｒｅａｎｄｍａｙｂｅａｐｐｌｉｅｄｔｏｂｌｕｅ,ｖｉｏｌｅｔａｎｄｕｌｔｒａｖｉｏｌｅｔ(ＵＶ)ｌｉｇｈｔｅｍｉｔｔｉｎｇｄｅｖｉｃｅｓｓｕｃｈａｓｌｉｇｈｔｅｍｉｔｔｉｎｇｄｉｏｄｅｓ(ＬＥＤｓ),ｌａｓｅｒｄｉｏｄｅｓ(ＬＤｓ),ａｎｄｈｉｇｈｔｅｍｐｅｒａｔｕｒｅｅｌｅｃｔｒｏｎｉｃｄｅｖｉｃｅｓ[1—3].Ｒｅｃｅｎｔｌｙ,ｃｏｌｕｍｎＩＩＩ—Ｖｎｉｔｒｉｄｅｓｈａｖｅｂｅｅｎｏｎｅｏｆ…     

Fabrication of GaN epitaxial films on Al2O3/Si (001) substrates

Single crystal GaN films of hexagonal modification have been fabricated on Al₂O₃/Si (001) substrates via a low pressure metalorganic chemical deposition (LP-MOCVD) method. the full width at half-maximum of (0002) X-ray diffraction peak for the GaN film 1.1 μm thick was 72 arcmin, and the mosaic structure of the film was the main cause of broadening to the X-ray diffraction peak. At room temperature, the photoluminescence (PL) spectrum of GaN exhibited near band edge emission peaking at 365 nm. Project supported by the “863” Advanced materials Committee of China and the Planning Commission of China.     

Structure and internal stress of Au films deposited on SiO2／Si（100） andmica by dc sputtering

Au films with a thickness of about 300 nm were deposited on SiO2/Si(100) and mica substrates by dc sputtering. X-ray diffraction spectroscopy and field emission scanning electron microscopy were used to analyze the structure and internal stress of the Au films. The films grown on SiO2/Si(100) show a preferential orientation of [111] in the growth direction. However the films grown on mica have mixture crystalline orientations of [111], [200], [220] and [311] in the growth direction and the orientations of [200] and [311] are slightly more than those of [111] and [220]. An internal stress in the films grown on SiO2/Si(100) is tensile. For Au films grown on mica the internal stresses in the [111]-and [311]-orientation grains are compressive while those in the [200]- and [220]-orientation grains are tensile. Au films grown SiOJSi(100) have some very large grains with a size of about 400 nm and have a wider grain size distribution compared with those grown on mica.     

空位掺杂(La(0.7-x)Y0.3)2/3Ca1/3MnO3的结构及其微观机制研究

利用标准的固相反应法在1 200℃烧结了(La(0.7-x)Y0.3)2/3Ca1/3MnO3(x=0,0.02,0.04,0.08,0.10)样品,冷却后,取出部分在1 350℃进行再烧结.利用X射线衍射(XRD)和扫描电镜(SEM)对其晶体结构及表面微观结构进行了研究.X射线衍射测量分析表明样品均为单相,单胞仍然具有正交对称性结构(空间群为Pnm a).通过扫描电镜研究表明,当化合物x=0.04时,(La(0.7-x)Y0.3)2/3Ca1/3MnO3的表面形貌表现为致密度最好.样品在1 350℃再烧结条件下,当x≤0.04时,可以大大降低样品的晶粒大小和孔隙;但当x>0.04时,再烧结对样品的晶体结构和表面微观结构影响不大.