平面Si/PCBM与纳米Si/PCBM有机-无机杂化异质结的对比研究（英文）

本研究采用平面硅与纳米硅分别与旋涂法生长的[6,6]-苯基C61-丁酸甲酯(PCBM)形成有机–无机杂化异质结,对比研究了两种异质结界面电学特性的差异。结果显示,平面Si/PCBM和纳米Si/PCBM两种异质结都表现出明显的整流特性,但相对于平面Si/PCBM异质结,纳米Si/PCBM异质结有较大的导通电压和较小的电流密度。为了深入研究导致这种差异的相关物理机制,通过阻抗谱(IS)表征技术进一步研究了两种异质结因界面变化而产生的电阻、电容的变化趋势。阻抗测试分析表明,Si/PCBM异质结界面存在的大量缺陷致使寄生效应进一步增大,影响了器件中电荷的输运。     

SiGe/Si异质结光电器件

SiGe/Si异质结光电器件及其光电集成(OEIC)是硅基光电研究的一个非常引人注目的领域.综述了SiGe/Si异质结材料的基本性质,SiGe/Si异质结光电器件的结构、性能、应用及其光电集成.重点介绍了SiGe/Si光电探测器及其与其他相关器件的集成.     

基于高电阻率衬底的Si/SiGe HBT

介绍了一种基于电阻率高达1000Ω·cm的硅衬底的锗硅异质结晶体管的研制.首先根据衬底寄生参数模型分析了衬底对器件高频性能的影响,然后设计了器件的材料与横向结构尺寸,该器件采用掩埋金属自对准技术在3μm工艺线上制备而成,测得其典型直流电流增益为120,BVCEO为9.0V,fT为10.2GHz,fmax为5.3GHz,比同结构尺寸的常规N 衬底Si/SiGe HBT的fT和fmax分别高出3.9GHz和1.5GHz.     

新型锗硅异质结远红外探测器研制成功

工作于8～12μm波段的远红外探测器在遥感、制导、夜视技术等方面有着重要的应用。特别在海弯战争以后,更加受到各国军方和高科技界的重视。1990年美国加州里工学院喷气推进实验室发展了一种新型的锗硅异质结远红外探测器,它具有金属硅化物肖脱基(PtSi/Si和IrSi/Si)势垒探测器的优点,即工艺简单、大面积的均匀性好、读出电路简单、能和硅大规模集     

Mg_2Si/Si异质结的制备及I-V特性研究

采用磁控溅射和热处理系统制备Mg_2Si/Si异质结。首先在n-Si(111)衬底上沉积Mg膜,经热处理后得到Mg_2Si/Si异质结。利用XRD、SEM、表面轮廓仪、伏安特性测试仪和霍尔效应测试仪,研究了Mg_2Si/Si异质结的晶体结构、表面形貌、Mg_2Si薄膜厚度、I-V特性及导电类型。结果表明,成功制备了Mg_2Si/Si异质结,并得到其平均载流子浓度(-9.30×1012 cm-3)、导通电压(0.31V)、导通电流(0.6mA)、工作电压(0.53V)等,测得该异质结为n-n型。     

热处理中Si/SiGe/Si界面互扩散

利用高分辨率X射线衍射(HRXRD)和拉曼光谱(Raman spectrum)研究了由扩散引起Si/Si Ge/Si异质结中Si/Si Ge异质界面互混的现象。结果表明:应变弛豫前Si/Si Ge异质界面互混程度随热载荷的增加而增强;Si/Si Ge异质界面的硼(B)浓度梯度抑制了界面互扩散。总之,Si/Si Ge互扩散作用越强诱发Si/Si Ge异质界面越粗糙,从而导致器件性能恶化。     

InGaP/GaAs微波HBT器件与电路研究及应用进展

概述了近年来微波InGaP/GaAs异质结双极晶管(HBT)器件和集成电路的研究和应用现状,着重阐述了HBT器件的热设计、降低偏移电压、离子注入隔离、湿法腐蚀,以及用于电路设计的等效电路模型等关键问题.     

Ag/Bi4Ti3O12/p-Si异质结的制备及其C-V特性研究

为制备符合铁电存储器件要求的高质量铁电薄膜,采用溶胶-凝胶(Sol-Gel)工艺,制备了Si基Bi4Ti3O12铁电薄膜及MFS结构的Ag/Bi4Ti3O12/P-Si异质结,对Bi4Ti3O12薄膜的相结构特征及异质结的C-V特性进行了测试与分析.XRD图谱显示,Si基Bi4Ti3O12薄膜具有沿c-轴择优取向生长的趋势,而Ag/Bi4Ti3O12/p-Si异质结顺时针回滞的C-V特性曲线则表明,该异质结可实现电极化存储.此外,对该异质结C-V特性曲线的非对称及向负偏压方向偏移的产生原因也进行了分析.在此基础上,为提高铁电薄膜的铁电性能及改善其C-V特性提出了合理的结构设想.     

β-Ga2O3/p-SiNWs异质结光学特性与电学性质研究

氧化镓(Ga₂O₃)是一种宽禁带的半导体材料,超大的禁带宽度(4.9eV)、较高击穿电场强度和高热稳定性,使其成为一种很有应用前景的材料。本文以p型硅纳线阵列(p-SiNWs)为衬底,使用磁控溅射法制备了β-Ga₂O₃/p-SiNWs异质结,探究了其光学与电学性质。与纯Si相比,p-SiNWs表现出优良的“陷光”特性,其反射系数约为纯Si的1/6,且随着p-SiNWs长度的增加,反射系数逐渐降低。室温下光致发光光谱(PL)测试发现,异质结在551nm附近出现典型的绿色发射峰。β-Ga₂O₃/p-SiNWs异质结具有明显的整流特性,在V=1.40V时其整流系数高达1724,随着p-SiNWs长度增加异质结理想因子逐渐增加,最佳理性因子为1.98。通过计算logI-logV图对其电荷传输机制进行了探究。退火可以提高β-Ga₂O₃薄膜的结晶度,从而提高异质结的电学特性。     

新型硅基双异质外延SOI材料Si/γ-Al2O3/Si制备

异质外延法是目前制备新型SOI材料的技术途径之一。采用低压化学气相沉积技术(LPCVD)在硅衬底上先外延γ-Al2O3绝缘单晶薄膜，制备出硅衬底上外延氧化物外延结构γ-Al2O3/Si(EOS)，然后采用类似SOS薄膜生长的常压CVD(APCVD)方法在EOS上外延硅单晶薄膜，形成新型硅基双异质SOI材料Si／γ-Al2O3／Si。利用反射高能电子衍射(RHEED)、X射线衍射(XRD)、俄歇电子能谱(AES)及MOS电学测量等技术表征分析了Si(100)／γ-Al2O3(100)／Si(100)SOI异质结构的晶体结构、组分和电学性能。测试结果表明，已成功实现了高质量的新型双异质外延SOI结构材料Si(100)／γ-Al2O3(100)／Si(100)，γ-Al2O3与Si外延薄膜均为单晶，γ-Al2O3薄膜具有良好绝缘性能，SOI结构界面清晰陡峭，该SOI材料可应用于CMOS电路的研制。     

Electrical Performance of Electron Irradiated SiGe HBT and Si BJT

The change of electrical performances of 1 MeV electron irradiated silicon-germanium (SiGe) heterojunction bipolar transistor (HBT) and Si bipolar junction transistor (BJT) was studied. After electron irradiation, both the collector current IC and the base current IB changed a little, and the current gain β decreased a little for SiGe HBT. The higher the electron irradiation fluence was, the lower the IC decreased. For conventional Si BJT, IC and IB increased as well as /? decreased much larger than SiGe HBT under the same fluence. The contribution of IB was more important to the degradation of β for both SiGe HBT and Si BJT. It was shown that SiGe HBT had a larger anti-radiation threshold and better anti-radiation performance than Si BJT. The mechanism of electrical performance changes induced by irradiation was preliminarily discussed.     

Non-selective growth of SiGe heterojunction bipolar trasistor layers at 700 °C with dual control of n- and p-type dopant profiles

This paper describes the growth of the collector, base, and emitter layers of a SiGe HBT in a single epitaxy process. A non-selective SiGe heterojunction bipolar transistor growth process at 700 °C has been developed, which combines n-type doping for the Si collector, p-type doping for the SiGe base and n-type doping for the Si emitter cap. Control of the collector doping concentration by varying the growth conditions is shown. The boron tailing edge from the SiGe base into the Si emitter layer was removed by interrupting the growth process with a hydrogen flow after the SiGe base growth but before the Si emitter growth to remove the dopant gas from the chamber. The layer thicknesses are compared using three different analytical techniques–secondary ion mass spectroscopy (SIMS), transmission electron microscopy (TEM), and spectroellipsometry. A good agreement was obtained for the three different methods.     

Effects of neutron irradiation on SiGe HBT and Si BJT devices

The change of electrical performance of SiGc HBT and Si BJT is studied after irradiation with 1.3×10¹³ and 1.0×10¹⁴ reactor fast neutrons cm^–2. I _c and decrease, while I _b increases generally with an increasing neutron irradiation fluence for SiGe HBT. For Si BJT, I _c increases at low V _be bias, decreases at high V _be bias; I _b increases; and decreases much more than a SiGe HBT at the same fluence. It is shown that a SiGe HBT has much better anti-radiation performance than a Si BJT. The mechanism of performance changes induced by irradiation is discussed.     

Mesa and planar SiGe-HBTs on MBE-wafers

SiGe-HBTs have the potential for outstanding analog and digital or mixed-signal high frequency circuits widely based on standard Si technology. Here we review on MBE grown transistors and circuits. Processes and results of a research-like SiGe HBT and two possible production relevant HBT versions are presented. The high frequency results with f_max and f_T up to 120 GHz and a minimum noise figure of 0.9 dB at 10 GHz demonstrate the advantage of using MBE samples with steep and high base doping and high germanium contents. A comparison to the concept of reported low doped, low germanium and triangular profiled SiGe base layers, realized by UHV-CVD, is given. In addition, some circuit demonstrators of SiGe-ICs will be presented.     

Selective and non-selective growth of self-aligned SiGe HBT structures by LPCVD epitaxy

Silicon-germanium (SiGe) heterojunction bipolar transistors (HBT) have become increasingly important for high speed applications. Novel device structures are often required to fully exploit the advantages from incorporation of a heterojunction. In this work, a growth technique is described which uses both selective and non-selective growth of Si and SiGe to produce an advanced SiGe HBT structure. The surface morphology of the material grown is examined using Nomarski contrast optical microscopy and scanning electron microscopy (SEM), and the surface of the epitaxial areas appears smooth with a low defect density. The growth surface is reasonably planar, as needed for further device processing, which suggests the required thicknesses of both selective and non-selective epitaxy were achieved. The Ge and B profiles of the material are measured using secondary ion mass spectroscopy (SIMS), and the layer thicknesses are found to meet the device specification. The crystallinity and defects in the material are examined by transmission electron microscopy (TEM). The material produced is shown to be suitable for fabrication into the proposed device.     

The behavior of Ti silicidation on Si/SiGe/Si base and its effect on base resistance and fmax in SiGe hetero-junction bipolar transistors

The relation between Ti silicidation and base resistance in SiGe hetero-junction bipolar transistors (HBT) was investigated. The Ti layer deposited on the Si/SiGe/Si base converted to Ti silicide during two-step annealing. The thickness of the Ti silicide, which was identified as the Ti(Si_1-xGe_x) phase of uniform composition, abruptly increased over the annealing temperature of 650/850 °C, and as a result it accomplished a very low extrinsic base resistance. The Ti silicidation affected the base resistance of real devices (R_B), which was extracted from simulating the electrical data of SiGe HBTs such as I –V curves, forward Gummel plots, forward current gain curves, and s-parameter plots. It was shown that the R_B was compatible with the theoretical relation which included the small-signal unity-gain frequency (f_T), the maximum oscillation frequency (f_max) and R_B. f_max varied more sensitively with R_B than f_T, which was due to the inherent property of f_max being inversely proportional to R_B. The f_max of the SiGe HBT reached 47.4 GHz when Ti silicidation was performed at the annealing temperature of 650/850 °C. This silicidation condition is thought to be an appropriate temperature for Ti silicidation applicable to SiGe HBT fabrication. © 2001 Kluwer Academic Publishers     

High-quality n-Si/i-p+-i SiGe/n-Si structure grown by ultra high vacuum chemical molecular epitaxy

The n-Si/i-p⁺-i SiGe/n-Si structure was grown by ultra high vacuum chemical molecular epitaxy, and analysed by high resolution X-ray diffraction, cross-sectional transmission electron microscopy, and secondary ion mass spectroscopy. A high-quality SiGe base layer with an abrupt interface to the Si was obtained. No defects were observed in the n-Si/i-p⁺-i SiGe/n-Si structure. Both the Ge and boron atoms are uniformly distributed in the p⁺-SiGe layer, and the changes of profile of both boron and Ge atoms are abrupt from the n-Si to the SiGe layer. A high-performance microwave power SiGe heterojunction bipolar transistor (HBT) was made from the n-Si/i-p⁺-i SiGe/n-Si structure. Therefore, device-quality n-Si/i-p⁺-i SiGe/n-Si structures can be grown by ultra high vacuum chemical molecular epitaxy.     

Empirical global modelling of Si/SiGe heterojunction bipolar transistors

A simple and straightforward extraction procedure for a global model of silicon/silicon-germanium (Si/SiGe) heterojunction bipolar transistors (HBTs) is presented. The model has been constructed using functions that describe the dependence of the most nonlinear extracted small-signal equivalent circuit model (SSECM) parameters on the terminal voltages. The other model parameters are assumed to be voltage independent. An artificial neural network fitting tool has been used to obtain these relations. The model has been implemented in a software package without any convergence problems and has been evaluated by direct current, small-signal and large-signal network analyser measurements. An excellent correspondence has been obtained between the measurements and the output of the simulations for the extracted model. Because of its high accuracy, the model is very efficient in radio frequency circuit design. To the author's knowledge, this is the first time that a global model for a Si/SiGe HBT has been derived directly from .a SSECM.     

Solid-phase epitaxy of undoped amorphous silicon by in-situ postannealing

The solid phase epitaxy (SPE) of undoped amorphous Si (a-Si) deposited on SiO₂ patterned Si(001) wafers by reduced pressure chemical vapor deposition (RPCVD) using a H₂-Si₂H₆ gas system was investigated. The SPE was performed by applying in-situ postannealing directly after deposition process. By transmission electron microscopy (TEM) and scanning electron microscopy, we studied the lateral SPE (L-SPE) length on sidewall and mask for various postannealing times, temperatures and a-Si thicknesses. We observed an increase in L-SPE growth for longer postannealing times, temperatures and larger Si thicknesses on mask. TEM defect studies revealed that by SPE crystallized epi-Si exhibits a higher defect density on the mask than at the inside of the mask window. By introducing SiO₂-cap on the sample with 180 nm Si thickness following postannealing at 570 °C for 5 h, the crystallization of up to 450 nm epi-Si from a-Si is achieved. We demonstrated the possibility to use this technique for SiGe:C heterojunction bipolar transistor (HBT) base layer stack to crystallize Si-buffer layer to widen the monocrystalline region around the bipolar window and to improve base link resistivity of the HBT.