发射极-基极-发射极结构PNP型AlGaAs/GaAs HBT电流增益的理论分析

建立了PNP型异质结双极晶体管基区少数载流子浓度的解析模型.理论分析了发射极-基极-发射极布局的PNP型HBT的电流增益.讨论了不同基极电流成分,如外基区表面复合电流,基极接触处的界面复合电流,基区体内复合电流,以及刻蚀台面处的台面复合电流对电流增益的影响.     

发射极-基极-发射极结构PNP型AlGaAs/GaAsHBT电流增益的理论分析

建立了 PNP型异质结双极晶体管基区少数载流子浓度的解析模型 .理论分析了发射极 -基极 -发射极布局的PNP型 HBT的电流增益 .讨论了不同基极电流成分 ,如外基区表面复合电流 ,基极接触处的界面复合电流 ,基区体内复合电流 ,以及刻蚀台面处的台面复合电流对电流增益的影响     

发射极-基极-发射极结构PNP型AlGaAs/GaAs HBT电流增益的理论分析

建立了PNP型异质结双极晶体管基区少数载流子浓度的解析模型。理论分析了发射极－基极－发射极布局的PNP型HBT的电流增益。讨论了不同基极电流成分,如外基区表面复合电流,基极接触处的界面复合电流,基区体内复合电流,以及刻蚀台面处的台面复合电流对电流增益的影响。     

Ge组分对SiGe HBT直流特性的影响

制作了基区Ge组分分别为0.20和0.23的多发射极指数双台面结构SiGe异质结双极型晶体管(HBT)。实验结果表明,基区Ge组分的微小增加,引起了较大的基极复合电流,但减小了总的基极电流,提高了发射结的注入效率,电流增益成倍地提高。Ge组分从0.20增加到0.23,HBT的最大直流电流增益从60增加到158,提高了约2.6倍。     

精细的几何图形改进微波双极晶体管的性能

休利特—派卡公司采用精细的几何图形制出了亚微米发射极条,制出了频率高、增益大而又保持噪声低的 HXTR6101器件,其性能是在4千兆赫下,增益为9.0～9.5分贝,典型噪声系数为2.3～2.7分贝。休利特—派卡公司的这种技术,包括离子注入、局部氧化、计算机辅助设计以及自对准工艺。采用制造精细图形的关键工艺—离子注入和自对准技术,在二氧化硅层上同时制做发射极和基极接触窗口。自对准技术可消除最苛刻的对准和硅双极晶体管中的二个主要噪声源:基极扩展电阻中的热噪声和跨越发射极和基极结注入电流中的散粒噪声。作者宣称,要提高这种器件的增益,必须把集电极—基极结电容和集电极—基极键合区     

I~2L晶体管的基极电流

对于I~2Lnpn晶体管来说,介绍了允许将基极电流分成不同成分的方法:在氧气化层和金属复盖的Fp区中电子的复合电流,在高掺杂n~+发射区中空穴复合电流以及流到P型衬底的空穴漏电流。在固定发射极—基极电压时对不同几何形状的IL器件基极电流进行了比较。讨论了几种预防寄生效应的措施。在540～650ml的发射极—基极电压范围内进行了测量,不同的基极电流密度被表示为外加的发射极—基极电压的一个函数。对所测得的电流密度推导出数学表达式并与理论相比较。文章指出为了解释实验值和理论值之间的差异,器件处于重掺杂范围时应考虑到禁带宽度变窄的影响。此外,它表明实验测定的四个集电极I~2L门的基极电流与计算值能很好地相符。对这个门来说,电子复合电流仅仅是基极电流的20%,而空穴复合电流是基极电流的主要成分。     

非晶态发射极晶体管(FFJ)

采用非晶态硅作为双极型微波功率晶体管的发射极材料,利用这种硅层的垂直电阻的镇流作用,能够消除发射极边缘的注入电流集边现象。与通常晶体管相比,FFJ的有效发射极面积对基极面积之比值提高2～3倍,输出功率-阻抗乘积提高5～10倍。 由于FFJ的发射极-基极结电容仅仅取决于它的发射极掺杂情况,因此,可以同时得到较小的基极电阻r_b和较高的发射极截止频率f_(TE)。f_(max)的数值可以比通常的晶体管高3～5倍。     

射频晶体管3DG2714基极电阻R_(bb’)的分析与研究

射频晶体管具有高的特征频率fT,高的功率增益GP。为此在工程上多采用浓硼扩散形成嫁接基区。尽可能减少基极电阻Rbb’,同时采用梳状结构电极,浅结扩散,小的结面积等工艺,提高fT,从而双方面提高功率增益GP。文章以该公司生产的射频晶体管3DG2714为例,分析了发射结下基区部分电流流动状态,合理计算了这部分的基极电阻Rb1,分析了发射极与基极之间淡硼扩散区的电流流动状态,合理计算了这部分的基极电阻Rb2,忽略了两个影响极小的电阻,计算了总的基极电阻Rbb’。为减小基极电阻提高功率增益的射频晶体管设计制造提供了依据。     

用于低电压、宽带CDMA的HBT功率放大器

据《信学技报》(日)2010年109-361期报道,日本三菱电机高频光器件制作所开发了用于低电压、宽带CDMA的HBT功率放大器。HBT的主要特性为:DC电流增益100 typ,基极集电极耐压22 V,集电极发射极耐压15 V,基极集电极二极管等价直流阻抗6Ω(4 mA/100μm~2电流时)。该功率放大器在频率824 MHz、输出功率28 dBm时,功率增益27.7 dB,邻沟道泄漏功率抑制比-50.5 dBc,功率附加效率36%;在频率925 MHz时,功率增益27.5 dB,邻沟道泄漏功率抑制比-51.3 dBc,功率附加效率36%。其工作温度范围为-20～+85℃。     

无偏置源的多谐振荡器

普通等待式的多谐振荡器,为保持其中一个晶体管截止,要求有偏置电压(图a).在晶体管BG_1的基极接一个二极管D_1,可不用偏置源(图b).当电路处于静态时,供给BG_1基极电流唯一的电压是导通管BG_2的集电极-发射极饱和电压.这电压为激起通过BG_1的基极的电流是太小了,因BG_1的基极-发射极     

Development of the readout system for waveguide multilayer optical card

Waveguide multilayer optical card （WMOC） is a novel storage device of three-dimensional optical information. An advanced readout system fitting for the WMOC is introduced in this paper. The hardware mainly consists of the light source for reading, WMOC, motorized stages addressing unit, microscope imaging unit, CCD detecting unit and PC controlling ＆ processing unit. The movement of the precision motorized stage is controlled by the computer through Visual Basic （VB） language in software. A control panel is also designed to get the layer address and the page address through which the position of the motorized stages can be changed. The WMOC readout system is easy to manage and the readout result is directly displayed on computer monitor.     

Nanoimprint Lithography -A Next Generation High Volume Lithography Technique

IntroductionNanoimprint Lithography is a well-acknowl-edged low cost, high resolution, large area pattern-ing process. It includes the most promising methods,high-pressure hot embossing lithography (HEL) [2],UV-cured imprinting (UV-NIL) [3] and micro contactprinting (m-CP, MCP) [4]. Curing of the imprintedstructures is either done by subsequent UV-lightexposure in the case of UV-NIL or by cooling downbelow the glass transition temperature of the ther-moplastic material in case of HEL…     

Collinear phase-matching study of terahertz-wave generation via difference frequency mixed in GaAs and Inp

The collinearly phase-matching condition of terahertz-wave generation via difference frequency mixed in GaAs and InP is theoretically studied. In collinear phase-matching, the optimum phase-matching wave hands of these two crystals are calculated. The optimum phase-matching wave bands in GaAs and lnP are 0.95-1.38μm and 0.7-0.96μm respectively. The influence of the wavelength choice of the pump wave on the coherent length in THz-wave tuning is also discussed. The influence of the temperature alteration on the phase-matching and the temperature tuning properties in GaAs crystal are calculated and analyzed. It can serve for the following experiments as a theoretical evidence and a reference as well.     

Effects of the alloy compositions on the phonon-polaritons in ternary mixed crystals

Composition dependence of bulk and surface phonon-polaritons in ternary mixed crystals are studied in the framework of the modified random-element-isodisplacement model and the Bom-Huang approximation. The numerical results for Several Ⅱ - Ⅵ and Ⅲ- Ⅴ compound systems are performed, and the polariton frequencies as functions of the compositions for ternary mixed crystals AlxGa1-xAs, GaPxAS1-x, ZnSxSe1-x, GaAsxSb1-x, GaxIn1-xP, and ZnxCd1-xS as examples are given and discussed. The results show that the dependence of the energies of two branches of bulk phonon-polaritons which have phonon-like characteristics, and surface phonon-polaritons on the compositions of ternary mixed crystals are nonlinear and different from those of the corresponding binary systems.     

Influence of PVK ： NPB hole transporting layer on the characteristics of organic light-emitting devices

A doping system consisting of NPB and PVK is employed as a composite hole transporting layer （CHTL）. By adjusting the component ratio of the doping system, a series of devices with different concentration proportion of PVK ： NPB are constracted. The result shows that doping concentration of NPB enhances the competence of hole transporting ability, and modifies the recombination region of charge as well as affects the surface morphology of doped film. Optimum device with a maximum brightness of 7852 cd/m^2 and a power efficiency of 1.75 lm/W has been obtained by choosing a concentration proportion of PVK ： NPB at 1：3.     

New insert layer structure OLEDs

An insert layer structure organic electroluminescent device（OLED） based on a new luminescent material （Zn（salen）） is fabricated. The configuration of the device is ITO/CuPc/NPD/Zn（salen）/Liq/LiF/A1/CuPc/NPD/Zn（salen）/Liq/LiF/A1. Effective insert electrode layers comprising LiF（1nm）/Al（5 nm） are used as a single semitransparent mirror, and bilayer cathode LiF（1 nm）/A1（100 nm） is used as a reflecting mirror. The two mirrors form a Fabry-Perot microcavity and two emissive units. The maximum brightness and luminous efficiency reach 674 cd/m^2 and 2.652 cd/A, respectively, which are 2.1 and 3.7 times higher than the conventional device, respectively. The superior brightness and luminous efficiency over conventional single-unit devices are attributed to microcavity effect.     

Analysis of error performance on Turbo coded FDPIM

Due to variable symbol length of digital pulse interval modulation（DPIM）, it is difficult to analyze the error performances of Turbo coded DPIM. To solve this problem, a fixed-length digital pulse interval modulation（FDPIM） method is provided. The FDPIM modulation structure is introduced. The packet error rates of uncoded FDPIM are analyzed and compared with that of DPIM. Bit error rates of Turbo coded FDPIM are simulated based on three kinds of analytical models under weak turbulence channel. The results show that packet error rate of uncoded FDPIM is inferior to that of uncoded DPIM. However, FDPIM is easy to be implemented and easy to be combined, with Turbo code for soft-decision because of its fixed length. Besides, the introduction of Turbo code in this modulation can decrease the average power about 10 dBm, which means that it can improve the error performance of the system effectively.     

A method for calculating the center position of collimated light

It is a key problem to accurately calculate beam spots＇ center of measuring the warp by using a collimated laser. A new method, named double geometrical center method （DGCM）, is put forward for the first time. In this method, a plane wave perpendicularly irradiates an aperture stop, and a charge couple device （CCD） is employed to receive the diffraction-beam spots, then the geometrical centers of the fast and the second diffraction-beam spots are calculated respectively, and their mean value is regarded as the center of datum beam. In face of such adverse instances as laser intension distributing defectively, part of the image being saturated, this method can still work well. What＇s more, this method can detect whether an unacceptable error exits in the courses of image receiving, processing and calculating. The experimental results indicate the precision of this method is high.     

Resolution Enhancement Technology:Integrated Process Solutions using OPC

DUV lithography, using the 248 nm wavelength, is a viable manufacturing option for devices with features at 130 nm and less. Given the low kl value of the lithography, integrated process development is a necessary method for achieving acceptable process latitude. The application of assist features for rule based OPC requires the simultaneous optimization of the mask, illumination optics and the resist.Described in this paper are the details involved in optimizing each of these aspects for line and space imaging.A reference pitch is first chosen to determine how the optics will be set. The ideal sigma setting is determined by a simple geometrically derived expression. The inner and outer machine settings are determined, in turn,with the simulation of a figure of merit. The maximum value of the response surface of this FOM occurs at the optimal sigma settings. Experimental confirmation of this is shown in the paper.Assist features are used to modify the aerial image of the more isolated images on the mask. The effect that the diffraction of the scattering bars (SBs) has on the image intensity distribution is explained. Rules for determining the size and placement of SBs are also given.Resist is optimized for use with off-axis illumination and assist features. A general explanation of the material' s effect is discussed along with the affect on the through-pitch bias. The paper culminates with the showing of the lithographic results from the fully optimized system.     

Preparation and Characterization of TaN ALD Precursors

High purity organic-tantalum precursors for thin film ALD TaN were synthesized and characterized.Vapor pressure and thermal stability of these precursors were studied.From the vapor pressure analysis,it was found that TBTEMT has a higher vapor pressure than any other published liquid TaN precursor,including TBTDET,TAITMATA,and IPTDET.Thermal stability of the alkyl groups on the precursors was investigated using a 1H NMR technique.The results indicated that the tertbutylimino group is the most stable group on TBTDET and TBTEMT as compared to the dialkylamido groups.Thermal stability of TaN precursors decreased in the following order:TBTDET ＞ PDMAT ＞ TBTEMT.In conclusion,precursor vapor pressure and thermal stability were tuned by making slight variations in the ligand sphere around the metal center.