InyAl1-yAs线性渐变缓冲层对InP基HEMT材料性能的影响

采用气体源分子束外延（GSMBE）技术,研究了InP衬底上In_yAl_1-yAs线性渐变缓冲层对In_0.66Ga_0.34As/In_yAl_1-yAs高迁移率晶体管（HEMT）材料特性影响。研究了不同厚度和不同铟含量的In_yAl_1-yAs线性渐变缓冲层对材料的表面质量、电子迁移率和二维电子气浓度的影响。结果表明,在300 K（77 K）时,电子迁移率和电子浓度分别为8 570 cm²/（Vs）^-1（23 200 cm²/（Vs）-1）3.255E12 cm^-2（2.732E12 cm^-2）。当In_yAl_1-yAs线性渐变缓冲层厚度为50 nm时,材料的表面形貌得到了很好的改善,均方根粗糙度（RMS）为0.154 nm。本研究可以为HEMT器件性能的提高提供强有力的支持。     

具有低噪声及高线性度的高性能MOCVD-SiNx/AlN/GaN 毫米波MIS-HEMTs

文章在超薄势垒AlN/GaN异质结构上采用金属有机化学气相沉积（MOCVD）原位生长SiN_x栅介质,成功制备了高性能的SiN_x/AlN/GaN金属-绝缘体-半导体高电子迁移率晶体管（MIS-HEMTs）。深能级瞬态谱（DLTS）技术测试SiN_x/AlN的界面信息,显示其缺陷能级深度为0.236 eV,俘获截面为3.06×10^-19 cm^-2,提取的界面态密度为10¹⁰~10¹² cm^-2eV^-1,表明MOCVD原位生长的SiN_x可以有效降低界面态。同时器件表现出优越的直流、小信号和噪声性能。栅长为0.15 μm的器件在2 V的栅极电压（V_gs）下具有2.2 A/mm的最大饱和输出电流,峰值跨导为506 mS/mm,最大电流截止频率（f_T）和最大功率截止频率（f_MAX）分别达到了65 GHz和123 GHz,40 GHz下的最小噪声系数（NF_min）为1.07 dB,增益为 9.93 dB。V_ds = 6 V时对器件进行双音测试,器件的三阶交调输出功率（OIP3）为32.6 dBm,OIP3/P_dc达到11.2 dB。得益于高质量的SiN_x/AlN界面,SiN_x/AlN/GaN MIS-HEMT显示出了卓越的低噪声及高线性度,在毫米波领域具有一定的应用潜力。     

波长拓展型InGaAsBi近红外探测器

InGaAs光电探测器广泛应用于短波红外检测。在InGaAs中掺入Bi可以减小带隙,延长探测波长。通过控制In和Bi的组分可使In_yGa_1-yAs_1-xBi_x与InP晶格匹配,同时,扩展探测波长至3 μm以上。设计并研究了In_0.394Ga_0.606As_0.913Bi_0.087 p-i-n光电探测器的光电性能。计算了不同温度、吸收层厚度和p（n）区掺杂浓度下的暗电流和响应率特性。获得了3 μm的截止波长。该结构为拓展InP基晶格匹配的短波红外探测器的探测波长提供了一种可行的方法。     

电流增益截止频率为441 GHz的InGaAs/InAlAs InP HEMT

本文设计并制作了f_T > 400 GHz的In_0.53Ga_0.47As/In_0.52Al_0.48As 铟磷高电子迁移率晶体管（InP HEMT）。采用窄栅槽技术优化了寄生电阻。器件栅长为54.4 nm,栅宽为2 × 50 μm。最大漏极电流I_DS.max为957 mA/mm,最大跨导g_m.max为1265 mS/mm。即使在相对较小的V_DS = 0.7 V下,电流增益截止频率f_T达到了441 GHz,最大振荡频率f_max达到了299 GHz。该器件可应用于太赫兹单片集成放大器和其他电路中。     

基于激光数据的北极海水二氧化碳分压研究

星载激光雷达作为一种新型的主动遥感技术,为全球海洋昼夜以及极地冬季海水二氧化碳分压的研究提供了可能。研究通过使用云-气溶胶激光雷达与红外探路者卫星（CALIPSO）数据,对全球海表面叶绿素a（Chla）浓度进行了反演,并构建了基于激光数据的前向神经网络模型（FNN-LID）,重构了北冰洋海水二氧化碳分压（pCO₂）昼/夜长时序数据集。在此基础上,对基于主动遥感的极地海水Chla浓度和海水pCO₂数据进行了验证与分析。结果显示,基于该算法的反演产品,具有较高的数据质量,不论是和其他被动遥感的产品还是独立浮标观测数据集都有较好的一致性,且能够有效“填充”极地冬季的数据空白。在北冰洋海区,受陆源强烈影响的边缘海都表现为较高的海表Chla浓度。北冰洋海水pCO₂的空间格局表现出经向的差异,且pCO₂的季节变化十分剧烈,甚至超过80 μatm。近20年来,北冰洋稳定地表现为大气二氧化碳的汇,而在东西伯利亚海和喀拉海等海冰显著衰退的地区,海面pCO₂的增长率非常显著。     

Hf4+离子掺杂BNT对电卡性能的影响

该文采用传统固相合成法制备了Bi_0.5Na_0.5Ti_(1-x)Hf_xO₃(x=0, 0.02, 0.04和0.06)陶瓷,通过X线衍射仪(XRD)和扫描电子显微镜(SEM)表征了其相结构、微观表面,并研究了其介电性能、铁电性能及比热容与相变的关系。通过构建电场和温度的条件,共同调控铁电相变。再借助麦克斯韦方程,通过间接法计算,最终在50 ℃、70 kV/cm的电场下,在Bi_0.5Na_0.5TiO₃-0.04Hf陶瓷中通过诱导畴变得到了0.5 K的负电卡效应。     

Li、Ce掺杂对NBTa-CBN高温压电陶瓷性质的影响研究

采用传统固相反应法制备了Ca_0.5(Na_0.5Bi_0.5)_0.5-3x(Li_0.5Ce_0.5)_3xBi₂TaNb_0.99Mn_0.01O₉(CNBTNM-LC100x)高居里温度(T_C)压电陶瓷。研究了Li、Ce复合离子掺杂对陶瓷结构和电学性质的影响。结果表明,随着Li、Ce掺杂量的增加,CNBTNM-LC100x陶瓷的晶体结构趋于由正交相向四方相转变,压电常数d₃₃逐渐增大,当x＞0.04(x为摩尔分数)时,d₃₃趋于降低。x=0.04时,具有最优的综合电学性能,d₃₃约为15.9 pC/N,600 ℃下直流电阻率ρ约为5.9×10⁵ Ω·cm,介电损耗tan δ(1 MHz)约为7%,T_C约为887 ℃。     

SiC JBS二极管和SiC MOSFET的空间辐照效应及机理

基于第六代650 V 碳化硅结型肖特基二极管(SiC JBS Diode)和第三代900 V 碳化硅场效应晶体管(SiC MOSFET),开展SiC功率器件的单粒子效应、总剂量效应和位移损伤效应研究。20~80 MeV质子单粒子效应实验中,SiC功率器件发生单粒子烧毁(SEB)时伴随着波浪形脉冲电流的产生,辐照后SEB器件的击穿特性完全丧失。SiC功率器件发生SEB时的累积质子注量随偏置电压的增大而减小。利用计算机辅助设计工具(TCAD)开展SiC MOSFET的单粒子效应仿真,结果表明,重离子从源极入射器件时,具有更短的SEB发生时间和更低的SEB阈值电压。栅-源拐角和衬底-外延层交界处为SiC MOSFET的SEB敏感区域,强电场强度和高电流密度的同时存在导致敏感区域产生过高的晶格温度。SiC MOSFET在栅压偏置(U_GS=3 V,U_DS=0 V)下开展钴源总剂量效应实验,相比于漏压偏置(U_GS=0 V,U_DS=300 V)和零压偏置(U_GS=U_DS=0 V),出现更严重的电学性能退化。利用中带电压法分析发现,栅极偏置下氧化层内的垂直电场提升了陷阱电荷的生成率,加剧了阈值电压的退化。中子位移损伤会导致SiC JBS二极管的正向电流和反向电流减小。在漏极偏置下进行中子位移损伤效应实验,SiC MOSFET的电学性能退化最严重。该研究为空间用SiC器件的辐射效应机理及抗辐射加固研究提供了一定的参考和支撑。     

半导体超晶格太赫兹倍频器研究

提出一种基于电场驱动的GaAs基微带超晶格高阶谐波产生的太赫兹倍频器,利用平衡方程方法分析了倍频器在磁场下峰值功率输出和在参数空间(E_dc,E_ac)的分布情况。研究表明,在(E_dc,E_ac)的参数平面内,磁场对二次和三次谐波功率的峰值影响不大,但磁场会拓宽谐波输出功率的峰值区域,提高在(E_dc,E_ac)参数空间内输出峰值功率的概率。当E_ac确定时,谐波发射功率峰值的位置会受到直流电场产生的布洛赫振荡频率f_B、交流电场产生的调制布洛赫振荡频率f_MB和磁场引起的回旋振荡频率f_c的影响而发生变化。研究表明,基于半导体超晶格的太赫兹倍频器是很有应用潜力的太赫兹波发生器件。     

Effect of deposition conditions on the physical properties of SnxSy thin films prepared by the spray pyrolysis technique

Tin sulfide thin films (Sn_xS_y) with an atomic ratio of y/x = 0.5 have been deposited on a glass substrate by spray pyrolysis. The effects of deposition parameters, such as spray solution rate (R), substrate temperature (T_s) and film thickness (t), on the structural, optical, thermo-electrical and photoconductivity related properties of the films have been studied. The precursor solution was prepared by dissolving tin chloride (SnCl₄, 5H₂O) and thiourea in propanol, and Sn_xS_y thin film was prepared with a mole ratio of y/x = 0.5. The prepared films were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM) and UV-vis spectroscopy. It is indicated that the XRD patterns of Sn_xS_x films have amorphous and polycrystalline structures and the size of the grains has been changed from 7 to 16 nm. The optical gap of Sn_xS_x thin films is determined to be about 2.41 to 3.08 eV by a plot of the variation of (αhν)² versus hν related to the change of deposition conditions. The thermoelectric and photo-conductivity measurement results for the films show that these properties are depend considerably on the deposition parameters.     

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.     

Curved crystal spectrometer for the measurement of X-ray lines from laser-produced plasmas

In order to diagnose the laser-produced plasmas, a focusing curved crystal spectrometer has been developed for measuring the X-ray lines radiated from a laser-produced plasmas. The design is based on the fact that the ray emitted from a source located at one focus of an ellipse will converge on the other focus by the reflection of the elliptical surface. The focal length and the eccentricity of the ellipse are 1350 mm and 0.9586, respectively. The spectrometer can be used to measure the X- ray lines in the wavelength range of 0.2-0.37 nm, and a LiF crystal （200） （2d = 0.4027 nm） is used as dispersive element covering Bragg angle from 30° to 67.5°. The spectrometer was tested on Shengnang- Ⅱ which can deliver laser energy of 60-80 J/pulse and the laser wavelength is 0.35 μm. Photographs of spectra including the 1 s2p ^1P1-1s^2 ^1S0 resonance line（w）, the 1s2p ^3P2-1s^2 1S0 magnetic quadrupole line（x）, the 1s2p ^3P1-1 s^2 ^1S0 intercombination lines（y）, the 1 s2p ^3S~1-1 s^2 ^1S0 forbidden line（z） in helium-like Ti Ⅹ Ⅺ and the 1 s2s2p ^2P3/2-1 s622s ^2S1/2 line（q） in lithium-like Ti Ⅹ Ⅹhave been recorded with a X-ray CCD camera. The experimental result shows that the wavelength resolution（λ/△ 2） is above 1000 and the elliptical crystal spectrometer is suitable for X-ray spectroscopy.     

Cost-effective test solutions for smart card and other integrated flash applications

From its emergence in the late 1980s as a lower cost alternative to early EEPROM technologies, flash memory has evolved to higher densities and speedsand rapidly growing acceptance in mobile applications.In the process, flash memory devices have placed increased test requirements on manufacturers. Today, as flash device test grows in importance in China, manufacturers face growing pressure for reduced cost-oftest, increased throughput and greater return on investment for test equipment. At the same time, the move to integrated flash packages for contactless smart card applications adds a significant further challenge to manufacturers seeking rapid, low-cost test.     

An improved parallel thinning algorithm with two subiterations

The parallel thinning algorithm with two subiterations is improved in this paper. By analyzing the notions of connected components and passes, a conclusion is drawn that the number of passes and the number of eight-connected components are equal. Then the expression of the number of eight-connected components is obtained which replaces the old one in the algorithm. And a reserving condition is proposed by experiments, which alleviates the excess deletion where a diagonal line and a beeline intersect. The experimental results demonstrate that the thinned curve is almost located in the middle of the original curve connectivelv with single pixel width and the processing speed is high.     

Theoretical analysis of the relationship between the Brillouin gain coefficient and the strain in the optical-fiber sensors

The relation between the power of the Brillouin signal and the strain is one of the bases of the distributed fiber sensors of temperature and strain. The coefficient of the Bfillouin gain can be changed by the temperature and the strain that will affect the power of the Brillouin scattering. The relation between the change of the Brillouin gain coefficient and the strain is thought to be linear by many researchers. However, it is not always linear based on the theoretical analysis and numerical simulation. Therefore, errors will be caused if the relation between the change of the Brillouin gain coefficient and the strain is regarded as to be linear approximately for measuring the temperature and the strain. For this reason, the influence of the parameters on the Brillouin gain coefficient is proposed through theoretical analysis and numerical simulation.     

Novel fiber-optical interferometer with miniaturized probe for in-hole measurements

Today, micro-system technology and the development of new MEMS （Micro-Electro-Mechanical Systems） are emerging rapidly. In order for this development to become a success in the long run, measurement systems have to ensure product quality. Most often, MEMS have to be tested by means of functionality or destructive tests. One reason for this is that there are no suitable systems or sensing probes available which can be used for the measurement of quasi inaccessible features like small holes or cavities. We present a measurement system that could be used for these kinds of measurements. The system combines a fiber optical, miniaturized sensing probe with low-coherence interferometry, so that absolute distance measurements with nanometer accuracy are possible.     

Electronic Structure of Semiconductor Nanocrystals

This paper reviews our recent development of the use of the large-scale pseudopotential method to calculate the electronic structure of semiconductor nanocrystals, such as quantum dots and wires, which often contain tens of thousands of atoms. The calculated size-dependent exciton energies and absorption spectra of quantum dots and wires are in good agreement with experiments. We show that the electronic structure of a nanocrystal can be tuned not only by its size,but also by its shape. Finally,we show that defect properties in quantum dots can be significantly different from those in bulk semiconductors.     

Critical Stage Rule-Based Real Time Dispatch（RTD）System in Highly-Mixed-Products （HMP） FAB

An improving utilization and efficiency of critical equipments in semiconductor wafer fabrication facilities are concerned. Semiconductor manufacturing FAB is one of the most complicated and cost sensitive environments. A good dispatching tool will make big difference in equipment utilization and FAB output as a whole. The equipment in this paper is In-Line DUV Scanner. There are many factors impacting utilization and output on this equipment group. In HMP environment one of the issues is changing of reticule in this area and idle counts due to load unbalance between equipments. Here we'll introduce a rule-based RTD system which aiming at decreasing the number of recipe change and idle counts among a group of scanner equipment in a high-mixed-products FAB.     

GaAsSb/InAlAs PA DHBTs Grown by Production MBE

The epi material growth of GaAsSb based DHBTs with InAlAs emitters are investigated using a 4 × 100mm multi-wafer production Riber 49 MBE reactor fully equipped with real-time in-situ sensors including an absorption band edge spectroscope and an optical-based flux monitor. The state-of-the-art hole mobilities are obtained from 100nm thick carbon-doped GaAsSb. A Sb composition variation of less than ± 0.1 atomic percent across a 4 × 100mm platen configuration has been achieved. The large area InAlAs/GaAsSb/InP DHBT device demonstrates excellent DC characteristics,such as BVCEO＞6V and a DC current gain of 45 at 1kA/cm2 for an emitter size of 50μm × 50μm. The devices have a 40nm thick GaAsSb base with p-doping of 4. 5 × 1019cm-3 . Devices with an emitter size of 4μm × 30μm have a current gain variation less than 2% across the fully processed 100mm wafer. ft and fmax are over 50GHz,with a power efficiency of 50% ,which are comparable to standard power GaAs HBT results. These results demonstrate the potential application of GaAsSb/InP DHBT for power amplifiers and the feasibility of multi-wafer MBE for mass production of GaAsSb-based HBTs.     

Teleportation of an arbitrary unknown N-qubit entangled state under the controlling of M controllers

A new quantum protocol to teleport an arbitrary unknown N-qubit entangled state from a sender to a fixed receiver under M controllers(M < N) is proposed. The quantum resources required are M non-maximally entangled Greenberger-Home-Zeilinger (GHZ) state and N-M non-maximally entangled Einstein-Podolsky-Rosen (EPR) pairs. The sender performs N generalized Bell-state measurements on the 2N particles. Controllers take M single-particle measurement along x-axis, and the receiver needs to introduce one auxiliary two-level particle to extract quantum information probabilistically with the fidelity unit if controllers cooperate with it.