用溅射淀积法外延生长优质Cd_xHg_(1-x)Te薄膜

采用汞蒸汽等离子体阴极溅射技术,已同时在几种CdTe衬底上(总面积为20cm~2)外延生长了Cd_xHg_(1-x)Te薄膜。薄膜在加热到310℃的衬底上生成,其淀积速率为0.6μm.h(总厚度≤30μm)。采用不同的实验方法对薄膜的结晶学特性进行了分析,这些方法包括:反射X-射线形貌、衍射分布图的半值宽度(FWHM)测量、透射电子显微镜分析(TEM)和卢瑟福反向散射分析(RBS)。TEM法,摆动曲线和RBS的结果揭示出薄膜具有很高的结晶学质量(外延层内的位错密度接近10~4cm~(-2))。在4K和300K之间测量了Cd_xHg_(1-x)Te外延层的霍耳系数。衬底温度为285℃时淀积的外延层(镉的组分为0.23,厚度16μm),在77K测量的结果是:载流子浓度n大约为2.7×10.(16)cm~(-3);霍耳迁移率为64000cm~2·V~(-1·S~(-1)。当镉的组分为0,31时(外延层厚度为18μm),则得到n=1.6×10~(16)cm~(-3);霍耳迁移率为16000cm~2·V~(-1)·S~(-1)。淀积出来的外延膜在双温区炉子内的汞气氛中退火后,其电学性质得到改善。n型外延膜的电子迁移率提高到接近用非最佳退火参量得到的体材料的水平。     

偏压对溅射ITO膜载流子浓度和迁移率的影响

研究了基体偏压对 ITO 膜载流子浓度和迁移率影响的机理,并就载流子浓度和迁移率随偏压变化的实验结果与理论结果作了比较,两者基本吻合。获得了n_e=3.2×10~(20)cm~(-3),U_H=50cm~2V~(-1)s~(-1)的 ITO 膜。     

单温区碲镉汞液相外延生长

本文首次报道单温区开管生长优质碲镉汞液相外延层,表面光亮、界面平坦清晰。组分x≤0.2时,均匀性△x=0.004,室温下红外透过率达50％以上,典型X射线双晶衍射迥摆曲线半峰宽为176arc s,原生样品呈P型。在77K下,载流子浓度为0.5～5×10~(16)cm~(-3),霍耳迁移率为2.5～4×10~2V~(-1)s~(-1)。文章还详细研究了初始过冷度△T_i对碲镉汞液相外延的影响。     

新颖的外延HgCdTe

有一种新颖的外延HgCdTe,其p型的迁移率大于250cm~2/V.s,而n型的为100000cm~2/V.s。载流子浓度P型的为2×10~(17)/cm~3,而n型的为5×10~(14)。据说,高迁移率、低载流子浓度的材料在红外传感器上将有新的用场。     

分子束外延砷化镓单晶薄膜

MBE GaAs单晶薄膜的载流子浓度(1.8-8)×10~(16)cm~(-3),室温迁移率 3000-5000cm~2/V.3最高达5466cm~2/V.s,相应的77K迁移率为1.59 ×10~4cm~2/V.s.对高杂质浓度的外延层进行了阴极荧光(4.2K) 和SIMS 测量分析.     

分子束外延GaAs掺Se

利用Se电化学喷射炉产生的Se分子束,对分子束外延(MBE)GaAs掺杂,获得了载流子浓度为 10~(15)-10~(15)cm~(-3)的N型 GaAs. 载流子浓度 8.0 ×10~(15)-5.76 × 10~(15)cm~(-3)范围相应的室温迁移率为6350-5200cm~2/V·s.还研究了各种生长参数对载流子浓度的影响.对实验结果给予了定性的解释.     

退火温度对铝掺杂氧化锌薄膜晶体质量及光电性能的影响

研究了退火温度对原子层沉积(ALD)生长的铝掺杂氧化锌(AZO)薄膜光电性能的影响,结果发现:AZO薄膜在600℃退火后,X射线衍射峰的半峰全宽从未退火时的0.609°减小到0.454°,晶体质量得到提升;600℃退火后,薄膜的表面粗糙度从未退火时的0.841 nm降低至0.738 nm;400℃退火后,薄膜的载流子浓度和迁移率均达到最大值,分别为1.9×10~(19) cm~(-3)和4.2 cm~2·V~(-1)·s~(-1),之后随着退火温度进一步升高,载流子浓度和迁移率降低;退火温度由300℃升高到600℃过程中薄膜的吸收边先蓝移后红移。     

Ar~+激光结晶非晶硅膜电学性质研究

本文使用TEM分析、X射线衍射以及电导和霍耳效应联合测量等手段研究了Ar~+激光结晶a-Si:H膜的结构和电学性质.结果表明a-Si:H液相激光结晶膜(LP-LCR)的平均晶粒尺寸达数十微米,呈<111>择优取向,室温电导率为1.5(Ω·cm)~(-1),电子霍耳迁移率达36cm~2V~(-1)s~(-1),是一种有应用前景的薄膜.     

离子注入InSb平面型线列探测器的研究

采用n型InSb体晶材料。77K下的载流子浓度(1～3)×10~(14)cm~(-3),迁移率>5×10~5cm/V·S,位错密度<100/cm~2,用普通的工艺进行磨、抛,然后光刻成平面型16元线列。光刻胶作掩蔽层,进行Be~+注入,注入能量50～200keV,剂量10~(13)～10~(15)cm~(-2),然后经一定的     

氧化锡导电膜的性能和制备方法

氧化锡(SnO_2)导电膜是一种应用广泛的透明金属氧化膜,它是一种多晶结构的薄膜。在可见光范围内透过系数大于0.9,在红外区受到强吸收。纯氧化膜是一种宽禁带的n型半导体,其导电电子浓度为10~(19)～10~(20)cm~(-3),霍耳迁移率30cm~2V~(-1)s~(-1),电阻率为10~8Ωcm。     

聚对苯撑苯并双(口恶)唑发光及其器件制备

采用光谱技术,研究了聚对苯撑苯并双(口恶)唑(PBO)溶液的光敏发光特性,并用相对法估算出溶液发光效率在50%范围.结合光谱技术、半导体电学和电化学等研究手段,具体研究了以PBO为发光层的单层电致发光器件,研究结果显示,电致发光与薄膜的光致发光有具有相同的发光中心,峰值位于510 nm左右.同时发现,由于存制备过程中不同处理条件使得不同厚度薄膜残留的掺杂物质浓度不同,从而引起薄膜的导电性的不同.使得器件的阈值场强随PBO厚度的减小而逐渐增加.     

系统级封装新型埋入式电源滤波结构的研究

在高密度小尺寸的系统级封装(SiP)中,对供电系统的完整性要求越来越高,多芯片共用一个电源网路所产生的电压抖动除了会影响到芯片的正常工作,还会通过供电网路干扰到临近电路和其他敏感电路,导致芯片误动作,以及信号完整性和其他电磁干扰问题.这种电压抖动所占频带相当宽,几百MHz到几个GHz的中频电源噪声普通方法很难去除.结合埋入式电容和电源分割方法的特点,提出一种新型高性能埋入式电源低通滤波结构直接替代电源/地平面.研究表明,在0.65～4GHz的频带内隔离深度可达-40～75 dB,电源阻抗均在0.25ohm以下,实现了宽频高隔离度的高性能滤波作用.分别用电磁场和广义传输线两种仿真器模拟,高频等效电路模型分析这种低通滤波器的工作原理以及结构对隔离性能的影响,并进行了实验验证.     

Emerging interconnects: a state-of-the-art review and emerging solutions

Aluminium was a primary material for interconnection in integrated circuits (ICs) since their inception. Later, copper was introduced as interconnect material which has better metallic conductivity and resistance to electromigration. As the aggressive technology scaling continues, the copper resistivity increased because of size effects, which causes increase in delay, power dissipation and electromigration. The need to reduce the resistor-capacitor??????? delay, dynamic power utilisation and the crosstalk commotion is as of now the fundamental main impetus behind the presentation of new materials. The purpose of this paper is to do a survey of interconnect material used in IC from introduction of ICs to till date. This paper studies and reviews new materials available for interconnect application which are optical interconnects, carbon nanotube (CNT), graphene nanoribbons (GNRs) and silicon nanowires which are alternatives to copper. While doing a survey of interconnect material, it is found that multiwalled CNTs, multilayer GNR and mixed CNT bundles are promising candidates and are ultimate choice that can strongly address the problems faced by copper but on integration basis copper would last for coming years.     

Arsenic deposition as a precursor layer on silicon (211) and (311) surfaces

We investigate the properties of arsenic (As) covered Si(211) and Si(311) surfaces by analyzing data from x-ray photoelectron spectroscopy (XPS) and low-energy electron diffraction (LEED) images. We then create a model using total surface energy calculations. It was found that both Si(211) and Si(311) had 0.68±0.08 surface As coverage. Si(211) had 0.28±0.04 Te coverage and Si(311) had 0.24±0.04 Te coverage. The Si(211) surface replaces the terrace and trench Si atoms with As for a lower surface energy, while the Si edge atoms form dimers. The Si(311) surface replaces all terrace atoms and adsorbs an As dimer every other edge site. These configurations imply an improvement in the mean migration path from the bare silicon surface by allowing the impinging atoms for the next epitaxial layer, tellurium (Te), to bind at every other pair of edge atoms, and not the step terrace sites. This would ensure a nonpolar, B-face growth.     

光子晶体微腔发光二极管

光子晶体微腔因其具有增强自发辐射、定向输出和单模工作的能力而受到广泛关注。介绍了光子晶体微腔发光二极管的基本原理、设计、特性、制作及其典型器件。     

Comparative study of maximum power point tracking techniques for hybrid renewable energy system

The power generation demand is increasing day-by-day throughout the world, therefore, the use of hybrid systems becomes a significant solution. The hybrid renewable energy system (HRES) is used for delivering power in various regions in order to overcome intermittence of wind and solar resources. Because of increasing environmental problems, for example, greenhouse gas emission and energy cost have interested novel research into substitute methods in favour of electrical power generation. Maximum Power Point Tracking (MPPT) control method is a vast deal of novel research used for enhancing the efficiency of HRES. The authors have revealed that the hybrid techniques i.e. Global MPPT, fuzzy-neuro systems, Adaptive Neuro-Fuzzy Inference System (ANFIS), Perturbed and Observe (P&O) + Adaptive Neural Network (ANN) etc. can provide best results as compared to other MPPT control methods. This paper offering a state of art review of MPPT control techniques for HRES.     

用于单光子TOF测量的时间-幅度变换器

基于新型共源共栅电流源的积分方法,设计了一种用于单光子飞行时间(TOF)测量的时间-幅度变换器(TAC)。该方法有效简化了TAC电路结构,减小了TAC占用面积,显著提高了TOF的满量程范围(FSR)。采用0.18 μm标准CMOS工艺设计。集成TAC的单光子探测器像素单元的填充因子可达到26.8%。后仿真结果表明,该TAC在120 ns的FSR内具有230 ps的定时分辨率,微分非线性(DNL)低于0.05 LSB,积分非线性(INL)低于1.1 LSB。蒙特卡洛仿真表明,512个TAC像素间的不均匀性低于0.5 %。该TAC非常适用于高密度时间相关的单光子计数(TCSPC)探测器阵列。     

超宽带脉冲信号的光学生成方法研究

近年来超宽带(UWB)通信技术迅猛发展,在测量、雷达技术、民用和军事无线通信中有着重要的应用,UWB-over-fiber技术已经成为目前研究的热点,其中就包括UWB脉冲信号的产生方法。区别于传统的电子学方法,光子学产生方法不受电子瓶颈制约,可以实现很高的带宽,并且具有抗电磁干扰、重量轻、结构紧凑的优点。通过对比国内外本领域研究成果,讨论及总结了以下三种原理的UWB脉冲信号的光学生成方法:1)相位调制-强度调制转换(PM-IM);2)半导体光放大器(SOA)的非线性效应;3)频谱塑形和色散所致频域-时域映射,然后对各种方案进行了对比分析。     

Joint estimation of TOA and DOA in IR-UWB system using a successive propagator method

Impulse radio ultra-wideband (IR-UWB) ranging and positioning require accurate estimation of time-of-arrival (TOA) and direction-of-arrival (DOA). With receiver of two antennas, both of the TOA and DOA parameters can be estimated via two-dimensional (2D) propagator method (PM), in which the 2D spectral peak searching, however, renders much higher computational complexity. This paper proposes a successive PM algorithm for joint TOA and DOA estimation in IR-UWB system to avoid 2D spectral peak searching. The proposed algorithm firstly gets the initial TOA estimates in the two antennas from the propagation matrix, then utilises successively one-dimensional (1D) local searches to achieve the estimation of TOAs in the two antennas, and finally obtains the DOA estimates via the difference in the TOAs between the two antennas. The proposed algorithm, which only requires 1D local searches, can avoid the high computational cost in 2D-PM algorithm. Furthermore, the proposed algorithm can obtain automatically paired parameters and has better joint TOA and DOA estimation performance than conventional PM algorithm, estimation of signal parameters via rotational invariance techniques algorithm and matrix pencil algorithm. Meanwhile, it has very close parameter estimation to that of 2D-PM algorithm. We have also derived the mean square error of TOA and DOA estimation of the proposed algorithm and the Cramer-Rao bound of TOA and DOA estimation in this paper. The simulation results verify the usefulness of the proposed algorithm.     

多孔硅发光机制的分析

从量子力学的基本理论出发讨论了量子限制效应，推导出多孔硅有效禁带宽度增量并用量子限制效应和表面态及其物质在发光中作用的理论解释了ＰＳ光致发光的实验现象。