自组装半导体量子点在纳米电子器件中的应用

随着微电子工艺逐渐逼近其物理极限,具有量子特性的纳米电子器件的研制被提上日程.自组装半导体量子点由于缺陷少、生长技术成熟和具有δ函数形式的能态密度等优点而被广泛用于纳米电子器件制备中.本文按纵向输运器件、横向输运器件的分类扼要评述了该领域的最新进展,并对待解决的问题和发展前景作了分析.     

InP基三端太赫兹固态电子器件和电路发展

随着微电子技术的飞速发展,半导体器件的截止频率已经进入到太赫兹频段,太赫兹电路的频率特性得到极大发展。以固态器件为基础的太赫兹电路的工作频率进入到THz频段。本文重点介绍InP基双极器件和场效应器件的发展以及在太赫兹电路和系统中的应用。     

InP基转移电子器件接触性能的优化研究

The effect of the annealing time and annealing temperature on Ni/Ge/Au electrode contacts deposited on the n-type InP contact layer has been studied using a circular transmission line model. The minimum specific contact resistance of 3.210 7 cm2was achieved on the low-doped n-type InP contact layer with a 40 s anneal at 425 ℃. In order to improve the ohmic contact and reduce the difficulty in the fabrication of the high doped InP epi-layer, the doping concentration in the InP contact layer was chosen to be 51018cm 3in the fabrication of transferred electronic devices. Excellent differential negative resistance properties were obtained by an electron beam evaporating the Ni/Ge/Au/Ge/Ni/Au composite electrode on an InP epi-layer with a 60 s anneal at 380 ℃.     

MEMS光开关及其与光纤组装方式的研究

光开关是一种在光路中应用极其广泛的光无源器件,可用于扫描、投影、通讯等多种不同的领域,其中用于全光通讯中连接光纤之间的光开关日渐成为人们关注的焦点.高性能、低成本、又能大量生产的MEMS光开关很好地满足了全光网络对器件的要求.本文对这种MEMS光纤光开关的类型、特点以及研究现状进行了介绍,并给出了MEMS光开关与输入输出光纤的组装与自组装以及主要方式.     

光电子器件在光纤通信中的应用

随着国民经济的不断增长,光纤通信技术的不断创新,通信网络行业发展得到了质的飞跃。光电子器件应用作为光纤通信发展过程的重中之重,是一个不可或缺的关键内部,直接关系到光纤通信技术各项功能的完善及光纤通信事业的稳定建设发展。光纤通信主要包括了三个环节,分别是光发送、光接收以及光传输,在各个工作环节中配备了不同的光电子关键器件。本文将进一步对光电子器件在光纤通信中的应用展开分析与探讨,旨在为光纤通信事业的发展提供科学依据。     

碳基射频电子器件研究进展

以三维体材料金刚石、二维材料石墨烯和准一维材料碳纳米管为代表的碳基电子材料,分别拥有超宽禁带、超高载流子迁移率、优异的导热性能和机械特性,以及独特的低维结构带来的各种量子效应,在射频大功率、高线性、太赫兹以及光电混频等器件领域,具有技术提升的巨大潜力。分别介绍了这三种典型碳基材料的基本电学特性,聚焦金刚石微波功率器件、石墨烯高频器件和电路以及碳纳米管高线性器件和电路,分析了从材料至器件层面的优势和挑战,并展望了碳基材料成为下一代半导体功能材料的前景。     

InP基应变补偿多量子阱的研究进展

介绍了InP基应变补偿MQW的研究进展 ,对应变补偿和非应变补偿MQW的特性做了对比。讨论了InP基应变补偿MQW存在的问题及如何优化InP基应变补偿MQW的生长条件。     

ICP刻蚀技术及其在光电子器件制作中的应用

简单介绍了ICP(inductively coupled plasma)刻蚀设备的结构和刻蚀机理，报道了ICP刻蚀硅、二氧化硅和Ⅲ—Ⅴ族材料的一些最新进展，重点介绍ICP刻蚀技术在光电子器件制作方面的进展和应用前景。     

Interface strain in organometallic vapor phase epitaxy grown InGaAs/InP superlattices

The spatial distribution of strain in organometallic vapor phase epitaxy grown InGaAs/InP superlattice structures has been studied by varying the thicknesses of the InGaAs well and the InP barrier layers and measuring the strain. High resolution x-ray diffraction rocking curves were used to measure the strain from angular separation between the zeroth-order superlattice peak and the substrate (004) peak. The results are consistent with a compressive strain resulting from arsenic carryover into the InP following InGaAs growth. The strain is not localized at the interfaces but extends into the InP barrier layer. The amount of arsenic carryover increases with the growth time of the InGaAs well.     

The growth of InP crystals from the melt

The growth of InP crystals from the melt is discussed on the basis of new data on the pTx relations for the In/P system in the vicinity of stoichiometric InP. The preparation of nominally undoped n-type material by the gradient-freeze technique with visual control of the seeding process is described. Zn- and Cd-doped p-type crystals were prepared in a modified almost-isothermal apparatus in order to obtain uniform stoichiometry and regular dopant distribution. The crystals were characterized in terms of their chemical purity, dopant distribution, physical defects and electrical properties.     

The formation of low resistance electrical contacts to shallow junction InP devices without compromising emitter integrity

An investigation is made into the possibility of providing low resistance contacts to shallow junction InP devices which do not require sintering and which do not cause device degradation even when subjected to extended annealing at elevated temperatures. We show that the addition of In to Au contacts in amounts that exceed the solid solubility limit lowers the as-fabricated (unsintered) contact resistivityR _c to the 10^-5 ohm-cm² range. If the In content is made to correspond exactly to that required to form the intermediate compound Au₉ln₄, then the contacts so formed are stable, both electrically and metallurgically, even after extended annealing (12 hr) at 400° C. We next consider the contact system Au/Au₂P₃ which has been shown to exhibit as-fabricatedR _c values in the 10^-6 ohm-cm² range, but which fails quickly when heated. We show that the substitution of a refractory metal (W, Ta) for Au preserves the lowR _c values while preventing the destructive reactions that would normally take place in this system at high temperatures. We show, finally, thatR _c values in the 10 ohm-cm² range can be achievedwithout sintering by combining the effects of In or Ga additions to Au contacts with the effects of introducing a thin Au₂P₃ layer at the metal-InP interface.     

反馈型光电混合振荡器环内非线性现象的研究

对反馈型光电混合振荡器建立了一种新的理论解 析模型,不仅可以准确描述振荡器的功率 与相噪特性,而且能够实现与Yao′s的经典近似线性模型兼容,清晰地体现非线性对增益进 行压缩的物理机理。采用近似线性分析方法,综合考虑了光电调制器与微波放 大器的非线性,建立了适用范围 更广、精确度更高的理论解析模型,进而分析了微波放大器的非线性对振荡信 号强度与相位噪声的影响。实验结果 表明,本文模型均能实现对振荡信号的功率与相噪进行 准确描述。此外,还分析了微波放大器有色噪声通过非线性 实现上转换的物理现象,提出了 “在光电振荡器(OEO)设计中让电光调制器非线性对环路增益进行压缩、保证微波放大器工 作在线性区域是一种降低振荡信号近载频相噪的有效方式”的工程方法。     

The lattice position of diffused Zn in InP

We have measured the substitutional fraction (f_s) for Zn atoms diffused into InP crystals using the proton-induced x-ray excitation (PIXE) technique. Diffusion times ranged from 15–60 min at 425–650° C. For several samples with diffusion depths in the range 0.75-3.7 μm (as determined by SIMS analysis), we find that the Zn impurity atoms reside almost totally on lattice sites: f_s = 0.9 ± 0.1. Contrary to results of an earlier study, we find no evidence for precipitates in the diffused layers. However, only ∼10^-3-10^-1 of the Zn is electrically active, consistent with Tuck and Hooper’s suggestion of neutral V_p Zn_In V_p complexes.     

某机载光电系统主镜的轻量化设计与分析

为了达到某新型机载光电系统的轻小型化要求,对共孔径组件中ΦΦ445 mm的主镜开展了轻量化设计。首先,对比分析了多种轻量化形式特点,确定了主镜材料和结构形式。然后,以主镜轻量化率和面形精度为目标,综合理论计算与有限元分析手段,对相关参数进行迭代优化,确定出镜厚为68 mm,面板厚度为6 mm,筋板厚度为4 mm,优化后轻量化率达62 %。接着,对主镜开展工程分析,在1 g重力作用下,单一主镜光轴竖直时RMS达1.13 nm,光轴水平时RMS达0.23 nm,冲击振动下最大局部应力为0.19 MPa,组件状态下主镜RMS达11.67 nm,各项指标均满足设计要求。最后,借助干涉仪对实物主镜进行光学检测,面形精度RMS实测值为15.19 nm,进而验证了轻量化设计分析的准确性。     

炉内大容量合成高纯InP

介绍了在高压单晶炉内每次直接合成1000g InP的新工艺。对合成的InP进行测试表明,非掺杂InP的载流子浓度一般为3～6×10~(15)cm~(-3),迁移率4200cm~2/V.s以上,最高可达4700～4900cm~2/V.s,其纯度优于用水平法(HB)合成的InP。     

Evaluation of encapsulation and passivation of InGaAs/InP DHBT devices for long-term reliability

Device encapsulation and passivation are critical for long-term reliability and stability. Several encapsulation techniques were evaluated in terms of degradation of electrical characteristics, gap filling under the mesa structures, and adhesion to the semiconductor and metal surfaces. These included plasma enhanced chemical vapor deposited (PECVD) SiO₂, electron cyclotron resonance CVD SiN_x, spin-on glass, benzocyclobutene, and polyimide. Damage from plasma exposure caused gain degradation in the devices. Spin-on coatings cause little to no gain degradation, provided that there is minimal stress in the cured film. SOG and BCB films have acceptable adhesion properties and were excellent for gap filling. Polyimide films have excellent adhesion properties, however, they were poor at gap filling and had a great deal of shrinkage during curing. Device passivation was evaluated using double heterojunction bipolar transistor structures with either an abrupt or graded emitter-base junction. Abrupt junction devices had the self-aligned base metal directly on the p⁺ InGaAs base. Graded junction devices had the base metal on top of graded InGaAsP layers, which the metal was diffused through, to make contact to the base region. Abrupt junction devices stressed at an initial J_E of 90 kA/cm² at a V_CE of 2V at 25°C degraded 20% within 70 h of operation, whereas, the graded junction devices show no degradation in dc characteristics after operation for over 500 h. Typical common emitter current gain was 50. An f_t of 80 and f_max of 155 GHz were achieved for 2×4 μm² emitter size devices.     

The influence of plasma etching on trap levels in InP

Electroreflectance (ER) and deep level transient spectroscopy (DLTS) were carried out to characterize the effects of CF₄ plasma etching on defect levels in InP. Different chamber gas pressures were conducted to study effects on the etching result. Similar ER spectra were obtained from the starting InP wafer and the wafer after plasma etching plus rapid thermal annealing (RTA) which showed good restoration of material properties by RTA. Two impurity of structural related features, T1 and T2, were observed from these ER spectra at energy positions about 0.112 and 0.178 eV below bandgap. Two trap levels, El and E2, with activation energy 0.15 and 0.55 eV, were detected from the initial wafer by DLTS. Trap El may correlate with the Tl and T2 levels observed by ER. Similar traps were found in plasma etched samples after rapid thermal annealing with one of the DLTS peaks labeled E2 shifted to the higher temperature side as the plasma etching chamber pressure increased. We identified El to be a residual electron trap from material growth and E2 to be an interface trap arising from Schottky diode fabrication.     

Reduction of dislocations in GaAs and InP epitaxial layers by quasi ternary growth and its effect on device performance

It is shown that strained isoelectronically doped buffer layers grown on GaAs and InP substrates allow one to reduce the dislocation density as well as the deep level concentration. Photoluminescence measurements show an improved near gap luminescence and a reduced deep level emission. This has been also confirmed by DLTS measurements. The higher material quality is also reflected in the device performance. GaAs Schottky diodes (n ˜0.5 · 10¹⁶Cm^-3) exhibit a leakage current of 100 pA up to 50 V reverse bias at room temperature even with large Schottky contact area of 125 μm × 60 μm. This technique allows the quality of electronic and optoelectronic devices to be improved.