Si基多量子阱SiGe/Si波导光电探测器的制备和研究

采用分子束外延MBE技术,在Si衬底上外延 高质量的20周期SiGe/Si多量子阱(MQW)层;以SiGe/Si MQW材料作 为吸收区,在Si基上制备波导型PIN光电探测器;金 属Al制作在器件的台面上下,形成金属-半导体肖特基接触。测试结果表明,器件在－2V偏压 下,对台面面积为7500μm²,暗电流为0.1μA;在0V偏压下,探测器的光响应谱的吸收 峰值为1008nm,并可以观察到随着吸收长度的 增大,响应信号也随之增大。     

七芯光纤的制备和传输特性的研究

在光纤传输系统中,未来众多通信新业务对传输 容量和传输速度提出了更高的需求, 而采用多芯光纤(MCF)的空分复用(SDM)技术可以有效解决传统单模光纤(SMF)对传输容量的 限制。本文采用光 束传输法和有限元法设计了一种7芯光纤,基于优化的结构参数制备了相应的7芯光纤。搭 建了MCF传输特性测试平台,对所制备的7芯光纤进行测试和分析,得其传输损耗为 0.36dB/km、弯 曲损耗为0.053dB和芯 径间串扰为－18.5dB。这种结构的7芯光纤制备简单,性能良好, 对SDM技术的发展具有重要的推动作用。     

Fabrication and characteristics of A Te-Se-CdO structure

A Te-Se-CdO layer structure has been fabricated by epitaxial growth of a selenium film on a monocrystalline tellurium substrate, followed by deposition of the counterelectrode by reactive sputtering from a cadmium target in the presence of a trace of air. Examination by RHEED has shown the counterelectrode to be CdO in polycrystalline form and the selenium film to be monocrystalline. The structures were found to give a maximum photovoltaic responsivity near 550 nm, at which wavelength the quantum efficiency was around 60% for a CdO thickness of 0.2 micron. The responsivity was affected by the CdO film thickness and the contacts to it but was insensitive to conditions relating to the selenium film, with variations in the thickness up to 10 microns, in the orientation between the (0001) and planes and in the polishing conditions of the tellurium stustrate. Values of equivalent series and shunt resistance were determined from output current-voltage results by curve fitting and the shunt resistance was found to vary inversely with illuminance.     

ZnO纳米颗粒的紫外光探测器制备及其特性

为了发展高性能、低成本和结构简单的ZnO紫外 光探测器。在本文中,利用溶液法,制备出ZnO 纳米颗粒,采用透射电子显微镜(TEM)、X射线衍射仪(XRD)、紫外-可见分光光度计和荧光 光谱仪,分别 研究了ZnO纳米颗粒的形貌、晶相结构和光学特性。结果显示:样品呈球形状的颗粒,尺寸 分布在6~8.5nm 之间,平均粒径为7.1nm,为六方纤锌矿结构。发现ZnO纳米颗 粒的陡峭吸收边出现在370nm附近,在390nm 处出现一个很强的近带边发射峰和一宽泛的可见光发光带。此外,利用制备的ZnO纳米颗粒 ,旋涂在刻蚀 有叉指电极的FTO(SnO₂:F)上,制备出紫外光探测器,测试了它在暗态和365 nm紫外光照下的电流-电压(I-V) 和电流-时间(I-t)特性。结果表明:紫外光探测器的灵敏度、光响应度、响 应时间、恢复时间分别为62.4(在 －3.5V处),13.6A/W(在+5V处), 15s。另外,它的光响应机理主要由于ZnO纳米 颗粒表面吸附的氧起主导作用。     

光子晶体微纳光纤的制备新方法及其特性研究

为了形成胶体晶体-微纳光纤结构,采用提拉生长法,将单分散的聚苯乙烯微球在微纳光纤表面自组装生长成胶体晶体,并用扫描电子显微镜和光谱仪对胶体晶体的显微形貌和透射光谱特性进行了表征。结果表明,聚苯乙烯微球有序堆积,自组装成胶体晶体,其结构为面心立方密排结构,表面为面心立方结构的[111]面。胶体晶体-微纳光纤的透射光谱在1400.8nm处有透射峰,对应于面心立方结构在[111]方向上的光子带隙。这种光子晶体微纳光纤在光纤传感器及滤波器方面有广阔的应用前景。     

Si基Ge波导光电探测器的制备和特性研究

以外延Ge薄膜为吸收区,在Si基上制备了Ge波导光电探测器。利用超高真空化学汽相淀积(UHV/CVD)设备,采取低温高温两步法,在Si(100)衬底上外延出厚度约为500nm的高质量纯Ge层。探测器采用脊型波导结构,Al电极分别制作在波导的台面上下形成背对背肖特基结。I-V特性测试表明,在-1V偏压下,暗电流密度为0.2mA/cm2。由于Si与Ge热失配引起外延的Ge薄膜受到0.2%张应变,减小了Ge带隙,光响应波长范围扩展到1.60μm以上。在70mW、1.55μm入射光照射下,测得光电流比暗电流高出近1个数量级。     

ZnO纳米线场效应管的制备及光电特性

本文采用水热法生长的ZnO纳米线制得悬浮ZnO纳米线场效应晶体管,该场效应管的跨导为0.396μS,迁移率为50.17cm^2/Vs,VGS = 0 V时电阻率为0.96×102Ωcm,开关态电流比（Ion/Ioff）为10^5。该效应管在紫外下曝光（2.5μw/cm2）后显示了穿通现象和开启电压漂移（从-0.6V 到 +0.7V）,且由于漏极感应势垒的降低,使得源漏电流减少一半（从560nA到320nA）。悬浮ZnO纳米线场效应管的这些性质揭示了它的一些内在属性和器件方面的应用。     

Fabrication and photoelectrical characteristics of ZnO nanowire field-effect transistors

rease by almost half of the source-drain current (Ids, from 560 nA to 320 nA) due to drain-induced barrier lowering.Continued work is underway to reveal the intrinsic properties of suspended ZnO nanowires and to explore their device applications.     

金属Al与半导体Ge欧姆接触的制备和表征

基于圆形传输线模型,通过测试样品的比接 触电阻率和电流-电压(I-V)特性曲线,分析 对比了Al与Si基上外延生长的p型Ge、n型Ge和n型Si的接触特性。实验结果发现,由于金 属与Ge材料接触存在强烈的费米钉效应,导致金属与n型Ge接触有高的接触电阻,难实 现低的比接触电阻率;而Al与p型Ge在掺杂浓度为4.2×10¹⁸ cm－3时,并且经过退火,比接 触电阻率能达到4.0×10－7 Ω·cm²;Al与n型Ge和n型Si接 触电极相比,后者可形成良好的 欧姆接触,其比接触电阻率较n型Ge接触降低了1个量级,经合金化处理后的Al/n⁺Si接触 电阻率能达到5.21×10－5 Ω·cm²,达到了制作高性能Ge 光电器件的要求。     

Si基Ge波导共振腔增强型光电探测器的制备和特性研究

采用低温缓冲层技术,在硅(Si)衬底上生长了质量 优良的锗(Ge)薄膜。Ge层受到由于Si和Ge热膨胀系数不同引入张应变,大小约为0. 16%。以 外延的Ge层作为吸收区,前后以Ge/空气作为分布布拉格反射镜(DBR),在Si基上制备波导共 振腔增强 型(RCE)光电探测器。测试表明,器件在－1V偏压下,暗电流密度为14.9mA/cm²;在零偏压下, 器件的响应光谱在1.3~1.6μm波长范围内观察到4个共振增强峰,分 别位于1.35、 1.50μm,光响应波长范围扩展到1.6μm以上,采用传输矩阵法模拟的 响应光谱与实验测得结果近似吻合;在1.55μm入射光的照射下,测 得光响应度为21.4mA/W。     

Fabrication and stress analysis of annular-trench-isolated TSV

The large mismatches among the coefficients of thermal expansion (CTE) of the metal via, insulator liner, and Si substrate of the through-silicon via (TSV) induce thermal stresses within and around the TSV during thermal-cycled fabrication processes. Reduction of thermal stress in the Si substrate is important for minimizing the deviations in the device characteristics. An annular-trench-isolated (ATI) structure was proposed for the TSV to solve the thermal issues, which occur during the three-dimensional (3D) integrated circuit (IC) integration, by stress redistribution. The concept of ATI TSV is based on retaining a Si-ring between the metal core and insulator layer during the fabrication process. We realized the ATI TSV using a via-last fabrication approach, with two deep silicon etching processes (Bosch processes) for the insulator layer and the metal core. Parylene-HT was utilized as the insulator to achieve high uniformity. With a vacuum-assisted filling system, the vias were filled with a solder material. ATI TSVs with diameters of 10 μm and 2-μm-thick Parylene-HT insulation layers were demonstrated. Studies on the thermal stress levels of the ATI TSV were carried out by finite-element method (FEM) simulation, along with comparisons with regular and annular TSVs. We revealed that the ATI TSV shows lower thermal stresses in the Si substrate than the regular and annular TSVs. The ATI TSV is a possible candidate for 3D IC integration with stress-sensitive devices.     

纳米硅/单晶硅异质结MAGFET制作及特性

A MAGFET using an nc-Si/c-Si heterojunction as source and drain was fabricated by CMOS technology, using two ohm-contact electrodes as Hall outputs on double sides of the channel situated 0.7L from the source. The experimental results show that when VDS = -7.0 V, the magnetic sensitivity of the single nc-Si/c-Si heterojunction magnetic metal oxide semiconductor field effect transistor （MAGFET） with an L ： W ratio of 2 ： 1 is 21.26 mV/T, and that with an L ： W ratio of 4 ： 1 is 13.88 mV/T. When the outputs of double nc-Si/c-Si heterojunction MAGFETs with an L ： W ratio of 4 ： 1 are in series, their magnetic sensitivity is 22.74 mV/T, which is an improvement of about 64% compared with that of a single nc-Si/c-Si heterojunction MAGFET.     

Fabrication and performance characteristics of InGaAsP ridge-guide distributed-feedback multiquantum-well lasers

The fabrication and performance characteristics of InGaAsP ridge-guide distributed-feedback lasers with multiquantum-well active layers are reported. The lasers are 320 ?m long and have four active wells (?300 ? thick). The lasers have threshold current ?100 mA at 30°C, external differential quantum efficiency ?0.1 mW/mA/facet at 30°C and To? 60 K and can be operated in the same DFB mode up to 70°C. The measured frequency chirp is about a factor of 3 smaller than that for conventional double-heterostructure lasers. The smaller chirp should allow larger repeater spacing for high-bit-rate long-distance fibre transmission systems applications.     

Fabrication and characteristics of the nc-Si/c-Si heterojunction MAGFET

A MAGFET using an nc-Si/c-Si heterojunction as source and drain was fabricated by CMOS technology, using two ohm-contact electrodes as Hall outputs on double sides of the channel situated 0.7L from the source. The experimental results show that when V_(DS) = -7.0 V, the magnetic sensitivity of the single nc-Si/c-Si heterojunction magnetic metal oxide semiconductor field effect transistor (MAGFET) with an L : W ratio of 2 : 1 is 21.26 mV/T,and that with an L : W ratio of 4 : 1 is 13.88 mV/T. When the outputs of double nc-Si/c-Si heterojunction MAGFETs with an L : W ratio of 4 : 1 are in series, their magnetic sensitivity is 22.74 mV/T, which is an improvement of about 64% compared with that of a single nc-Si/c-Si heterojunction MAGFET.     

宽光谱聚合物热光开关的制备及容噪特性研究

利用聚合物/SiO₂混合材料脊形波 导结构以及化学气相沉积(CVD)、涂膜和湿法刻蚀等 工艺,设计并制备了一种低功耗 马赫-曾德尔干涉(MZI)热光开关。测试了波导芯层和包覆层材料的色散特性,模拟分析了 器件的输出功率和光谱性能。以可调 谐激光器作为光源,实验测试了所制备器件的开关、响应和光谱特性。在1〖KG －1/ 6〗550nm中心波长下,器件的开关功耗约为7.8mW, ON与OFF状态间的消光比达32.6dB。在纯净方波驱动电压信号(峰峰 值为3V_pp)作用下,测得器件的上升和下降时间分别 为107μs。保持器件在1550nm波长下的驱动功率不变,测得器 件的输出光谱约为50nm(1520～1570nm),且在此范 围内,器件的消光比大于18dB。利用NE555等 集成电路自主制作了一种噪声幅度可调的含噪信号驱动源,借此研究了器件 的容噪特性。结果显示,当要求器件的消光比大于10dB时,可允许的最大噪声幅度为1.1V_pp。     

Fabrication and characteristics of GaP-AlGaP tapered waveguide semiconductor Raman amplifiers

We have fabricated GaP-AlGaP tapered waveguide semiconductor Raman amplifiers, and analyzed the effect of tapering in pulse-pumped high-gain operation. The finesse measurement and 80-ps pulse pumped Raman amplification experiment were performed. Although the tapering has caused additional optical loss, the highest gain of 23 dB has been obtained for a tapered waveguide with input facet of 6.0 /spl mu/m/sup 2/ and back facet of 2.9 /spl mu/m/sup 2/ at averaged input power of 170 mW (peak power 26 W). It is shown that the optical loss of the pump light is more severe than the linear optical loss of the signal light when the gain is higher than 20 dB.     

Fabrication and analysis of deep submicron strained-Si n-MOSFET's

Deep submicron strained-Si n-MOSFETs were fabricated on strained Si/relaxed Si_0.8Ge_0.2 heterostructures. Epitaxial layer structures were designed to yield well-matched channel doping profiles after processing, allowing comparison of strained and unstrained Si surface channel devices. In spite of the high substrate doping and high vertical fields, the MOSFET mobility of the strained-Si devices is enhanced by 75% compared to that of the unstrained-Si control devices and the state-of-the-art universal MOSFET mobility. Although the strained and unstrained-Si MOSFETs exhibit very similar short-channel effects, the intrinsic transconductance of the strained Si devices is enhanced by roughly 60% for the entire channel length range investigated (1 to 0.1 μm) when self-heating is reduced by an ac measurement technique. Comparison of the measured transconductance to hydrodynamic device simulations indicates that in addition to the increased low-field mobility, improved high-field transport in strained Si is necessary to explain the observed performance improvement. Reduced carrier-phonon scattering for electrons with average energies less than a few hundred meV accounts for the enhanced high-field electron transport in strained Si. Since strained Si provides device performance enhancements through changes in material properties rather than changes in device geometry and doping, strained Si is a promising candidate for improving the performance of Si CMOS technology without compromising the control of short channel effects     

单面键合面发射激光器的研制与分析

键合长波长垂直腔面发射激光器(VCSEL)的研制对于光通信的发展具有重要意义,可以有效克服传统外延生长方法的诸多难題.文章通过对布喇格反射镜、有源区和光学腔的设计,结合键合技术进行工艺设计,研制出单面键合长波长垂直腔面发射激光器,并对器件进行了光泵浦测试与分析.器件的光泵激射证明结构及工艺设计是合理的,键合后的界面可以承受腐蚀、剥离、氧化等后续工艺,且键合界面未对器件光学性能造成明显不良影响.