高品质因子聚合物可重构微环谐振腔滤波器

以聚合物ZPU-44和聚砜(PSU,polysulfone risi n)分别作为波导包层和芯层材料,采用倒脊形波导结构,设计并 优化了聚合物可重构微环谐振腔滤波器的波导截面参数、弯曲半径、耦合区波导长度和间距 以及调谐电极 等结构参数,分析了其谐振滤波特性。采用传统的微加工工艺制备了聚合物可重构微环谐振 腔滤波器并进 行了测试。结果表明,其在通信波段1550nm附 近的自由光谱范围(FSR)为0.15nm,3dB带宽约为0.0235nm, 品质因子Q达6.60×10⁴,在0~ 4V电压范围内实现了0.5~12.95dB消光比的调谐,且 谐振波长调谐一 个FSR的电压为4.75V,与理论设计基本 相 符。本文的聚合物可重构微环谐振腔滤波器可用于集成波导可调谐光延时线和可调谐滤波。     

热光聚合物微环谐振腔滤波器的研究

设计并制备了一种热光聚合物微环谐振腔滤波器。微谐振环采用跑道型结构,通过光束传播法(BPM)对其弯曲半径进行了设计和优化。采用传统的接触式光刻曝光工艺制备了微环谐振腔滤波器并对其进行了光谱测试,实验结果表明,所设计的器件在1 550nm附近的自由光谱范围(FSR)为112pm,消光比约为12.8dB,3dB带宽约为0.026nm,品质因子Q为5.96×104,调制效率是6.13pm/mW;同时测量了器件的响应时间,得到的响应时间约为1.5ms。     

SoI基微环谐振可调谐滤波器

采用电子束光刻和ICP刻蚀等工艺制作出绝缘体上Si(SoI)基纳米线波导微环谐振(MRR)滤波器,波导截面尺寸为300 nm×320 nm,微环半径为5 μm.测试结果表明,器件的自由频谱宽度(FSR)为16.8nm,1.55μm波长附近的消光比(ER)为18.1 dB.通过对MRR滤波器进行热光调制,在21.4～60...     

基于微环谐振腔的耦合谐振光波导反射镜

研究了一种基于微环谐振腔的耦合共振光波导反射镜.基于耦合模理论,对这种新型波导反射镜的反射光谱进行了数值分析,详细讨论了直波导与微环谐振腔之间的耦合系数和相邻微环谐振腔之间的耦合系数对反射光谱的影响.计算结果表明这种反射镜的反射光谱存在多峰结构,在弱耦合的情况下可以实现波长选择性反射滤波,并且发现在这种波导反射镜中存在类似于原子系统中电磁诱导透明现象的耦合共振诱导透明现象.     

基于氮化硅微环和载波分离的可重构微波光子带通滤波器

基于Add-Drop型氮化硅微环滤波器,利用光学单边带调制和光载波分离的方法,实现可重构微波光子带通滤波器。滤波器带宽和带外抑制比分别达到726 MHz和37.0dB。并且通过改变光载波波长实现1.64~23.41GHz的滤波器频率调谐;通过调节微环耦合系数实现0.683~2.246GHz的滤波器带宽调谐,在带宽调谐范围内带外抑制比大于26dB。     

SOI基微环谐振可调谐滤波器

采用电子束光刻和ICP刻蚀等工艺制作出基于SOI纳米线波导微环谐振滤波器。滤波器微环半径为5μm左右,波导截面尺寸为(350nm～500nm)220nm不等。测试结果表明,波导宽度为450nm时器件性能最为理想,其自由频谱宽度为16.8nm,1.55μm波长附近的消光比为22.1dB。通过对微环滤波器进行热光调制,在21.4℃～60℃温度范围内实现了4.8nm波长范围的可调谐滤波特性,热光调谐效率达到0.12nm /℃。同时,研究了基于单环和双环的多通道上下载滤波器,实验结果表明多通道滤波器的信号传输存在串扰,主要是不同信道之间的串扰,尤其在信号上载时,会在相邻信道产生较大串扰。     

新型的可调谐微环谐振器的设计

为了改进微机电系统中的传感器应用范围和特性参数,采用微纳光纤制作了环形谐振腔结构,设计的结构具有尺寸小、损耗低,品质因素高等优点。理论上分析了微纳光纤的光传输模式特性,通过电场的传数矩阵推导了谐振腔中的速度变化与光强变化间的关系,得到了加速度作用下微环谐振腔的谐振波长、周长、有效折射率的变化值间的函数关系。仿真结果分析表明:设计的微环波导电场波动明显,耦合效率较好;光谱强度和3 dB带宽变化较小,Q值达到104;在质量块每增加10 g时,输出光谱图约向右漂移3 nm;加速度与谐振波长漂移量基本呈线性关系,可以通过谐振波长的漂移量来实现对加速度的测量。研究结果能够为全光网络和微机电系统提供实现多种功能的光波导器件。     

基于微环谐振腔和OFDM技术的慢光缓存

提出一种新的具有较大带宽延时积(BDP)的光缓存结构。该结构基于一个单独的微环谐振腔和一个OFDM(正交频分复用)技术的发射机。较大的带宽延时积是通过将数据分布在OFDM的子载波上然后由谐振腔来获得的。建立了一个包括整个系统的数值模型,并且在仅考虑5条子载波的仿真中实现了较大的带宽延时积。     

基于Mach-Zehnder结构微环谐振腔全光逻辑门的研究

为了解决全光逻辑门结构所需抽运能量过大的问题,提出了一种基于Mach-Zehnder结构微环谐振腔的全光控制逻辑门结构。通过在微环波导上加入空气孔加强对光的限制,增强了带边附近的3阶非线性效应,从而减小达到所需相移的抽运能量。将微环谐振腔与Mach-Zehnder结构结合,采用光学Kerr效应控制不同微环内相移的改变,从而实现不同逻辑门功能。同时进行了理论分析与仿真验证,计算了不同尺寸空气孔对于结构的影响,并对于不同逻辑功能的控制方法,验证了结构的可行性。结果表明,这种逻辑门结构所需抽运能量不超过10dBm,延迟处于皮秒量级,速度快,器件的尺寸处于微米量级,该结构可以同时实现不同的逻辑门状态,对于全光网络的研究有指导意义。     

Mechanism of selective Si3N4 etching over SiO2 in hydrogen-containing fluorocarbon plasma

This paper describes the mechanism of selective Si₃N₄ etching over SiO₂ in capacitively-coupled plasmas of hydrogen-containing fluorocarbon gas, including CHF₃, CH₂F₂ and CH₃F. The etch rate of Si₃N₄ and SiO₂ is investigated as a function of O₂ percentage in all plasma gases. Addition of O₂ in feed gases causes plasma gas phase change especially H density. The SiO₂ etch rate decreases with increase of O₂ percentage due to the decline of CF_x etchant. The Si₃N₄ etch rate is found to be strong correlated to the H density in plasma gas phase. H can react with CN by forming HCN to reduce polymer thickness on Si₃N₄ surface and promote the removal of N atoms from the substrate. Thus the Si₃N₄ etch rate increases with H intensity. As a result, a relative high selectivity of Si₃N₄ over SiO₂ can be achieved with addition of suitable amount of O₂ which corresponds to the maximum of H density.     

基于氮化硅陶瓷毛细芯的低温回路热管研究

利用氮化硅陶瓷多孔材料作为毛细芯设计了一种以乙烷为工质的低温回路热管样机, 并对其降温及传热性能进行了研究。试验结果表明,通过在蒸发器上施加4 W的热量, 这种低温回路热管能够在常温下实现启动,并能顺利实现降温;在降温过程中,通过不断增大加热功率,可以加快低温回路 热管的降温;当蒸发器的温度为190 K时,该样机可以稳定传输30 W的热量。     

Two Layer Surface Exfoliation on Si3N4/Si by Sequential Implantation of He and H Ions

n-Type Si(100) wafers with a thermally grown Si₃N₄ layer (∼170 nm) were sequentially implanted with 160 keV He ions at a dose of 5 × 10¹⁶ cm⁻² and 110 keV H ions at a dose of 1 × 10¹⁶ cm⁻². Depending on the annealing temperature, surface exfoliations of two layers were observed by optical microscopy and atomic force microscopy. The first layer exfoliation was found to correspond to the top Si₃N₄ layer, which was produced at lower annealing temperatures. The other was ascribed to the implanted Si layer, which was formed at higher temperatures. The possible exfoliation processes are tentatively discussed, and potential applications of such phenomena are also suggested.     

基于Si3N4掩模的太阳电池选择性掺杂工艺研究

设计了基于Si3N4掩模的太阳电池选择性掺杂工艺,并对其工艺参数进行了仿真优化。选择性掺杂电池的一次掺杂条件为仿真所得最佳非选择性掺杂电池的工艺参数。运用SILVACO软件分别对选择性掺杂的时间、预淀积浓度和温度进行了仿真研究。仿真结果表明,随着选择性掺杂的预淀积浓度的增加,光谱响应率先增加后降低;随着扩散温度和扩散时间的增加,电池的光谱响应率逐渐减小。所得最佳选择性掺杂工艺参数为预淀积磷硅玻璃杂质浓度1×1019 cm-3、扩散温度800℃、扩散时间5min。     

Effects of CH2F2 and H2 flow rates on process window for infinite etch selectivity of silicon nitride to ArF PR in dual-frequency CH2F2/H2/Ar capacitively coupled plasmas

The process window for the infinite etch selectivity of silicon nitride (Si₃N₄) layers to ArF photoresist (PR) and ArF PR deformation were investigated in a CH₂F₂/H₂/Ar dual-frequency superimposed capacitive coupled plasma (DFS-CCP) by varying the process parameters, such as the low frequency power (P_LF), CH₂F₂ flow rate, and H₂ flow rate. It was found that infinitely high etch selectivities of the Si₃N₄ layers to the the ArF PR on both the blanket and patterned wafers could be obtained for certain gas flow conditions. The H₂ and CH₂F₂ flow rates were found to play a critical role in determining the process window for infinite Si₃N₄/ArF PR etch selectivity, due to the change in the degree of polymerization. The preferential chemical reaction of hydrogen with the carbon in the hydrofluorocarbon (CH_xF_y) layer and the nitrogen on the Si₃N₄ surface, leading to the formation of HCN etch by-products, results in a thinner steady-state hydrofluorocarbon layer and, in turn, in continuous Si₃N₄ etching, due to enhanced SiF₄ formation, while the hydrofluorocarbon layer is deposited on the ArF photoresist surface.     

Co3O4/Fe2O3异质结复合材料的制备及其紫外光光电探测性能

分别采用旋涂法和水热法在FTO衬底上制备Co₃O₄种子层和Co₃O₄薄膜,再在Co₃O₄薄膜上水热生长Fe₂O₃纳米棒,获得了高质量的Co₃O₄/Fe₂O₃异质结复合材料。通过改变Fe₂O₃前驱体溶液浓度来改变异质结复合材料中Fe₂O₃组分的含量。结果表明,Fe₂O₃纳米棒覆盖在呈网状结构的Co₃O₄薄膜上,随着Fe₂O₃前驱体溶液浓度即Fe₂O₃组分含量的增加,Co₃O₄/Fe₂O₃异质结复合材料对紫外光的响应逐渐增强,当Fe₂O₃前驱体溶液浓度为0.015mol/L时,异质结复合材料有着很好的光电稳定性,并表现出较高的响应率(12.5mA/W)和探测率(4.4×10¹⁰Jones)。     

用于非易失性相变存储器中Si2Sb2Te5在CF4/Ar等离子体下的反应离子刻蚀

Phase change random access memory（PCRAM） is one of the best candidates for next generation nonvolatile memory,and phase change Si₂Sb₂Te₅ material is expected to be a promising material for PCRAM.In the fabrication of phase change random access memories,the etching process is a critical step.In this paper,the etching characteristics of Si₂Sb₂Te₅ films were studied with a CF₄/Ar gas mixture using a reactive ion etching system.We observed a monotonic decrease in etch rate with decreasing CF4 concentration,meanwhile,Ar concentration went up and smoother etched surfaces were obtained.It proves that CF4 determines the etch rate while Ar plays an important role in defining the smoothness of the etched surface and sidewall edge acuity.Compared with Ge₂Sb₂Te₅, it is found that Si₂Sb₂Te₅ has a greater etch rate.Etching characteristics of Si₂Sb₂Te₅ as a function of power and pressure were also studied.The smoothest surfaces and most vertical sidewalls were achieved using a CF₄/Ar gas mixture ratio of 10/40,a background pressure of 40 mTorr,and power of 200 W.     

Oxidation characteristics of Si0.85Ge0.15 nanowires

Oxidation characteristics of Si_0.85Ge_0.15 nanowires were investigated using transmission electron microscopy (TEM) analyses. Si_0.85Ge_0.15 nanowires were grown in a tube furnace by vapor–liquid–solid (VLS) method and thermally oxidized at 925 °C for 1–8 h. After oxidation, oxide thicknesses were measured using TEM images. Si_0.85Ge_0.15 nanowires showed a thicker oxide than Si nanowires, for the whole range of oxidation time. The oxidation rate of Si_0.85Ge_0.15 nanowires significantly decreased in nanowires with diameters less than 150 nm. Long-term oxidation in Si_0.85Ge_0.15 nanowire resulted in the oxidation of germanium atoms.     

NH3-Ar气氛下制备的Zn3N2薄膜的结构和光学性能

在NH3-Ar气氛下,用RF磁控溅射金属Zn靶在玻璃衬底上室温制备了Zn3N2薄膜,研究了NH3分压对Zn3N2薄膜的结构和光学特性的影响。XRD分析表明Zn3N2薄膜出现多晶结构,具有(321)择优取向。当NH3分压从5%变化到25%时,Zn3N2薄膜的间接光学带隙从2.33eV升高到2.70eV。室温下Zn3N2薄膜在437nm和459nm波长出现了发光峰,并对发光机理进行了分析。