低压化学气相沉积技术制备锗反蛋白石三维光子晶体

采用溶剂蒸发对流自组装法将单分散SiO2微球组装形成三维有序胶体晶体模板,用低压化学气相沉积法填充高折射率材料锗,酸洗去除SiO2模板,获得了锗反蛋白石三维光子晶体.通过扫描电镜、X射线衍射仪和紫外-可见-近红外光谱仪对锗反蛋白石的形貌、成分、结构和光学性能进行了表征.结果表明:锗在SiO2微球空隙内具有较高的结晶质量,填充致密均匀.通过改变沉积工艺,可控制锗的填充率;制备的锗反蛋白三维光子晶体具有明显的光学反射峰,表现出光学带隙效应.测试的光学性能与理论计算基本吻合.     

中红外完全带隙Si反蛋白石光子晶体的制备与光学性能研究

通过溶剂蒸发对流自组装法制备SiO2胶体晶体,采用低压化学气相沉积法填充Si,制备得到Si反蛋白石(opal)三维光子晶体.采用扫描电子显微镜对Si反opal的显微形貌进行表征,采用平面波展开法理论模拟Si反opal的光子带隙,采用傅里叶变换红外光谱仪测试其光学性能.研究结果表明:Si在SiO2微球空隙内填充致密均匀,显微红外光谱测试的光子带隙反射峰位置及带宽与理论计算基本符合.变角度反射光谱测试表明,Si反opal沿不同角度入射时在中心波长3319nm处均存在明显的反射峰,证明其具有完全光子带隙,带隙位于中红外大气窗口区域.     

低温等离子体增强化学气相沉积法制备Ge反opal三维光子晶体及其光学性能

通过溶剂蒸发对流自组装法制备SiO2三维有序胶体晶体模板,采用等离子体增强化学气相沉积法在200℃低温条件下填充高折射率材料Ge,获得了Ge反opal三维光子晶体.实现了低于GeH4热分解温度的低温填充.通过扫描电镜、X射线衍射仪和傅里叶变换显微红外光谱仪对Ge反opal的形貌、成分和光学性能进行了表征.结果表明:沉积得到无定型态Ge,退火后形成多晶Ge,Ge在SiO2微球空隙内填充致密均匀.Ge反opal的反射光谱有明显的光学反射峰,表现出光子带隙效应,其带隙中心波长为1650nm和2640nm,测试的光学性能与理论计算基本符合.采用SU-8光刻胶薄膜也进行了Ge沉积,证实了SU-8模板可以耐受这一沉积温度.低温沉积降低了Ge的填充温度,可以直接采用不耐高温的高分子材料作为初始模板,单次复型制备得到多种构型的完全带隙三维光子晶体.     

圆柱形蛋白石和反蛋白石结构光子晶体的制备及其光学性质

研究了在圆柱曲面基底上自组装空心和实心的圆柱形蛋白石和反蛋白石结构光子晶体的方法. 用垂直沉积法在不同曲率半径的毛细管内自组装了空心圆柱形聚苯乙烯(PS)蛋白石结构光子晶体薄膜和二氧化硅 (SiO₂) 反蛋白石结构薄膜; 用类重力沉积法制得实心圆柱形蛋白石和反蛋白石结构光子晶体, 并讨论了这一生长方式中的状态变化过程及影响因素. 用扫描电子显微镜对样品内部结构进行了表征, 用光谱仪测试了光子晶体薄膜的反射光谱, 结果表明: 基底曲率半径和微球粒径的大小是影响空心蛋白石和反蛋白石薄膜质量的主要因素; 微球大小是影响实心结构有序性的主要因素. 关键词： 反蛋白石 空心圆柱 溶胶凝胶协同自组装     

蛋白石型光子晶体红外隐身材料的制备

基于光子晶体的红外隐身材料,主要采取一维层层堆叠结构和三维木堆结构等来实现对红外波段电磁波辐射性能的调控.本文报道了一种操作简易、成本低廉的光子晶体红外隐身材料制备方法.通过优化的垂直沉积法,微米级SiO_2胶体微球自组装成高质量的蛋白石型光子晶体结构.对SiO_2胶体微球进行优选,成功制备了禁带位于2.8—3.5μm,8.0—10.0μm的SiO_2胶体晶体蛋白石型光子晶体材料.该材料可改变目标相应波段的红外辐射特征,具有目标红外波段的隐身效果.     

热处理温度对蛋白石晶体的影响

 采用等体积快速混合法制备了不同粒径的单分散SiO₂微球,通过重力垂直沉降自组装形成了蛋白石模板,研究了热处理温度对蛋白石晶体模板形貌、结构与光学性能的影响。SEM,TG-DSC,UV-Vis等分析表明：热处理可提高组装微球的粘合性与模板的机械强度;SiO₂胶体模板煅烧温度在700～800 ℃较为合适;热处理能够改变蛋白石晶体光子带隙的位置,随着煅烧温度的升高,带隙发生蓝移并且带隙逐渐变窄。     

柔性PMMA反蛋白石结构薄膜的制备及表征

以粒径为270 nm的SiO_2微球胶体晶体作为模板,向其中填充过量单体MMA,热聚合后形成SiO_2/PMMA复合结构光子晶体,将此光子晶体浸泡入浓度为20%的HF溶液中,刻蚀半小时后得到脱离ITO玻璃基板的柔性PMMA反蛋白石结构薄膜.该薄膜为周期有序的三维多孔结构,孔径大小均一,约为210 nm,外观蓝紫色与测试得到的带隙位置相对应.分析其微观形貌可知,对模板的过量填充产生了一层附着于胶体晶体上表面的PMMA致密层,致密层与其下层PMMA反蛋白石结构骨架在热聚合过程中由于体积收缩产生一定的应力差,使反结构薄膜自发从原基板脱离,从而获得柔性反蛋白石结构光子晶体.该薄膜可用于柔性光子晶体器件的制备.     

孔径梯度变化的聚苯乙烯多孔薄膜的制备

 为了对聚合物多孔材料的微观孔结构进行控制,利用垂直沉积技术,制备了蛋白石结构和多层异质结构的SiO₂胶体晶体,并通过模板导向前驱物填充手段,获得了反蛋白石结构和孔径梯度变化的聚苯乙烯多孔薄膜。扫描电镜分析表明,聚苯乙烯多孔结构精确复制了原始模板的反结构。光学透射谱显示,填充聚苯乙烯后复合蛋白石光子禁带位置相对原始模板发生红移,除去模板后,光子禁带位置发生蓝移。根据布拉格衍射方程,计算出胶体晶体模板空隙的填充分数。     

采用溶胶凝胶协同自组装与光刻相结合的方法在反蛋白石结构薄膜中引入二维缺陷

采用溶胶凝胶协同自组装与光刻相结合的方法,在光子晶体反蛋白石结构中引入缺陷,通过溶胶凝胶协同自组装方法在硅片上垂直沉积胶体晶体复合薄膜,把BP212正性光刻胶均匀旋涂在复合薄膜上,通过曝光、显影等光刻工艺,把掩膜版图案复制在复合薄膜上,用此样品再次垂直沉积一层复合薄膜,使图案被复合薄膜覆盖.最后去除胶体微球与光刻胶图案,从而在反蛋白石结构中引入缺陷,用扫描电子显微镜对样品进行表征.分析了光刻胶图案对胶体微球排列的影响.     

成分和拓扑形貌可控的氧化锌/氧化钛复合反蛋白石的合成及其光催化性

利用自组装胶体晶体模板导向电沉积制备氧化锌反蛋白石,利用液相沉积法在室温下制备复合氧化锌/氧化钛反蛋白石. 当对氧化锌反蛋白石进行20 min的液相沉积处理时,可以获得具有非密堆积三维有序多孔结构的氧化锌/氧化钛复合反蛋白石. 当液相沉积时间达到60 min时,则得到壁厚明显增强的纯氧化钛反蛋白石(TIO-LPD60). 讨论了样品成分和拓扑形貌变化的机理. 紫外光催化性能的初步研究显示,反蛋白石膜的光催化性能同时受到来自成分和拓扑形貌两方面的显著影响. 对比纯的氧化锌或者氧化钛反蛋白石,尽管样品具有相似的反蛋白石壁厚,ZnO/TiO₂复合反蛋白石被证实具有明显增强的光催化活性. 然而,当反蛋白石壁厚从约52 nm增加到约90 nm时,TIO-LPD60显示了最高的光催化活性.     

Mid infrared band gap properties of 3-dimensional silicon inverse opal photonic crystal

By the solvent vaporization convection self-assembly method, 1.86 μm silica microspheres were assembled into a colloidal crystal template with long-range order. High refractive index silicon was then filled in the voids of the silica template by the low pressure chemical vapor deposition method. A 3-dimensional silicon inverse opal photonic crystal was obtained with a photonic band gap simulated by a plane wave expansion method. Its micro modality and photonic band gap properties were characterized by scanning electron microscopy and Fourier transform IR spectrometer. There was a good agreement between the measured spectra and the simulated results. The tilt-angle reflectance spectra showed that an obvious reflection peak at 3319 nm stayed in existence with different incidence directions. This result proved that silicon inverse opal has a complete photonic band gap in the mid infrared range. This study opens up an opportunity to create Si-based photonic crystal devices for atmosphere mid infrared photodetection.     

A colloidal crystal double-heterostructure fabricated with the angle controlled inclined deposition method

A self-assembly method, named the angle controlled inclined deposition method, is developed for fabricating well-ordered silica and polystyrene colloidal crystals. A high-quality colloidal crystal with a flat and uniform surface over a large area can be produced rapidly using a minute quantity of suspension and without any additional equipment. By controlling the inclined angle, we can fabricate colloidal crystals with diverse numbers of layers. A colloidal crystal double-heterostructure (composed of three different colloidal photonic crystals) can be rapidly fabricated with this method. Both experimental and simulation results show that the photonic band gap of the double-heterostructure is not a simple superposition of that of the compositional colloidal crystals along the stacking direction.     

Fabrication of Colloidal Photonic Crystals with Heterostructure by Spin-Coating Method

Colloidal photonic crystal heterostructures, composed of two opaline photonic crystal films of silica spheres with different diameters, are fabricated by a two-step spin-coating method. Scanning electron microscopy （SEM） and UV-vis spectrophotometer are used to characterize the heterostructures. The SEM images show good ordering of the two-layer colloidal crystals constituting the heterostructures. The transmission spectra measured from the （111） plane in the heterostructure show that the composite colloidal photonic crystals have double photonic stop bands. Furthermore, when the sizes of the silica spheres used for fabricating the composite photonic crystal are slightly different, the transmission spectrum shows that the composite photonic crystals have more extended bandgap than that of the individual photonic crystals due to partial overlapping of its two photonic stop bands.     

A colloidal crystal microstructure fiber: fabrication and characterization

A method of fabricating colloidal crystal microstructured fiber is presented. The proposed structure relies on partial etching of the cladding layer of a single-mode fiber and growth of colloidal photonic crystals inside eroded area. The photonic crystal cylindrical annulus embedded in fiber is characterized by optical and scanning electron microscopy. The optical characterization was analyzed by optical transmission spectroscopy. The measurement results show a about 1550-nm band gap. The results also reveal the possibility of cladding cylindrical fibers with three-dimensional photonic crystals.     

二氧化硅蛋白石光子晶体中粒子重构对光学性质的影响

使用自组装法制备了蛋白石结构二氧化硅纳米球三维光子晶体,并对样品在150,300,450℃温度下进行了热处理.随热处理温度的升高,光子晶体禁带中心波长出现22.5 nm的蓝移,且禁带宽度变窄.对于在450℃热处理的样品,其测量的禁带中心波长为572.5 nm,与理论计算结果有较大差异.引起样品光学特性变化的原因是热处理...     

Observations of defect propagation in [100]-oriented opal-type photonic crystals

Charged colloidal suspensions have been used as experimental models for the study of crystal nucleation. Here we propose that the technique of template-assisted colloidal self-assembly can be used to visualize the effects of defect propagation in atomic crystal films produced using epitaxial growth. Templates with periodic line defects were used to grow [100]-oriented three-dimensional photonic crystals by means of the template-assisted colloidal self-assembly method, aided by capillary and gravitational forces. The defect propagation in the [100]-oriented photonic crystal was observed using scanning electron microscopy, both at the surface of the crystal and on cleaved facets. This method is useful in the understanding of defect propagation in the growth of colloidal films on templates - and the same approach may also prove useful for the understanding of atomic crystal growth on substrates with defects. Additionally, the deliberate incorporation of line defects may prove valuable as a way of introducing waveguide channels into three-dimensional photonic crystals.     

Ultrasmall-angle X-ray scattering analysis of photonic crystal structure

The results of an ultrasmall-angle X-ray scattering study of iron(III) oxide inverse opal thin films are presented. The photonic crystals examined are shown to have fcc structure with amount of stacking faults varying among the samples. The method used in this study makes it possible to easily distinguish between samples with predominantly twinned fcc structure and nearly perfect fcc stacking. The difference observed between samples fabricated under identical conditions is attributed to random layer stacking in the self-assembled colloidal crystals used as templates for fabricating the inverse opals. The present method provides a versatile tool for analyzing photonic crystal structure in studies of inverse opals made of various materials, colloidal crystals, and three-dimensional photonic crystals of other types.     

Photonic crystals for the visible spectrum by holographic lithography

We describe a general and flexible technique for the fabrication of three-dimensional photonic crystals that is particularly well adapted to the production of structures with the sub-micron periodicity required for applications in the visible optical spectrum. Three-dimensional microstructure is generated by using a four-beam laser interference pattern to expose a thick layer of photoresist. Exposed areas are rendered insoluble; unexposed areas are dissolved away leaving a three-dimensional photonic crystal formed of cross-linked polymer with air-filled voids. The polymeric structure may be used as a template for the production of photonic crystals with higher refractive index contrast. Photonic crystals made of polymer and of TiO₂ have been characterized by scanning electron microscopy and by optical diffraction measurements.