激光剥离GaN表面的抛光技术

激光剥离(LLO)技术是研制新型氮化镓(GaN)基谐振腔结构光电子器件的关键技术。然而LLO后的GaN表面往往具有较大的粗糙度,而制作谐振腔结构器件需要很高的表面平整度,因此需要对LLO后的GaN表面进行抛光。分别采用金刚石粉抛光液和胶粒二氧化硅抛光液进行机械抛光和化学机械抛光(CMP),并对比了两种方法获得的抛光结果,研究发现前者会在抛光后的GaN表面引入划痕,而采用后者可以得到亚纳米级平整度的表面。进一步的实验结果表明,胶粒二氧化硅抛光液同样适用于图形化衬底外延片激光剥离后的GaN表面抛光。     

纳米级三氧化二铝对碱性钨抛光液的影响

研究了纳米级三氧化二铝颗粒的加入对以二氧化硅为磨料的碱性钨抛光液的影响。首先用单一因素法分析了三氧化二铝与二氧化硅质量比对原有碱性钨抛光液的去除速率的影响,以及氧化剂体积分数和pH值对抛光液去除速率的影响,取最优值,然后对添加三氧化二铝抛光液抛光后晶圆表面粗糙度进行了测试分析。实验结果显示在三氧化二铝与二氧化硅质量比为1∶2,二氧化硅水溶胶与去离子水体积比为1∶1,氧化剂体积分数为2%,pH值为9时,去除速率达到175 nm/min,较原有碱性钨抛光液提高约1倍,表面粗糙度为2.24 nm,能满足实际生产要求。     

长直SiO_2纳米线的制备和结构表征

采用磁控溅射法,以Si粉和溅金Si(111)为原料,加入C粉,在Si(111)衬底上制备无定形SiO2纳米线。首先,在Si(111)衬底上分别溅射厚度为18和36 nm的Au。然后,在1 100℃条件下处理80 min。用扫描电子显微镜(SEM)、X射线光电子能谱(XPS)、傅里叶红外光谱(FTIR)和X射线衍射方法 (XRD)等测试手段对退火后的SiO2纳米线的表面相貌、微观结构进行分析。结果表明,反应后有大量长而直的SiO2纳米线生成。而且随着溅射Au厚度的增加,SiO2纳米线的数量增多,且长度更长。这表明,SiO2纳米线的生长与溅射Au的厚度密切相关。     

抛光压力对PS/CeO2纳米复合磨粒抛光性能的影响

以采用改进无皂乳液聚合法制备的纳米尺寸聚苯乙烯(PS)微球为内核,采用原位化学沉淀法制备了不同壳层厚度的PS/CeO2核/壳包覆结构复合微球。将所制备的复合颗粒用于二氧化硅介质层的化学机械抛光,用原子力显微镜测定晶片的微观形貌和粗糙度。电镜结果表明:复合颗粒呈规则球形,其PS内核尺寸约为72 nm,CeO2壳厚为5~20 nm。抛光结果显示:在本实验范围内,抛光速率随抛光压力的增加而增大,而过低(2.4 psi,1 psi=6 895 Pa)或过高(6.1 psi)的抛光压力均使晶片表面产生划痕。当抛光压力适中(4.5 psi)时,经复合磨料(壳厚约为13 nm)抛光后的晶片表面无明显划痕,在5μm×5μm范围内表面均方根粗糙度为0.265 nm,抛光速率达98.7 nm/min。     

基于纳米颗粒的铜锌锡硫硒薄膜制备

采用热注入法制备了Cu2ZnSnS4(CZTS)纳米颗粒,并形成高分散、稳定的"墨水",采用滴注方法形成CZTS前驱体薄膜。利用X射线衍射(XRD)、拉曼光谱(Raman)、透射电子显微镜(TEM)和紫外-可见光谱(UV-VIS)对CZTS纳米颗粒的晶体结构、表面形貌和带隙进行了表征。Raman数据显示合成的纳米颗粒为纯的CZTS,不存在ZnS和Cu2SnS3等杂相。傅里叶红外光谱(FTIR)和UV-VIS表明合成的CZTS纳米颗粒表面被油胺(OLA)包覆,并且其带隙为1.52 eV。对CZTS前驱体薄膜在硫化氢气氛和固态硒气氛中退火处理,得到铜锌锡硫硒(CZTSSe)薄膜。结果表明,经硫化氢处理后薄膜表面平整但CZTS晶粒并没长大,而经过固态硒处理后得到了结晶质量较好的CZTSSe薄膜。     

纳米结构分子吸附引起的表面增强拉曼散射研究

利用模板印刷技术,制备了具有不同局域表面等离子体共振(LSPR)峰的Au纳米空心半球壳结构,并以4-巯基苯胺(4-ATP)为探针分子研究了纳米结构表面吸附分子对表面增强拉曼散射(SERS)强度的影响。结果表明,当纳米结构的LSPR峰位处于激发光波长的短波长或"马鞍型"位置时,SERS强度随吸附分子数的增加而增大;当处于长波长位置时,SERS强度呈现先增大后减小的趋势。利用分子吸附理论和纳米结构表面局域场强度变化,对此现象进行了解释。     

银纳米颗粒界面层对有机太阳能电池光敏层相分离的影响

通过原子力显微镜(AFM)和X射线光电子能谱(XP S)表征,研究了在光敏层与阳极缓冲层界面引入银(Ag)纳米颗粒界面层后对PTB7:PC70BM光 敏层相分离的影响,并通过接触角测试对其影响机理进行了分的,结果表明,当引入Ag纳米 颗粒界面层后,光敏层的表面形貌并没有发生 明显的改变,但是光敏层在横向与纵向方向有了更好的相分离;并发现,引入Ag纳米颗粒引 起 的光敏层优化的相分离,本质上源于其底部PEDOT:PSS层表面能的减小,其中起关键作用的 是乙醇溶剂;通过紫外-可见吸收光谱以及相关电池性能测试确认,乙醇溶剂处理PEDOT:P SS表面有助于提高电池的电性能。 本文研究表明,在有机太阳能电池(OSCs)中引入金属纳米颗粒,不仅要考虑其 光学效应,还要考虑由于光敏层相分离的变化引起的电学效应。     

纳米金增敏的压电乙肝IgM免疫传感器研究

研究了在石英晶体表面上组装纳米金,利用水溶性聚合物聚乙二醇(PEG)为凝集剂,加入聚乙烯醇(PVA)增加其凝聚力,利用金纳米粒子对传感器的信号放大增敏作用、比表面积大和较好的生物相溶性等优良特征,在晶振表面固定乙肝核心抗体(IgM),构建了一种高灵敏度的乙肝液相压电免疫传感器。应用于样本检测。该方法与酶联免疫分析方法(ELISA)无显著差异。     

单壁碳纳米管表面增强拉曼散射的新方法

依据碳纳米管独特的力学性能,在银表面直接研磨单壁碳纳米管(SWCNTs),在形成纳米级粗糙银表面的同时,SWCNTs管也吸附在银表面上,在银表面粗糙程度和SWCNTs厚度适中的区域得到了高质量的表面增强拉曼散射(SERS)谱。理论分析和实验结果表明,该方法是正确可行的。     

提高发光二极管出光效率的新方法

利用高分子共混物的微相分离和自组装原理,制备出具有纳米微孔的PMMA薄膜,以此为掩膜对发光二极管(LED)表面进行湿法腐蚀,得到表面微结构,并研究了腐蚀时间对表面形貌的影响.测试结果表明,当微孔直径在500 nm左右、腐蚀深度约140 nm时,所得到的表面微结构能使LED在20 mA的注入电流下光功率平均提高18%.     

TiO2, ZnO and nanobimetallic silica catalyzed photodegradation of methyl green

The present works describes a method for degradation and decolorization of methyl green (MG) on semiconducting oxides and nanobimetal (Ag/Pt) doped silica sol–gel powder by using UV and solar light. Bimetallic nanoparticles are the recent research interest because of the high catalytic activity and tunable surface plasmon resonances. In this study the nanobimetal (Ag/Pt) doped silica sol–gel powder were prepared and characterized. Silica sol–gel powder was characterized by FT-IR spectroscopy, SEM with EDX, TEM, DRS and XRD analysis. The results of photodegradation of methyl green on TiO₂, ZnO and nanoAg/Pt bimetal doped silica sol–gel powder were presented and compared.     

Characterization of moisture properties of polymers for IC packaging

In this paper we determined the water uptake of a die attach and a molding compound. The two types of polymer which were selected are a die attach filled with silver particles and an epoxy molding compound filled with silica particles. The water absorption is carried out in an adjustable thermal and humidity chamber, SGA-100, at different temperatures and humidity levels. Moisture absorption equilibrium of test data were obtained by experiment. The moisture absorption equilibrium prediction equation was modeled by using the extrapolated experimental data. Diffusion coefficients at different temperature were obtained from the moisture absorption experiments.     

激光立体成形粉末流输送的数值模拟研究

激光立体成形(LSF)技术是一项基于同步送粉激光熔覆技术的先进增材制造技术。粉末流的输送对于沉积层的形成至关重要。通过建立载粉气流的湍流模型并基于粉末颗粒在气体湍流中的运动分析,采用数值模拟方法建立粉末流输送的数学模型,并利用Fluent软件进行求解,从而获得粉末流的质量浓度分布。将实验测量结果与模拟计算结果进行对比分析。结果表明,计算结果与实验测量结果比较吻合。对比粉末粒径范围为50~240μm的粉末流和粉末粒径范围为65~75μm的粉末流的模拟结果发现,在相同送粉工艺条件下,粒径分布范围不同则粉末流颗粒质量浓度有明显差异。     

Sputtered silica waveguides with an embedded three-dimensional structure

Single-mode sputtered silica waveguides (SS guides) are fabricated by filling channels of 8-μm width in a silica substrate with core silica material and embedding with a cladding layer. Silica deposition process is carried out by bias sputtering. The measured waveguide loss was 1.2 dB/cm. The change of cross-sectional profile in the sputtering process on the channel is analyzed with the result in good agreement with experiments. The optimum sputtering condition for filling the channel is elucidated. The method is applied to embedding gratings fabricated on the silica substrate.     

选区激光烧结聚苯乙烯粉的基础实验研究

为了探寻选区激光烧结工艺参量对聚苯乙烯粉烧结质量影响的规律,并通过工艺参量的优化来提高其烧结精度与强度,采用对聚苯乙烯粉进行热重/差示扫描量热法实验分析、利用SLS300快速成型机对聚苯乙烯粉烧结等方法,进行了理论分析和实验验证,发现烧结温度在150℃～260℃之间时,试样烧结尺寸精度较高。结果表明,聚苯乙烯粉烧结件的x向和y向尺寸精度受工艺参量影响较小,而z向尺寸精度受工艺参量影响较大;弯曲强度表现为随激光功率、扫描间隔、分层厚度的增大而减小的变化趋势。这对于工艺参量优化选择来提高聚苯乙烯粉的烧结质量提供了实验依据。     

Engineered Sensitivity of Structured Tin Dioxide Chemical Sensors: Opaline Architectures with Controlled Necking

Structure–property relationships in tin dioxide materials have been studied utilizing a reverse templating strategy to synthesize opaline structures with controlled neck dimensions between spheres. The necking dimensions could be controlled by sintering the parent silica opals at temperatures between 700 and 1050 °C. Inverted polymer opals were synthesized by infiltrating the silica opals with styrene, followed by thermally induced polymerization, and removal of the silica with HF. Tin dioxide opals with controlled microstructures were then synthesized from these inverted polymer opals. The gas sensing response of these materials to carbon monoxide could be understood as a function of the necking diameter in the resulting tin dioxide opals.     

铁基合金粉末激光熔覆的显微硬度分析

本文用前期实验选出的最佳工艺参数及熔覆层数,通过两种铁基合金粉末对45号钢,按同步供料法进行激光熔覆实验;对最佳工艺参数及熔覆层数时的熔覆层的显微硬度进行分析.     

基于光整加工技术的粉体图像灰度分布相似性检测

为光整加工技术当中的烧结型滚抛磨块的粉体原 料均匀性判断提供理论依据,提出 一种粉体图像相似性检测理论。首先利用采样转盘采集粉体样本,并通过数字显微镜采集粉 体图像,将采集到的粉体图像进行灰度化、降采样、滤波和锐化处理,滤除采集过程中出现 的噪声,使得图像细节更加清晰;其次提取基于灰度直方图的特征参数,利用均值法得到中 心图像的特征参数及权重;最后计算各图像与中心图像带权重的欧式距离,用距离均值表征 图像的灰度分布相似性。实验结果表明:通过仿真分析不同时刻采集到的粉体图像,得到粉 体混合过程中粉体图像灰度分布相似性随时间的变化趋势,为之后工作中粉体混合均匀性的 判断提供依据。     

Experimental characterization of proteins immobilized on Si-based materials

We studied the possibility to use techniques that are traditionally employed in microelectronics to detect biological molecules immobilized on and into Si-based materials having, as final goal, the structural characterization of a glucose biosensor. The inorganic immobilization surfaces used were both bulk and porous silicon dioxide and the biological molecule to monitor was the enzyme glucose oxidase, widely used as a sensing element in glucose biosensors. Bulk SiO₂ was used to optimize the immobilization protocol and the step-by-step characterization was mainly carried out by Atomic Force Microscopy measurements. Once optimized, the same protocol was used to anchor the enzyme in a porous Si dioxide matrix. Traditional measurement techniques may fail in biological molecule detection since C, basic element of such biological molecules, is present in Si as a contaminant, or introduced during sample preparation, e.g. for TEM cross section analysis.The enzyme monitoring was carried out by electron diffraction X-ray measurements coupled with scanning electron microscopy and to be sure of the protein presence, it was previously labelled with gold nano particles. We believe that this last measurement technique could be implemented for quantitative direct measurements of the biological molecules concentration in complex matrixes.     

Ni60激光熔覆工艺参量对涂层裂纹及厚度的影响

为了研究工艺参量对激光熔覆Ni60涂层裂纹及厚度影响,采用在45#钢基材表面熔覆Ni60合金粉末的正交试验方法,分析了影响裂纹产生的工艺参量的主次因素以及影响涂层厚度的主要因素,并对试验结果进行极差分析,获取了裂纹最少的最优工艺参量。结果表明,影响裂纹产生的主次因素为扫描速率＞送粉速率＞激光功率,裂纹最少的工艺参量为激光功率1400W,扫描速率4.0mm/s,送粉速率为1.0r/min,此时,在熔覆起始位置出现了一条短裂纹;对涂层厚度的影响程度主次因素为送粉速率＞扫描速率＞激光功率;经测量,熔覆层的硬度是基材的3.3倍,通过扫描电镜分析,涂层与基材形成良好的冶金结合,熔覆层晶粒组织均匀致密。该研究为Ni60合金粉末激光熔覆工程化应用提供了参考。