宽光谱监控法镀制高精度增透膜的研究

本文介绍了使用宽光谱监控系统镀制增透膜的基本原理和技术特点.给出了针对不同的膜层特性计算评价函数的方法,分别为能量法和特征点法,能量法适合膜层的光学特性对每一个波长点的权重要求都是一样的,特征点法适合于只对膜层光学特性的某几个特定波长的要求较高,并根据膜料光学参数的特性,分别设置权重因子,其它波长忽略不计.用工艺曲线代替理论设计曲线作为目标曲线,解决实际镀制的光谱特性与理论值存在偏差的问题,使评价函数的极小值趋近于零,达到最佳膜厚.这种简单而准确的方法对于提高宽带增透膜镀制精度和成品率有显著的效果,具有实际的应用价值.     

The individual effect of coating thicknesses and deposition temperatures on Raman spectra of carbon films deposited on silica glass fibers by thermal chemical vapor deposition

Abstract

Carbon films are deposited on silica glass fibers by thermal chemical vapor deposition using pure methane as the precursor gas, and the individual effect of coating thicknesses and deposition temperatures on Raman spectra of carbon films is investigated. The results show that if the temperature is fixed at 950°C, the D peak position, the full‐width‐at‐half maximum of D band, and the integrated intensity ratio of the D band to the G band increase with increasing the coating thickness. This is because the size and number of particles grown on the carbon film surface increase with increasing the coating thickness and the carbon film becomes more disordered. Alternatively, if the coating thickness is fixed at 1200 nm, the D peak position, the full‐width‐at‐half maximum of D band, and the integrated intensity ratio of the D band to the G band decrease with increasing the deposition temperature. This indicates that the carbon film becomes more ordered and its nano‐grain size increases as the deposition temperature increases from 925 to 1025°C.     

Effects of different acetylene/nitrogen ratios on characteristics of carbon coatings on optical fibers prepared by thermal chemical vapor deposition

The effects of C₂H₂/(C₂H₂ + N₂) ratios on the characteristics of carbon coatings on optical fibers prepared by thermal chemical vapor deposition are investigated. The C₂H₂/(C₂H₂ + N₂) ratios are set to 60, 70, 80, 90, and 100%. Additionally, the deposition temperature, working pressure, and mass flow rate are 1003 K, 133 kPa, and 40 sccm, respectively. The deposition rate, microstructure, and electrical resistivity of carbon coatings are measured. The low-temperature surface morphology of carbon-coated optical fibers is elucidated. Experimental results indicate that the deposition rate increases with increasing the C₂H₂/(C₂H₂ + N₂) ratio, and the deposition process is located at a surface controlled regime. As the deposition rate increases, the electrical resistivity of carbon coatings increases, while the ordered degree, nano-crystallite size, and sp² carbon atoms of the carbon coatings decrease. Additionally, the low-temperature surface morphology of the carbon coatings shows that if the carbon coating thickness is not smaller than 289 nm, decreasing the deposition rate is good for producing hermetic optical fiber coatings.     

表面粗糙度对PS-PVD热障涂层陶瓷层沉积的影响

研究基于等离子喷涂-物理气相沉积(PS-PVD)工艺的沉积表面的粗糙度对YSZ陶瓷层结构的影响,初步阐明了表面粗糙度对陶瓷层气相沉积过程的影响和涂层结构的形成规律。采用PS-PVD工艺在预制有NiCoCrAlYTa黏结层的K417G高温合金上制备YSZ陶瓷层;采用SEM、粗糙度检测仪、3D表面形貌仪等方法分析PS-PVD YSZ陶瓷涂层的形貌和结构特征。基体表面粗糙度对PS-PVD涂层结构有很大影响。结果表明:当基体表面粗糙度分别为 R a≤2μm, 2μm< R a<6μm, R a≥6μm时,涂层粗糙度分别在3.5~5,6~10,10~15μm区间;特征表面形貌"菜花头"的直径随着基体表面粗糙度的增加而逐渐增大, d P=38.5μm, d 280S =25.5μm, d 60S =38.7μm, d 24S =102μm, d S=137μm。表面粗糙度主要通过PS-PVD气相沉积过程中的阴影效应来影响涂层生长和形成差异性结构,随着基体表面粗糙度的增加,YSZ陶瓷层受阴影效应影响增大,表面形貌"菜花头"尺寸和柱状结构间间隙增大,形成更加疏松的结构。     

CdZnTe晶体生长用石英管的镀碳工艺研究

使用金相显微镜、推力分析仪测试等手段研究了镀碳工艺参数对碳膜的表面形貌、碳膜和石英结合力的影响。获得了一个优化的镀碳工艺参数,即在镀碳温度为950～1100℃,气体流量为4～7ml/h,镀碳时间为6h,冷却时间为12h的条件下得到的碳膜较为均匀,而且和石英结合的较好。使用该工艺条件镀膜的石英管生长出的CdZnTe晶体表面光洁,位错密度低,约为4×104cm-2。     

高激光损伤阈值266nm紫外增透膜研究

为了研制高激光性能紫外增透膜,分别使用HfO2/SiO2和Al2O3/MgF2两种高低折射率材料组合,采用物理气相沉积技术,设计制备了266 nm增透膜;分析测试了不同材料所组成的增透膜的剩余反射率、粗糙度、光学损耗、界面电场强度和激光诱导损伤阈值等特性。研究结果表明,两组不同膜料制备的266 nm增透膜都能达到剩余反射率<0.2%的要求,且激光诱导损伤阈值都大于5 J/cm(2266 nm,7 ns)。     

Optimization of PECVD silicon oxynitride films for anti-reflection coating

In this work, amorphous silicon oxynitride films were deposited on silicon substrates by plasma-enhanced chemical vapor deposition (PECVD). The main purpose was to use silicon oxynitride film as a single-layer anti-reflection coating for Si-based optoelectronic devices. The chemical information was measured by infrared spectroscopy. Surface and cross-section morphology was determined by a scanning electron microscope. Spectroscopic ellipsometry (SE) was applied to measure the refractive index, extinction coefficient and thickness. The results of SE presented the refractive indices varied in the range of 1.83-1.92 by altering SiH₄/NH₃ ratio. One-side polished silicon substrate coated with silicon oxynitride film exhibited low reflectance, and two-side polished silicon substrate coated with silicon oxynitride film exhibited high transmittance. The results suggested that silicon oxynitride film was a very attractive single-layer anti-reflection coating.     

流态化CVD制备TiO2-ZnS复合粒子的研究

为了制备TiO2-ZnS复合粒子,采用流态化化学气相沉积(CVD)法,探讨了其包覆工艺,借助SEM、XRD、EPMA等测试手段研究了复合粒子结构和包覆过程特征.结果表明:TiO2均匀沉积在ZnS超细颗粒原生粒子表面,形成TiO2-ZnS复合粒子;在包覆过程中同时存在成核和成膜包覆.     

Initiated chemical vapor deposition of a siloxane coating for insulation of neural probes

Recent advances in the field of neuroprosthetics have brought the possibility of human utilization into the near term. However, current implant coating chemistries require thicknesses of ~ 25 μm in order to provide the required electrical insulation, significantly increasing the diameter of the neural probe shanks and resulting surgical damage upon implantation. In this work, a novel biopassivation coating is created through initiated chemical vapor deposition (iCVD) of trivinyl-trimethyl-cyclotrisiloxane. The resulting material is a highly crosslinked organosilicon polymer matrix which is synthesized directly on the surface of the substrate. This material possesses an electrical resistivity which allows for a coating thickness on the order of only 5 μm. The material has also been demonstrated to retain its electrical properties in a simulated biological environment for over 3 years.     

致密SiC包覆层低温流化床化学气相沉积制备及形成机制

一般致密SiC材料的制备需要极高的温度,而降低制备温度一直是SiC制备领域的重要研究方向。采用流化床化学气相沉积法,在球形二氧化锆陶瓷颗粒上制备了厚度为几十微米的SiC包覆层。通过对不同温度SiC包覆层的显微形貌及微观结构变化规律研究,给出了沉积效率变化规律,发现低温产物富硅,而高温产物富碳。对不同氩气含量的实验研究发现,氩气的加入可以促进沉积反应向富碳方向移动,从而可以在显著降低温度的条件下制备出致密SiC包覆层。综合实验结果给出了流化床化学气相沉积方法在不同温度及氩气浓度条件下制备SiC的物相分布图。      

低压化学气相沉积MoSi2涂层微观结构及氧化性能

为了防止Mo合金的高温氧化,本研究采用低压化学气相沉积技术在Mo合金表面制备MoSi2抗氧化涂层,借助X射线衍射仪、扫描电镜及能谱仪等分析手段,对涂层的微观结构进行了研究,测试了涂层的抗氧化和抗热震性.结果表明:MoSi2涂层结构致密,仅有少量微裂纹存在,表现出良好的抗热震和抗氧化性能;经20次1300℃-室温循环热震实验后,涂层未出现开裂与脱落现象;涂层试样在1300℃氧化气氛下氧化180 h,失重率小于0.83%,分析揭示了涂层试样氧化失重的主要原因为氧扩散通过涂层与Mo基体发生反应,生成极易挥发的MoO、MoO2、MoO3,氧在涂层中的扩散速率决定了涂层的失重速率.