无支撑、光学级MPCVD金刚石膜的研制

利用引进的6 kW微波等离子体化学气相沉积设备,进行了无支撑金刚石膜工艺的初步研究。在800~1050℃的基片温度范围内,金刚石膜都呈(111)择优取向;基片相对位置对沉积较大面积、光学级金刚石膜至关重要。制出0.25 mm厚Φ50 mm的无支撑金刚石膜。拉曼光谱和X射线衍射分析表明,合成的金刚石膜晶体结构完整,sp2含量极低;透过率测试结果说明了优良的光学性能:截止波长225 nm,光学透过率(λ≥2.5μm)≥70%。     

硫化锌窗口上CVD法制备金刚石膜的研究进展

金刚石具有优异的红外透过性能,可作为硫化锌红外窗口的保护膜。但由于CVD金刚石的沉积过程会刻蚀硫化锌衬底,导致在窗口表面直接生长金刚石膜比较困难。本文主要综述了近年来通过添加过渡层沉积金刚石薄膜的方法和光学焊接金刚石厚膜的方法来增强硫化锌窗口的性能,并介绍了CVD金刚石膜的光学应用及其目前所存在的问题,最后对未来CVD金刚石膜发展的方向作出了展望。     

由红外透过谱确定金刚石膜的光学常数及相关因素

结合金刚石膜的具体情况,考虑到色散效应、膜的微结构、表面粗糙度及样品中自由载流子和C-H的吸收等多种因素对红外透过谱的影响,在无吸收单层膜透过率模型的基础上进行了修正,给出了自支撑金刚石薄膜透过率的数学模型.并对不同制备方法和工艺参数下沉积的金刚石膜的红外透过谱用Levenberg-Mar-quardt算法进行非线性最小二乘拟合,从而确定出样品的红外光学常数和其它影响透过率的因素.这些结果对正确分析金刚石薄膜的红外光学性质是很重要的.     

金刚石膜红外光学性质的研究

采用热灯丝化学气相沉积(CVD)方法,通过独特的衬底表面预处理工艺及控制沉积参数,制备出了晶粒细、表面光滑的单片金刚石膜样品。采用SEM观察了样品生长面的表面形貌,通过激光Raman对样品进行了金刚石结构的确认。在450～4000cm~(-1)范围测试了金刚石膜样品的红外光学透过谱,通过分析认为:平均透过率随波长减小而衰减主要是由于金刚石膜生长面的表面粗糙度引起光谱散射造成的。     

大面积金刚石自支撑膜机械抛光的优化工艺研究

研究了一种用于抛光等离子体溅射CVD法制备的金刚石自支撑膜的高效安全的抛光工艺.试验探索了转盘转速、金刚石粉颗粒尺寸、磨盘表面形状对金刚石自支撑膜磨抛速率的影响.研究表明:带槽盘对金刚石自支撑膜的粗研磨效果明显,速率较高,平面盘对提高金刚石自支撑膜的表面粗糙度有利;不同颗粒的金刚石粉对应着各自合适的能充分利用其磨削能力的转速,在这个转速下,金刚石自支撑膜的磨抛速率在12μm/h左右.本文通过对新的工艺参数的探索,为金刚石自支撑膜后续加工提供有力的技术支持.     

微波PCVD法大尺寸透明自支撑金刚石膜的制备及红外透过率

采用微波PCVD方法制备出直径50mm膜厚300um的大尺寸透明自支撑金刚石膜.在甲烷体积分数2%的条件下制备的透明自支撑金刚石膜经过两面抛光后在500cm-1-4000cm-1红外波段范同内红外透过率达到70%,但是其生长速率只有1um/h-2um/h.在体积分数4%甲烷浓度下制备的自支撑透明金刚石膜,其生长速率达到7um/h～8um/h,经过两面抛光之后膜厚为260um的金刚石膜的在500cm-1～4000cm-1红外波段范围内红外透过率达到60%左右,而且膜中心和边缘区的红外透过率基本相同.这些结果为大尺寸金刚石厚膜在红外窗口上的实际应用奠定了基础.     

大面积光学级金刚石自支撑膜制备、加工及应用

大面积光学级金刚石自支撑膜的制备和加工是近年来在CVD金刚石研究领域的最重要的技术进展之一.在军事和民用光学领域有非常重要的应用前景.本文综述了北京科技大学近年来在CVD金刚石膜光学应用领域的研究进展.给出了采用高功率直流电弧等离子体喷射(DC Arc Plasma Jet)CVD工艺制备大面积光学级金刚石自支撑膜的研究结果,并报导了对所制备的光学级金刚石自支撑膜的光学、力学(机械)、热学、微波介电性能和抗激光损伤等方面的最新研究结果.     

CVD金刚石的高温氧化及其保护

化学气相沉积(CVD)金刚石具有优异的机械、光学和热学性能,成为高速长波红外窗口的首选材料,但是当高速飞行时,由于空气动力加热会产生很高的温度而使其迅速遭受氧化,甚至完全失效.简要概述了CVD金刚石高温氧化现象及机理、抗氧化保护的最新研究进展.     

富氮N_2/CH_4/H_2体系中金刚石纳米线的制备研究

使用微波等离子体化学气相沉积(MPCVD)法在富氮N_2/CH_4/H_2体系中纳米金刚石膜沉积进行研究。使用扫描电子显微镜对纳米金刚石膜的表面形貌进行测试,使用光射线光电子能谱(XPS)和拉曼光谱对纳米金刚石膜的表面化学结构进行表征。结果表明,氮气浓度的改变对纳米金刚石膜的表面形貌和晶粒尺寸都有明显影响。在氮气浓度为85%时,纳米金刚石膜的表面由平均长度为2.5μm金刚石纳米线组成,晶粒尺寸在85%最低,为8 nm。纳米金刚石膜氮元素含量随氮气浓度上升而上升在95%为2.68%。晶粒尺寸下降,晶界含量上升,C=C键含量上升;晶粒尺寸上升,晶界含量下降,C=C含量下降。C-C键含量随着晶粒尺寸下降而下降,随晶粒尺寸上升而上升,同时C-C峰的FWHM值在氮气浓度为85%时最低为1.16 e V。     

MPCVD制备纳米金刚石真空窗口的研究

微波等离子体化学气相沉积装置用于制备纳米金刚石膜和纳米金刚石真空窗口,气源为H2、CH4、Ar和少量O2。扫描电镜、拉曼光谱、X射线衍射仪、原子力显微镜用于表征和分析纳米金刚石膜,自制的漏气率测量装置测出纳米金刚石真空窗口漏气率。结果表明:金刚石膜厚20μm、表面平均粗糙度Ra=34. 6 nm,平均晶粒尺寸35 nm,金刚石窗口漏气率为2. 78×10-9Pa·m3/s。     

Chemical bonding and optoelectrical properties of ruthenium doped yttrium oxide thin films

Highly infrared transparent conductive ruthenium doped yttrium oxide (RYO) films were deposited on zinc sulfide and glass substrates by reactive magnetron sputtering. The structural, optical, and electrical properties of the films as a function of growth temperature were studied. It is shown that the sputtered RYO thin films are amorphous and smooth surface is obtained. The infrared transmittance of the films increases with increasing the growth temperature. RYO films maintain greater than ∼65% transmittance over a wide wavelength range from 2.5 μm to 12 μm and the highest transmittance value reaches 73.3% at ∼10 μm. With increasing growth temperature, the resistivity changed in a wide range and lowest resistivity of about 3.36 × 10⁻³ Ω cm is obtained at room temperature. The RYO thin films with high conductivity and transparency in IR spectral range would be suitable for infrared optical and electromagnetic shielding devices.     

Optimisation of diamond-like carbon films by unbalanced magnetron sputtering for infrared transmission enhancement

Diamond-like carbon (DLC) films have potential applications in infrared transmission enhancement. Reducing or eliminating mechanical stress and optical absorption of DLC is important in such applications because relatively thick films are necessary. In this work, DLC was deposited in an unbalanced magnetron sputtering (UBMS) system. Mechanical and optical properties of the DLC films were analysed. Thick DLC films were deposited which satisfied applications for the infrared windows at 3–5 and 8–10 μm. At optimised conditions, the stress in the DLC films decreased with increasing thickness, approaching 1 GPa. For single side DLC coated silicon substrate, about 69% transmittance was achieved at wavelengths near 5 μm, close to the theoretical value for non-absorbing DLC material. Other properties such as surface roughness, wetting angle, and stability were also studied, which showed that the DLC films produced in the UBMS system were excellent for infrared transmission enhancement applications in tough environments.     

基底温度对直流溅射Nb掺杂TiO2薄膜性能的影响

采用陶瓷靶直流磁控溅射,以玻璃为基底制备2.5wt%Nb掺杂TiO2薄膜,控制薄膜厚度在300~350 nm,研究了不同基底温度下所制得薄膜的结构、形貌和光学特性.XRD分析表明,基底温度为150℃、250℃和350℃时,薄膜分别为非晶态、锐钛矿(101)和金红石相(110)结构.基底温度250℃时,锐钛矿相薄膜的晶粒尺寸最大,约为32 nm.薄膜表面形貌的SEM分析显示,薄膜粗糙度和致密度随基底温度升高得到改善.薄膜的平均可见光透过率在基底温度为250℃以内约为70%,随基底温度升高至350℃,平均透过率下降为59%,金红石相的存在不利于可见光透过.Nb掺杂TiO2薄膜的光学带宽在3.68~3.78 eV之间变化.基底温度为250℃时,锐钛矿相薄膜的禁带宽度最大,为3.78 eV.     

Study of the moderate-temperature growth process of optical quality synthetic diamond films on quartz substrates

Growth of undoped and boron-doped diamond films on quartz substrates at moderate temperature of 500 °C by microwave plasma chemical vapor deposition method was studied in terms of growth rate, surface roughness and optical transmittance. Similar density of diamond seed particles on quartz surfaces seeded mechanically before the deposition process and diamond grains within diamond films grown on those substrates is observed. The growth rate is found similar to that reported for diamond deposited on silicon substrates in the same plasma deposition system, although with substantially higher activation energy. Furthermore, increased level of dopant concentration in the gas mixture resulted in a decrease of the growth rate, while a gradual reduction of the surface roughness occurred at high dopant levels. Overall, the highest measured regular optical transmittance of the undoped diamond film on quartz was 45% at 1100 nm (including quartz absorption), whereas that of boron-doped diamond peaked 5% at 700 nm (tail absorption of boron centers).     

Thin gold films on SnO2:In: Temperature-dependent effects on the optical properties

Gold films with thicknesses of 5 ± 0.5 nm were sputter deposited onto SnO₂:In-coated glass kept at different temperatures up to 140 °C, and similar films, deposited onto substrates at 25 °C, were annealing post treated at the same temperatures. Nanostructures and optical properties were recorded by scanning electron microscopy and spectrophotometry in the 0.3 to 2.5 μm wavelength range, respectively. Annealing had a minor influence on the optical transmittance despite significant changes in the scale of the nanostructure, whereas deposition onto substrates heated to 140 °C yielded granular films with strong plasmon absorption of luminous radiation. These results are of considerable interest for optical devices with gold films prepared at elevated temperature or operating at such temperature.     

低红外发射率耐高温涂层的制备及机理

以漂浮态铝粉为填料,有机硅树脂作为粘合剂,制备了耐高温低红外发射率涂层。对填料的添加量、涂层的固化温度进行了优化研究,对填料及涂层进行了结构、形貌的表征,并测试了涂层的红外发射率与耐热性能。研究结果表明,填料添加量为30%、400℃固化2h,涂层红外发射率(3～5μm,8～14μm)最低可达0.10～0.12,且涂层可在600℃条件下长时间使用。此外,分析认为涂层发射率的降低是消除粘合剂吸收及致密的片层连续结构两者协同作用的结果,并提出新的涂层结构模型对低发射率机理进行了阐述。     

晶粒尺寸对氧化钒薄膜电学与光学相变特性的影响

采用直流对靶磁控溅射方法制备氧化钒薄膜,通过改变热处理温度获得了具有不同晶粒尺寸的相变特性氧化钒薄膜,对氧化钒薄膜相变过程中电阻和红外光透射率随温度的突变性能进行研究.结果表明:经300℃和360℃热处理后,薄膜内二氧化钒原子分数达到40%,氧化钒薄膜具有绝缘体-金属相变特性,薄膜的晶粒尺寸分别为50nm和100nm;...     

工艺条件对金刚石膜红外透射率影响的研究

为了优化金刚石沉积工艺,制备高透射率的CVD金刚石薄膜,采用傅里叶红外光谱仪对不同工艺条件下制备的CVD金刚石膜的红外透射率进行了测量,分析了不同工艺条件对金刚石膜红外透射率的影响,获得了最佳沉积参数.结果表明,金刚石膜的红外透射率与工艺条件密切相关,当衬底温度为750℃,碳源体积分数为2%,压强为2.5kPa时沉积的金刚石膜红外透射率最佳.     

Multifunctional transparent ZnO nanorod films

Transparent ZnO nanorod (NR) films that exhibit extreme wetting states (either superhydrophilicity or superhydrophobicity through surface chemical modification), high transmittance, UV protection and antireflection have been prepared via the facile ammonia hydrothermal method. The periodic 1D ZnO NR arrays showed extreme wetting states as well as antireflection properties due to their unique surface structure and prevented the UVA region from penetrating the substrate due to the unique material property of ZnO. Because of the simple, time-efficient and low temperature preparation process, ZnO NR films with useful functionalities are promising for fabrication of highly light transmissive, antireflective, UV protective, antifogging and self-cleaning optical materials to be used for optical devices and photovoltaic energy devices.