Application of a grid hollow cathode for substrate cleaning before vacuum deposition of coatings

The results of experimental applications of a gas discharge with a grid hollow cathode for substrate cleaning before coating deposition via the magnetron sputtering method and for their final polishing are presented. The dependences of the ion sputtering efficiency on the pressure and power of the discharge are investigated. It is revealed that sputtered material redeposition substantially contributes to the sputtering process. It is found that ion etching ensures smoothing of microroughnesses and microscratches and improves the optical properties of polished monocrystalline molybdenum substrates (mirrors).     

提高InGaAsP/InP DH面发光管输出光功率的研究

用改进了的射频溅射仪,对InGaAsP/InPDH面发光管窗口沉积Al2O3抗反射层,以提高光功率的输出。本文采用了两种涂层途径,其一是对单个发光管窗口直接涂层,另一则是对发光管管芯片上窗口涂层,并对二者作了比较。     

Effects of rare earth and tantalum on graphite-like carbon coatings

The graphite-like carbon (GLC) coating with low friction and good wear resistance is appreciable to make further improvement. Ce, Y and Ta are doped into GLC by using mosaic in the target of magnetron sputtering process. The result shows that yttrium composed in chromium interlayer can increase the bonding strength and refine the microstructure of the GLC coating. For the surface layer of GLC, incorporation of Ta improves wear resistance and deposition rate, in the mean time the friction coefficient is decreased. As the modifications of interlayer and top layer are composed together to form complex GLC coating, the specific wear rate is reduced and the hardness, bonding strength and anti corrosion behavior are improved.     

Yttrium oxide thin films prepared under different oxygen-content atmospheres: microstructure and optical properties

Yttrium oxide films were prepared on silicon wafers by reactive magnetron sputtering at different oxygen flow rates to investigate the microstructure and optical properties for desirable planar optical waveguiding applications. Under the different conditions of target surface, the deposition rate, structure, and optical properties have great changes. The deposition rate increases to the maximum, and then monotonically decreases. Oxygen content in films increases and the composition of films transforms from stoichiometry to an oxygen-rich state. Y₂O₃ films grow with the (222) preferred growth orientation at low oxygen flow rate, and then turn into the (622) orientation; the microstructure evolves from crystal structure to amorphous state as oxygen flow rate increases from 2 to 12 sccm. Sufficient oxygen makes films low-order structure and oxygen-rich films have poor crystallinity. Very smooth film has been obtained at oxygen flow rate of 12 sccm. The refractive index can be greatly modulated by the oxygen-content factor. It is convincing that the controllable structure and optical properties of Y₂O₃ films can be achieved by adjustment the oxygen flow rate for desired optical design and applications.     

Mechanical properties of the plasma-enhanced magnetron sputtering Si-C-N coatings

The mechanical properties of plasma-enhanced magnetron sputtering Si-C-N hard coatings with various compositions are characterized. The effect of chemical composition on the microstructure and properties of coating is investigated. The results show that the microstructure and mechanical properties of Si-C-N coatings are very sensitive to chemical composition. The nanocrystalline/amorphous composite structure is beneficial to the coating's mechanical properties. It also reveals that Si-C-N coating with low Si and high C concentrations has the highest hardness (≥40 GPa) and the best wear property with dry friction coefficient about 0.2.     

Growth of Ga-doped ZnO films with ZnO buffer layer by sputtering at room temperature

Gallium-doped zinc oxide films have been grown on glass substrates with and without ZnO buffer layers by r.f. magnetron sputtering at room temperature. In this approach, the grey relational Taguchi method analysis is adopted to solve the coating process with multiple deposition qualities. Optimal coating parameters can then be determined by using the gray relational grade as a performance index. The GZO coating parameters (r.f. power, sputtering pressure, O₂/(Ar+O₂) flow-rate ratios, and deposition time) are optimized, by taking into account the multiple performance characteristics (structural, morphological, deposition rate, electrical resistivity, and optical transmittance). The results indicate that with the grey relational Taguchi method, the electrical resistivity of GZO films is reduced from 9.23×10⁻³ to 5.77×10⁻³ Ω cm and optical transmittance increases from 79.42% to 82.95%, respectively. The ZnO buffer layer can reduce the electrical resistivity of GZO films from 5.77×10⁻³ to 2.38×10⁻³ Ω cm. It can be anticipated that room temperature deposition enables film deposition onto polymeric substrates for flexible optoelectronic devices.     

Influence of amorphous hydrogenated carbon coating on the strength and cracking resistance of a glass in the high-strength state

The strength of sheet glass treated by etching in a hydrofluoric acid with subsequent deposition of an amorphous hydrogenated carbon coating 50 nm thick is investigated. The carbon coating is applied by ion magnetron sputtering of a chemically pure graphite target. It is shown that the strength of the sheet glass after coating is retained at a level of 2.4 GPa. The leaching of the surface glass layer upon treatment in water at a temperature of 96°C prior to the deposition of a coating leads to an increase in the strength by 12%. The cracking resistance of the glass is examined by the microindentation technique. It is revealed that the load P _c which corresponds to the formation of 50% of all the cracks increases by a factor of three upon deposition of the coating and by a factor of 15 after the preliminary leaching of the glass surface. The assumption is made that the preliminary leaching of the glass surface considerably enhances the adhesion of the hydrogenated carbon film to the glass surface and, thus, improves its protective properties.     

Experimental study on Ti N coated racetrack-type ceramic pipe

Ti N film was coated on the internal surface of a racetrack-type ceramic pipe by three different methods:radio-frequency sputtering, DC sputtering and DC magnetron sputtering. The deposition rates of Ti N film under different coating methods were compared. The highest deposition rate was 156 nm/h, which was obtained by magnetron sputtering coating. Based on AFM, SEM and XPS test results, the properties of Ti N film, such as film roughness and surface morphology, were analyzed. Furthermore, the deposition rates were studied with two different cathode types, Ti wires and Ti plate. According to the SEM test results, the deposition rate of Ti N/Ti film was about 800 nm/h with Ti plate cathode by DC magnetron sputtering. Using Ti plate cathode rather than Ti wire cathode can greatly improve the film deposition rate.     

氢稀释对FTS沉积a-Si:H薄膜结构特性的影响

采用对靶磁控反应溅射技术,以氢气作为反应气体在不同的氢稀释比条件下制备了氢化非晶硅薄膜.利用台阶仪、傅里叶红外透射光谱、Raman谱和紫外-可见光透射谱测量研究了不同氢稀释比对氢化非晶硅薄膜生长速率和结构特性的影响.分析结果发现,利用对靶磁控溅射技术能够实现低温快速沉积高质量氢化非晶硅薄膜的制备.随着氢稀释比不断增加,薄膜沉积速率呈现先减小后增大的趋势.傅里叶红外透射光谱表明,氢化非晶硅薄膜中氢含量先增大后变小.而Raman谱和紫外-可见光透射谱分析发现,氢稀释比的增加使氢化非晶硅薄膜有序度和光学带隙均先增大后减小.可见,此技术通过改变氢稀释比R能够实现氢化非晶硅薄膜结构的有效控制.     

太阳能选择性吸收涂层高温光谱吸收率的测量方法

太阳能热发电是高效利用太阳能资源的有效途径之一,对缓解能源危机和环境污染具有重要的推动作用和深远的社会意义。选择性吸收涂层是太阳能真空集热管的重要组成部分,是决定太阳能与热能转换效率的关键因素。针对高温状态下太阳能选择性吸收涂层光学性能的表征问题,提出一种适用于高温金属-陶瓷选择性吸收涂层太阳光谱吸收率的测量方法。基于双探测器的傅里叶光谱仪和具有涂层加热功能的积分球,研制了能够防止高温氧化并模拟涂层工作温度的高真空测量装置,实现0.3～2.5 μm、室温-700 ℃太阳光谱吸收率的测量。选取磁控溅射制备的Mo-SiO₂选择性吸收涂层作为测量样品,该样品具有双吸收层的多层膜结构。对涂层样品不同温度下的太阳光谱吸收率进行了测量实验,室温测量值与理论计算值进行了对比分析,结果表明具有较好的一致性,最大偏差仅为2.9%,验证了涂层太阳光谱吸收率测量方法的可行性。高温光谱吸收率测量对涂层参数设计的优化及吸收性能的提高具有重要的指导意义及推动作用。     

氢稀释对FTS沉积a-Si∶H薄膜结构特性的影响

采用对靶磁控反应溅射技术,以氢气作为反应气体在不同的氢稀释比条件下制备了氢化非晶硅薄膜.利用台阶仪、傅里叶红外透射光谱、Raman谱和紫外-可见光透射谱测量研究了不同氢稀释比对氢化非晶硅薄膜生长速率和结构特性的影响.分析结果发现,利用对靶磁控溅射技术能够实现低温快速沉积高质量氢化非晶硅薄膜的制备.随着氢稀释比不断增加,薄膜沉积速率呈现先减小后增大的趋势.傅里叶红外透射光谱表明,氢化非晶硅薄膜中氢含量先增大后变小.而Raman谱和紫外-可见光透射谱分析发现,氢稀释比的增加使氢化非晶硅薄膜有序度和光学带隙均先增大后减小.可见,此技术通过改变氢稀释比R能够实现氢化非晶硅薄膜结构的有效控制.     

Correlation of optical properties with the fractal microstructure of black molybdenum coatings

Coating is commonly used for improving the optical properties of surfaces for solar collector applications. The coating morphology depends on the deposition conditions, and this determines the final optical characteristics. Coating morphologies are irregular and of fractal nature, so a suitable approach for its characterization should use methods borrowed from fractal analysis. The aim of this work is to study the fractal characteristics of black molybdenum coatings on copper and to relate the fractal parameters to the optical properties. To this end, coating surfaces were prepared via immersion in a solution of ammonium paramolybdate for different deposition periods. The fractal analysis was carried out for SEM and AFM images of the coating surface and the fractal properties were obtained with a recently developed high-dimensional extension of the well-known detrended fluctuation analysis (DFA). The most salient parameter drawn from the application of the DFA is the Hurst index, a parameter related to the roughness of the coating surface, and the multifractality index, which is related to the non-linearity features of the coating morphology. The results showed that optical properties, including absorptance and emittance, are decreasing functions of the Hurst and multifractality indices. This suggests that coating surfaces with high absorptance and emittance values are related to complex coating morphologies conformed within a non-linear structure.     

Deposition of ultrahard Ti–Si–N coatings by pulsed high-current reactive magnetron sputtering

We report on the results of investigation of properties of ultrahard Ti–Si–N coatings deposited by pulsed high-current magnetron reactive sputtering (discharge pulse voltage is 300–900 V, discharge pulse current is up to 200 A, pulse duration is 10–100 μs, and pulse repetition rate is 20–2000 Hz). It is shown that for a short sputtering pulse (25 μs) and a high discharge current (160 A), the films exhibit high hardness (66 GPa), wear resistance, better adhesion, and a lower sliding friction coefficient. The reason is an enhancement of ion bombardment of the growing coating due to higher plasma density in the substrate region (10¹³ cm^–3) and a manifold increase in the degree of ionization of the plasma with increasing peak discharge current (mainly due to the material being sputtered).     

Direct Monitoring of Thickness and Refractive Index of Optical Thin Film Deposited on Fiber End-face

We propose a system for depositing thin films on waveguides which enables low-temperature deposition and precise control of the refractive index and film thickness. It is composed of a conventional ion-beam sputtering (IBS) system and a new system for directly monitoring film characteristics during deposition. We controlled refractive indices over a wide range from 1.52 to 1.97 by moving the sputtering targets (SiO₂ and Si₃N₄) in the IBS system. The refractive index or film thickness was in-situ monitored by observing the optical power reflected from the end-face of a monitoring fiber set in the deposition chamber. Antireflection coating films were successfully deposited on a fiber end-face and a laser diode chip facet with low reflectivity from 0.05 to 0.07%. This deposition system is attractive for constructing highly functional optical devices for future photonic networks.     

Direct comparison of the electrical,optical, and structural phase transitions of VO2 on ZnO nanostructures

We examined the temperature-dependent electrical, optical, and structural properties of VO₂ on ZnO nanorods with different lengths in the temperature range from 30 to 100 °C. ZnO nanorods with a uniform length were grown on Al₂O₃ substrates using a metal organic chemical vapor deposition, and subsequently, VO₂ was ex-situ deposited on ZnO nanorods/Al₂O₃ templates using a sputtering deposition. The optical properties of the VO₂/ZnO nanorods were measured simultaneously with direct current (DC) resistance using the reflectivity of an infrared (IR) laser beam with a wavelength of 790 nm. The local structural properties around V atoms of VO₂/ZnO nanorods were simultaneously measured with the DC resistance using x-ray absorption fine structure at the V K edge. Direct comparison of the temperature-dependent resistance, IR reflectivity, and local structure reveals that an optical phase transition first occurs, a structural phase transition follows, and an insulator-to-metal transition finally appears during heating.     

溅射功率对Mo薄膜微结构和性能的影响

 实验采用直流磁控溅射沉积技术在不同溅射功率下制备Mo膜,研究了不同溅射功率下Mo膜的沉积速率、表面形貌及晶型结构,并对其晶粒尺寸和应力进行了研究。利用原子力显微镜观察样品的表面形貌发现随着溅射功率的增加,薄膜表面粗糙度逐渐增大。X射线衍射分析表明薄膜呈立方多晶结构,晶粒尺寸为14.1～17.9 nm;应力先随溅射功率的增大而增大,在40 W时达到最大值(2.383 GPa),后随溅射功率的增大有所减小。     

Fabrication of broadband antireflection coatings using broadband optical monitoring mixed with time monitoring

Multi-layer optical coatings with complex spectrum requirements, such as multi-band pass filters, notch filters, and ultra-broadband antireflection coating, which usually contain very thin layers and sensitive layers, are difficult to be fabricated using a quartz crystal monitoring method or a single wavelength optical monitoring system(SWLOMS). In this paper, a broadband antireflection(AR) coating applied in the wavelength range from 800 nm to 1800 nm was designed and deposited by ion beam sputtering(IBS). Ta_2O_5 and Si O_2 were chosen as high and low refractive index coating materials,respectively. The optimized coating structure contains 9 non-quarter-wave(QW) layers totally with ultra-thin layers and sensitive layers in this coating stack. In order to obtain high transmittance, it is very important to realize the thickness accurate control on these thin layers and sensitive layers. A broadband optical monitoring mixed with time monitoring strategy was successfully used to control the layer thickness during the deposition process. At last, the measured transmittance of AR coating is quite close to the theoretical value. A 0.6% variation in short wavelength edge across the central 180 mm diameter is demonstrated. A spectrum shift of less than 0.5% for 2 continuous runs is also presented.     

Effects of the ion-beam voltage on the properties of the diamond-like carbon thin film prepared by ion-beam sputtering deposition

Diamond-like carbon(DLC) thin film is one of the most widely used optical thin films.The fraction of chemical bondings has a great influence on the properties of the DLC film.In this work,DLC thin films are prepared by ion-beam sputtering deposition in Ar and CH4 mixtures with graphite as the target.The influences of the ion-beam voltage on the surface morphology,chemical structure,mechanical and infrared optical properties of the DLC films are investigated by atomic force microscopy(AFM),Raman spectroscopy,nanoindentation,and Fourier transform infrared(FTIR) spectroscopy,respectively.The results show that the surface of the film is uniform and smooth.The film contains sp2 and sp3hybridized carbon bondings.The film prepared by lower ion beam voltage has a higher sp3 bonding content.It is found that the hardness of DLC films increases with reducing ion-beam voltage,which can be attributed to an increase in the fraction of sp3 carbon bondings in the DLC film.The optical constants can be obtained by the whole infrared optical spectrum fitting with the transmittance spectrum.The refractive index increases with the decrease of the ion-beam voltage,while the extinction coefficient decreases.     

磁控溅射制备铬薄膜的结构和光电学性质(英文)

用直流磁控溅射技术在石英基片上制备不同厚度(5nm～114nm之间)的铬膜.使用X射线衍射仪和分光光度计分别检测薄膜的结构和光学性质,利用德鲁特模型和薄膜的透射、反射光谱计算铬膜的厚度和光学常量,并采用Van der Pauw方法测量薄膜电学性质.结果表明:制备的铬薄膜为体心立方的多晶态,随着膜厚的增加,薄膜的结晶性能提高,晶粒尺寸增大;在可见光区域,当膜厚小于32nm时,随着膜厚的增加,折射率快速减小,消光系数快速增大,当膜厚大于32nm时,折射率和消光系数均缓慢减小并逐渐趋于稳定;薄膜电阻率随膜厚的增加为一次指数衰减.     

磁控溅射制备铬薄膜的结构和光电学性质

用直流磁控溅射技术在石英基片上制备不同厚度(5 nm~114 nm之间)的铬膜.使用X射线衍射仪和分光光度计分别检测薄膜的结构和光学性质,利用德鲁特模型和薄膜的透射、反射光谱计算铬膜的厚度和光学常量,并采用Van der Pauw方法测量薄膜电学性质.结果表明:制备的铬薄膜为体心立方的多晶态,随着膜厚的增加,薄膜的结晶性能提高,晶粒尺寸增大;在可见光区域,当膜厚小于32 nm时,随着膜厚的增加,折射率快速减小,消光系数快速增大,当膜厚大于32 nm时,折射率和消光系数均缓慢减小并逐渐趋于稳定;薄膜电阻率随膜厚的增加为一次指数衰减.