YbF3 is proposed as a substitute for ThF4 in anti-reflection or reflection coatings in the infrared (IR) range. In this letter, we study on the properties of the YbF3 thin film deposited with different deposition parameters, and find the deposition rate of YbF3 has a large effect on the substrate particles deposition both on number and area. Moreover, we find the deposition temperature is a main factor of element content. In the end, we produce an anti-reflection coating on Ge substrate, and its average transmission reaches 99.5%, which can satisfy the practical requirement.

The service life of the large primary mirror with aluminum coating can be effectively prolonged by a protective layer. The SiOx (1<x<2) protective material which is thermally evaporated from up to bottom is studied. Environmental adaptability experiment, spectral measurement and micro-morphology analysis are executed on bare SiOx coatings within different oxygen concentrations, and the repeatability verification is implemented by testing the SiOx protected aluminum coatings. The results show that the SiOx coatings can meet the protective qualification within oxygen flow of 50 sccm (p=5.6 \times 10-3 Pa). The fine compactness of the coating has excellent moisture resistance with the average molecular spacing of 0.335 nm. In addition, the average reflectivity of the SiOx protected aluminum coating is 90.47% in the band 400 -2 500 nm and the coating is confirmed to have good environmental performance.

We report the simulation results on the thickness uniformity of optical coatings deposited on spherical substrates by optimizing the geometric configuration parameters, such as tilting angle of the substrate holder and position of the evaporation source in a 1 000-mm-diameter planetary rotation stage (PRS). We reveal that good film uniformity on convex spherical surfaces or flat substrates, as well as concave surfaces with weak to moderate curvatures can be obtained through appropriate tilting of the substrate holder. For 300-mm-diameter substrates with clear aperture to radius of curvature (CA/RoC) between -0.3 and 0.7, the achievable film uniformity is above 99%. The source position is optimized to achieve good film uniformity.

While infrared (IR) hard protective film of ZnS optical window is used in high temperature environment, its optical and mechanical stabilities are the premise of the IR optical system. IR hard protective film is deposited on ZnS optical windows by chemical vapor deposition (CVD), and ablation experiments are done to the maximum temperature the film can endure. The effects of ablation temperature on the optical and mechanical properties of the protective films are investigated by surface profiler, Fourier-transform infrared (FTIR) spectrometry, IR ellipsometer, and Metallographic microscope. It is shown that the optical and mechanical properties of ZnS hard protective film change little before 500 oC, and film refractive index and optical thickness reduce while ablation temperature surpassing 500 oC, forming crater-like ablation structure, which leads to the reduction of film combination significantly.

A sol-gel method for the preparation of silica coating that varied in refractive index is developed. Silicon dioxide sol is obtained by hydrolysis and co-condensation reactions occurred in acid-catalyzed system. Surface morphology, refractive index, and transmission spectrum of the samples are studied. The results of transmission spectra of single-sided coatings show that the average transmittance of the samples increases about 4% compared with the uncoated one in the spectra range from 400 to 1 200 nm in the case of vertical incidence. For the double-sided coating the maximum transmittance is 99% at the wavelength of 840 nm.

Liquid metals-such as lead (Pb) or lead-bismuth (PbBi) are used as reactor core coolants for accelerator driven systems (ADS) proposed for high-level radioactive waste transmutation. Compatibility of steels with liquid PbBi is a key problem because steels are attacked by dissolution of the components in PbBi, so it has to form a stable coating on steel surface. There are many methods to prepare anti-corrosion coatings on steel, such as hot dipping, pack cementation, plasma spaying, and physical vapor deposition (PVD). Compared with other methods, the PVD method is easy to control the thickness of the coating and the obtained coatings are dense which is crucial to the anti-corrosion ability of the coatings. In this letter, PVD aluminum coatings are developed on the surface of T91 steel and different heat-treatment atmosphere is used to adjust the microstructure, aluminum content, and the phase of the coatings. It is found that the coatings have good adherence ability with steel. The aluminum content and the phase of the coating can be adjusted by the heat-treatment atmosphere. Corrosion tests are performed in oxygen-saturated liquid PbBi at 550 oC for 1 000 h, the phase and composition of the coating do not change drastically. All the results indicate that the PVD is a useful method to prepare coatings on the surface of steel used in liquid PbBi.

This letter describes a method for modelling film thickness variation across the deposition area within plasma enhanced chemical vapour deposition (PECVD) processes. The model enables identification and optimization of film thickness uniformity. Comparison between theory and experiment is provided for PECVD of diamond-like-carbon (DLC) deposition onto flat and curved substrate geometries. Results show DLC uniformity of 0.30% over a 200-mm flat zone diameter within overall electrode diameter of 300 mm. Use of the modelling method for PECVD using metal-organic chemical vapour deposition (MOCVD) feedstock is demonstrated, specifically for deposition of silica films using metal-organic tetraethoxy-silane.

High sophisticated optical monitoring systems like the OMS 5000 from Leyboldoptics are commonly used in vacuum coating system to improve the capabilities and reliability of production processes concerning optical performance and repeatability optics. This letter describes a method to perform high end optical filters with additional backside blocking over a wide spectral range. The direct monitoring with intermittent measurement on a large area rotating substrate holder is used to facilitate a narrow band pass filter of 2-nm half bandwidth at 532 nm and high transmittance together with a complex blocking filter to retard disturbing radiation from the ultraviolet (UV) range to the near infrared range. The machine is an ARES 1 350 coating system with basically standard configuration.

This contribution presents a magnetron sputter deposition tool with broadband optical monitor and online re-optimization capability for high volume production. The layer termination relies on a comparison of the actually measured reflection spectrum with a pre-calculated target spectrum. Spectra recorded after each deposited layer are analyzed by the re-optimization module and–in case of significant deviations–layer thicknesses and target spectra for the remaining layers are recalculated. This technique significantly improves the performance and reproducibility in case of highly demanding coating designs and is able to correct abnormal production errors in individual layers, which will lead to coating failure without reoptimization.

We demonstrate that ultra-thin porous alumina membrane (PAM) is suitable for controlling of both size and site of Ge nanodots on Si substrates. Ge nanodots are grown on Si substrates with PAM as a template at different temperatures with molecular beam epitaxy (MBE) method. Ordered Ge nanodot arrays with uniform size and high density are obtained at 400 and 500 oC. Spatial frequency spectrums transformed from scanning electron microscopy images through fast Fourier transform are utilized to analyze surface morphologies of Ge nanodots. The long-range well-ordered Ge nanodot arrays form a duplication of PAM at 400 oC while the hexagonal packed Ge nanodot arrays are complementary with PAM at 500 oC.

Trimethylamine (TMA), TiCl4, and water are applied as the precursors to deposit Al2O3 and TiO2. With different substrate temperatures, the optical properties and surface morphologies of the two oxides TiO2 and SiO2 are studied, respectively. With substrate temperature of 120 oC, amorphous TiO2 can be obtained, and the surface roughness (RMS) is only 0.928 nm. Applying Al2O3 and TiO2 deposited in 120 oC as low and high refractive index materials, anti-reflection (AR) coating at single point (550 nm) is designed. Furthermore, with the calibrated growth rates, this AR coating is fabricated, and its ultimate reflectance for the AR coating at 550 nm is less than 0.2%, which can meet the requirement for most applications.

A novel optimization procedure for optical precision sputter coaters with respect to the film homogeneity is demonstrated. For a coater concept based on dual cylindrical sputtering sources and a rotating turn-table as sample-holder, the inherent radial decay of the film thickness must be compensated by shaper elements. For that purpose, a simulation model of the particle flux within such a coater is set up and validated against experimental data. Subsequently, the shaper design is optimized according to the modeled metal flux profile. The resulting film thickness deviations are minimized down to ±0.35%.

During the last decade, striking improvements could be achieved for the precise control of deposition processes in optical coating technology. For example, as a consequence of enormous progresses in measurement and computer technology, direct optical monitoring in a broad spectral range can be considered as a common tool in many production environments nowadays. Besides the development of the corresponding hardware and measurement channels, advanced approaches for the evaluation of the acquired data and new multiple sensor monitoring strategies moved into the focus of modern research on the way towards deterministic deposition techniques. In this context, also innovative concepts for the simulation of deposition processes to forecast the result for a specified coating design and automatic online correction algorithms gained of importance to reduce the risk of failure in coating production. The present contribution will be dedicated to selected aspects in this field, especially addressing broad band optical monitoring systems. A short review on examples for existing hardware configurations and software tools will be presented illustrating the advantages of modern process control techniques. Novel approaches based on the modeling of thin film growth are discussed as an additional strategy to improve the predictability of coating processes.

Fabrication of Ag or Au nanocolumns by oblique angle deposition (OAD) is now prevalent for their surface enhanced Raman scattering (SERS) property and their biosensor application. However, the size, shape, and the density of nanocolumns are not directed in a desired way. To sufficiently realize the growth process controlled by multiple physical factors like deposition angle (\alpha), substrate temperature (T), and deposition rate (F), we develop a three-dimensional (3D) kinetic Monte Carlo (KMC) model for simulating processes of Ag nanocolumnar growth by oblique angle deposition. The dependences of nanocolumnar morphologies on these factors are analyzed. The mimical results reach a reasonable agreement with the experimental morphologies generated by OAD.

A comprehensive material study of different transparent conductive oxides (TCOs) is presented. The layers are deposited by pulsed direct current (DC) magnetron sputtering in an inline sputtering system. Indium tin oxide (ITO) films are studied in detail. The optimum pressure of 0.33 Pa (15Ar:2O2) produces a 300-nm thin film with a specific resistivity \rho of 2.2 \times 10-6 m and a visual transmittance of 81%. Alternatively, ZnO:Al and ZnO:Ga layers with thicknesses of 200 and 250 nm are deposited with a minimum resistivity of 5.5 \times 10-6 and 6.8 \times 10-6 m, respectively. To compare the optical properties in the ultraviolet (UV) range, the optical spectra are modeled and the band gap is determined.