Co-sputtering Of Metals Research Articles

Searching novel complex solid solution electrocatalysts in unconventional element combinations

Despite outstanding accomplishments in catalyst discovery, finding new, more efficient, environmentally neutral, and noble metal-free catalysts remains challenging and unsolved. Recently, complex solid solutions consisting of at least five different elements and often named as high-entropy alloys have emerged as a new class of electrocatalysts for a variety of reactions. The multicomponent combinations of elements facilitate tuning of active sites and catalytic properties. Predicting optimal catalyst composition remains difficult, making testing of a very high number of them indispensable. We present the high-throughput screening of the electrochemical activity of thin film material libraries prepared by combinatorial co-sputtering of metals which are commonly used in catalysis (Pd, Cu, Ni) combined with metals which are not commonly used in catalysis (Ti, Hf, Zr). Introducing unusual elements in the search space allows discovery of catalytic activity for hitherto unknown compositions. Material libraries with very similar composition spreads can show different activities vs. composition trends for different reactions. In order to address the inherent challenge of the huge combinatorial material space and the inability to predict active electrocatalyst compositions, we developed a high-throughput process based on co-sputtered material libraries, and performed high-throughput characterization using energy dispersive X-ray spectroscopy (EDS), scanning transmission electron microscopy (SEM), X-ray diffraction (XRD) and conductivity measurements followed by electrochemical screening by means of a scanning droplet cell. The results show surprising material compositions with increased activity for the oxygen reduction reaction and the hydrogen evolution reaction. Such data are important input data for future data-driven materials prediction.

Surface dispersion engineering of Ag–Au alloy films

By controlling the content ratio of Ag and Au during the metal co-sputtering process, we demonstrate that the surface dispersion properties of alloy metal films can be manipulated with no need to tune the geometric parameters for surface patterns. This inexpensive technology provides a different way to engineer the surface dispersion properties of plasmonic metamaterial components on a chip.

Nanocomposite and nanostructured films with plasma polymer matrix

Nanocomposite and nanostructured films have been studied for several decades mainly due to their unique physical, chemical or bioresponsive properties. The main attention has been paid to metal/plasma polymer nanocomposites prepared by simultaneous plasma polymerization and metal co-sputtering or evaporation. These nanocomposite films are concisely reviewed. More complex composites that are prepared by metal oxide incorporation into plasma polymer matrices using RF sputtering are discussed. Recently emerged utilization of beams of nanoclusters for the deposition of these nanocomposites and preparation of nanostructured surfaces of plasma polymers by various plasma based methods is described.

SEM analysis and selenization of Cu–In alloy films produced by co-sputtering of metals

Co-sputtered copper–indium (Cu–In) alloy layers were investigated as precursors for CuInSe 2 (CIS) formation. Results of scanning electron microscopy (SEM), EDS and X-ray diffraction (XRD) studies reveal the inhomogeneity of the films composition. The films have a rough surface structure with well-defined islands crystallized within the film matrix. The elemental composition of the island-type crystals corresponds to the compound CuIn 2 and the composition of the matrix area corresponds to the Cu11In 9 phase. The influence of heating temperature, time and Se pressure on the morphology and composition of films is studied using SEM, XRD and Raman spectroscopies. Thereby optimal technological parameters for the production of single-phase CIS layers are determined.

Organic films prepared by polymer sputtering

Deposition of organic films by means of radio frequency (rf) sputtering of conventional polymers became the center of attention in the 1970s. The interest was particularly in polytetrafluoroethylene (PTFE) and recently it has been renewed. In addition to PTFE, polyimide and polyethylene (PE) sputtering has also been studied. Findings from these studies are briefly reviewed. Our results of the kinetics of rf magnetron sputtering of PTFE by energy resolved mass spectrometry are shown in more detail. Various CXFY species were detected in the discharge, with the composition affected by the discharge parameters. It is assumed that CF, CF2, and CF3 fragments from the sputter process are the most important for film growth. The morphology of fluorocarbon plasma polymer films deposited on Si substrates at various temperatures was observed by means of scanning electron microscopy. It was concluded that below +23 °C, a columnar structure appears. The structure and basic properties of hydrocarbon plasma polymer films prepared by rf sputtering of PE are concisely presented. Composite metal/plasma polymer films prepared by polymer and metal cosputtering are briefly discussed.

Application-oriented modifications of deposition processes for diamond-like-carbon-based coatings

Hydrogenated amorphous carbon films (a-C:H) exhibit some “diamond-like” properties as high wear resistance and low electrical conductivity. However, to fulfil requirements for special applications, e.g. high wear resistance combined with high electrical conductivity or low surface energy, the films had to be modified. These modifications can be realized by the incorporation of other elements (metals, F, O, N or Si) into the a-C:H network structure either by co-sputtering of metals or by adding adequate reactive gases to the working gas. It was found that the surface energy of a-C:H films can be definitely changed by the incorporation of elements such as F, N, O or Si into the films, using a mixture of acetylene with, for example, fluorinated hydrocarbons, nitrogen or silicon-based hydrocarbons as a working gas. Hard coatings with decreased or increased wetting angles against water were prepared. For example a Teflon ®-like material with low adhesion forces could be deposited, while the tribological properties of this coating are similar to those of diamond-like carbon coatings. Metal-containing amorphous hydrocarbon (M-C:H) films with 15 at.% metal (e.g. Ta, W, Ti or Nb) or less have nearly the same wear resistance and friction coefficient as a-C:H, but their electrical conductivities are several orders higher. The variation in the metal concentration in such coatings has to be kept under good control to increase the adhesion forces to the substrate material by the use of metallic interface layers. We have developed a reactive d.c. magnetron sputtering technique for the preparation of M-C:H films with well-defined metal contents in the graduated interface and in the functional top coat respectively. A reproducible preparation of coatings with desired metal contents was achieved for different industrial components.

Serial cosputtering of metals: modelling of sputtering from a periodically codeposited surface

Serial cosputtering is a simple yet powerful tool for the deposition of multilayered thin films with unique physical properties. This article studies one specific cosputtering system and discusses how the so-called “sputter yield amplification effect” can be utilized to increase the deposition rates by the suitable choice of both materials used and operating conditions. The main emphasis is placed on computer modelling of the system with a view to optimizing the whole technological process. Comparisons between experiment and computer simulation in a number of typical situations is presented.