T. Strunskus

Condensation coefficients and initial stages of growth for noble metals deposited onto chemically different polymer surfaces

The initial stages of growth of noble metals deposited onto untreated as well as Ar+ beam-treated polymer surfaces were investigated by means of X-ray photoelectron spectroscopy (XPS), transmission electron microscopy (TEM), and radiotracer methods. Condensation coefficients C of the metals on the polymer surfaces were determined by comparison of the XPS signals of the metals with the nominal thicknesses measured by a quartz microbalance during deposition. These measurements were combined with radiotracer measurements, which allow to determine C independently with high accuracy and sensitivity. C was found to depend strongly on the chemical composition of the polymer surface, e.g., at room temperature, C varies between 0.95 for PMDA-ODA polyimide and 0.002 for Teflon AF. By ion beam treatment of the latter, C was raised considerably. During nucleation of the metal on the polymer surface, C increases strongly with metal coverage. C also depends on the deposition rate of the metal and decreases strongly at elevated temperatures.

Formation of metal-polymer interfaces by metal evaporation: influence of deposition parameters and defects

Abstract Metal–polymer interfaces with different but well defined morphologies were prepared by evaporating noble metals (Au, Ag, Cu) onto chemically different polymers, i.e. bisphenol-trimethyl cyclohexane polycarbonate (TMC-PC), pyromellitic dianhydride-oxydianiline (PMDA-ODA) polyimide (PI), polystyrene (PS) and the low-k dielectric Teflon AF 1601. The interfaces were characterised using transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS) and atomic force microscopy (AFM). The combination of these techniques allowed one to determine morphological parameters such as concentration and distribution of metal clusters at the surface and in the near-surface region. In addition, radiotracer measurements yielded exact metal condensation coefficients C and was used to determine the extent of diffusion of metal atoms into the polymers. First experiments on the macroscopic adhesion of Cu on TMC-PC showed that the initially low peel strength can be increased substantially by subsequent annealing above the polymer glass transition temperature, T g .

Plasmonic tunable metamaterial absorber as ultraviolet protection film

Plasmonic metamaterials designed for optical frequency have to be shrunk down to few 10th of nanometer which turns their manufacturing cumbersome. Here, we shift the performance of metamaterial down to ultraviolet (UV) by using ultrathin nanocomposite as a tunable plasmonic metamaterial fabricated with tandem co-deposition. It provides the possibility to realize a plasmonic metamaterial absorber for UV frequency with marginal angle sensitivity. Its resonance frequency and intensity can be adjusted by changing thickness and filling factor of the composite. Presented approach for tunable metamaterials for high frequency could pave the way for their application for thermo-photovoltaic, stealth technology, and UV-protective coating.

Surface oxidation of amorphous Zr65Cu17.5Ni10Al7.5 and Zr46.75Ti8.25Cu7.5Ni10Be27.5

Abstract The initial oxidation and the native oxidation of the amorphous alloys Zr65Cu17.5Ni10Al7.5 (henceforth, called the Inoue alloy) and Zr46.75Ti8.25Cu7.5Ni10Be27.5 (Vitreloy 4 or V4) at room temperature were studied by X-ray photoelectron spectroscopy (XPS). The XPS analysis of the oxide films showed that the major constituent was Zr(IV) oxide, possibly as ZrO2 along with small amounts of the oxides of Ti, Be (in the alloy V4) and of Al (in Inoue alloy in the native oxide case) while Cu and Ni in both the alloys were present in their metallic forms only. The results are explained using the heat of formation data and the diffusion behaviour of the alloying elements.

Evidence of noble metal diffusion in polymers at room temperature and its retardation by a chromium barrier

Recent applications of organic low-k dielectrics in microelectronics have stimulated many investigations of metal diffusion in polymers. Here we report results from radiotracer measurements of 110mAg diffusion in trimethylcyclohexane polycarbonate. Serial sectioning was carried out with 190 eV krypton ions in and opposite to the diffusion direction to rule out sputtering artifacts. Ag was found to be strongly immobilized by self aggregation. In contrast to earlier reports, however, trace amounts of Ag were clearly seen to diffuse into the polymer even at room temperature. A chromium film of only one tenth of a monolayer turned out to be an effective diffusion barrier.

Condensation coefficients of noble metals on polymers: a novel method of determination by x-ray photoelectron spectroscopy

We developed a method to determine condensation coefficients, C, of noble metals on polymer surfaces and to determine cluster sizes by means of XPS only, or in combination with transmission electron microscopy (TEM). The surface concentration of the adatoms was determined using a mathematical correction of the XPS intensity that takes into account cluster growth of the noble metals on the polymer surfaces. We establish our method with experimental results of C for Cu and Ag on pyromellitic dianhydride (PMDA)–4,4′-oxydianiline (ODA) polyimide, bisphenol-A polycarbonate, trimethylcyclohexane bisphenol-A polycarbonate, polystyrene and Teflon AF 1601. Values of C for Ag determined with the XPS method agree well with those of radiotracer measurements. The condensation coefficient varies by three orders of magnitude from 1 to 0.002, depending on the deposition parameters and properties of the adsorbents. The method can be applied in general to investigate the deposition of non-wetting metals on solid surfaces. Copyright

Determination of condensation coefficients of metals on polymer surfaces

We used X-ray photoelectron spectroscopy (XPS) in combination with transmission electron microscopy to characterize the nucleation and growth of noble metals deposited onto polymers and to determine the condensation coefficients of the metals. The surface concentration of the adatoms was determined using a mathematical correction of the XPS intensity to take into account the cluster formation of noble metals on polymer surfaces. Condensation coefficients for Cu and Ag depend strongly on the chemical composition of the polymer and on temperature and can vary by more than three orders of magnitude already at room temperature. The influence of the deposition parameters and the metal/polymer morphology on the condensation coefficient will be discussed.

Formation and material analysis of plasma polymerized carbon nitride nanoparticles

This paper deals with the analysis of nanoparticles polymerized in nitrogen/acetylene and argon/acetylene gas mixtures in low temperature rf discharges. The polymerization process was monitored by means of mass spectroscopy. The chemical characteristics of the material were obtained in situ by infrared absorption spectroscopy and ex situ by means of near edge x-ray absorption fine structure spectroscopy. These data were supported by complimentary elemental analyses such as deuteron induced gamma emission, Rutherford backscattering, and nuclear reaction analysis. Although morphology showed no differences, further material analysis shows clearly nitrogen incorporation in the nanoparticles, mostly by multiple bonds. In comparison with the nanoparticles from argon/acetylene plasma, the amount of carbon in carbon-nitride nanoparticles remains unchanged, whereas hydrogen content strongly decreases. The results of mass spectroscopy on neutrals and ions lead to the assumption that carbon-nitride nanoparticles are formed by copolymerization of two kinds of precursors: hydrocarbon and nitrogen containing hydrocarbon species.

Highly versatile concept for precise tailoring of nanogranular composites with a gas aggregation cluster source

A concept for the precise tailoring of a wide variety of nanogranular composites with a gas aggregation cluster source and a magnetron is presented. Electrical charging of the preformed clusters and the substrate in a plasma is discussed as a fundamental physical hindrance for conventional co-sputtering with a cluster source. The proposed concept overcomes this hindrance and is experimentally demonstrated for the deposition of a dielectric aluminum nitride matrix with embedded magnetic cobalt clusters. Chemical, magnetic, and structural analyses of the composite confirm the feasibility of the proposed concept as a versatile route for the preparation of nanocomposites.

Deposition and tuning of nanostructured hydrocarbon deposits: From superhydrophobic to superhydrophilic and back

Carbonaceous fluorine free nanoparticles synthesized in a low temperature acetylene discharge are used in a first step for the production of (super)hydrophobic coatings. In a second step, the influence of different plasma and UV induced functionalizations on the wetting characteristics of these materials is investigated. The experiments show that the superhydrophobic surfaces can be turned continuously and reversibly into hydrophilic (superhydrophilic) surfaces by means of the different treatment methods. The reversibility of these processes is studied in a third step. It is shown that the changes of the surface which are induced by the plasma treatment can be undone by means of EUV irradiation. The switchability of the surface due to external stimuli can be easily used for the controlled production of patterned surfaces. This is demonstrated by means of one simple example.