The influence of the charge density of polyelectrolytes on the growth of polyelectrolyte multilayers via layer-by-layer self-assembly from pure aqueous solutions was studied. Multilayers were built from strong polyanions, namely poly(styrenesulfonate) and an exfoliated synthetic hectorite, and cationic copolymers of diallyldimethylammonium chloride (DADMAC) with N-methyl-N-vinylformamide (NMVF) for which the composition and thus the charge density was varied systematically. The analysis of the system {cationic copolymer/poly(styrenesulfonate)} reveals that a critical linear charge density λc of 0.036 elementary charge/Å of contour length is necessary to obtain stable multilayer growth in pure water. Above λc, the increment of thickness/deposition cycle varies with the linear charge density of the cationic copolymers, in good agreement with current theories of polyelectrolyte solutions. As linear charge density increases, the system passes successively through a charge-dependent "Debye-Hu ¨ckel" regime and then through a chargeindependent "strong-screening" regime where counterion condensation dominates the behavior. Analogous results were obtained for the variation of the basal spacing of internally structured hybrid multilayers {cationic copolymer/hectorite}. However, by contrast with the first system, no critical linear charge density was found for the hybrid system. This is explained by additional, nonelectrostatic interactions between the clay platelets and the formamide fragment.

In this contribution, we discuss the crystalline properties of strained and strain-relaxed CVD-grown GeSn layers with Sn content in the range 6.4-12.6 at.%. A positive deviation from Vegard's law was observed and a new experimental bowing parameter was extracted for GeSn: b GeSn = 0.041 Å (in excellent agreement with recent theoretical predictions). The GeSn critical thickness for strain relaxation as a function of Sn concentration was determined, resulting in significantly higher values than those predicted by equilibrium models. A composition-dependent strain relaxation mechanism was also found, with the formation of an increasing density of GeSn pyramidal islands in addition to misfit dislocations at lower Sn concentration.

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The process characteristics, the surface chemistry, and the resulting film properties of Ru deposited by atomic layer deposition from (ethylbenzyl)­(1-ethyl-1,4-cyclohexadienyl)­Ru(0) (EBECHRu) and O2 are discussed. The surface chemistry was characterized by both combustion reactions as well as EBECHRu surface reactions by ligand release. The process behavior on TiN starting surfaces at 325 °C was strongly influenced by Ti­(O,N) x segregation on the growing Ru surface with consequences for both the growth per cycle as well as the film properties. For optimized process conditions, the films showed high purity with low C and O concentrations of the order of 1020 at./cm3. Higher deposition temperature led to strong (001) fiber texture of the films on SiO2 starting surfaces. Annealing in forming gas improved the crystallinity and led to resistivity values as low as 11 μΩcm for Ru films with a thickness of 10 nm.