This study focuses on the elaboration of PEMFC electrodes containing ultra-low platinum (Pt) loadings by direct liquid injection metal organic chemical vapor deposition (DLI-MOCVD). DLI-MOCVD offers a large number of advantages for the elaboration of model PEMFC electrodes. First, by using different metal precursors or elaboration temperature, the size of the Pt nanoparticles and thus the intrinsic catalytic activity can easily be tailored in the nanometer range. In this work, Pt nanoparticles (1–5nm) with remarkable low degree of agglomeration and uniform distribution were deposited onto the microporous side of a commercial gas-diffusion layer (GDL). Second, reduction of the Pt loading is made possible by varying the Pt deposition time and its influence of the cell performance can be extracted without variation of the thickness of the catalytic layer (in previous studies, a decrease of the catalyst utilization was observed when increasing the Pt loading, i.e. the thickness of the catalytic layer (CL)). The electrocatalytic activity of home-made Pt nanoparticles elaborated by DLI-MOCVD was measured in liquid electrolyte or in complete fuel cell operating on H2/O2 or H2/air and compared vs. that of a commercially available electrode containing 500μgPtcm−2 (PtRef500). At the cathode, the performance of the electrodes containing 104–226μg of Pt per cm2 of electrode compares favorably with that of the PtRef500 in H2/O2 conditions. In H2/air conditions, additional mass-transport losses are detected in the low-current density region but the high effectiveness of our electrodes improves the performance in the high-current density region. At the anode, the Pt loading can be reduced to 35μgPtcm−2 without any voltage loss in agreement with previous observations.

Vanadium oxide films were synthesised by chemical vapour deposition (CVD) from pure of triisopropoxyvanadium oxide (VO(OC3H7)3) and oxygen as precursors. The influence of the substrate on the crystallinity of the vanadium oxide films was studied before and after annealing at 500°C. On mica substrates, as-deposited film was composed of crystalline V2O5 as revealed by XRD. On Pt, Ti, stainless steel, glass and F-doped SnO2 substrates, an annealing procedure was required to get V2O5. SEM investigations have clearly evidence V2O5 plates but the kinetics growth seems to be strongly dependent on the nature of the substrate. The insertion/extraction of Li+ into the host structure was investigated in 1M LiClO4-PC with annealed V2O5 films deposited on Ti, Pt and stainless steel substrates. The best electrochemical performances were obtained in the potential range 3.8–2.8V versus Li/Li+ with V2O5 films deposited onto stainless steel substrate: the reversible capacity reaches after subsequent cycles was about 115mAhg−1 (rate C/23). In a wider potential range (between 3.8 and 2.2V versus Li/Li+), V2O5 deposited onto Ti substrate exhibited the higher electrochemical performances (220mAhg−1 for a rate of C/23).

Bottom-contact tetracene light-emitting transistors employing a mercaptosilane derivative self-assembled monolayer as adhesive between gold concentric interdigitated source/drain electrodes and SiO2 gate dielectric are described. Devices that employ the mercaptosilane adhesive have a higher mobility and electroluminescence compared to those employing a standard metallic adhesive. This is rationalized in terms of the large, well interconnected grains found in tetracene films deposited on substrates using the mercaptosilane adhesive. Our work represents a step forward in the understanding of physical processes at semiconductor/metal and semiconductor/dielectric interfaces in organic devices.

An auger electron spectroscopy study was carried out on Rh-containing micro-structures grown by electron beam induced deposition (EBID) of the iso-structural and iso-electronic precursors [RhCl(PF3)2]2 and [RhCl(CO)2]2. A material containing between 55 and 60at.% Rh was obtained from both precursors. The chemical composition of structures grown from the two different precursors indicates a similar decomposition mechanism. Deposits grown from [RhCl(PF3)2]2 showed a chemical composition independent of electron energy and electron dose in the investigated range of conditions.

Individual carbon nanotubes (CNTs) often occur in randomly dispersed two-dimensional as well as three-dimensional configurations that make device fabrication difficult. Making electrical contact to such CNTs is of practical interest. To this end, we make contact to individual metallic single-walled carbon nanotubes (SWNTs) using the focused electron-beam-induced deposition (FEBID) of pure gold. The SWNTs are grown by chemical vapor deposition on a flat substrate, and the gold leads are made through FEBID using inorganic metallic precursor gas, chloro(trifluorophosphine)gold(I), or AuClPF3, in a high vacuum scanning electron microscope. The same scanning electron microscope is also used to image carbon nanotubes, allowing for simultaneous alignment. We find equivalent one-dimensional resistivities for the SWNTs of 10–15kΩ∕μm for both FEBID gold leads and leads deposited using conventional electron-beam lithography (EBL) and thermal evaporation of gold, suggesting similarly low contact resistances. We use electrostatic force microscopy to verify quantitatively similar contact resistances for one nanotube sample, 10(±6) and 54(±6)kΩ, for FEBID and EBL leads, respectively, with most voltage dropping across the long metallic SWNT.

Capping layers are intended to solve electro-migration failure observed at the etch-stop/copper interface. A complete NiMo-P electroless 8" wafer plating process is presented in this article for capping of copper lines. Thin barrier films were selectively deposited onto narrow copper lines. As deposited, the NiMo-P cap is mainly a Ni amorphous matrix doped with Mo and P. The composition of a standard cap is Ni88Mo3.3-P-8.7 and appears to be an efficient barrier to copper diffusion. An alkali-free deposition bath was also developed yielding promising electrical results in narrow features.

Copper thin films were grown on SiO2 substrates by chemical vapor deposition using the precursor (MHY)Cu(hfac) and were examined by scanning electron microscopy. The affinity for copper chemical vapor deposition of the substrate surface is higher after the formation of self-assembled monolayers of 3-mercaptopropyltrimethoxysilane onto the substrate surface. Furthermore, the affinity is greatly enhanced by a subsequent UV-light irradiation of the organosilane monolayer, in air, prior to deposition. Hence, sticky copper films were obtained by copper CVD on flat and patterned surfaces. We have demonstrated by XPS that the initial surfacic thiol groups that have been oxidized into sulfonic type groups act as nucleation sites for copper CVD.

We have studied the morphology, the structure and the chemical composition of micro- and nano-structures grown by electron beam-induced deposition of [RhCl(PF3)2]2. Transmission electron microscopy revealed that the deposits are made up of face centered cubic crystalline Rh grains (4–6nm in diameter) immersed in an amorphous matrix. Auger electron spectroscopy and electron energy loss spectroscopy showed that a carbon contamination layer is present at the deposit surface, while the bulk material contains the elements Rh (60at%), P (20at%), Cl, O and N (remaining 20at%). The structure, the chemical composition of the deposits and the size of the Rh nano-crystals are independent of the deposit shape and of the deposition parameters, within the range explored in this work.

Vanadium oxide films were synthesized by chemical vapor deposition from pure or diluted VO(OC3H7)(3) precursor. An annealing process at 500 degreesC was required to obtain crystallized V2O5. X-ray diffraction patterns have pointed out the influence of the operating conditions for the vanadium oxide deposition on the crystallites sizes. No significant difference in the roughness factor was observed by atomic force microscopy measurements before and after annealing at 500degreesC. As-deposited V6O13 films were also directly obtained by changing the operating conditions. The insertion/deinsertion of Li+ into the host structure was investigated in 1 M LiClO4-propylene carbonate. V2O5 films exhibit low irreversible capacity and high cyclability even for a deep lithium insertion ratio; in addition, only small amounts of gamma-phases were formed during cycle life at low potential without significant effects on its electrochemical performance. After subsequent cycles between 3.8 and 2.2 V vs. Li/ Li+, the reversible capacity is found to be approximate to250 mAh g(-1) (y approximate to 1.65) close to the theoretical one. V6O13 films exhibit reversible capacity of about 410 mAh g(-1) ( y approximate to 7.9). (C) 2004 The Electrochemical Society.

Self-assembled monolayers of organosilanes deposited onto SiO2/Si substrate surfaces by either vapour-phase or wet chemical methods can act as ultrathin interfacial barriers which effectively prevent the diffusion of copper into the SiO2 dielectric, enhance its adhesion onto it and also offer the possibility of achieving selective copper chemical vapour deposition. The initial stages of copper nucleation by chemical vapour deposition on organosilane treated SiO2 surfaces at different substrate temperatures are investigated in detail by scanning electron and atomic force microscopy. The growth behaviour of copper clusters before coalescence is elucidated and analysed in detail. At temperatures below 190 °C nucleation occurs mostly on already formed copper clusters and coalescence is obtained due to an increase of the size of clusters in three dimensions. Above that temperature, secondary nucleation of smaller size clusters on the gaps among the larger clusters is observed, leading to coalescence almost in two dimensions. The stable clusters density initially increases with precursor injection time, passes through a maximum and then decreases, due to an increase at low temperatures of the size of clusters. An almost substrate temperature independent maximum clusters density which is obtained in the low temperatures region, indicates that nucleation of copper atoms occurs on surface defect sites which are assumed to be Cu(I) atoms. A low value of the apparent activation energy for nucleation, indicates higher affinity for copper chemical vapour deposition of the organosilane treated SiO2 as compared to TiN substrates used previously. At 200 °C, coalescence following the initial nucleation period, results in continuous films with low roughness and low average height, thus leading to the practical realization of a thin yet continuous film.

The copper precursors bis-hexafluoroacetylacetonato-copper Cu(hfac)(2), vinyl-trimethyl-silane-copper(I) hexafluoroacetylacetonate (hfac)Cu(VTMS), 2-methyl-1-hexen-3-yne-copper hexafluoroacetylacetonate (hfac)Cu(MHY), and dimethylbutenecopper(I) hexafluoroacetylacetonate (fac)Cu(DMB) are compared with respect to deposition rates and metal content obtained by focused electron beam induced deposition. Exposure was performed with 25 keV electrons in a Cambridge S100 scanning electron microscope equipped with a lithography system. Tip deposition rates increase with increasing precursor vapor pressure and range between 47 nm/s for (hfac)Cu(DMB) to about 4 nm/s for Cu(hfac)(2). A decay of deposition rates with time, i.e., tip length, is observed. Electric four-point measurements indicate an insulating behavior of deposited lines for all precursors. In contrast, Cu contents of up to 45-60 atom % were found by Auger electron spectroscopy in thin rectangular deposits using (hfac)Cu(DMB) and (hfac)Cu(VTMS) as precursors. A discussion in terms of monolayer coverage, completeness of precursor molecule dissociation, and precursor stability is presented. (C) 2004 The Electrochemical Society.

The determination of the X-ray crystal structure of Cu(I) (1,1,1,3,5,5,5-heptafluoro-pentane-2,4-dionato) (vinyltrimethylsilane) or Cu(pfac)(VTMS), a close analogue to Cu(hfac)(VTMS), which is the most widely used precursor for copper CVD, gives us an unique insight about the molecular structure of such compounds. In particular, two short F…H distances between CF3 groups of a molecule and the alkenyl hydrogen atoms of the neighboring molecule reveal intermolecular interactions specifically related to the structure of the VTMS ligand.

Deposition of both pure and Pd-doped diamond-like films (DLF) is reported under laser irradiation of the interface glass–liquid aromatic hydrocarbons. The deposited DLF are 100nm thick and have excellent adherence to glass surface. The doping of DLF by Pd is gained by addition of Pd(acac)2 to the liquid hydrocarbon, either benzene C6H6 or toluene C6H5CH3. AFM imaging of the doped DLF shows the cluster-like structure of sub-micrometer size. The Pd clusters promote the CVD Cu deposition from a gas phase precursor resulting thus in the selective metal deposition on the doped DLF. Similarly, the area-selective deposition of both Cu and Ni on the doped DLF is achieved from corresponding electroless plating solutions. It is demonstrated that the DLF represents a diffusion barrier for Cu diffusion into the glass substrate.

Platinum thin films are suitable candidates as electrodes for high permittivity and ferroelectric oxides. Pt films were prepared by metal organic chemical vapor deposition (MOCVD) using a direct liquid delivery system. This method is based on the oxidative decomposition of (methylcyclopentadienyl)trimethylplatinum (MeCpPtMe3), as a precursor, diluted in cyclohexane solvent. Different deposition conditions were used to grow high purity platinum films on TiO2/SiO2/Si and SiO2 substrates. Adhesion properties of the Pt CVD films on TiO2 were found to be better than directly on SiO2 since TiO2 acts as a 'glue layer'. Platinum films deposited exhibit a roughness ranged from 3.1 to 4.5 nm and a thickness between 60 and 100 nm.

Experimental and theoretical techniques have been applied to study the decomposition of the [RhCl(PF3)(2)](2) molecule which is known as a precursor in electron beam induced deposition (EBID) of Rh. Mass spectrometry (MS) has been carried out to study the electron ionisation and fragmentation of isolated molecules. Auger electron spectroscopy has been used to characterize the EBID deposit. The MS data indicate the presence of free phosphorus and rhodium ions. This is in agreement with the analysis of the composition of the EBID deposit containing: 60% Rh, 12-25% P, 2-13% Cl, no F, 3-20% O and N. Theoretical calculations ( density functional theory) has been used to characterize the precursor molecule and to derive the enthalpies of several simple decomposition reactions. The calculated geometries are in a good agreement with the available X-ray crystallographic data. The [RhCl(PF3)(2)](2) appears not to be rigid: the PF3 groups can rotate with a relatively low barrier (0.6 kcal mol(-1)) whereas the barrier for the butterfly-like motion of (RhCl)(2) moiety is only 3.5 kcal mol(-1). According to the theoretical results, the lowest energy pathway of the decomposition corresponds to a consecutive loss of PF3 ligands, resulting in a (RhCl)(2) moiety (without phosphorus). The same conclusion is also valid for the ionised precursor. Experimental data combined with the theoretical results concerning the energetics of the considered various simple decomposition processes indicate that the electron induced dissociation of the precursor cannot be seen as a simple one-step decomposition process.

Platinum (Pt), ruthenium (Ru), and ruthenium dioxide (RuO 2 ) have been considered as possible candidates as electrodes for high permittivity and ferroelectric oxides. The films were grown by metal organic chemical vapor deposition (MOCVD). High purity Pt films with near bulk resistivities (11 w z cm) were deposited. The Pt, Ru and RuO 2 films were found to be continuous and smooth and exhibited excellent adhesion properties on the underlying substrates. The temperature dependent electrical conductivity of the Ru and RuO 2 films was metallic type. Room temperature resistivities as low as 18 and 30 w z cm were determined for Ru and RuO 2 , respectively.