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The atomic structure and composition of non-interfacial ITO and ITO-Si interfaces were studied with Transmission Electron Microscopy (TEM) and X-ray Photoelectron Spectroscopy (XPS). The films were deposited by DC magnetron sputtering on mono-crystalline p-type (100) Si wafers. Both as deposited and heat treated films consisted of crystalline ITO. The ITO/Si interface showed a more complicated composition. A thin layer of SiOx was found at the ITO/Si interface together with In and Sn nanoclusters, as well as highly oxygen deficient regions, as observed by XPS. High energy electron exposure of this area crystallized the In nanoclusters and at the same time increased the SiOx interface layer thickness.

Crystalline and amorphous nanoparticles of silicon in thin silica layers were examined by transmission electron microscopy, electron energy loss spectroscopy, and x-ray photoelectron spectroscopy ͑XPS͒. We used XPS data in the form of the Auger parameter to separate initial and final state contributions to the Si 2p energy shift. The electrostatic charging and electron screening issues as well as initial state effects were also addressed. We show that the chemical shift in the nanocrystals is determined by initial state rather than final state effects, and that the electron screening of silicon core holes in nanocrystals dispersed in SiO 2 is inferior to that in pure bulk Si.

Impact of titanium addition on film characteristics of Hf O 2 gate dielectrics deposited by atomic layer deposition J. Appl. Phys. 98, 054104 (2005); 10.1063/1.2030407Microstructure characterization of sol-gel prepared MoO 3 -TiO 2 thin films for oxygen gas sensors Thin films of MoO 3 deposited on Si(111) and Al 2 O 3 (001) substrates by atomic layer deposition have been investigated by x-ray photoelectron spectroscopy (XPS), atomic force microscopy (AFM), and Raman spectroscopy for detailed characterization of composition and morphology. Comparison of angle resolved x-ray photoelectron spectroscopy (ARXPS) and XPS depth profiles based on Ar þ sputtering is reported. Sputtering induces a reduction of molybdenum in MoO 3 from þIV to metallic Mo as the interface toward Si is approached, whereas ARXPS on a 10 nm thin film shows that Mo(VI) remains outside the interface toward Si where lower valent molybdenum compounds are formed. Upon annealing, the as-deposited amorphous thin films of MoO 3 crystallize into bor a-MoO 3 as identified by x-ray diffraction. The current study provides a convenient route toward formation of metastable b-MoO 3 and a full crystallization pathway from amorphous to crystalline a-MoO 3 . Combined AFM and Raman analysis have been performed on thin films of a-MoO 3 deposited on Al 2 O 3 (001) and prove that the crystallization proceeds via island growth at 600 C. The Raman intensity ratios between different bands depend strongly on morphology and size of crystalites.

This work is investigating the chemical grafting on Ti surface of a polymer/calcium phosphate coating of improved adhesion for enhanced bioactivity. For this purpose, a whole new methodology was developed based on covalently attaching a hyperbranched poly(ethylene imine) layer on Ti surface able to promote calcium phosphate formation in a next deposition stage. This was achieved through an intermediate surface silanization step. The research included optimization both of the reaction conditions for covalently grafting the intermediate organosilicon and the subsequent hyperbranched poly(ethylene imine) layers, as well as of the conditions for the mechanical and chemical pretreatment of Ti surface before coating. The reaction steps were monitored employing FTIR and XPS analyses, whereas the surface morphology and structure of the successive coating layers were studied by SEM combined with EDS. The analysis confirmed the successful grafting of the hybrid layer which demonstrated very good ability for hydroxyapatite growth in simulated body fluid.

In this work we present a significant advancement in cubic silicon carbide (3C-SiC) growth in terms of crystal quality and domain size, and indicate its potential use in photovoltaics. To date, the use of 3C-SiC for photovoltaics has not been considered due to the band gap of 2.3 eV being too large for conventional solar cells. Doping of 3C-SiC with boron introduces an energy level of 0.7 eV above the valence band. Such energy level may form an intermediate band (IB) in the band gap. This IB concept has been presented in the literature to act as an energy ladder that allows absorption of sub-bandgap photons to generate extra electron-hole pairs and increase the efficiency of a solar cell. The main challenge with this concept is to find a materials system that could realize such efficient photovoltaic behavior. The 3C-SiC bandgap and boron energy level fits nicely into the concept, but has not been explored for an IB behavior.For a long time crystalline 3C-SiC has been challenging to grow due to its metastable nature. The material mainly consists of a large number of small domains if the 3C polytype is maintained. In our work a crystal growth process was realized by a new approach that is a combination of initial nucleation and step-flow growth. In the process, the domains that form initially extend laterally to make larger 3C-SiC domains, thus leading to a pronounced improvement in crystalline quality of 3C-SiC. In order to explore the feasibility of IB in 3C-SiC using boron, we have explored two routes of introducing boron impurities; ion implantation on un-doped samples and epitaxial growth on un-doped samples using pre-doped source material. The results show that 3C-SiC doped with boron is an optically active material, and thus is interesting to be further studied for IB behavior.For the ion implanted samples the crystal quality was maintained even after high implantation doses and subsequent annealing. The same was true for the samples grown with pre-doped source material, even with a high concentration of boron impurities.We present optical emission and absorption properties of as-grown and boron implanted 3C-SiC. The low-temperature photoluminescence spectra indicate the formation of optically active deep boron centers, which may be utilized for achieving an IB behavior at sufficiently high dopant concentrations. We also discuss the potential of boron doped 3C-SiC base material in a broader range of applications, such as in photovoltaics, biomarkers and hydrogen generation by splitting water.

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