C. Gravalidis

Surface kinetics and subplantation phenomena affecting the texture, morphology, stress, and growth evolution of titanium nitride films

We present a thorough study of the microstructure, texture, intrinsic stress, surface, and interface morphology of transition metal nitride (mainly TiN but also CrN) films grown on Si by reactive sputter deposition, with emphasis to the mechanisms of adatom migration on the surface and subplantation of energetic species. In order to study the effects of adatom mobility and the subplantation probability we vary the ion energy and growth temperature. For the experimental part of this work we used nondestructive, statistically reliable x-ray techniques (diffraction, reflectivity, scattering). The x-ray results are compared and correlated with supporting data of in situ spectroscopic ellipsometry as well as Monte Carlo simulations of the irradiation effects and surface diffusion of adatoms. We found that the texture and the surface and interface morphology are sensitive to the mechanism of dissipation of the impinging ions. If the energy is enough to overcome the subplantation threshold (∼50eV), then the film...

Surface-activation processes and ion-solid interactions during the nucleation and growth of ultra-thin amorphous carbon films

Amorphous carbon (a-C) films have been grown by processes using Ar or C ions. The films hybridization states were qq evaluated by Auger electron spectroscopy, X-ray photoelectron spectroscopy and X-ray reflectivity. It was found that the films grown using C (Ar ) exhibit a sp (sp ) surface, while the deeper monolayers are sp (mixed sp -sp ) bonded. These results qq 23 3 3 2

X-ray diffuse scattering investigation of thin films

Abstract X-ray Diffuse Scattering (XDS) is presented, a technique, which determines the roughness, morphology and nanoparticle distribution of thin films. XDS is complementary to X-ray Diffraction and Reflectivity (XRD–XRR). The ability of XDS is demonstrated to investigate the films’ nanoscale surface structure and to determine additional geometrical features such as correlation length and fractal characteristics. It is shown that XDS can be used for the study of the surface morphology, as well as, phase identification of amorphous materials and combined with XRR for quantitative analysis of composite films using the Distorted Wave Born Approximation (DWBA) with the concept that the film surface behaves like a Self-Affined medium. As model systems we study nanocrystalline Boron Nitride (BN) and amorphous Carbon (a-C) films. XDS spectra of BN films containing both cubic and hexagonal phases exhibit two set of Yoneda peaks, located at angles characteristic of the corresponding BN densities, while BN films containing only hexagonal phase exhibit one characteristic set. This indicates that the two BN phases are not atomically mixed. The opposite: strong atomical mixture of sp2 and sp3 components, was found in a-C films by XDS. Additionally, the growth mechanism for a-C films deposited with or without ion bombardment assistance is predicted and discussed.

Insights on the Optical Properties of Poly(3,4-Ethylenedioxythiophene):Poly(styrenesulfonate) Formulations by Optical Metrology

Poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS) is among the most widely used polymers that are used as printed transparent electrodes for flexible Organic Electronic (OE) devices, such as Organic Photovoltaics (OPVs). The understanding of their optical properties and the correlation of the optical properties with their electronic properties and metallic-like behavior can lead to the optimization of their functionality as transparent electrodes in multilayer OE device architectures. In this work, we study the optical properties of different PEDOT:PSS formulations by non-destructive Spectroscopic Ellipsometry (SE), from the infrared to the far ultraviolet spectral regions. The optical response of PEDOT:PSS includes an intense optical absorption originated from the conductive part (PEDOT) at lower photon energies, whereas the electronic transition energies of the non-conductive PSS part have been measured at higher photon energies. Based on the different PEDOT:PSS formulations, the optical investigation revealed significant information on the relative contribution of conductive PEDOT and insulating PSS parts of the PEDOT:PSS formulation in the overall optical response, which can strongly impact the final device functionality and its optical transparency.

Thin Film Deposition and Nanoscale Characterisation Techniques

In this chapter the basic categories of the thin film deposition techniques are presented. The rf magnetron sputtering (MS) deposition conditions and their effect to the optical, nanostructural and nanomechanical properties of: (a) single layer and multilayer, hard and soft carbon-based thin films grown on rigid Si substrate and (b) AlOx thin films grown on flexible polyethylene terephthalate (PET) substrate are presented and discussed. Finally the Spin coating technique for the development of thin films from the liquid phase and the solvent effect to the PEDOT:PSS thin film thickness are given.