In the present work we describe an investigation of the influence of low-energy ion irradiation (1-keV ${\mathrm{Ar}}^{+}$) on the surface structure of polycrystalline diamond and amorphous carbon films with various degrees of graphitization. Photoelectron spectroscopy (PES) with excitation energies in the ultraviolet and x-ray regime is employed to monitor the radiation-induced modification of the electronic structure of the surface which is closely linked to the local bonding environment of the carbon atoms. A comparison of the mean photoelectron escape depth and the thickness of the irradiation affected layer also illustrates the suitability of PES for this investigation. For the chemical vapor deposition (CVD)-diamond film a gradual change from typical diamond features to amorphous carbon is observed for ion doses surpassing 6\ifmmode\times\else\texttimes\fi{}${10}^{14}$ ${\mathrm{cm}}^{\mathrm{\ensuremath{-}}2}$. The structural changes in the diamond lattice are expressed in a broadening of the C 1s core-level peak, and increasing contributions from p-\ensuremath{\pi} states around 3--4 eV in the valence-band spectra. Likewise the peak located at 13 eV (He II, h\ensuremath{\nu}=40.82 eV), characteristic of diamond, is no longer apparent for ion doses exceeding 3\ifmmode\times\else\texttimes\fi{}${10}^{15}$ ${\mathrm{cm}}^{\mathrm{\ensuremath{-}}2}$. The diamond surface clearly shows a tendency to amorphize rather than graphitize under ion irradiation. To complement the results for the diamond film, we irradiated two amorphous carbon films with different microstructures: (A) a predominantly amorphous film, and (B) a film with graphitic inclusions. The destruction of graphitic structures in film (B) is apparent even for the lowest ion dose (1.5\ifmmode\times\else\texttimes\fi{}${10}^{14}$ ${\mathrm{cm}}^{\mathrm{\ensuremath{-}}2}$), and expressed in an increase in the width of the C 1s core-level peak and a smearing out of the valence-band spectral features. The resultant valence-band and core-level spectra (total ion dose: 3\ifmmode\times\else\texttimes\fi{}${10}^{15}$ ${\mathrm{cm}}^{\mathrm{\ensuremath{-}}2}$) are very similar to the one obtained for the amorphous film (A), which, on the other hand, does not show any significant changes in its structure upon irradiation. The irradiation of both diamond and graphitic structures with low-energy ${\mathrm{Ar}}^{+}$ ions leads to the formation of a predominantly amorphous surface layer. \textcopyright{} 1996 The American Physical Society.
Titanium aluminum nitride films (Ti1−xAlxN) have been deposited by reactive magnetron cosputtering. Elemental compositions of these films have been determined by core level photoelectron spectroscopy. Scanning electron microscopy reveals a columnar film growth. This is also reflected by the topography of film surfaces as studied by atomic force microscopy. By x-ray diffraction a crystalline atomic structure is revealed. Single phase samples can be obtained, consisting of the substitutional solid solution (Ti, Al)N. Crystallites show preferential orientation. The optical properties of these films have been investigated by spectrophotometry in the UV-VIS-NIR wavelength range. Depending on the elemental composition, the optical constants vary from metallic to dielectric behavior. For film compositions with x<0.5 typical features are a tunable transmission maximum and reflection minimum in the visible spectral range, a high infrared reflection, and a low infrared absorption. Due to these optical properties, Ti1−xAlxN films are promising candidates for applications such as coatings for solar control windows and optical selective solar absorbers.
Natural type IIb diamond surfaces of (100), (110), and (111) orientation, as well as chemical vapor deposited (CVD) diamond thin films with (100), (110), or mixed orientation are probed by photoelectron spectroscopy in the ultraviolet (UPS) and X-ray (XPS) energy regimes. Dramatic changes can be observed in the valence band and core level spectra of these surfaces upon annealing, hydrogen-plasma exposure, or pulsed dye laser irradiation. The observed changes can be reversed by the exposure of the surfaces to atomic hydrogen (deuterium). The valence band spectra reveal specific surface reconstructions for all three surface preparation methods and moreover a cleaning effect is observed following laser irradiation of CVD diamond surfaces. A comparison to a multitude of theoretical and experimental studies on diamond surface reconstruction is made to elucidate the connection between electronic properties and atomic surface structures.
