J. P. Zhao

Overall energy model for preferred growth of TiN films during filtered arc deposition

TiN films with different preferred crystalline orientations have been prepared by a new cathodic arc evaporation technique - filtered arc deposition (FAD). The evolution of the preferred orientation in the TiN films was investigated systematically. Three kinds of preferred orientation, i.e. the (200), (111), and (220) preferred orientation, were achieved continuously in one deposition procedure by varying the film thickness and substrate bias which determines the bombarding energy of the deposited energetic particles. At the initial stage of film growth, the (200) orientation is dominant at a lower substrate bias. When the film becomes thicker and/or substrate bias increases, the preferred orientation will be (111) instead of (200). If the substrate bias increases further, then the preferred (220) growth occurs at any film thickness. The evolution of the preferred orientation from (200) to (111) and then to (220) is discussed on the basis of a new concept, the so-called overall energy which consists of the surface energy, the strain energy, and the stopping energy. The preferred orientation of TiN films is determined by the competition between the surface energy, the strain energy and the stopping energy.

Optical and electrical properties of nitrogen incorporated amorphous carbon films

Nitrogen incorporated amorphous carbon (a-C:N) films on silicon (111) wafer, quartz, and Ti/C substrates with nitrogen concentration up to 20 at. % are prepared by filtered arc deposition. The nitrogen concentration and area density of the films were measured by Rutherford backscattering. The electrical properties of the films were investigated by Hall electrical measurements. The optical properties of the films were characterized by ultraviolet–visible and infrared reflection spectrometry. Results indicate that the optical band gap and area density of a-C:N films decrease with increasing nitrogen pressure, accompanied with an increase of nitrogen concentration and reflectivity of the films. Furthermore, the influence of nitrogen concentration on the optical band gap of the films is discussed. The dielectric constant, refractive index and absorption coefficient of a-C:N films in infrared region were investigated. The results indicate that the optical constants of a-C:N show considerable variation with wav...

Thickness-independent electron field emission from tetrahedral amorphous carbon films

Electron field emission properties of tetrahedral amorphous carbon films of different thicknesses have been studied. The experimental results indicate that there exists no close relationship between threshold electric field and film thickness. Different field emission models are used to examine the experimental results in order to explain the thickness-independent electron field emission properties.

Evolution of the texture of TiN films prepared by filtered arc deposition

Three kinds of textures, i.e., (200), (111), and (220) of TiN films prepared by filtered arc deposition have been continuously observed with varying film thickness and bombarding energy of the deposited particles. The evolution of the texture from (200) to (111), then to (220) is discussed on the basis of the so‐called overall energy which consists of the surface energy, the strain energy, and the stopping energy of the films.

Electrical properties of nitrogen incorporated tetrahedral amorphous carbon films

Abstract The electrical properties of nitrogen incorporated tetrahedral amorphous carbon (ta-C:N) films studied by Hall measurements over the range of 15–300 K were reported. Results indicated that the electrical properties of ta-C:N films are related to nitrogen pressure, which was the only variable during film deposition. The electrical resistivity of the ta-C:N films decreases with nitrogen pressure, accompanied by an increase of nitrogen concentration in the films. The influence of thermal annealing on the electrical properties of ta-C:N films was also investigated. The variation of the electrical properties of ta-C:N films may arise from the development of graphite-like structures in these films due to the incorporated nitrogen and annealing effects.

DETERMINATION OF THE SP3/SP2 RATIO IN TETRAHEDRAL AMORPHOUS CARBON FILMS BY EFFECTIVE MEDIUM APPROXIMATION

In this article, a method for the determination of the sp3/sp2 ratio for highly tetrahedral amorphous carbon (ta-C) films is presented. This method is an optical characterization according to the Bruggeman effective medium approximation based on simulation of the infrared reflection spectrum. The simulation reflectivity is in good agreement with the experimental spectrum, and the obtained results of sp3 content are in good agreement with electron energy loss spectroscopy data, suggesting that this is an effective method for obtaining the sp3/sp2 ratio of ta-C films.

Enhanced electron field emission properties of diamond-like carbon films using a titanium intermediate layer

Substantially improved uniformity and enhanced electron field emission properties of hydrogen-free diamond-like carbon (DLC) films were obtained using a titanium intermediate layer after the annealing process. Large emission current densities of 2.08 mA cm-2 at 14.3 V µm-1 and 7.20 mA cm-2 at 25.7 V µm-1 were achieved for DLC/Ti/Si film annealed at 430 °C for 0.5 h. Its field emission was much more uniform than that of as-prepared DLC/Ti/Si and DLC/Si films. Secondary ion mass spectroscopy (SIMS) showed that C has been amply diffused into the Ti layer. An x-ray photoelectron spectroscopy (XPS) spectrum of the annealed DLC/Ti/Si film after 10 min of argon ion sputtering showed the formation of TiC at the interface between the DLC and Ti/Si substrate. This interaction and interdiffusion of C and Ti could significantly lower the Schottky barrier height between the DLC and Ti/Si substrate. The result was that electrons induced from the Ti/Si substrate can be easily penetrated into DLC films, which enhances the field emission properties.

Preparation of thin films by filtered arc deposition and ion assisted arc deposition

Abstract The present work focuses on Filtered Arc Deposition (FAD) and Ion Assisted Arc Deposition (IAAD) techniques. The properties of TiN, a-diamond and a-C:N films prepared by FAD and IAAD have been investigated in respect to surface morphologies, field emission behavior and optical properties.

Field emission from amorphous diamond films prepared by filtered arc deposition

Nonhydrogenated amorphous carbon films have been prepared by filtered arc deposition (FAD), which provides carbon ions with optimum kinetic energies at practical deposition rates. It was found that the carbon atoms were so highly tetrahedrally bonded that the films were referred to as amorphous diamond (α-D). The field emission behaviour of the α-D films has been studied for the first time. The field emission current more that 10 μA was detected at an electric field intensity of 18 V/μm. Such a low threshold field provides the designer of flat panel displays with an opportunity to develop a planar emitter, rather than the conventional Spindt-tip field emitter which requires lithographic and microstructural burdens.

Optical properties of CNx films prepared by filtered arc deposition

Abstract CN x films on silicon (111) wafer, quartz and Ti C substrates with nitrogen concentration up to 20 at% have been prepared by a new plasma deposition technique-filtered arc deposition. The nitrogen concentration and area density of the films were measured by Rutherford back-scattering. The optical properties of the films were characterized by ultravioletvisible and infrared reflection spectrometry. Results indicate that the optical band gap and area density of the CN x films decrease with increasing nitrogen pressure, accompanied with an increase of nitrogen concentration and reflectivity of the films. Furthermore, the influence of nitrogen pressure on the optical band gap of the films is discussed.