B.E. Storey

Carbon films produced by fast atom bombardment

Abstract A fast atom bombardment (FAB) source has been used to produce thin carbon films using butane (calor gas) and butane-argon mixtures. The films were produced on CR39 polycarbonate, glass, aluminium foil and single-crystal sodium chloride substrates. The films were studied by X-ray photoelectron spectroscopy, Auger electron spectroscopy, transmission electron microscopy and transmission electron diffraction. The carbon films were largely amorphous with small crystallites scattered across the film surface. The majority of these crystallites have been identified as either the alphacarbine or the Ries crater forms of carbon. Some of the crystallites were found to decompose in the electron beam during transmission electron microscope studies. It is suggested that hydrogen, argon, or a hydrocarbon gas is trapped between the layers during the growth of these hexagonal layer structured forms of carbon. Prolonged electron irradiation is likely to lead to the evolution of this intercalated material. Auger spectra are presented that suggest that argon ion bombardment also produces evolution of intercalated material and hence significantly modifies the surface of the films.

The characterization of ultra-hard carbon films produced from pre-processed carbon powder in a hybrid physical vapor deposition system

Abstract The characteristics of carbon films deposited from a new carbon evaporation source material have been investigated. The source material is produced in the plasma chamber of a saddle field ion source and redeposited utilizing a hybrid deposition system under development. Extensive characterization of the structural, microstructural, optical, and mechanical properties of the carbon films are reported. Raman spectroscopy and optical evaluation of the films indicated that the carbon bonding was mainly graphitic with some sp 3 bonding present. Hydrocarbon bonding is also detected. Microbeam and surface analysis studies also confirm these conclusions. The mechanical properties of the films were not consistent with a high density of sp 3 bonding.

Application of computer programs to matrix corrections in the surface analysis of amorphous films

Abstract The computer programs AQUA and QUAX have been developed to enable the rapid quantification of surface analysis by AES and XPS. The compilation of library files of basic elemental data to enable the computer programs to perform matrix calculations automatically is discussed. The benefits of this system of programs in investigating the effects of using different methods of calculation of parameters such as attenuation length (AL) or backscattering factor on the calculated matrix factor and the final composition are demonstrated. Carrying through this range of calculations with the AQUA and QUAX computer surface analysis systems is shown to speed up the process of quantitative surface analysis by AES and XPS. In this investigation matrix factors and surface compositions have been calculated for a number of materials including films of amorphous silicon carbide and amorphous silicon nitride with a range of compositions. For the amorphous silicon carbide system, AES and XPS quantification with a range of methods for AL correction gave good agreement provided an SiC standard was used.

Characterisation of carbon films containing boron and nitrogen

Abstract Carbon films containing small quantities of boron and nitrogen have been prepared using a dual ion beam system. The films have been characterised using surface analytical techniques and by transmission electron microscopy and diffraction. Small crystallites of alpha-carbine or Ries-crater carbon have been identified in these mainly amorphous films. The substrates used were glass, stainless steel, silicon, germanium and single crystal sodium chloride. The incorporation of boron and nitrogen produced films adherent to all of the substrate materials. These films were resistant to temperature variation, acid and chemical attack. Optical properties of the films have been evaluated. The liquid impact damage thresholds for the films deposited on germanium have been determined and suggest an improvement on the damage threshold for bulk germanium. The results of Raman spectroscopy support the microbeam analysis findings.

Extensions to computer programs for quantitative surface analysis

Abstract Recent modifications to an integrated set of computer programs for the quantitative interpretation of x-ray photoelectron and Auger electron spectra are described. A number of simple examples are used to demonstrate the ability of the software to perform calculations by a variety of routes as determined by a series of menus. The facility within the system to display graphically the calculated variation in matrix factors with specimen composition is shown to be a useful aid to quantitative analysis.

Electron spectroscopy amd electron microscopy of a-C:H films

Abstract Some of the techniques used in electron Spectroscopy and electron microscopy may be combined to give a full characterization of new materials. This requires a correlation of results from structural, microstructural and analytical techniques. Hydrogenated amorphous carbon (a-C:H), diamond and diamond-like carbon films were examined using XPS, XAES, TEM and SEM.