Energy Secondary Ion Mass Spectrometry Research Articles

Surface and interface study of molybdenum evaporated on NiO(100) surfaces

A great many characterizations have been carried out on NiMo catalysts by means of various techniques. However, little is known about their real surface structure. Molybdenum deposition was performed under uhv on cleaved NiO(100) surfaces. The growth mode was determined by Auger electron spectroscopy, reflection high energy electron diffraction and secondary ion mass spectrometry. The overgrowth of a poorly crystallized MoO 2 film is evidenced for deposition at room temperature. Upon thermal treatments the nucleation and growth of nickel islands occur within an amorphous MoO x layer with x > 2. Despite the relative simplicity of this non-supported catalyst, one can consider that the superficial phases obtained in this study may be found at the surface of real NiMo catalysts.

Influence of substrate- and atmospheric-temperatures on diamond deposition

Diamond thin films have been formed on molybdenum substrates with a mixture of methane and hydrogen gas using the electron-assisted chemical vapor deposition (EACVD) method. The surface morphology, crystal structure and composition of the films obtained were characterized by scanning electron microscopy, reflection high energy electron diffraction and secondary ion mass spectrometry. The experimental results revealed that substrate heating is necessary to eliminate the hydrogen atoms occluded into the film during the course of diamond deposition. The hydrogen is frozen in the film without the substrate heating. This may prohibit the rearrangement of the carbon atoms in the film and will produce an amorphous film.

Growth of Sr1−xBaxF2 films on InAs by molecular beam epitaxy

Heteroepitaxial films of Sr1−x BaxF2 have been deposited onto (001), (110), and (111)B oriented InAs substrates by molecular beam epitaxy. The epitaxial growth was studied by reflection high energy electron diffraction (RHEED), electron microscopy, x-ray diffraction, and secondary ion mass spectrometry (SIMS). The films grown epitaxially on the (001) and (110) substrates exhibit {111} faceting, and smooth and featureless growth occurs only on the (111)B oriented substrates. Single crystalline Sr1−x BaxF2 films lattice-matched to the InAs substrates are grown at temperatures higher than 200, 450, and 400 °C on the (001), (110), and (111)B faces, respectively. SIMS profiles indicate that the interdiffusion between epitaxial film and substrate is rather small even at a growth temperature of 520 °C. The change in RHEED patterns during the thermal cleaning of substrate surfaces is also described.

The condensation of lead on a gold {100} surface

The initial stages of the condensation of lead on a gold {100} surface were studied by Auger electron spectroscopy, low energy electron diffraction and secondary ion mass spectrometry and a quartz oscillator was used for the absolute determination of lead exposure. The structural transitions in the submonolayer range and the subsequent intermetallic compound formation are analysed in detail. It is shown that the intermetallic compound Au 2Pb is formed.

Study of contamination on copper surface with abrasive materials by low energy secondary ion mass spectrometry.

A low energy secondary ion mass spectrometer was constructed. An argon ion gun was designed by the authors and a modefied quadrupole type mass analyser was used as a detector. The best operating condition was established as follows: ion accelerating voltage; 500V, argon pressure;5×16mm. Surface contamination on copper surface with abrasive materials were investigated for chemical etching with hydrochloric acid Al2O3powder emulsion polishing, Al2O3abrasing paper polishing and SiC abrasing paper polishing. The latter two methods gave very strong peak of27Al. The best result for positive ions was obtained with samples treated by chemical etching with hydrochloric acid.