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Ultrathin amorphous SiO2 films are radio frequency sputter deposited onto thin film gold electrodes and incorporated as the insulating barrier in metal/insulator/metal tunnel junctions of the type Au/SiO2/Pb. Inelastic electron tunneling spectra (IETS) recorded at 4.2 K reveal characteristic zero bias anomalies associated with rapid variations in the Pb density of states on either side of the superconducting gap which shows unequivocally that tunneling is the primary conduction mechanism through the junctions at this temperature. Full IET spectra reported are essentially identical to those previously recorded for similar SiO2 films on aluminum. Atomic force and scanning tunneling microscope images of the SiO2 and underlying gold films are also presented; these data confirm that the SiO2 films are sufficiently uniform and continuous for IETS.

Amorphous SiO films are prepared by radio‐frequency planar magnetron sputtering in a background of argon. Inelastic electron tunneling spectra are presented of the films incorporated in Al/SiO/Pb tunnel junctions with the aluminium films pre‐ or post‐oxidized relative to the SiO deposition stage. Both the aluminium and lead junction electrodes are evaporated in a standard oil diffusion pumped, liquid nitrogen trapped vacuum system at a base pressure of 10−7 Torr; aluminium oxidation is achieved either by admitting oxygen into the vacuum chamber or by performing a low power dc oxygen glow discharge. Spectra obtained are similar, but not identical, to those obtained for evaporated SiO films. Different types of silicon hydride species are observed depending on the environment to which the SiO films are exposed after their deposition. Possible reactions of the films with water vapor are discussed which could produce the observed hydrides which are also assigned. Reverse bias tunneling spectra provide strong e...

Inelastic electron tunneling spectroscopy (IETS) is used to record the vibrational spectra of thin films of amorphous SiOx prepared by radio‐frequency planar magnetron sputter deposition in argon. The SiOx films are incorporated as the insulating barriers in aluminium SiOx/lead tunnel junctions, with no prior or subsequent oxidation of the aluminium films. Peak assignments are presented by comparison with infrared, Raman, and neutron scattering data for bulk silica, and a plausible stoichiometry is proposed. The SiOx barriers can be considered as model glass substrates for further adsorption studies, and hence extend the analytical capabilities of IETS.

We used the atomic force microscope to determine the distributions of 150–200 nm diameter styrene-butadiene (SB) latex spheres with TR. = 45 °C deposited at sub monolayer coverages from water suspensions onto mica, glass, calcite and cellophane surfaces. Two deposition methods are used: drying of μl drops and dipping. For drop drying, the distributions are extremely inhomogeneous. A high density ring forms at the boundary of the area wet by the drop. At low suspension densities on cellophane, the ring is a close-packed monolayer several micrometers wide. Thicker rings form on calcite and glass. Inside the rings, the particle density is very low and non uniform; e.g., monolayer thick islands form on mica, short chains are predominant on calcite, small clusters form on glass, and isolated spheres occur on cellophane. Particle densities are substantially reduced near some substrate defects but are enhanced near others. For the dipping method, homogeneous distributions are obtained on glass and cellophane. The density of adsorbed particles increases linearly with immersion time and the distribution of monomers, dimers, and trimers is not characteristic of random adsorption.

We have constructed an inexpensive sample mounting stage for studies of temperature dependent processes in a surface force microscope (SFM). The stage is constructed from a Peltier thermoelectric heater secured to a standard SFM mounting stage with silver paint. The sample temperature can be varied from room temperature to about 100°C thus making it possible to use the SFM to observe thermally activated processes at lateral spatial resolutions of 10-20 nm. Approximately 10 minutes is required to reach thermal equilibrium following a 5°C temperature change. The lateral magnification must be calibrated at each temperature. We illustrate the capabilities of the stage with images of polystyrene spheres just below their glass transition temperature of 100°C.