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The reaction of sputter deposited layers of Ti on the (001) surface of a synthetically grown single crystal type IIb boron doped diamond has been investigated using Auger electron spectroscopy with depth profiling, Rutherford backscattering spectroscopy (RBS) and Raman spectroscopy. Electrical characteristics of the contacts were measured using I–V data and separated from substrate electrical effects using Hall measurements of the carrier concentration and mobility. Heat treatments above 425 °C were found necessary to cause the transition from a rectifying to an ohmic contact. Without a protective 150 nm layer of Au, oxidation of the Ti layer was observed at T≥425 °C, even for annealing in forming gas. This was detrimental to the adhesion of the layer and the long term stability of the ohmic contact resistance. With a protective Au film, low resistance, adherent ohmic contacts were observed even after 1 h at 750 °C, even though Ti diffused along Au grain boundaries to form nodules of TiO2 at the Au/ambient interface. Interfacial carbides were detected by both Auger peak shape changes and RBS measurements for annealing temperatures as low as 500 °C, and their appearance correlated with the transition to ohmic contacts. The carbides increased in thickness to about 50 nm after 1 h at 750 °C.

The oxidation kinetics of a grade 300 maraging steel in air at temperatures ranging from 300 to 600°C have been determined using Auger electron spectroscopy in conjunction with argon ion sputtering. A limited-thickness type of growth was observed up to the relatively high temperature of 480 OC. Above 480 "C, the kinetics were parabolic.A thin gold layer sputtered onto the surface before oxidation resulted in a change in the kinetics from limitedthickness to approximately parabolic growth at temperatures below 480"C, while it remained parabolic above 480 "C.The limited-thickness oxide growth is described in terms of space-charge effects, as outlined by the theory of Fromhold. Tbe insulating properties of a thin mixed spinel oxide present at the metaloxide interface is critical in bringing about the space charge in tbe oxide. A change in the electrical conductivity of the mixed spinel is associated with a change in the oxidation kinetics

Measurement of the nonequilibrium surface concentration in a Fe–10 at. % Si (110) sample as an function of temperature reveals specific interrelated segregation behavior. A review of the initial processes in this single crystal shows the existence of certain interactions. In agreement with work on the other ternary systems, evidence has been found that carbon and silicon show a repulsive interaction in the segregation process. At lower temperatures the surface free energy favors the carbon and above a transition temperature, the silicon on the surface. On the other hand, silicon and phosphorus cosegregate, which is indicative of an attractive interaction. This has the effect that much less phosphorus is available for segregation to the surface or grain boundaries than in a pure Fe–P system. The LEED pattern for the silicon covered surface is the same as for a 1% Si sample viz. a c(7×1) superstructure with reference to the c(a×(2a)1/2) surface net, where a is the unit cell parameter in the [001] direction. Elongation of the spot in one direction indicates a change of order in the [001] direction in agreement with the silicon island formation. The pattern of the phosphorus covered surface shows a maximum surface coverage by phosphorus in good agreement with the observed value as determined by AES.

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