Surface diffusion is shown to be the important factor in sputter–induced ripple and cone development on GaAs and InP surfaces for conditions typical of depth profiling when using surface analysis techniques. Ripple formation has been observed on both GaAs and InP when sputtered using Cs+ and O+2 ion beams. For GaAs, the ripple ‘‘wavelength’’ increases with sample temperature in the range from 45 to 100 °C, in qualitative agreement with the surface diffusion model of Bradley and Harper. No ripple formation is observed when the GaAs sample is cooled to −30 °C where surface diffusion is limited, or heated above 100 °C, where a proposed surface phase change may alter the diffusion rate. Ripple development also occurs on InP, but it is impossible to observe at 100 °C due to extensive cone formation. At this elevated temperature, Ar+ sputtering of InP leads to a surface enrichment of indium that is accompanied by a change in the In M4,5N4,5N4,5 Auger line shape toward that for indium metal. This result, together with the observation that cone formation is eliminated for sputtering at −20 °C, supports the intrinsic model where sputtering causes indium enrichment and surface diffusion that results in the agglomeration of indium metal into clusters. These clusters produce cone formation, possibly through the difference in sputter rates of indium and InP.

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Characterization of atomic-layer-deposited silicon nitride / SiO 2 stacked gate dielectrics for highly reliable pmetal-oxide-semiconductor field-effect transistors The metal-insulator interface of hydrogen-sensitive metal-insulator-semiconductor capacitors, with SiO 2 as the insulator and Pt as the metal contact, has been studied. The thin Pt films were prepared in ultrahigh vacuum by electron beam evaporation and dc magnetron sputtering. Deposition parameters were substrate temperature and sputtering pressure. The hydrogen responses of the differently prepared devices were measured in a semi-inert ambient ͑and used as a measure of the concentration of available adsorption sites for hydrogen at the interface͒. A large variation of responses was found for differently prepared sensors, and the magnitude of the response was found to increase for decreasing bonding strength between the Pt film and the SiO 2 substrate, as determined by scratch adhesion measurements. The bonding strength was controlled via the energetics of the Pt deposition flux. The largest interfacial roughness, from cavities between noncoalesced metal grains, and the poorest adhesion, was obtained by a reduced surface diffusion during growth and incomplete coalescence of the metal grains on the oxide surface as studied by transmission electron microscopy and atomic force microscopy. From x-ray photoelectron spectroscopy studies it was concluded that no chemical bonds were formed between Pt and SiO 2 . It is inferred that the hydrogen active in the sensor response is adsorbed on the oxide side of the interface in a spillover process. The difference in hydrogen response between differently prepared devices can be explained by a difference in concentration of available adsorption sites giving rise to a detectable dipole moment, on the oxide due to a blocking by Pt atoms in contact with the oxide. Thus, the concentration of Pt atoms in contact with the oxide affects both the hydrogen response and the metal-oxide adhesion.

This article reports on the growth and analysis of CrBN nanocrystalline materials using an ion beam assisted deposition process. In addition, this article addresses the utilization of spectroscopic ellipsometry for in situ analysis of ternary nitrides. Coatings, with a total thickness of 1.5 Ϯ0.2 m, were deposited at low temperatures (Ͻ200°C) on silicon substrates using ion beam assisted deposition. These coatings were characterized postdeposition using x-ray diffraction ͑XRD͒, atomic force microscopy ͑AFM͒, x-ray photoelectron spectroscopy ͑XPS͒, Auger electron spectroscopy ͑AES͒, visible-light spectroscopic ellipsometry ͑VIS-SE͒, infrared spectroscopic ellipsometry ͑IR-SE͒, and nanoindentation. The primary phases in the films were investigated using XRD. The surface morphology and nanocrystalline nature of the coatings ͑grain size of 5-7 nm͒ were deduced using AFM. The elemental composition and phase composition of the samples were determined from XPS and AES measurements and were subsequently deduced from the analysis of the VIS-SE data, and these correlated well. XPS, AES, and IR-SE revealed the crystal structure of the BN phase in the ternary compounds. The correlation of the results from these various techniques indicates that in situ SE may be a potential technique to control the growth of ternary nitride coatings in the future. The mechanical properties of the coatings were evaluated using nanohardness testing. The hardness and elastic modulus were measured to be 19-22 GPa and 250-270 GPa, respectively.