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Boron suboxide BO[sub x] thin films have been deposited on Si (100) by reactive rf magnetron sputtering of B powders in an Ar/O[sub 2] atmosphere. Elastic recoil detection analysis and x-ray diffraction were used to study the influence of the O incorporation on the film composition and structure and relate them to mechanical properties, which were evaluated by nanoindentation. As x in BOx was increased from 0.08 to 0.18, the elastic modulus of the x-ray amorphous films decreased from 273 to 231 GPa, by 15%. This can be understood using classical molecular dynamics (MD) with a Buckingham-like interaction potential: The increase in the O concentration and corresponding formation of B-O bonds, shown to be longer than the B-B bonds, resulted in larger ionic contributions as well as a density reduction. This increased ionicity was responsible for the observed decrease in elastic modulus. As even more O was incorporated (x > 0.18), the H concentration increased, exceeding 0.3 at. %. This may cause the formation of boric acid (H[sub 3]BO[sub 3]) as a result of the chemical reaction with H[sub 2]O upon atmosphere exposure. The presence of van der Waals and hydrogen bonding, associated with H[sub 3]BO[sub 3] formation, provides a reasonable explanation for the extensive decrease in elastic modulus from 231 to 15 GPa, by 94%. The parameterization for the Buckingham-like interaction potential, introduced in this study, can be used for MD simulations of amorphous BOx systems without H[sub 3]BO[sub 3]. [ABSTRACT FROM AUTHOR]

The influence of ion energy on the hydrogen incorporation has been investigated for alumina thin films, deposited by reactive magnetron sputtering in an Ar/O2/H2O environment. Ar+ with an average kinetic energy of ∼5 eV was determined to be the dominating species in the plasma. The films were analyzed with x-ray diffraction, x-ray photoelectron spectroscopy, and elastic recoil detection analysis, demonstrating evidence for amorphous films with stoichiometric O/Al ratio. As the substrate bias potential was increased from -15 V (floating potential) to -100 V, the hydrogen content decreased by ∼70%, from 9.1 to 2.8 at. %. Based on ab initio calculations, these results may be understood by thermodynamic principles, where a supply of energy enables surface diffusion, H2 formation, and desorption [Rosén et al., J. Phys.: Condens. Matter 17, L137 (2005)]. These findings are of importance for the understanding of the correlation between ion energy and film composition and also show a pathway to reduce impurity incorporation during film growth in a high vacuum ambient. [ABSTRACT FROM AUTHOR]

In this paper, junctions with reduced Hf coupling were fabricated by ion beam deposition and oxidation, using CoFeB electrodes. The CoFeB layer has a strong (111) texture that can be the origin of lower Hf and coercivity when compared, with CoFe. Junctions processed down to 2 × 4 μm² with 40-Å-thick CoFeB bottom electrodes have 42% of tunneling magnetoresistance (TMR), (R × A ∼ 400 Ω·μm²), Hc of ∼10 Oe and Hf of ∼2 Oe. CoFe-based junctions (R × A ∼ 500 Ω·μm²) have lower TMR (∼35%) and larger Hf (∼5-6 Oe) and Hc (∼12-14 Oe). Local chemical. composition analysis of the cross section indicated Fe-O segregation with very little Co grown on top of the barrier for CoFe-based junctions and not for CoFeB ones. [ABSTRACT FROM AUTHOR]

Ab initio calculations are used to design a crystalline boron-oxygen-yttrium (BOY) phase. The essential constituent is yttrium substituting for oxygen in the boron suboxide structure (BO[SUB0.17]) with Y/B and O/B ratios of 0.07. The calculations predict that the BOY phase is 0.36 eV/atom more stable than crystalline BO[SUB0.17] and experiments confirm the formation of crystalline thin films. The BOY phase was synthesized with reactive rf magnetron sputtering and identified with x-ray and selected area electron diffraction. Films with Y/B ratios ranging from 0.10 to 0.32, as determined via elastic recoil detection analysis, were grown over a wide range of temperatures (300- 600[SUP°]C) and found to withstand 1000[SUP°]C. [ABSTRACT FROM AUTHOR]