The special structure of obliquely evaporated films has its origin in shadowing phenomena during film growth. Because of shadowing, the film consists of bundles of inclined columns with the bundles being aligned perpendicularly to the vapour incidence direction. The column inclination angle lies between the film normal and the vapour incidence direction. Different models found in literature relating process parameters and film structure are discussed. It is found that surface diffusion plays an important role, especially with regard to the difference between random and directional surface diffusion. The latter is induced by the oblique evaporation process. A quantitative expression is given for the relation between process conditions and surface diffusion including the influence of substrate temperature, rate and contamination with residual gasses. Using these models and adding our new calculations, the relation between surface diffusion and film structure is discussed in detail and found to be consistent with measurements published in the literature. © 1997 Elsevier Science S.A.

Magnetic tunnel junctions have become ubiquitous components appearing in magnetic random-access memory, read heads of magnetic disk drives and semiconductor-based spin devices. Inserting a tunnel barrier has been key to achieving spin injection from ferromagnetic (FM) metals into GaAs, but spin injection into Si has remained elusive. We show that Schottky barrier formation leads to a huge conductivity mismatch of the FM tunnel contact and Si, which cannot be solved by the well-known method of adjusting the tunnel barrier thickness. We present a radically different approach for spin-tunnelling resistance control using low-work-function ferromagnets, inserted at the FM/tunnel barrier interface. We demonstrate that in this way the resistance-area (RA) product of FM/Al2O3/Si contacts can be tuned over eight orders of magnitude, while simultaneously maintaining a reasonable tunnel spin polarization. This raises prospects for Si-based spintronics and presents a new category of ferromagnetic materials for spin-tunnel contacts in low-RA-product applications.

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In this paper features are discussed that are related to the nucleation and growth of thin films deposited by physical vapour deposition. Although the paper is mainly focused on oblique-incidence deposition, a normally-impinging vapour flux will also be described. Two cases of oblique-incidence deposition will be discussed: one obliquely-impinging flux and two obliquely-impinging fluxes from opposite directions. With respect to the microstructure, both similarities and differences between these depositions will be deser~ed. Further, a special feature of two obliquely-impinging vapour fluxes is dealt with, which is the local composition in the lateral direction (parallel to the substrate). The oblique and opposing directions can induce an inhomogeneous chemical composition. This process is referred to as process-induced compositional separation. In addition to reviewing the literature, the paper summarizes experimental data on obliquely co-evaporated Co-Cr, Co-Ag and Co-Ta films. It will be shown from these experimental data that the two vapour directions can be exploited to tailor compositional inhomogeneities.

A set of reference samples for comparing the results obtained with different Magnetic Force Microscopes (MFM) has been prepared. These samples consist of CoNi/Pt magneto-optic multilayers with different thickness. The magnetic properties of the multilayer are tailored in such a way that a very fine stripe domain structure occurs in remanence. On top of this intrinsic domain structure, bits were written thermomagnetically using different laser powers. These samples have been imaged in six different laboratories employing both home-built and commercial magnetic force microscopes. The resolution obtained with these different microscopes, tips and measurement methods varies between 30 and 100 nm.