Physical vapor deposition under conditions of obliquely incident flux and limited adatom diffusion results in a film with a columnar microstructure. These columns will be oriented toward the vapor source and substrate rotation can be used to sculpt the columns into various morphologies. This is the basis for glancing angle deposition (GLAD), a technique for fabricating porous thin films with engineered structures. The origin of the columnar structure characteristic of GLAD films is discussed in terms of nucleation processes and structure zone models. As deposition continues, the columnar structures are influenced by atomic-scale ballistic shadowing and surface diffusion. Competitive growth is observed where the tallest columns grow at the expense of smaller features. The column shape evolves during growth, and power-law scaling behavior is observed as shown in both experimental results and theoretical simulations. Due to the porous nature of the films and the increased surface area, a variety of chemical applications and sensor device architectures are possible. Because the GLAD process provides precise nanoscale control over the film structure, characteristics such as the mechanical, magnetic, and optical properties of the deposited film may be engineered for various applications. Depositing onto prepatterned substrates forces the columns to adopt a planar ordering, an important requirement for photonic crystal applications.

Glancing angle deposition: Fabrication, properties, and applications of micro- and nanostructured thin films

Magnetic anisotropy has been observed in evaporated Permalloy films deposited at oblique incidence of the vapor. Electron micrographs of such films reveal chains of crystallites whose long axes are oriented perpendicular to the vapor beam. A ``self‐shadowing'' model is proposed to explain chain growth, i.e., the area behind a crystallite is left vacant because it is in the crystallite's shadow. Oriented crystallite chains are thus caused by a purely geometric process; their existence has also been demonstrated for Au, Pt, W, and Mg. Oriented chains give rise to a number of macroscopic effects: magnetic anisotropy, anisotropic resistance, dichroism, and anisotropic resonance linewidth. Experiments involving the stripping of oblique‐incidence Permalloy films from their substrates indicate the presence of an anisotropic strain which, in conjunction with magnetostriction, gives another contribution to the magnetic anisotropy; this contribution explains the observed compositional dependence of the magnetic ani...

Oblique‐Incidence Anisotropy in Evaporated Permalloy Films

https://ris.utwente.nl/ws/files/6644857/Abelmann97oblique.pdf

Oblique evaporation and surface diffusion

The birefringent property of obliquely deposited metal oxides was studied with a view to applying it to optical retardation plates. By finding favorable conditions to form transparent films of large retardation and low opacity, we developed homogeneous quarterwave plates with a bilayered structure 60 x 250 mm in size and ~3 microm thick on glass substrates. These retardation plates can work with a normally incident light based on form birefringence caused by the characteristic anisotropic microstructure inside the film. They showed promising optical properties which can compete with the conventional types of retardation plate.

Thin film retardation plate by oblique deposition

Glancing angle deposition (GLAD) is a physical vapour deposition method used to fabricate highly functional thin films with an engineerable columnar morphology. Recent developments in GLAD technology have produced columnar nanostructures of increased complexity, including periodic, nanofibrous, perforated, and graded porosity thin films for use in applications ranging from sensors and actuators to optical filters, microfluidics, and catalysis. A brief review of GLAD methodology and historical developments is followed by a discussion of the latest developments in this field.

Nanostructure engineering in porous columnar thin films: recent advances

Evaporated films of Permalloy are found to be uniaxially anisotropic under all the conditions of preparation studied so far, including deposition in dc, zero, and rotating‐circular magnetic fields. Three principal effects have been identified as contributing to this anisotropy, namely; (1) the formation of directed Fe pairs in the Ni matrix, (2) an effect due to the angle‐of‐incidence between the substrate and the depositing beam, and (3) anisotropic stress in combination with the isotropic magnetostriction. The evidence for directed pairs comes from the compositional dependence of the anisotropy; the angle‐of‐incidence effect is demonstrated by depositing onto tilted substrates; anisotropic stress effects are shown by detaching the film from the substrate. The simultaneous presence and interaction of the above effects is thought to be the reason for the variability in the anisotropy which is encountered in Permalloy films.

Donald O. Smith

Papers

Anisotropy in Permalloy Films