Columnar Grain Structure in Cobalt Films Evaporated Obliquely at Low Substrate Temperatures

Abstract

We investigated the columnar grain structure in cobalt films evaporated obliquely at a low substrate temperature. The substrate temperature TS was varied from 113 to 313 K. The incidence angle was 60°, and the pressure during evaporation was 4.0 ×10-3 Pa. In the TS range of 230–270 K, the tops of the columnar grains exhibited the {0001} crystal habit and their bundling was formed, but at a TS below 220 K, the crystal habit disappeared and the bundling diminished. Furthermore, at a high pressure of 0.02 Pa obtained by closing the main valve halfway during evaporation, the bundling was also formed at a TS below 220 K, which indicates the exhibition of crystal habit. These results support our assertion that there exists a crystallographic contribution to the bundle formation through the crystal habit. The analysis of residual gas suggests that the disappearance and reappearance of the crystal habit at a TS below 220 K are due to contamination by H2O and N2 molecules, respectively.

Perspectives on oblique angle deposition of thin films: From fundamentals to devices

“…This bundling association has since been reported in a large variety of OAD thin films prepared by either evaporation or MS [143][144][145][223][224][225][226], and though development of this microstructural arrangement has been mainly reported for metal thin films [10,11,54,56,144,145,223,224], it has also been utilized as a template structure with oxides to develop new composite thin films (see for example [225] and [226]). Surprisingly, aside from some detailed discussions in early reviews [10], this bundling phenomenon has not attracted much attention in recent investigations on OAD thin films.…”

Solid-State Dewetting of Gold Aggregates/Islands on TiO2 Nanorod Structures Grown by Oblique Angle Deposition

“…This could be observed in the SEM images in Figure S1 (see the Supporting Information) that show the as-deposited TiO 2 nanorods grown in the form of clusters: a bunch of TiO 2 nanorods coalesce perpendicular to the rod tilt direction and form an elongated nanorod chain. This growth phenomenon was referred to as the bundling effect in related studies for the OAD growth of different dielectrics and metals. − An analysis of Figure S1 (see the Supporting Information) has shown that the average diameter of the TiO 2 nanorod is about 15 nm, and the nanorod cluster spans hundreds of nanometers in the direction perpendicular to the rod tilt direction. Along the tilt direction of the TiO 2 nanorods, the spacing between the nanorods, that is, nanorod clusters, increased as the deposition angle was increased from 80° (Figure a) to 89° (Figure g) owing to the increasingly strong shadowing effect.…”

Biaxially Textured Titanium Thin Films by Oblique Angle Deposition: Conditions and Growth Mechanisms

“…Tailoring the texture of nanostructured thin films has been in the focus of manifold research activities in the last decades, and some promising applications for such films can already be deduced . In addition to representing a powerful technique to create thin films composed of 3D separated nanowires, oblique angle deposition (OAD) bears the potential to tailor the texture of these films . The characteristic of OAD is that the substrate is tilted to a highly oblique incidence angle θ OAD with respect to the particle flux direction.…”