Abstract
Glancing angle deposition (GLAD), in which the deposition angle is highly inclined to the substrate normal during vapor deposition, enables fabrication of thin films comprised of structured nano-elements. In general, when a thin film is released from a substrate, the film spontaneously bends or rolls-up to form an external structure such as tube due to the presence of residual stress. It is however challenging to realize desired three-dimensional external structures by controlling the bending of films. The bending deformation depends on internal 'shape' of films as well as the mechanical properties of materials. In this study, we tried to control the external structure of thin films by controlling the shape of constituent nano-elements by GLAD. We fabricated Ti thin films comprising of oblique nanocolumns, in which the porosity in the column-tilt direction is larger than that of the transverse direction, on a sacrificial resin layer coated on a Si substrate by GLAD with the deposition angle of 60 degrees. When the film was released from the substrate, bending deformation occurred around the transverse direction to form tube structure regardless of the sample shape, suggesting that we can control the direction of bending by using the anisotropic shape of nano-elements.
