Flexible Morphology Control of Nanotube Arrays from Glancing Angle Deposition
Z.F. Huang, K.D. Harris, M.J. Brett
University of Alberta, CA
Keywords: silicon nanotubes, morphology control, glancing angle deposition
Abstract:Recently, silicon nanotubes (SiNTs) have attracted considerable attention. However, it has been challenging to grow SiNTs without any template. Another challenge is to engineer the shape of SiNTs, which to date has been limited mostly to use of columnar templates. This work introduces a template from glancing angle deposition (GLAD) to fabricate SiNTs in diverse shapes, such as columnar and helical. GLAD employs e-beam evaporation at glancing incidence to deposit porous films with different shapes. Then GLAD porous films are covered with a shell layer of material. After expose the template columns at their tops, an appropriate etchant is used to dissolve the internal GLAD columns and leave the tube arrays standing on the wafer. This approach has been demonstrated for the fabrication of columnar and helical SiNT arrays. The morphology and surface density are adjustable by those of GLAD-template porous films, and the wall thickness of NTs is engineered by the coating time. This work explores a new fabrication technique for NTs, which can be potentially utilized to create NTs of a wide variety of materials and morphologies. The NT arrays show promise for device applications requiring high surface area materials, such as hydrogen storage for fuel cells.