| AVS 57th International Symposium & Exhibition | |
| Advanced Surface Engineering | Wednesday Sessions |
| Session SE+TF-WeA |
| Session: | Glancing Angle Deposition (GLAD) II |
| Presenter: | M. Suzuki, Kyoto University, Japan |
| Authors: | M. Suzuki, Kyoto University, Japan H. Moriwaka, Kyoto University, Japan K. Nakajima, Kyoto University, Japan K. Kimura, Kyoto University, Japan |
| Correspondent: | Click to Email |
It is well known that obliquely deposited thin films show various shape related properties due to not only their complex columnar shapes but also their unique surface morphology. For example we have succeeded to prepare in-line aligned noble metal nanorod arrays on a template layer with anisotropic surface roughness originating from the bundled columns created by serial-bideposition technique (SBD)1. Our nanorod arrays show the excellent surface enhanced Raman scattering properties. However, it is difficult to avoid the irregularities in size and shapes of the columns in the obliquely deposited thin films. On the other hand, recently, much attention has been paid on the pattern formation by ion beam erosion (IBE) at oblique incidence. When the flat surface is irradiated with the ion beam, quasi-periodic ripple patterns are self-organized. These ripple patterns seem to be more regular than the morphology found in the obliquely deposited thin films. However, the ripples in IBE surface are too gentle to use their functionaries or to use them as a template for the shadowing growth. In this work, we tried to reduce the irregularities of columnar shapes of obliquely deposited thin films by IBE.
Layers of Ge with an anisotropic surface morphology were prepared by SBD technique on a Si substrate. During the SBD, the deposition angle for Ge measured from the surface normal was fixed at an angle of 82°, while the azimuthal angle was changed rapidly by 180° with each deposition of an approximately 10 nm thick layer. After 15 cycles of SBD, Ge layers with an thickness of 300 nm were obtained. The surface of the Ge layer was irradiated with Xe+ ions of 5 keV up to the fluence of 0.5, 1.5, 3.0×1016 ions /cm2 at an angle of incidence of 45° or 70° The planes of incidence of Ge vapor and Xe+ ions are perpendicular to each other.
The average aspect ratio of the surface corrugation is 1.4 for the non-irradiated Ge films and significantly increases with increase of fluence. At the fluence of 3.0×1016 ions /cm2, the aspect ratio reaches 7 mainly due to the elongation of the surface corrugation along the incident direction of the ion beam. The width of the surface corrugation is wider for 45° incidence than 70° incidence. Remarkably, distinct periodicity is found in the autocorrelation images of the SEM of the surface. These results are understood in terms of the directive sputtering toward the forward direction of the ion beam and the redeposition of the sputtered atoms, and are characteristic for the ion beam erosion of the porous materials.
1. M. Suzuki, et al., Appl. Phys. Lett., 88, 203121 (2006).