AVS 53rd International Symposium
    Advanced Surface Engineering Wednesday Sessions
       Session SE-WeM

Paper SE-WeM9
Onset of Nanocolumn Formation in Extreme Self-Shadowing Conditions

Wednesday, November 15, 2006, 10:40 am, Room 2007

Session: Glancing Angle Deposition
Presenter: K. Kaminska, National Research Council, Canada
Authors: A. Amassian, Cornell University
K. Kaminska, National Research Council, Canada
M. Suzuki, Kyoto University, Japan
L. Martinu, Ecole Polytechnique de Montreal, Canada
K. Robbie, Queens University, Canada
Correspondent: Click to Email
We have investigated the early stages of growth of glancing angle deposited (GLAD) amorphous silicon (a-Si) films onto room-temperature c-Si (001) substrates. Using a combination of in situ spectroscopic ellipsometry and ex situ atomic force microscopy (AFM), we have found that following nucleation, the normal incidence (0@sup o@ from substrate normal) deposit coalesces into a continuous and smooth film in the thickness (t) range between 1 < t < 5 nm, whereas the GLAD deposit (87@sup o@ from substrate normal) does not coalesce, instead becoming increasingly porous for t > 1 nm. Atomic force microscope scans of GLAD deposits detected a significant roughening behaviour in this thickness range, and revealed large disc-like island formations with spacing in the range of ~45±10 nm. The difference in sub-nanometer growth behaviours of normal incidence and GLAD deposits are attributable to the presence of extreme atomic self-shadowing in the latter case, which significantly alters the nucleation and growth patterns of the first monolayers of a-Si with respect to normal incidence depositions. The disc-like formations form the seeds to nanocolumns observed during subsequent growth, a conclusion which is also supported by 3D Monte-Carlo simulations.