Abstract
Polycrystalline Si films were deposited on poly(ethyleneterephthalate) (PET-Mylar®) and glass (7059 Corning) substrates at 140 and 200 °C, respectively. X-ray diffraction and Raman spectroscopy were used to confirm the polycrystalline nature of the films. The largest grain size obtained was 95 nm. Raman spectroscopy also showed a simultaneous presence of an amorphous phase. The relative fraction of this amorphous phase was controllable by adjusting the composition of the sputtering gas. Films deposited with only Ar or Ar+H2 sputtering gas show a very small polycrystalline Si peak. With the addition of up to 10% Kr to the gas mixture, a very strong polycrystalline peak appears in the Raman spectra. X-ray diffraction also confirmed the polycrystalline nature of the films. The Kr effect was related to the energetic condensation. The presence of Kr increased the energy of the sputtered atoms. Even after collision with the sputtering gas, these atoms impinge on the substrate surface with enough residual energy that the ad-atoms experience enhanced diffusion, which leads to polycrystalline film formation. For our system, the final energy of the ad-atoms was calculated to be 1.92 eV, which is more than the activation energy for surface self-diffusion for Si.
Published Version
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