Berlin 2008 – wissenschaftliches Programm

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O: Fachverband Oberflächenphysik

O 89: Metal Substrates: Epitaxy and Growth

O 89.6: Vortrag

Freitag, 29. Februar 2008, 10:45–11:00, MA 041

What causes the high island densities in pulsed laser deposition? — Georg Rauchbauer, Florian Wimmer, Andreas Buchsbaum, Gerhard Betz, Peter Varga, and •Michael Schmid — Inst. f. Allg. Physik, TU Wien, Österreich

Pulsed laser deposition (PLD) is a method for growing thin films that combines nonthermal particle energies (typically 30 to 200 eV) with ultrahigh-vacuum compatibility. Compared to thermal deposition, PLD-grown films show a significantly higher island density and improved layer-by-layer growth. These features were attributed to either the high instantaneous particle flux or the high particle energies. Using scanning tunneling microscopy (STM), we have studied the nucleation and growth of Pt and Co on Pt(111) by PLD and we show that the high particle flux is not sufficient to explain the island densities observed. Experiments at low temperature, where adatom motion is frozen, and molecular dynamics simulations show that particle energies of ≈ 100 eV are sufficient to create small adatom clusters by “failed sputtering”. These clusters serve as nucleation centers and explain the differences between thermal deposition and PLD. We propose that the same mechanism is effective in sputter deposition.