Regensburg 2004 – scientific programme

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DS: Dünne Schichten

DS 17: Schichtherstellung II

DS 17.1: Talk

Thursday, March 11, 2004, 15:15–15:30, HS 31

Investigations on the long-time stability of thin Pr_xO_y-films on Si(100) grown by Pulsed Laser Deposition — •Markus Ratzke, Dirk Wolfframm, Mathias Kappa, and Jürgen Reif — LS Experimentalphysik II, BTU Cottbus and JointLab IHP/BTU, Universitaetsplatz 3-4, 03044 Cottbus, Germany

We have studied the long-time stability of thin Pr_xO_y-films on Si(100), produced by Pulsed Laser Deposition from sintered Pr₆O₁₁ targets. In particular, the surface morphology and the chemical layer/interface composition were investigated.

For Pr_xO_y films grown at 650 ^∘C substrate temperature, we find clear evidence of a change in surface morphology with time after film preparation: while the surface immediately after deposition is characterized by large splashes (mainly Pr₂O₃) superimposed on a background of mixed oxides (Pr₂O₃, Pr₆O₁₁), after the surface becomes more homogeneous. No similar effect was observed for layers grown at 900 ^∘C substrate temperature.

An analysis of XPS spectra (Pr 3d, O 1s, Si 2p) showed that not only the line shape of the Pr 3d and O 1s core level spectra changed but also the Pr 3d/O 1s intensity ratio. This transition of chemical environment suggests the formation of Praseodymium Hydroxide. Since Pr₆O₁₁ is well known for its strong hygroscopic behaviour, Pr(OH)₃ will preferably be formed between the splashes (Pr₂O₃), accompanied by the appearance of PrO₂.