Optical and structural characterization of Ge clusters embedded in ZrO2

• DOI: 10.1016/j.apsusc.2017.03.153
• Publication Date: 2017-03-20T14:30:19Z
• Authors: E. Agocs; Z. Zolnai; A.K. Rossall; J.A. van den Berg; B. Fodor; D. Lehninger; L. Khomenkova; S. Ponomaryov; O. Gudymenko; V. Yukhymchuk; B. Kalas; J. Heitmann; P. Petrik
• Keywords: QC Physics / fizika; 0103 physical sciences; 01 natural sciences; QC

The change of optical and structural properties of Ge nanoclusters in ZrO2 matrix have been investigated by spectroscopic ellipsometry versus annealing temperatures. Radio-frequency top-down magnetron sputtering approach was used to produce the samples of different types, i.e. single-layers of pure Ge, pure ZrO2 and Ge-rich-ZrO2 as well as multi-layers stacked of 40 periods of 5-nm-Ge-rich-ZrO2 layers alternated by 5-nm-ZrO2 ones. Germanium nanoclusters in ZrO2 host were formed by rapid-thermal annealing at 600-800 ∘C during 30 s in nitrogen atmosphere. Reference optical properties for pure ZrO2 and pure Ge have been extracted using single-layer samples. As-deposited multi-layer structures can be perfectly modeled using the effective medium theory. However, annealed multi-layers demonstrated a significant diffusion of elements that was confirmed by medium energy ion scattering measurements. This fact prevents fitting of such annealed structure either by homogeneous or by periodic multi-layer models