Local structure analysis of rewritable optical media during phase change
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In this solution, EXAFS method was applied to Ge2Sb2Te5 thin film (20 nm thickness), the material of rewritable optical media, to analyze local structural change during phase change. EXAFS spectra of the sample in crystalline and amorphous phase were measured at Ge, Sb and Te K-edge. The EXAFS method is a powerful technique to study local structure (distance, coordination number, species of neighbor atoms) of selected elements both in crystalline states and in non-crystalline states. Figure 1 shows radial structure function of Te atom after Fourier transform of EXAFS spectra. Simultaneous analysis of EXAFS data set at 3 edges revealed that the fast rewritable mechanism is due to the change in position of Ge atom in rigid building blocks.
Fig. 1 Radial structure function for Te atom in crystallized and amorphized samples.
Fig. 2 Fragments of the local structure of GST around Ge atoms in the crystalline (left)
and amorphous (right) states (red: Ga).
[ A. V. Kolobov, P. Fons, A. I. Frenkel, A. L. Ankudinov, J. Tominaga, T. Uruga, Nature Materials 3, 703-708 (2004), Fig. 1(c), 5,
©2004 Nature Publishing Group ]
Scientific keywords
| A. Sample category | inorganic material |
|---|---|
| B. Sample category (detail) | metal, alloy, semiconductor, solid-state crystal, amorphous, glass, inorganic thin film |
| C. Technique | absorption and its secondary process |
| D. Technique (detail) | XAFS, EXAFS, XANES |
| E. Particular condition | polarization (linear), room temperature |
| F. Photon energy | X-ray (4-40 keV) |
| G. Target information | chemical bonding, local structure, structural change, function and structure, function, phase transition |
Industrial keywords
| level 1---Application area | storage device |
|---|---|
| level 2---Target | CD-R、DVD |
| level 3---Target (detail) | |
| level 4---Obtainable information | structure of non-crystalline material, interatomic distance, crystal structure, local structure, electronic state |
| level 5---Technique | XAFS |
Inquiry number
SOL-0000001053