Abstract
Structural changes in amorphous and crystallized GST-225 films induced by the reaction with oxygen are studied at different depth scales. The mechanism of interaction of the very top surface layers with oxygen is studied with low-energy ion scattering (LEIS) technique, while the modifications of chemistry in the underlying surface layers are investigated with high-resolution X-ray photoelectron spectroscopy (XPS). The changes averaged through the overall film thickness are characterized by micro-Raman spectroscopy. The oxygen exposure leads to a depletion of GST-225 film surfaces in Te and formation of the antimony and germanium oxides. The antimony oxide complexes are found throughout the whole thickness of the films after their prolonged storage in air, whereas no evidence for formation of pure GeO 2 phase is found in the volume of the films through Raman spectroscopy. A tendency to form Ge-rich phase within the ∼10 nm surface layer is additionally observed by LEIS profiling during crystallization of GST-225 film at 300 °C in oxygen atmosphere.
Original language | English |
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Pages (from-to) | 533-541 |
Number of pages | 9 |
Journal | Applied Surface Science |
Volume | 332 |
DOIs | |
State | Published - Mar 30 2015 |
Externally published | Yes |
Funding
The authors thank U.S. National Science Foundation , through International Materials Institute for New Functionality in Glass (grant no. DMR-0844014 ), for initiating the international collaboration and providing partial financial support for this work. A.K. acknowledges financial support from NSF grant DMR-1409160 . S.K. would like to thank the Russian Foundation for Basic Research (grant no. 14-03-00314 ) and the scientific program #24 of the Presidium of the Russian Academy of Sciences “Basic Foundation of the Technology of Nanostructures and Nanomaterials” for financial support of this study. Y.G.C. was financially supported by Basic Science Research Program of the National Research Foundation of Korea ( 2012R1A1A2003832 ).
Keywords
- Chalcogenide glass
- LEIS
- Phase-change memory
- Raman
- XPS