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Effects of Oxygen-doping on Crystallization and Physical Properties of Ge2Sb2Te5 Films
Published online by Cambridge University Press: 01 February 2011
Abstract
Oxygen-doped Ge2Sb2Te5 films (denoted as Ge2Sb2Te5-O) with oxygen concentration in between 0 and 10.3 at. % were prepared by direct current magnetron reactive sputtering with Ge2Sb2Te5 target. Both the crystallization temperature and activation energy of Ge2Sb2Te5-O films increased, while the crystalline grain size refined with oxygen concentration. For both amorphous and crystalline phases, optical band gap Egopt increases with oxygen concentration – a similar trend as observed in resistivity measurements. X-ray diffraction results showed that the face center cubic (fcc) structure maintained even after 400°C anneal with oxygen addition in between 7.5 − 8.3 at.% - a different phenomenon from undoped Ge2Sb2Te5 film, but with crystallinity diminished gradually with oxygen concentration. Only Sb2Te3 diffraction peak was observed in the 10.3 at.% O film after 400°C anneal. In conjunction with the bonding information obtained from X-ray photoelectron spectroscopy (XPS), effects of oxygen on the microstructures, thermal properties, resistivity and stability of fcc structure are examined and the embedded mechanisms are discussed in this study.
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- Copyright © Materials Research Society 2008
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