The phase transitions of Ge2 Sb2 Te5 (GST) films after bombardment with 40 keV N2+ ions were investigated. Comparing the nitrogen incorporated GST films with a pure GST film, the suppression of a crystalline grain growth was more effective in the N2+ implanted GST film than in a nitrogen codeposited GST film, i.e., x-ray diffraction data showed that the intensities of the crystalline diffraction peaks were decreased and the full widths at half maximum were broader than that of a pure GST film. This suppression of crystallization owing to the incorporation of nitrogen drastically reduced the roughness of surface morphology and decreased the electrical conductivity of the crystalline film. A near edge x-ray absorption fine structure experiment and x-ray photoemission spectroscopy data demonstrated that the suppression of crystalline grain growth is due to the formation of Ge3 N4 and interstitial N2 molecules. In N2+ implanted GST films, in particular, interstitial N2 molecules played a major role in the suppression of crystallization.
Bibliographical noteFunding Information:
This research was partially supported by the National Research Project for the Phase-change Random Access Memory Development by the Korean Ministry of Commerce, Industry, and Energy.
All Science Journal Classification (ASJC) codes
- Physics and Astronomy(all)