Effects of N2+ ion implantation on phase transition in Ge2Sb2Te5 films

• Published in: Journal of applied physics 2006-10, Vol.100 (8)
• Main Authors: Kim, YoungKuk, Baeck, J. H., Cho, M.-H., Jeong, E. J., Ko, D.-H.
• Format: Article
• Language: eng ; jpn
• ISSN: 0021-8979; 1089-7550
• DOI: 10.1063/1.2357640

The phase transitions of Ge2Sb2Te5 (GST) films after bombardment with 40keV 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 Ge3N4 and interstitial N2 molecules. In N2+ implanted GST films, in particular, interstitial N2 molecules played a major role in the suppression of crystallization.