Effects of N 2 + ion implantation on phase transition in Ge 2 Sb 2 Te 5 films

• Published in: Journal of applied physics 2006-10, Vol.100 (8), p.083502-083502-5
• Main Authors: Kim, YoungKuk, Baeck, J. H., Cho, M.-H., Jeong, E. J., Ko, D.-H.
• Format: Article
• ISSN: 0021-8979; 1089-7550
• DOI: 10.1063/1.2357640

The phase transitions of Ge 2 Sb 2 Te 5 (GST) films after bombardment with 40 keV N 2 + 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 N 2 + 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 Ge 3 N 4 and interstitial N 2 molecules. In N 2 + implanted GST films, in particular, interstitial N 2 molecules played a major role in the suppression of crystallization.