Understanding atomic structures of amorphous C-doped Ge₂Sb₂Te₅ phase-change memory materials

详细信息    查看全文

• 作者：Konstantin B. Borisenko^a ; ^{konstantin.borisenko@materials.ox.ac.uk"" rel=""nofollow} ; Yixin Chen^a ; David J.H. Cockayne^a ; Se Ahn Song^b ; ^{sasong@samsung.com"" rel=""nofollow} ; Hong Sik Jeong^c
• 关键词：Phase-change memory materials ; Electron diffraction ; Amorphous materials ; Molecular dynamics ; Density functional theory
• 刊名：Acta Materialia
• 出版年：2011
• 出版时间：June 2011
• 年：2011
• 卷：59
• 期：11
• 页码：4335-4342
• 全文大小：1203 K

文摘

The atomic structure of thin films of the carbon-doped Ge₂Sb₂Te₅ (GST) rapid phase-change memory material Ge₂Sb₂Te₅C (10 % C-GST) was investigated by reverse Monte Carlo refinement using experimental electron diffraction reduced scattering data accompanied by density functional theory (DFT) molecular dynamics (MD) simulations and energy optimizations. For comparison, the structure of amorphous Ge₂Sb₂Te₅C₂ (18 % C-GST) was obtained by DFT MD simulation of cooling from the melt. The results suggest that the carbon dopant forms atomic scale carbon clusters coordinated predominantly by Ge atoms. This becomes more evident with increasing carbon concentration. For 10 % C-GST the building blocks of the matrix can be identified as squares of Ge(Sb)–Te–Sb(Ge)–Te atoms, related to the elementary building blocks of the corresponding crystalline structure of the metastable cubic phase of pure GST. The increased contribution of homopolar Te–Te bonds and Sb(Te)–Te–Sb(Te)–Te square fragments is suggested with the higher dopant level in 18 % C-GST.