| Summary: | The local structure change of Ge induced by carbon doping in as-deposited Ge2Sb2Te5 films were studied by extended X-ray absorption fine structure and Raman spectrum. Ge-C bonds are formed at the expense of reducing the coordination of Ge-Ge and Ge-Te bonds, and make the local structure of Ge to be a well-defined tetrahedral geometry, which increases the rigidity of amorphous network and reduces the number of ABAB rings, thus the crystallization temperature of carbon-doped Ge2Sb2Te5 (CGST) films are enhanced. The reduced proportion of the tetrahedral units GeTe4−nGen (n = 1, 2) caused by carbon doping accounts for the weaker Raman peak intensity at ∼124 cm−1 in CGST films. Meanwhile, the impact of doping carbon on the crystalline structure of CGST films were investigated by high resolution transmission electron microscope.
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