XAFS analysis on amorphous and crystalline new phase change material GeCu₂Te₃

The structure of crystalline and amorphous GeCu₂Te₃ phase change material was investigated by x-ray absorption fine structure. The averaged interatomic distances of Ge-Te and Cu-Te in the crystal phase are confirmed to contradict the x-ray diffraction data, and are mostly equal to the experimental data in the amorphous phase. As regards the coordination numbers, the atomic configurations around the Ge atoms are a small modification of the crystalline one, while those around the Cu atoms are quite different and the large number of the Cu-Cu homopolar coordination become an important role in the amorphous phase. The x-ray absorption near edge structure data near the Ge K edge show a similarity of the local atomic configurations around the Ge atoms between the crystalline and amorphous GeCu₂Te₃. However, those near the Cu K edge indicate a large smearing-out on the amorphization, corresponding the large differences in the atomic configurations around the Cu atoms.