Arai T, Sato M, Umesaki N
Department of Applied Physics, National Defense Academy, Yokosuka 239-8686, Japan.
J Phys Condens Matter. 2007 Aug 22;19(33):335213. doi: 10.1088/0953-8984/19/33/335213. Epub 2007 Jul 4.
Reverse Monte Carlo analyses of crystalline and amorphous Ge(2)Sb(2)Te(5) thin films were carried out using x-ray diffraction data and three spectra from extended x-ray absorption fine structure measurements. To produce a crystal model, we employed a large system with 12 800 Ge, 12 800 Sb and 32 000 Te atoms. The obtained model for the crystal structure was used for the initial configuration of the amorphous model. As a result of a series of reverse Monte Carlo analyses with various constraints, we found that the partial pair distribution function in the amorphous state with the largest deviation from the crystal state is a Ge-Sb pair and the distance is less than 2.7 Å. This suggests that Sb atoms in amorphous Ge(2)Sb(2)Te(5) thin film have a four-coordinate within 3.2 Å.
利用X射线衍射数据和扩展X射线吸收精细结构测量得到的三个光谱，对晶体和非晶态Ge₂Sb₂Te₅薄膜进行了反向蒙特卡罗分析。为了构建晶体模型，我们采用了一个包含12800个Ge原子、12800个Sb原子和32000个Te原子的大体系。所得到的晶体结构模型被用于非晶模型的初始构型。通过一系列具有各种约束条件的反向蒙特卡罗分析，我们发现非晶态中与晶体态偏差最大的部分对分布函数是Ge-Sb对，其距离小于2.7 Å。这表明非晶态Ge₂Sb₂Te₅薄膜中的Sb原子在3.2 Å范围内具有四配位。
