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本文用掠入射荧光XAFS研究 (Ge4/Si4) 5 /Si(0 0 1 )形变超晶格的局域结构 .超晶格中的Ge Ge和Ge Si第一配位键长分别为RGe Ge =0 .2 43nm和RGe Si =0 .2 38nm ,与晶态Ge(RGe Ge =0 .2 45nm)和共价Ge Si键长RGe Si =0 .2 40nm相比 ,其配位键长缩短了 0 .0 0 2nm ,表明Ge原子周围的晶格产生了扭曲 ,Ge Ge配位数为 1 .8和Ge Si配位数为 2 .2显然偏离了理论的配位数Ge Ge为 3和Ge Si配位数为 1 .我们提出Ge和Si原子的位置交换模型来解释 (Ge4/Si4) 5 超晶格的界面结构
In this paper, the localized structure of (Ge 4 / Si 4) 5 / Si (001) superlattices is studied by grazing incident fluorescence XAFS.The first coordination bond lengths of Ge Ge and Ge Si in superlattices are RGe Ge = 0 .2 43nm and RGe Si = 0.383nm, the coordinate bond length is shortened compared with the crystalline Ge (RGeGe = 0.245nm) and the covalent GeSi bond length RGeSi = 0.240nm 0 .0 0 2nm, indicating that the lattice around Ge atoms distorted, Ge Ge coordination number of 1.8 and Ge Si coordination number of 2.2 obviously deviate from the theoretical coordination number of Ge Ge is 3 and Ge Si coordination number is 1. We propose a positional exchange model of Ge and Si atoms to explain the interfacial structure of (Ge4 / Si4) 5 superlattice