Local Lattice Distortion of Ge Impurity in Si (001): Multiple-Scattering EXAFS Study

The local structure of dilute Ge impurity in the Si host has been studied by fluorescence x‐ray absorption fine structure spectra through multiple‐scattering data analysis method. Contrary to the elongation of 0.029 A for the Ge‐Si distance in the first shell, the Ge‐Si interatomic distance in the second shell shows a contraction of about 0.013 A relative to the corresponding Si‐Si distance in the Si host. This coincides with the theoretical prediction by Mousseau and Thorpe [Phys. Rev. B 46, 15887 (1992)] which includes both the bond length mismatch and bond‐angle deviation. It turns out that the contraction of the second‐shell Ge‐Si distance is due to the deviation of Ge–Si–Si bond‐angle from the ideal tetrahedral angle. From the Ge‐Si distances within the first three shells, it is revealed that the dilute Ge doped into Si host can lead to the local distortion rather than the average lattice change.