Atomic-Structure Of The C(4x2) Surface Reconstruction Of Ge(001) As Determined By X-Ray-Diffraction

The c(4 X 2) reconstruction of Ge(001) has been studied by x-ray diffraction of 150 K by measuring in-plane reflections and out-of-plane intensities of fractional order rods. The structure consists of an alternate arrangement of buckled dimers (tilt angle 19 degrees -/+ 1 degrees) along the [110] and [1 (1) over bar 0] surface directions. The dimer rows are not straight along the [110] direction but show a slight zigzag with an amplitude of 0.340 -/+ 0.005 Angstrom.