Three-dimensional reconstruction of atoms in surface X-ray diffraction

We have developed a method of determining directly the structure of surfaces and interfaces as three-dimensional images using X-ray diffraction. The intensity profile along an integral order rod is interpreted as an interference pattern between scattered waves from a substrate whose structure is already known and from surface layers whose structure is the target of investigation. This mechanism is the same as that of holography and has a potentiality to reconstruct electron density. Atomic images of Ge in a-Si/Ge/Si(001) have been obtained by this method.