Semiconductor Interface Structure Studied by X-Ray Diffraction(Interfaces by various techniques)

Semiconductor interface structures have been studied by employing the technique of grazing incidence X-ray diffraction (GID) with the use of synchrotron radiation. Multiple-wavelength anomalous dispersion (MAD) method, a powerful direct method, has been modified and applied for the first time to an interface. This allows us to separate heavy and light atoms in a model-independent fashion and so deduce the structure. Of the numerous √ structures, only boron induced √ structure has been observed in the buried interface. MAD method has been applied to the Si/B√/GeSi(111) interface structure and direct evidence for ordering of the Ge and Si atoms at this interface has been obtained. Specially, it has been found that boron lies in a substitutional site surrounded by four nearest-neighbor Si atoms with Ge in the other sites. In order to study the stress at the SiO_2/Si interface, the X-ray intensity of the silicon substrate 311 reflection in an extremely asymmetric scheme of small incident angle and large exit angle has been measured for various silicon oxide thickness. X-ray rocking curve studies reveal that silicon substrate lattice is highly stressed even in the thin-SiO_2/Si interface