Structure of an incommensurate 90° Si grain boundary resolved with the help of a Cs-corrector for illumination

The atomic structure of an incommensurate (001)/(110) Si grain boundary (GB) or 90° Si GB has been studied by transmission electron microscopy (TEM) and refined by atomistic simulations (Stillinger-Weber potential). Samples were made by bonding one (001) Si wafer with one (110) Si wafer and carefully orienting the 2 wafers in order that they have a common [10] direction. In the interfacial direction perpendicular to [10], the [110]_I direction of grain I is parallel to the [001]_II direction of grain II and, as the ratio of these 2 vectors is , it is impossible to find 2 integers n and m such that n[110]_I=m[001]_II. The structure is incommensurate in this direction. Z-contrast images obtained in an FEI-Titan microscope equipped with a probe Cs-corrector easily resolve the Si dumb-bells in the two grains and allow us to determine the complex atomic structures of the interface. On the other hand, near on-axis high resolution TEM images obtained in a JEOL 4000EX microscope are very efficient to analyse the long range order of the interface.