Atomic structure of the GaAs/Si interface

The atomic structure of the GaAs/Si(100) interface is studied using high resolution transmission electron microscopy. The samples studied were grown by molecular beam epitaxy using a conventional two-step growth process of a relatively low-temperature (405 °C) GaAs buffer layer followed by a higher temperature (575 °C) device layer. Following this growth procedure, the interface is found to be atomically rough with nonuniform distributions of steps, and to contain regions of disrupted crystallinity. These regions are found to be more prevalent in material which has undergone only low-temperature (buffer layer) GaAs deposition. By using the atomic resolution microscope at the National Center for Electron Microscopy, Lawrence Berkeley Laboratories, we are also able to atomically image the same area of interface along orthogonal 〈011〉 directions, observing qualitatively similar structures.