title: Interfacial atomic structure analysis at sub-angstrom resolution using aberration-corrected STEM.
abstract: The atomic structure of a SiGe/Si epitaxial interface grown via molecular beam epitaxy on a single crystal silicon substrate was investigated using an aberration-corrected scanning transmittance electron microscope equipped with a high-angle annular dark-field detector and an energy-dispersive spectrometer. The accuracy required for compensation of the various residual aberration coefficients to achieve sub-angstrom resolution with the electron optics system was also evaluated. It was found that the interfacial layer was composed of a silicon single crystal, connected coherently to epitaxial SiGe nanolaminates. In addition, the distance between the dumbbell structures of the Si and Ge atoms was approximately 0.136 nm at the SiGe/Si interface in the [110] orientation. The corresponding fast Fourier transform exhibited a sub-angstrom scale point resolution of 0.78 Å. Furthermore, the relative positions of the atoms in the chemical composition line scan signals could be directly interpreted from the corresponding incoherent high-angle annular dark-field image.
authors.affiliation: Instrument Technology Research Center, National Applied Research Laboratories, Hsinchu 30076, Taiwan.
authors.forename: Chien-Nan
authors.initials: CN
authors.lastname: Hsiao
authors.affiliation: Department of Electronic Engineering, Chang Gung University, Gueishan 33302, Taiwan.
authors.forename: Shou-Yi
authors.initials: SY
authors.lastname: Kuo
authors.affiliation: Department of Photonics Engineering, Yuan Ze University, Taoyuan 32003, Taiwan.
authors.forename: Fang-I
authors.initials: FI
authors.lastname: Lai
authors.affiliation: Instrument Technology Research Center, National Applied Research Laboratories, Hsinchu 30076, Taiwan.
authors.forename: Wei-Chun
authors.initials: WC
authors.lastname: Chen
keywords: Aberration correction; EDS; EELS; HAADF; HRSTEM; HRTEM; Z contrast