The past decade has witnessed rapid progress in the development of techniques for correcting lens aberrations in high-resolution transmission electron microscopy (HRTEM), resulting in significant enhancement in the directly interpretable spatial resolution in HRTEM images. Furthermore, in combination with advanced image processing and analysis, it is now possible to employ HRTEM as a quantitative technique for structural and chemical analysis at the atomic scale. In this paper we have applied these developments to investigate interfaces in InAs/GaSb superlattices, the main objectives being the mapping of changes in chemical composition and strain at each interface. For examining changes in composition we use the focal series reconstruction technique, which retrieves the quantum-mechanical electron wave function at the exit surface of the sample. The phase images of the electron wave function are then analyzed by linear multivariate statistical analysis to independently quantify change in the In/Ga and As/Sb contents across each interface. The strain profiles across interfaces are determined from HRTEM images, obtained from a TEM equipped with a spherical aberration corrector, employing the "peak-pair analysis" (PPA) algorithm. Finally, the high-angle annular dark-field imaging technique (HAADF), using a monochromated and probe corrected TEM, is also employed to examine interfaces.

Date Published: 22 January 2010
PDF: 9 pages
Proc. SPIE 7608, Quantum Sensing and Nanophotonic Devices VII, 76081S (22 January 2010);

Published in SPIE Proceedings Vol. 7608:
Quantum Sensing and Nanophotonic Devices VII
Manijeh Razeghi; Rengarajan Sudharsanan; Gail J. Brown, Editor(s)