Characterisation of InAs/GaAs short period superlattices using column ratio mapping in aberration-corrected scanning transmission electron microscopy

Abstract

. (2012) Characterisation of InAs/GaAs short period superlattices using column ratio mapping in aberration-corrected scanning transmission electron microscopy. Micron, 43 (10 AbstractThe image processing technique of column ratio mapping was applied to aberration-corrected high angle annular dark field (HAADF) images of short period MBE (molecular beam epitaxy) grown InAs/GaAs superlattices. This method allowed the Indium distribution to be mapped and a more detailed assessment of interfacial quality to be made. Frozen-phonon multislice simulations were also employed to provide a better understanding of the experimental column ratio values. It was established that ultra-thin InAs/GaAs layers can be grown sufficiently well by MBE. This is despite the fact that the Indium segregated over 3-4 monolayers. Furthermore, the effect of the growth temperature on the quality of the layers was also investigated. It was demonstrated that the higher growth temperature resulted in a better quality superlattice structure.

Oxygen octahedra picker: A software tool to extract quantitative information from STEM images

“…Quantitative analysis of these atomic resolution images often requires the extraction of atomic column positions and intensities, and measurement of atomic-column distances at the unit-cell level and beyond. Such quantitative analysis of atomic column information helps us gain new insight into materials behavior by characterizing ferroelectricity [8,9], composition [10][11][12][13], octahedral tilting [14,15], and strain [16]. Despite the great success of atomic resolution image analysis and application in addressing materials problems, there are rare resources about methods for indexing atomic column positions in atomic resolution images, especially for the case of ABF images, as well as for the measurement accuracy.…”