Regensburg 2013 – wissenschaftliches Programm

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MM: Fachverband Metall- und Materialphysik

MM 17: Topical Session: TEM-Symposium - HR Imaging & Analytic I

MM 17.2: Vortrag

Dienstag, 12. März 2013, 10:45–11:00, H4

Quantitative HAADF-studies on GaP/Si heterostructures — •Andreas Beyer, Nikolai Knaub, Benedikt Haas, Katharina Gries, Katharina Werner, and Kerstin Volz — Structure and Technology Research Laboratory, Philipps-Universität, Marburg, Germany

The growth of III/V-materials on Si enables a variety of new optoelectronic devices. We investigate GaP grown on Si as a model system. The growth of a polar material on nonpolar substrate holds several challenges as the interface is not necessarily charge neutral and anti-phase domains (APDs) can form at monoatomic steps of the Si-surface.

High resolution high angle annular darkfield (HAADF) measurements were carried out in a JEOL JEM 2200FS,equipped with a corrector for spherical aberration of the condenser lens system. For quantification of the data HAADF-intensities were simulated using an absorptive potential approach.

The simulated and experimental HAADF-images show that the intensity ratio of Si and GaP is not constant but a function of local TEM sample thickness and microscope parameters. This can be exploited to determine the thickness via high resolution HAADF images of the interface. The determined thickness values are compared to the ones derived by electron energy loss spectroscopy. For a known sample thickness the influence of element intermixing at the interface as well as the local atomic structure of present APDs on the HAADF-intensity is investigated and quantified.