Berlin 2012 – wissenschaftliches Programm

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HL: Fachverband Halbleiterphysik

HL 12: "New" Materials and New Physics in "Old" Materials II

HL 12.5: Vortrag

Montag, 26. März 2012, 12:45–13:00, EW 015

Chemical Composition of Novel III/V-alloys — •Tatjana Wegele, Vivien Voßebürger, Rafael Fritz, Kakhaber Jandieri, and Kerstin Volz — Faculty of Physics and Material Sciences Centre, Philipps-University Marburg, D-35032 Marburg

Low-priced and high-efficient solar cells are possible through combination of silicon technologies and III/V-ternary or -quaternary semiconductors. The conditions for high efficiency are a suitable band gap and high crystal quality. The latter implies good lattice-matching and consequently a specific chemical composition of III/V-alloys as well as the homogeneity of the distribution of the chemical constituents.

Cross-sectional dark-field transmission electron microscopy is a good opportunity to determine chemical composition using chemical sensitive reflections on the nanometre scale. For quantitative interpretations of these micrographs it has to be taken into account, that the chemical constituents, which have different covalent radius, induce a local strain and therefore impact the intensity of the respective dark-field image.

We study dilute ternary B- or N-containing compound semiconductors based on GaP and GaAs as well as novel quaternary alloys like (BGa)(AsP) and summarise the results of quantitative TEM imaging using chemical sensitive reflections in combination with structure factor calculation.