Regensburg 2013 – wissenschaftliches Programm

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MM: Fachverband Metall- und Materialphysik

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

MM 17.4: Vortrag

Dienstag, 12. März 2013, 11:15–11:30, H4

Novel III/V-Alloys Investigated Using Transmission Electron Microscopy — •Tatjana Wegele, Rafael Fritz, Vivien Vossebürger, Kakhaber Jandieri, and Kerstin Volz — Faculty of Physics and Material Science Centre, Philipps-University Marburg, D-35032 Marburg

Three- and four-compound III/V semiconductor layers are a must-have for efficient solar cells. We use boron atoms and/or arsenic atoms as substituents in GaP or GaAs host materials. The incorporation of these atoms allows to grow metastable materials lattice matched on a substrate with a band gap tuned nearly to a desired value. The amount of the incorporated substituents as well as the crystal quality and therefore the efficiency of the semiconductor devices depend on well-optimized growth conditions.

We investigated GaP-based (BGa)(AsP) and (BGa)P as well as GaAs-based alloys using transmission electron microscopy combining the following techniques: Dark-Field Imaging, High-Resolution Imaging, High-Angle Annular Dark-Field Imaging and Energy Dispersive X-ray Spectroscopy. The latter two are used in scanning TEM mode.

We were able to determine the chemical composition of the investigated layers and also to directly test the quality of the interfaces. The maximum possible concentration of incorporated substituent atoms, that do not produce any defects in the layers, was determined. Moreover the homogeneity or inhomogeneity of the substituents distribution in the three- and four-compound layers, respectively, were visualized and quantitatively studied.