DEFECT CHARACTERIZATION OF POLY-Ge AND VFG-GROWN Ge MATERIAL

Germanium is an attractive model system for studying the crystallization mechanism and optimization of the growth processes in photovoltaics. In comparison to Si it has a lower melting point and that is why its usage is cost effective. The main aim of our work was to verify the similarities in the growth related defect formation between Ge and Si. We apply standard Si characterization methods to poly and VGF-grown n-type Ge. Room temperature and 80 K EBIC measurements were done to reveal the defect structure. Photoluminescence spectra were used to characterize the optical properties as for instance the Ge band-to-band or defect originated transitions. Additionally, photoluminescence and cathodoluminescence maps were preformed to reveal the defect distribution/activity, too, by using the direct Ge band-to-band transition.