Improved performance of thin-film silicon solar cells on graphite substrates

Different physical properties of silicon thin-film layers deposited by chemical vapor deposition (CVD) on foreign substrates have been investigated. The electrical activity of crystal defects (grain boundaries, low-angle grain boundaries, and dislocations) which influence the quality of the layer system was investigated by high-resolution optical beam induced currents (OBIC) and electron beam induced currents (EBIC). Photoluminescence (PL) spectra indicate the existence of dislocations. Impurities like molybdenum (Mo) originating from the crystallization process were detected by deep level transient spectroscopy (DLTS). The boron profile at the p/sup +//p boundary between the seed layer and the epitaxial layer has been characterized by spreading resistance. A p-n junction silicon thin-film solar cell yields a confirmed cell efficiency of 8.3%, latest results up to 11.0% are obtained.