Si films grown epitaxially by low-temperature electron-cyclotron resonance chemical-vapor deposition (ECRCVD) were investigated by analyzing extended defects in these films. Extended defects were made visible by Secco etching and scanning (SEM) and transmission (TEM) electron microscopy were used to analyze them in detail. Films Grown on Si(1 0 0) wafers show different kinds of etch pits with characteristic shapes, sizes and crystallographic alignments. Their correlation to crystallographic defects is discussed. The typical total etch pit density for boron-doped samples grown at 580 degrees C on Si wafers is in the range of 10(8) cm(-2). Films grown on poly-Si seed layers on glass are strongly affected by Secco etch due to growth regions of different Structural qualities and a high density of extended defects. Solar cell test structures were prepared from both types of samples and their results discussed in view to the density of extended defects. (c) 2005 Elsevier B.V. All rights reserved.