Bright-field (BF) and annular dark-field (ADF) electron tomography in the transmission electron microscope (TEM) are used to characterize elongated porous regions or cracks (simply referred to as cracks thereafter) in micro-crystalline silicon (μc-Si:H) solar cell. The limitations of inferring the 3D geometry of a crack from a tilt series of images acquired from 100-nm-thick focused ion beam (FIB) milled TEM specimen are discussed. In an attempt to maximize the specimen tilt range and to reduce the effects of diffraction and phase contrast on the reconstruction, both BF and ADF electron tomography are used to acquire 360º tilt series of images from a FIB-prepared needle-shaped μc-Si:H specimen.