Hydrogenated microcrystalline silicon germanium (mu c-Si1-xGex:H) thin films were evaluated as a bottom cell absorber for multi-junction solar cells based on Si thin films. The crystallization behavior of mu c-Si1-xGex:H was examined. Raman spectroscopy and grazing angle X-ray diffraction showed that the crystallinity of the mu c-Si1-xGex:H films decreased with increasing Ge content. Fourier transform infrared spectroscopy revealed an increase in the intensity of the Ge-H and Ge-H-2 bonds in mu c-Si1-xGex:H due to the increased amorphous phase. The rapid GeH4 decomposition rate and preferential etching of Si bonds led to a decrease in crystallinity and an extremely high Ge content in the mu c-Si1-xGex:H films. The dark conductivity of mu c-Si1-xGex:H was affected by the internal crystallinity and an excessively high crystallinity deteriorated the electrical properties. The photo response increased from 10(2) to 10(3) with increasing Ge content. This study presents a comprehensive evaluation of the crystallization behavior of mu c-Si1-xGex:H films for solar cell absorber applications. (C) 2013 Elsevier B. V. All rights reserved.