Cu nanoparticle induced lateral growth of polycrystalline germanium (poly-Ge) was enabled by the application of biological nano fabrication process. The Cu nanoparticle was formed using a cage shaped protein by bio-mineralization. Crystallization temperature was decreased compared with a Ni nanopartide induced method. These results were confirmed by Raman spectrum and TEM analyses. In addition, metal contamination in the obtained poly-Ge film was evaluated by SIMS analyses. The bio-nanoparticle coating process is applicable for a low temperature device fabrication. (c) 2013 Elsevier B.V. All rights reserved