The synthesis of an array of core-shell homoepitaxial Si nanowires is demonstrated directly on glass substrates using nanowires with an average diameter of 38 nm as seed crystals. Furthermore, the array of core-shell nanowires (average length of 1.07 mu m) exhibit very high optical absorption of >88% over the wavelength range lambda = 300-610 nm, significantly higher than that of a thin film nanocrystalline Si film. The combination of high optical absorption and long range order are attractive for high performance large area applications such as epitaxial solar cells and image sensors. (C) 2013 Elsevier B.V. All rights reserved.