Strong resonant light emission in the wavelength range of 1.3-1.5 mu m from self-assembled Ge quantum dots (QDs) embedded in double heterostructure photonic crystal (PhC) nanocavities are demonstrated at room-temperature. The Ge QDs are grown on silicon-on-insulator (SOI) substrates by solid-source molecular beam epitaxy. Under optical excitation, light emission enhancement by a factor > 150 at resonant wavelength, and sharp resonant peaks with Q-factor up to 3870, are observed in the photoluminescence spectrum due to the existence of the PhC nanocavity. The effects of cavity design and cladding material on the light emission properties are also analyzed and discussed. Through lateral PIN diode structures, we also demonstrate enhanced resonant electroluminescence from Ge QDs embedded in PhC nanocavities under current injection. (c) 2012 Elsevier B.V. All rights reserved.