Enhancement of light emission from Ge quantum dots by photonic crystal nanocavities at room-temperature

Strong resonant light emission in the wavelength range of 1.3–1.5μm 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. ► Strongly enhanced light emission from Ge QDs in DH PhC nanocavities was observed. ► Sharp resonant peaks with Q-factor of about 4000 were obtained in the PL spectra. ► Emission spectra from different DH PhC nanocavities were investigated and analyzed. ► Room-temperature current-injected LEDs were realized by using lateral PIN diodes.