High-Quality-Factor Light-Emitting Diodes with Modified Photonic Crystal Nanocavities Including Ge Self-Assembled Quantum Dots on Silicon-On-Insulator Substrates

High-quality-factor room-temperature light-emitting diodes based on Ge self-assembled quantum dots are successfully fabricated by employing a lateral p--i--n diode structure and a modified L3-type photonic crystal nanocavity. Sharp resonant peaks with Q-factor larger than 800, corresponding to the cavity modes, are clearly observed in the electroluminescence spectrum under 50 μA injected current, which exceeds the performances of previously reported devices [X. Xu et al. : Opt. Express 20 (2012) 14714]. The output power collected by a single-mode fiber is measured to be about 6 pW under 3 mA current, indicating a forward step towards silicon-based light sources for practical applications.