Enhanced room-temperature electroluminescence from a germanium waveguide on a silicon-on-insulator diode with a silicon nitride stressor

Germanium (Ge) is an attractive material for monolithic light sources on a silicon chip. Introduction of tensile strain using a silicon nitride (SiN x ) stressor is a promising means for Ge-based light sources due to the enhancement of direct band gap recombination. We propose a device structure that enables current injection from a silicon-on-insulator (SOI) diode to a Ge waveguide with a SiN x stressor formed by a simple fabrication process. Direct-band-gap electroluminescence and direct-band-gap shrinkage due to the applied SiN x stressor was confirmed. Intensity of electroluminescence from the Ge waveguide with the SiN x stressor was about three times higher than that corresponding to the device without the SiN x stressor.