(Invited) Ge Optical Emitters Fabricated by Ge Condensation and Epitaxial Growth

Two types of Ge optical emitter, called Ge-on-insulator stripes and Ge-fins, were successfully fabricated on the buried oxide layer of a silicon-on-insulator wafer using a combined Ge condensation and selective epitaxial growth. Intense PL spectra from both structures show that the good crystallinity and the sufficient carrier confinement can be achieved, and the obvious red-shifts of the peaks were observed due to the tensile strain in the Ge active region applied through the fabrication processes. Moreover, the low dark current in I-V characteristics was obtained, and the electroluminescence corresponding to the direct recombination at the Γ valley was also observed by injecting forward currents into the Ge-fins. These results indicate that this combined technique efficiently improves the performance of Ge optical emitters.