Lasing from Glassy Ge Quantum Dots in Crystalline Si

Area of Science:

• Materials Science
• Optoelectronics
• Nanotechnology

Background:

• Standard silicon integration technology (SIT) faces limitations in microelectronic device speed.
• Group IV light sources are desirable for SIT compatibility but are hindered by bulk silicon (Si) and germanium (Ge) optoelectronic properties.

Purpose of the Study:

• To develop SIT-compatible semiconductor light-emitters using group IV elements.
• To investigate the optoelectronic properties of germanium quantum dots (QDs) in a silicon (Si) matrix after germanium-ion bombardment (GIB).

Main Methods:

• Epitaxial growth of Ge QDs within a defect-free Si matrix.
• Partial amorphization of Ge QDs using Ge-ion bombardment (GIB).
• Characterization of optical properties, including carrier lifetimes and photoluminescence (PL), up to room temperature.
• Fabrication and testing of microdisk resonators incorporating GIB-QDs.

Main Results:

• GIB-treated Ge QDs exhibit significantly shortened carrier lifetimes compared to conventional SiGe nanostructures.
• Negligible thermal quenching of photoluminescence (PL) was observed up to room temperature.
• Microdisk resonators demonstrated threshold behavior and superlinear PL intensity increase with pump power.
• Line width narrowing was observed with increasing pump power, indicating stimulated emission.

Conclusions:

• Partially amorphized Ge QDs in a Si matrix display extraordinary optical properties.
• This fully SIT-compatible group IV nanosystem enables light amplification via stimulated emission.
• The findings pave the way for high-speed, Si-integrated optoelectronic devices.