Uprooting defects to enable high-performance III-V optoelectronic devices on silicon

Area of Science:

• Materials Science
• Semiconductor Physics
• Nanotechnology

Background:

• Monolithic integration of III-V compound semiconductors with silicon faces challenges due to defect formation during deposition.
• High defect densities hinder the performance of integrated photonic and optoelectronic devices.

Purpose of the Study:

• To develop a scalable defect elimination strategy for creating ultra-low dislocation density germanium-on-silicon virtual substrates.
• To demonstrate the effectiveness of this strategy for enabling high-quality epitaxial growth for optoelectronic applications.

Main Methods:

• Utilized dislocation-selective electrochemical deep etching to remove dislocations from the epilayer.
• Employed thermal annealing to create nanovoids that attract and annihilate dislocations.
• Fabricated epi-ready Ge/Si virtual substrates on a wafer scale using a highly scalable process.

Main Results:

• Reduced average dislocation density by over three orders of magnitude (from ~10^8 cm^-2 to ~10^4 cm^-2) in a 1.5 µm thick Ge layer.
• Achieved an ultra-low dislocation density, epi-ready Ge/Si virtual substrate.
• Observed a significant enhancement in luminescence efficiency for GaAs grown on the developed virtual substrate.

Conclusions:

• The demonstrated defect elimination strategy is effective for producing high-quality Ge/Si virtual substrates.
• This scalable process shows promise for cost-effective industrial-scale production of integrated photonic and optoelectronic devices on silicon platforms.