Monolithically Integrated GaAs Nanoislands on CMOS-Compatible Si Nanotips Using GS-MBE

Area of Science:

• Materials Science
• Semiconductor Physics
• Nanotechnology

Background:

• Monolithic integration of III-V semiconductors with silicon (Si) is essential for next-generation optoelectronic and photonic devices.
• Current integration methods face challenges in achieving high-quality, defect-free interfaces.

Purpose of the Study:

• To investigate the selective growth of Gallium Arsenide (GaAs) nanoislands on silicon (Si) nanotips using gas-source molecular beam epitaxy (GS-MBE).
• To understand the impact of growth conditions on the morphology, crystalline structure, and defect formation of GaAs nanoislands.
• To explore the potential for CMOS-compatible Si-based nanophotonic technologies.

Main Methods:

• Fabrication of complementary metal oxide semiconductor (CMOS)-compatible Si(001) nanotip wafers.
• Gas-source molecular beam epitaxy (GS-MBE) for GaAs nanoheteroepitaxy (NHE).
• Characterization using scanning electron microscopy (SEM), high-resolution X-ray diffraction (HRXRD), and photoluminescence (PL) spectroscopy.

Main Results:

• Achieved selective growth of fully relaxed GaAs nanoislands on Si nanotips with monomodal size distribution (100-280 nm effective diameter) for lower deposition.
• Observed four distinct facet orientations ({001} planes) in smaller islands.
• Identified a transition to bimodal size distribution and increased twinning volume fraction with higher deposition, alongside the emergence of larger islands with multiple crystallographic facets.

Conclusions:

• Growth conditions significantly influence GaAs nanoisland morphology, crystalline structure, and defect formation during NHE on Si nanotips.
• Twinning is consistently observed, with its prevalence increasing with deposition.
• The findings provide critical insights into nanoheteroepitaxial growth dynamics, paving the way for advanced CMOS-compatible Si-based nanophotonic devices.