Effects of Dislocation Filtering Layers on Optical Properties of Third Telecom Window Emitting InAs/InGaAlAs Quantum...

Area of Science:

• Materials Science and Engineering
• Optoelectronics
• Semiconductor Physics

Background:

• Silicon's indirect bandgap hinders its use as a direct light source, limiting optical communication data rates.
• Integrating III-V light emitters with silicon electronics is essential for next-generation communication systems.

Purpose of the Study:

• To investigate InAs/InGaAlAs quantum dot (QD) structures grown on silicon substrates for 1.5 μm light emission.
• To mitigate lattice and thermal expansion mismatches between III-V materials and silicon during growth.
• To assess the optical quality and application potential of these novel Si-based structures.

Main Methods:

• Growth of InAs/InGaAlAs QDs directly on 5° off-cut Si substrates.
• Utilized dislocation defect filtering layers, strained superlattices, and supplementary QD layers.
• Employed photoreflectance and temperature-, time-, and polarization-resolved photoluminescence spectroscopy.
• Performed theoretical calculations of excitonic states using multiband and configuration-interaction methods.

Main Results:

• Successfully grew QD structures emitting at 1.5 μm, compatible with telecom platforms.
• Effectively mitigated defect generation through advanced growth strategies.
• Observed broader emission spectra in Si-based QDs compared to InP-based reference QDs due to varied QD populations.
• Identified promising defect filtering layer combinations for Si-based light emitters.

Conclusions:

• The designed QD structures on silicon effectively suppress defect generation.
• Broader emission spectra, while potentially limiting for lasers, offer advantages for tunable devices, sensors, and optical amplifiers.
• The study identifies optimal growth strategies and discusses prospects for further enhancing Si-based photonic integration.