1.3-μm InAs/GaAs quantum-dot lasers monolithically grown on Si substrates using InAlAs/GaAs dislocation filter layers

Area of Science:

• Materials Science
• Semiconductor Physics
• Optoelectronics

Background:

• Directly growing high-performance laser structures on silicon substrates is challenging due to lattice mismatch and defect generation.
• Quantum-dot lasers offer potential for on-chip integration, but require effective defect management for silicon compatibility.
• Strained-layer superlattices (SLSs) are investigated as potential solutions for defect reduction in heterostructures.

Purpose of the Study:

• To compare the effectiveness of Indium Aluminum Arsenide/Gallium Arsenide (InAlAs/GaAs) and Indium Gallium Arsenide/Gallium Arsenide (InGaAs/GaAs) strained-layer superlattices (SLSs) as dislocation filter layers.
• To evaluate these SLSs in 1.3-micrometer (μm) InAs/GaAs quantum-dot laser structures grown directly on silicon (Si) substrates.
• To demonstrate the performance of quantum-dot lasers on Si using optimized dislocation filtering.

Main Methods:

• Fabrication of 1.3-μm InAs/GaAs quantum-dot laser structures on Si substrates.
• Incorporation of InAlAs/GaAs SLSs and InGaAs/GaAs SLSs as dislocation filter layers.
• Characterization of threading dislocation propagation through the SLSs.
• Performance testing of broad-area lasers, including threshold current density and output power at room temperature.

Main Results:

• InAlAs/GaAs SLSs demonstrated superior performance in blocking threading dislocations compared to InGaAs/GaAs SLSs.
• The effectiveness of InAlAs/GaAs SLSs was attributed to their ability to mitigate dislocations originating at the GaAs buffer/Si substrate interface.
• Broad-area lasers grown on Si substrates utilizing InAlAs/GaAs dislocation filter layers achieved room-temperature lasing at approximately 1.27 μm.
• These lasers exhibited a low threshold current density of 194 A/cm² and a substantial output power of approximately 77 mW.

Conclusions:

• InAlAs/GaAs strained-layer superlattices are highly effective dislocation filter layers for InAs/GaAs quantum-dot lasers on Si.
• The use of InAlAs/GaAs SLSs enables the successful direct growth of high-performance 1.3-μm laser devices on silicon substrates.
• This work represents a significant step towards realizing integrated optoelectronics on silicon platforms.