InP-based quantum cascade lasers monolithically integrated onto silicon.

Area of Science:

• Optoelectronics
• Materials Science
• Semiconductor Physics

Background:

• Quantum cascade lasers (QCLs) are crucial optoelectronic devices.
• Integrating InP-based QCLs onto silicon substrates offers potential for scalable photonic integrated circuits.
• Previous efforts faced challenges in yield and reliability.

Purpose of the Study:

• To report lasing in a novel InP-based quantum cascade laser structure grown on a silicon substrate.
• To analyze the performance and limitations of these silicon-integrated devices.
• To identify pathways for improving device performance.

Main Methods:

• Fabrication of ridge-waveguide devices from a 40-stage InP-based QCL structure grown on a 6-inch silicon substrate using a metamorphic buffer.
• Utilizing an Al_0.78In_0.22As/In_0.73Ga_0.27As strain-balanced active region and an all-InP waveguide.
• Characterization of lasing performance, including emission wavelength, threshold current, and operating temperature.

Main Results:

• Successful demonstration of lasing at 4.35 µm from devices operating up to 170 K.
• Threshold current of approximately 2.2 A at 78 K for 3 mm x 40 µm devices.
• Observed lower yield and reliability compared to similar devices integrated onto GaAs.

Conclusions:

• Lasing is achievable for InP-based QCLs integrated on silicon, albeit with current limitations.
• Reducing strain in active region layers is critical for enhancing device yield and reliability.
• Further research into strain management is essential for advancing silicon photonics.