GeSnOI mid-infrared laser technology

Area of Science:

• Semiconductor physics
• Materials science
• Optoelectronics

Background:

• Germanium-tin (GeSn) alloys are promising for CMOS-compatible mid-infrared lasers.
• Tensile strain and tin alloying enable direct bandgap properties in GeSn.
• Existing GeSn laser technology faces challenges in optical confinement, strain, thermal, and defect management.

Purpose of the Study:

• To demonstrate a GeSn-on-insulator (GeSnOI) stack for monolithic integration of Group-IV semiconductor lasers.
• To address limitations in optical confinement and light management for near- and mid-infrared lasers.
• To develop a versatile photonic platform for silicon-based photonics.

Main Methods:

• Fabrication of microdisk-shape resonators on mesa structures from GeSnOI.
• Utilizing stressor layers as dielectric optical claddings in the GeSnOI stack.
• Bonding a GeSn alloy layer grown on a Ge strain-relaxed-buffer onto a Si(001) substrate.

Main Results:

• GeSnOI microdisk mesas showed significantly improved optical gain compared to conventional suspended microdisk resonators.
• Enhanced vertical out-coupling of in-plane radiation from disk whispering gallery modes was achieved.
• Up to 30% vertical out-coupling efficiency was demonstrated.

Conclusions:

• The GeSnOI approach is suitable for monolithic integration of planar Group-IV semiconductor lasers.
• This technology offers a valuable asset for developing silicon-based mid-infrared photonics.
• The method facilitates complex lightwave engineering on a versatile photonic platform.