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Challenges for room temperature operation of electrically pumped GeSn lasers
A R Ellis1, D A Duffy1, I P Marko1
1James Watt School of Engineering, University of Glasgow, Glasgow, G12 8LT, UK.
Scientific Reports
|May 5, 2024
Summary
Defect-related recombination limits germanium-tin (GeSn) lasers, accounting for 93% of threshold current at 85 K. Carrier leakage into L-valley states also significantly impacts performance, especially with small changes in band structure.
Area of Science:
- Materials Science
- Semiconductor Physics
- Optoelectronics
Background:
- Germanium-tin (GeSn) alloys show potential for on-chip lasers compatible with silicon photonics.
- Electrically pumped GeSn lasers face performance limitations hindering commercialization.
Purpose of the Study:
- Investigate dominant loss mechanisms in GeSn laser devices.
- Identify carrier recombination pathways affecting device performance.
- Provide insights for optimizing future GeSn laser designs.
Main Methods:
- Combined experimental and computational modeling approach.
- Utilized high hydrostatic pressure techniques at low temperatures to probe band structure.
- Analyzed carrier recombination pathways and leakage.
Main Results:
- Defect-related recombination accounts for 93 ± 5% of threshold current at 85 K.
- Carrier leakage into L-valley states is responsible for 1.1 ± 0.3% of threshold current at 85 K.
- A small decrease (30 meV) in L-valley separation energy drastically increases leakage to 50%, indicating thermal sensitivity.
Conclusions:
- Defect-related recombination is the primary loss mechanism in current GeSn lasers.
- Carrier leakage into L-valley states poses a significant challenge for high-temperature operation.
- Device design and growth optimization are crucial for improving GeSn laser performance and operational temperature range.
