High-performance Ge-on-insulator photodetector enabled by thick Ge spacer and tensile-strained GeSi/Ge multiple
Optics Express
|March 18, 2026
Summary
We developed novel Germanium-on-insulator (GOI) photodetectors using strained Germanium-Silicon/Germanium (GeSi/Ge) multiple quantum wells. Optimized designs achieve high responsivity and extended infrared detection for advanced imaging applications.
Area of Science:
- Optoelectronics
- Materials Science
- Semiconductor Physics
Background:
- Germanium-on-insulator (GOI) technology is crucial for advanced photonic integrated circuits.
- Developing high-performance photodetectors (PDs) for extended short-wavelength infrared (SWIR) detection remains a challenge.
Purpose of the Study:
- To present PIN GOI photodetectors incorporating tensile-strained GeSi/Ge multiple quantum wells (MQWs).
- To optimize the Ge spacer cap thickness for reduced dark current and controlled strain relaxation.
- To enhance responsivity and extend the detection wavelength for SWIR applications.
Main Methods:
- Systematic optimization of the Ge spacer cap thickness in GeSi/Ge MQW structures.
- Fabrication of PIN GOI photodetectors.
- Characterization using photoluminescence, spectral response measurements, and electrical measurements (-1 V bias).
Main Results:
- Optimized PDs achieved a dark current density of 2.20 mA/cm², responsivity of 1.01 A/W, and specific detectivity of 4.02 × 10¹⁰ cm·Hz¹/²·W⁻¹ at 1550 nm.
- Enhanced responsivity at 1550 nm was observed due to constructive optical interference.
- A thicker spacer extended the cutoff wavelength to 1700 nm, attributed to increased tensile strain in Ge₀.₈₆Si₀.₁₄.
Conclusions:
- The optimized GOI PDs with GeSi/Ge MQWs demonstrate high performance for SWIR detection.
- The study highlights the potential of tensile-strained MQWs in GOI platforms for extended SWIR imaging.
- This work paves the way for high-performance, Ge-based SWIR photodetectors.
