Highly-efficient (>70%) and Wide-spectral (400-1700 nm) sub-micron-thick InGaAs photodiodes for future...

Area of Science:

• Optoelectronics
• Semiconductor devices
• Nanophotonics

Background:

• Conventional photodetectors (PDs) with thick absorption layers (AL) suffer from low resolution and crosstalk.
• Achieving high quantum efficiency (QE) in thin PDs for broadband detection, especially in the short-wavelength infrared (SWIR) spectrum, remains a challenge.

Purpose of the Study:

• To demonstrate a novel sub-micron-thick InGaAs photodetector (PD) design for high-resolution imaging across the visible to SWIR spectrum.
• To enhance quantum efficiency (QE) and reduce electrical crosstalk in thin PDs using a guided-mode resonance (GMR) structure.

Main Methods:

• Fabrication of sub-micron-thick InGaAs PDs incorporating a TiO_x/Au-based guided-mode resonance (GMR) structure.
• Characterization of PD performance, including quantum efficiency (QE) and transit time, across a broad spectral range (400-1700 nm).

Main Results:

• Achieved remarkably high QE (>70%) from 400 to 1700 nm with a 0.98 μm absorption layer (AL) InGaAs PD.
• Reduced AL thickness by at least 2.5 times compared to previous studies while maintaining high QE.
• Observed enhanced transit time, crucial for decreasing electrical crosstalk.

Conclusions:

• The TiO_x/Au GMR structure effectively compensates for reduced AL thickness, enabling high QE in sub-micron-thick InGaAs PDs.
• This breakthrough offers a viable solution for developing high-resolution, low-noise broadband image sensors.
• The GMR approach simultaneously enhances QE and transit time, addressing key limitations in current photodetector technology.