An ultra-fast WSe₂ homojunction photodiode with a large linear dynamic range towards in-sensor image processing

Area of Science:

• Materials Science
• Optoelectronics
• Nanotechnology

Background:

• Two-dimensional (2D) semiconductors offer tunable photoresponse for in-sensor visual processing.
• Current 2D photodetectors face limitations in dynamic range and response speed, hindering real-world applications.

Purpose of the Study:

• To develop a high dynamic range (HDR) and ultrafast 2D photodetector.
• To overcome limitations of existing gate-tunable 2D photodetectors.

Main Methods:

• Utilized a localized electrostatic screening strategy.
• Fabricated a single-gate-tunable in-plane homojunction photodiode using WSe₂/PdSe₂ van der Waals (vdW) stacking.
• Leveraged efficient band alignment and reduced interface recombination inherent to vdW heterostructures.

Main Results:

• Achieved a bipolar high dynamic range (HDR) photodetector.
• Demonstrated a large physical linear dynamic range (LDR) of up to 142 dB.
• Attained an ultrafast response time as low as 8 ns.

Conclusions:

• The developed WSe₂/PdSe₂ photodiode offers superior performance for HDR imaging and low-latency in-sensor processing.
• The localized electrostatic screening strategy provides a pathway for creating tunable 2D photodetectors with enhanced LDRs.
• This advancement is promising for advanced visual processing in demanding lighting environments.