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Sensitive infrared photodetection enabled by in-sensor background-offset cancellation in a mixed-dimensional van der
Xin Li1,2, Jian Wang1,2, Jintao Fu3
1State Key Laboratory of Infrared Physics, Shanghai Institute of Technical Physics, Chinese Academy of Sciences, Shanghai, China.
Nature Communications
|July 8, 2026
Summary
This study introduces a novel infrared photodetector that cancels background noise at room temperature. It achieves this by inverting spectral polarity, overcoming limitations of thermal radiation for sensitive detection.
Area of Science:
- Optoelectronics
- Materials Science
- Photonics
Background:
- Broadband thermal radiation limits room-temperature infrared photodetection by introducing background photons.
- This background radiation causes a photocurrent offset, overwhelming weak signals under ambient conditions.
- Current detectors suffer from unipolar spectral integration, where all background photons contribute with the same polarity.
Purpose of the Study:
- To demonstrate an in-sensor background-offset cancellation mechanism for infrared photodetectors.
- To overcome the limitations imposed by broadband thermal radiation in ambient conditions.
- To enable sensitive photodetection without external subtraction or balanced readout.
Main Methods:
- Engineered wavelength-dependent photocurrent reversal within a single device.
- Utilized an optically reconfigurable mixed-dimensional Germanium/black phosphorus van der Waals heterostructure photodetector.
- Demonstrated spectral polarity inversion to achieve background-offset cancellation.
Main Results:
- Successfully suppressed the mean background-induced current under fixed blackbody illumination.
- Achieved a room-temperature detectivity of 7.89 × 10^10 Jones for a zero-bias device.
- The device performance is within a factor of 4.11 of the background-limited benchmark.
Conclusions:
- Spectral polarity inversion is an effective mechanism for in-sensor background-offset cancellation.
- The developed Ge/black phosphorus heterostructure photodetector shows significant potential for high-performance room-temperature infrared detection.
- This approach offers a pathway to overcome fundamental limitations in infrared photodetection.
