Polarity-Switchable Sensitive Photodetection in a Superconducting van der Waals Heterostructure

Area of Science:

• Condensed Matter Physics
• Materials Science
• Optoelectronics

Background:

• Switchable photoconductivity is crucial for advanced optical applications like logic gates and quantum computing.
• Existing polarity-tunable photodetectors often suffer from low responsivity and limited spectral range.
• Developing highly sensitive and spectrally broad photodetectors with tunable photoresponse is essential for efficient information processing.

Purpose of the Study:

• To introduce a novel superconducting photodetector based on a van der Waals heterostructure.
• To investigate the switchable positive and negative photoconductivity in this device.
• To explore the underlying physical mechanisms and potential applications in optoelectronics.

Main Methods:

• Fabrication of a NbSe2-WTe2-NbSe2 van der Waals heterostructure.
• Characterization of the photodetector's response under varying bias voltages, light power, and temperature.
• Analysis of photocurrent signals to determine responsivity and spectral range.

Main Results:

• The NbSe2-WTe2-NbSe2 photodetector exhibits switchable photoresponse across the visible to near-infrared spectrum.
• A negative photoresponse is observed at high bias voltages due to photoinduced superconducting phase transition.
• A positive photoresponse is detected at low bias voltages, linked to light-modulated Andreev reflection.
• Both positive (0.35 A/W) and negative (-5 A/W) photoresponsivity exceed 0.3 A/W.
• Photoconductivity polarity is tunable via bias voltage, light power, and temperature.

Conclusions:

• The developed superconducting photodetector offers high sensitivity and tunable photoresponse.
• Quantum effects at the superconducting interface play a significant role in the observed phenomena.
• This research paves the way for advanced optoelectronic devices in information processing and quantum technologies.