Ultra-sensitive suspended atomically thin-layered black phosphorus mercury sensors

Area of Science:

• Materials Science
• Nanotechnology
• Chemical Sensing

Background:

• Black phosphorus (BP) possesses unique properties for advanced sensors.
• Substrate interference degrades BP's electrical properties, masking its sensing potential.
• The optimal operating conditions for BP sensors remain largely unexplored.

Purpose of the Study:

• To demonstrate the first suspended black phosphorus (BP) sensor.
• To investigate BP sensor performance in the subthreshold regime for mercury detection.
• To elucidate the sensing mechanism of intrinsic BP.

Main Methods:

• Fabrication of suspended BP field-effect transistor (FET) sensors.
• Operation and characterization of the sensor in the subthreshold regime.
• Detection of ultra-low concentrations of mercury ions (Hg2+).

Main Results:

• Suspended BP sensors show enhanced sensitivity for mercury detection without substrate scattering.
• Maximum sensitivity and signal-to-noise ratio achieved in the subthreshold regime.
• Detection limit of 0.01 ppb for Hg2+, significantly below WHO limits, with a 3s response time.

Conclusions:

• Suspended BP in the subthreshold regime offers superior performance for trace mercury detection.
• The sensing mechanism is attributed to carrier density modulation via surface charge gating.
• Intrinsic BP demonstrates significant advantages as a highly sensitive and stable sensing material.