Ultra-High Sensitive NO₂ Gas Sensor Based on Tunable Polarity Transport in CVD-WS₂/IGZO p-N Heterojunction

Area of Science:

• Materials Science
• Nanotechnology
• Chemical Sensing

Background:

• Transition-metal dichalcogenides (TMDs) are promising for gas sensing.
• Nitrogen dioxide (NO2) is a critical pollutant requiring sensitive detection.
• Existing TMD-based gas sensors have limitations in sensitivity and tunability.

Purpose of the Study:

• To fabricate and characterize a novel p-N heterojunction thin-film transistor gas sensor.
• To investigate the NO2 gas-sensing performance of WS2/IGZO heterostructures.
• To explore the transistor properties and their modulation by NO2 exposure.

Main Methods:

• Fabrication of a WS2/IGZO heterojunction using chemical vapor deposition and sputtering.
• Gas-sensing measurements in both heterojunction diode and transistor modes.
• Analysis of gas response, sensitivity, and transistor characteristics (ambipolar behavior, p-type transition).

Main Results:

• Achieved record NO2 gas sensor response compared to other TMD-based sensors.
• Demonstrated high sensing response in diode mode (230% for 5 ppm, 18,170% for 300 ppm NO2).
• Exhibited ultrahigh sensitivity in transistor mode (6820% for 5 ppm, 499,400% for 300 ppm NO2), modulated by gate bias.
• Observed a transition from ambipolar to p-type behavior with increasing NO2 concentration.

Conclusions:

• The WS2/IGZO heterojunction device is a highly promising platform for NO2 gas detection.
• Gas-modulated transistor properties offer potential for tunable engineering in 2D material heterojunction devices.
• This work advances the development of high-performance gas sensors based on 2D materials.