Low-Temperature Ammonia Sensing Using Sulfurized WS₂ Thin Films

Area of Science:

• Materials Science
• Nanotechnology
• Chemical Sensing

Background:

• Gas sensors often require high operating temperatures, increasing energy consumption and limiting applications.
• Developing sensitive and selective gas sensors for ammonia (NH3) at lower temperatures is crucial for environmental monitoring and industrial safety.

Purpose of the Study:

• To investigate the gas sensing properties of tungsten disulfide (WS2) thin films at low operating temperatures.
• To optimize WS2 film deposition and sulfurization for enhanced ammonia (NH3) sensing performance.

Main Methods:

• Tungsten disulfide (WS2) thin films were prepared using sputtering and subsequent sulfurization at 800 °C on quartz and sapphire substrates.
• Material characterization included Raman spectroscopy, X-ray diffraction (XRD), and Field Emission Scanning Electron Microscopy (FESEM).
• Gas sensing performance was evaluated for ammonia (NH3) detection across a temperature range of 30-150 °C.

Main Results:

• Raman spectroscopy and XRD confirmed the formation of multilayer hexagonal 2H-WS2 phase.
• FESEM images revealed nanoparticle morphology with some texturing.
• The WS2 films demonstrated stable and high sensitivity to ammonia (NH3) in the 10-200 ppm range at low operating temperatures.
• A minimum limit of detection of 0.6 ppm for NH3 was achieved at 150 °C for WS2 films sulfurized for 60 min on quartz.

Conclusions:

• Tungsten disulfide (WS2) thin films are promising materials for low-temperature ammonia (NH3) gas sensing.
• Optimized sulfurization time and substrate choice significantly impact sensing performance.
• The developed WS2 gas sensors offer high sensitivity and a low limit of detection, suitable for practical applications.