Thickness effect on VOC sensing properties of sprayed In₂S₃ films

Area of Science:

• Materials Science
• Chemical Sensing
• Nanotechnology

Background:

• Indium(II) sulfide (In2S3) is a promising semiconductor material for gas sensors.
• Optimizing film thickness is crucial for enhancing sensor sensitivity and selectivity.
• Volatile Organic Compounds (VOCs) pose environmental and health concerns, necessitating effective detection methods.

Purpose of the Study:

• To investigate the effect of In2S3 film thickness on sensing performance for various VOCs.
• To correlate structural and morphological properties with gas sensing capabilities.
• To understand the gas detection mechanism and sensor selectivity.

Main Methods:

• Spray pyrolysis deposition of In2S3 films with varying thicknesses (0.8–6.1 μm).
• X-ray diffraction (XRD) for structural analysis (polycrystalline, cubic structure).
• Scanning Electron Microscopy (SEM) and 3D profilometry for surface morphology and roughness assessment.
• Gas sensing measurements for ethanol, methanol, and acetone using dynamic current control.

Main Results:

• Film thickness was successfully controlled from 0.8 μm to 6.1 μm by adjusting spray time (10–90 min).
• Increased surface roughness was observed with increasing film thickness.
• The In2S3 film deposited for 70 min exhibited optimal sensitivity to VOCs.
• The sensing mechanism involves oxidation of VOCs by chemisorbed oxygen.

Conclusions:

• Film thickness significantly influences the sensing performance of In2S3-based VOC sensors.
• Optimized In2S3 film thickness (around 70 min deposition) enhances sensitivity.
• The study provides insights into In2S3 material properties for developing selective VOC detection systems.