Fabrication and characterization of thin film CdO nanoparticles for gas sensing applications

The CdO thin films, with their high electrical conductivity and transparency, have attracted significant interest for solar cells, gas sensors, and electronic devices. This study investigates the structural, optical, and complex impedance spectroscopy characteristics of CdO thin films fabricated using nebulizer spray pyrolysis. The films exhibit a well-crystallized cubic structure with a preferred orientation along the (200) plane. Increasing substrate temperature leads to larger grain sizes and improved crystallinity. The CdO films demonstrate high transparency in the visible spectrum and exhibit a direct band gap ranging from 3 eV to 1.9 eV. Gas sensing experiments reveal that the CdO films exhibit sensitivity to ammonia gas, with impedance measurements indicating that the detection is facilitated by the grain boundary resistance. The CdO sensor device shows excellent sensitivity to ammonia, particularly at a temperature of 400 degrees C, and an appropriate frequency range is identified for optimal sensitivity. These findings demonstrate the potential of CdO thin films for gas sensing applications.