Exploration of highly sensitive LPG sensing performance of hexagonal ZnO thin films

The present manuscript reports the influence of annealing temperature on pristine ZnO thin films fabricated using spin coating technique. The casted films of ZnO are characterized in terms of structural, morphological, electrical, and gas sensing properties. Structural investigation reveals the wurtzite type hexagonal crystallinity of all the samples as confirmed Rietveld refinement study. The average crystallite size (39-51 nm) increased with increasing annealing temperature. The effect of annealing temperature on microstructure of ZnO can be clearly visualized from SEM micrographs. The real part of dielectric permittivity increases with increase in annealing temperature. The values of dielectric constant recorded at 10 Hz are found to be 17.7, 26.4, and 36.5 for ZnO@400 degrees C, ZnO@500 degrees C, and ZnO@600 degrees C, respectively, with low dielectric loss (tan delta) ranging 1.2-1.9. AC conductivity increases with increase in annealing temperature in high frequency region. LPG sensing response characteristics of fabricated ZnO thin films bearing thickness of 170 nm were analyzed for 100 to 250 degrees C temperature range along with annealing temperature from 400 to 600 degrees C. The results reflects that fabricated ZnO thin films offered sensitivity of 189% at optimal operating temperature of 180 degrees C and optimized annealing temperature is found to be 600 degrees C, respectively.

Automated summary

This paper investigates the influence of annealing temperature on spin-coated ZnO thin films. The results show that increasing the annealing temperature leads to larger crystallite size, higher dielectric constant, and increased AC conductivity. The LPG sensing response analysis indicates the optimal operating temperature and annealing temperature for the fabricated ZnO thin films.