Investigation of the growth temperature effect on H2 gas detection for ZnO thin films

In this study, 0.1 M and 100 mL CH3COOZn were used as precursors to growth ZnO thin films at 450 °C (S1) and 550 °C (S2) using ultrasonic spray pyrolysis. The crystal structure, surface morphology and sensor tests of the prepared films were investigated. XRD spectra show that it tends to grow towards (002) in both samples. The band gap values for the S1 and S2 samples were found to be 3.25 eV and 3.26 eV, respectively, using the absorption spectra. The absorbance values of both samples were obtained as stable in the range of 300 and 1000 nm and the absorbance were decreased with increasing temperature. From the SEM and AFM images, it is seen that if the growth temperature is increased from 450 °C to 550 °C, the surface morphology changes significantly and nanoplates are formed at 550 °C. In addition, it is understood from the AFM results that the surface roughness changes from 7 nm to 15 nm when the temperature is increased from 450 °C to 550 °C. The EDX results show that stoichiometry was achieved significantly for both samples. Finally, in the sensor tests were made for 1000 ppm at 300 °C. It was found that the sensor sensitivity was 32.7% and 7.7% for 450 °C and 550 °C, respectively, and the sensitivity decreased with increasing growth temperature.