Sensing of ethanol with nanosize Fe-ZnO thin films

Sensing of ethanol with iron doped ZnO (Fe-ZnO) thin films has been studied in this work. By X-ray diffraction spectroscopy, it is found that ZnO is the main compound in the low-iron (<10%) doped ZnO thin films. ZnFe 2 O 4 is also found as 20-50% of iron are doped on the thin films. The 5% Fe-ZnO thin film has a very high sensitivity (R air /R ethanol > 70) to 1000 ppm of ethanol at 300 K. It seems that iron can promote the sensivity of the ZnO thin film. The thin film doped with a greater amount (20-50%) of iron has, however, a much less sensitivity (<15) to ethanol. The chemical interactions between oxygen of ethanol and zinc on the Fe-ZnO thin film cause changes of the bond distances of Zn-O and Fe-O in the thin films to 1.90 and 1.98 Å which can be restored to 1.91 and 1.97Å, respectively, in the absence of ethanol.