Synthesis of flower shaped ZnO thin films for resistive sensing of NO2 gas

A soft chemical synthetic method is used to obtain highly crystalline ZnO flower thin films. Hexagonal wurtzite ZnO structure is observed from X-ray diffraction studies. A large-area jasmine flower-shaped morphology of ZnO is uniformly maintained at all deposition temperatures. The films were characterized by energy dispersive X-ray spectroscopy, Raman spectroscopy and field emission scanning electron microscopy. Elemental analysis showed the presence of Zn and O elements without any other impurity. Raman spectroscopy spectroscopy in combination with elemental and resistivity analysis indicated wurtzite ZnO structure and the presence of oxygen vacancies. The films deposited at 338 K were studied with respect to their gas sensing capability at operating temperatures of 473 K. They show a fast response (65 s) and recovery time (54 s) for NO 2 gas at a concentration as low as 10 ppm. Graphical abstract Large area jasmine flower-shaped morphology of ZnO is uniformly maintained for all deposition temperatures using soft chemical synthesis. The maintained flower shaped ZnO thin films at all deposition temperatures is highly sensitive to NO 2 gas.