Fabrication of Al-doped ZnO nanoparticles and their application as a semiconductor-based gas sensor for the detection of ammonia

A facile co-precipitation technique is used to fabricate ZnO and AZO (Al-doped ZnO) nanoparticles. It is analyzed and investigated that the effect of Al doping concentration has altered the structural and morphological properties of the nanoparticles. Increasing the concentration of doping has reduced the average crystallite size considerably in the range 18–24 nm. With the increased microstrain, we observe that bond length decreases for AZO nanoparticles. FESEM images indicate that morphology varies from the hexagonal crystalline phase of ZnO structure to the spherical shape of AZO samples. The UV–Vis spectroscopic studies showed that Al was incorporated into ZnO lattice as Al³⁺ due to the decreasing optical band gap of nanoparticles. The gas sensing responses of ZnO and AZO nanoparticles have been studied at optimum temperature with a low concentration of ammonia gas. The sensing studies revealed that the response of gas mainly relies on the size of the particles.