Design and fabrication of novel Ti1-xZnxO2 thin films-based devices for improved ammonia gas sensor applications

In this work, Ti_1-xZn_xO₂ thin films were developed using nebulizer assisted spray pyrolysis technique by altering the Zn concentration 0, 1, 2, 3, 4 and 5 wt%. The prepared gas sensors were characterised by various techniques to understand their structural, surface morphological, elemental, optical, and gas sensing properties. The crystalline structure of the synthesized thin films was found to be a tetragonal crystal system and an increasing trend on crystallite size with the rise of Zn concentration from 0 to 3 wt%. The surface morphology was studied by FESEM, and it was found that the film with x = 3 wt% Zn possessed a uniform morphology. The optical band gap of the Ti_1-xZn_xO₂ thin films decreased to 3.44 eV–3.34 eV with the introduction of Zn in the host matrix. At 3 wt% of Zn, thin film of Ti_1-xZn_xO₂ exhibited higher photoluminescence peaks which occurred due to oxygen defect sites created in the TiO₂ host. The significant gas detection characteristics such as gas response over ammonia detection and faster gas rise/fall time were observed as 1590, 7.8/10s, respectively for Ti_1-xZn_xO₂ thin film developed at 3 wt% of Zn. These results demonstrate that at 3 wt% Zn, the Ti_1-xZn_xO₂ film-based sensor could serve as an effective and low-cost alternative to conventional gas sensors.