Abstract
The high surface-to-volume ratio of ZnO thin films nanostructure makes them an attractive solution for various gas and Volatile Organic Compounds (VOCs) sensing applications. In the present study, a low-cost, simple sol–gel drop-coating method has been developed to deposit uniform ZnO thin films of two different thicknesses aimed at fabricating a negative barrier height MSM structure for detecting cancer-associated VOCs at levels up to 800 ppb. Core electron elastic scattering was considered to determine the energy band gap of the ZnO thin films through XPS analysis, and the results are consistent with the UV-visible findings. The room-temperature sensing of biomarkers makes these films suitable for point-of-care applications in cancer screening based on VOC signatures. The sensitivity of the ZnO film to these analytes is determined by factors such as surface-adsorbed oxygen, film thickness, analyte molecular weight, and the bonding between analyte atoms and surface hydroxyl groups. In conclusion, the room-temperature detection of cancer biomarker VOCs at the parts-per-billion (ppb) level using a very thin layer of drop-coated ZnO, coupled with the negative barrier variation with film thickness, represents a novel finding.
