Electrical properties of Sn doped ZnO thin films deposited by sol gel spin coating method for MSM gas sensor applications / Mohd Hannas Hosnon

This study focused on development of nanostructured ZnO thin films based metal-semiconductor-metal (MSM) gas sensor by sol gel spin coating method. There were three stages that has been studied to fabricate nanostructured ZNO based MSM gas sensor which are: (a) preparation of ZnO thin films by spin coating method (b) preparation of Sn doped ZnO thin films by spin coating method and (c) fabrication of nanostructured ZnO based MSM based sensor. The preparation of ZnO thin films were deposited using spin coating with 10 layers and annealing temperature (350 to 500°C) of ZnO thin film were determined. For preparation on nanostructured n-type doped ZnO thin films by spin coating method, effect of annealing temperature (350 to 500°C) and effect of n-type dopant (Sn concentration 0.2-1.0 at.%) on nanostructured ZnO were studied. X-ray diffraction (XRD), Field emission scanning electron microscope (FESEM), energy dispersive X-ray (EDS) and atomic force microscopy (AFM) were used to characterise the structural properties of nanostructured ZnO thin films. The UV-Vis-NIR spectrometer was employed to study the optical properties determination. The electrical properties were characterized by using current-voltage (I-V) measurement (Keithley 2400) to characterize the resistivity, conductivity and the electrical resistance behaviour of the thin films. Then, gold (Au) was deposited on nanostructured ZnO as an electrode to fabricate nanostructured ZnO based MSM gas sensor. The gas sensor devices have been characterized using current-voltage (I-V) measurement system to measure the sensitivity, response time and the recovery time. The O2 oxygen gas with flow rate 20 seem has been used for fabricated nanostructured ZnO thin film based gas sensor testing. The highest sensitivity behaviour of nanostructured Sn doped ZnO thin films with 1.0 at.% were determined to detect 20 seem of oxygen (O2) gas at room temperature which found to be 12.56%.