Surface Morphology of Fabricated TiO2-Graphene Thin Film by Spin-Coating Technique for pH Sensing Electrode Application

This paper presented the fabrication of TiO
2
-graphene hybrid thin film using spin-coating technique. The surface morphology and materials concentration has been studied using Field Emission Scanning Electron Microscopy (FESEM) and Surface Enhancement Raman Spectroscopy (SERS), respectively. Three parameters were varied for the study which are number of graphene solution drop on TiO2 thin film, spin coating speed and the dispersion time. From the FESEM images, the surface morphology resulted smooth surface for the sample of 3 drops of graphene at 3000 rpm for one-minute dispersion time. The peak of graphene (G) on the samples can be observed from the Raman spectra at 1600nm-1. The longer dispersion time of spin-coating showed the lower peak of G. The best sample was used as the sensing electrode for pH sensor by connecting the electrode with the Extended Gate Field Effect Transistor (EGFET) circuit. The TiO
2
-graphene sensing electrode was immersed in pH buffers to evaluate the sensing performance by calculating the linearity and sensitivity. The result shows high linearity and promising sensitivity value of 0.935 and 38 mV/pH, respectively.