Sensing Performance of EGFET pH Sensors with Zinc Oxide ( ZnO ) Nanowires

Zinc Oxide (ZnO) was deposited by Spray Pyrolysis Technique on the Ti/Pt sputtered substrate and was used as a pH sensor in Extended Gate Field effect transistor (EGFET) devices. The pH sensor was connected to a commercial MOSFET (CD4007UB). ZnO nanorods were prepared by spray of aqueous solutions containing Zinc Chloride (ZnCl2) and thiourea (tu) at different molar ratios (1:0, 1:0.25) and at constant temperature (520°C). Obtained layers by Spray Pyrolysis Technique were characterized by Scanning Electron Microscopy (SEM), Energy Dispersive X-Ray Spectrometry (EDS), Dektak Profilometer and Atomic Force Microscopy (AFM).Small addition of thiourea into ZnCl2 solution (ZnCl2: tu = 1:0.25) supports development of significantly thinner ZnO nanorods with higher aspect ratio compared to those obtained from ZnCl2 solution. The current sensitivity results showed a much greater sensitivity for the sample with ZnCl2 and thiourea than the sample obtained only by ZnCl2. Key wordsEGFET, Nanowires, pH, ZnO