Abstract
AbstractThe ion sensitive field effect transistor (ISFET) is a microsensor consists of the theorem of electrochemistry and the characteristic of a field effect transistor. The principle of the MOSFET is be used for ISFET. The metalline gate of the MOSFET is substituted for reference electrode / electrolyte / insulator. Hence, ISFET is a device composed of a ion selective electrode and a MOSFET device.In this thesis the silicon oxycarbide ( SiOxCy ) membrane has been prepared by high density plasma chemical vapor deposition, HDPCVD, method as a novel pH-sensitive layer under different gas flow rate (3MS/O2) and plasma power at different temperatures. The SiOxCy membrane was directly deposited on the p-type silicon substrate by HDPCVD to form the SiOxCy / Si EIS structure. The variations of flat band voltage were reported by C-V measurement to survey the sensitivity of membrane. The characteristics of membrane were measured and analysed by Electron spectroscopy for chemical analysis (ESCA), Energy dispersive spectrometer (EDS), n&k, Fourier transform IR (FTIR), Grazing incident X-ray diffraction and Atomic force microscopy (AFM), respectively.Experimental results show that the fabrication parameters and characteristics of SiOxCy membrane are determined at gas flow rate 20/2 (3MS/O2), the plasma power 600W at 200oC via the EIS structure. There exhibits the best pH response of about 56.35 mV/pH in the range of pH 1-11. The pH response increases to 64.35 mV/pH via the double layers of the EIS structure.