In our research, the glass was used as a substrate for H+ ion sensitive field effect transistor (ISFET). The sensitive characteristics of five structures for separative extend gate ion sensitive field effect transistors were studied, which include tin oxide/aluminum/micro slide glass, tin oxide/aluminum/corning glass, indium tin oxide (ITO) glass, tin oxide/indium, indium tin oxide glass and tin oxide/micro slide glass. Indium tin oxide thin film is the first time used as a H+ ion sensitive film which has a linear pH sensitivity of Nerstern response, about 58 mV/pH, between pH2 and pH12. In addition, the sensing area effect of the tin oxide/glass, tin oxide/ITO glass and ITO glass structure which without Al conductive layer will be discussed.
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