Fabrication of an Ion-Selective Field Effect Transistor using a Thin Film Gate by Ion Beam Sputtering Method and its Electrochemical Characteristics as a pH Sensor

摘要

The Ion-Selective Field Effect Transistor (ISFET) serves as a chemical sensor through ion selective membrane is placed on the gate surface. To allow the ISFET to indicate ion response, fine-ceramic films were fabricated using the ion-beam sputtering method (IBS). The gate materials studied here were Si{sub}3N{sub}4, BN, SiC and B{sub}4C. Electrochemical properties of the ISFET, such as its response characteristics and its analytical performance as a pH sensor are discussed. For BN and B{sub}4C film gates, the pH response follows the theoretical Nernst relationship (59.2 mV/pH at 25°C). The SiC and Si{sub}3N{sub}4 film gates do not follow Nernst's equation for pH response.