Okuma devreli yüksek hassasiyetli grafen tabanli ISFET pH sensörünün tasarimi ve simülasyonu

Electrochemical sensors are devices that use electrochemical reactions to detect and measure the concentration of analytes in a sample. As an electrochemical sensor, an ion-sensitive field-effect transistor, ISFET, is the basic structure of a biosensor. This thesis presents a high-sensitive pH sensor with a graphene-based dual-gate ISFET. Design and simulations of the proposed device are performed on SILVACO TCAD (Technology Computer Aided Design) software and Cadence Virtuoso environment. Graphene and aluminum oxide are used as channel and sensing film, respectively. The channel thickness is 10 nm, while the thickness of the device is 800 nm. The transfer and output characteristic curves of the device are obtained through simulations. Furthermore, Linearity, Stability and Temperature-dependency of the proposed device have been analyzed and discussed after designing a readout circuit using the 90nm Generic Process Design Kit (gpdk090) library. The effects of the back gate, channel material, and sensitive layer on device performance are evaluated by assessing the electrical characteristics, threshold voltage, and drain current. The sensitivity of the proposed device is achieved, approximately 18 times the Nernst limit, as 1066 mV/pH, which is the best performance score in the literature. The proposed device offers a novel ISFET structure with reliable and higher detection sensitivity.