Analytical Modelling of Graphene based Ion Sensitive Field Effect Transistors for pH Sensing

Graphene, with its extraordinary material properties has been a promising alternative to silicon in field effect transistors (FETs) for various sensing applications. Previously it has been experimentally shown that coating graphene with an oxide layer further enhances it for sensing applications. In this paper we present an analytical modelling of graphene based ISFETs for pH sensing using three different oxide layers, namely SiO
₂
, Al
₂
O
₃
and Ta
₂
O
₅
. We have performed a detailed comparative analysis, assuming standard experimental parameters, and have finally concluded that by coating the graphene surface with Tantalum Pentoxide (Ta
₂
O
₅
) the highest pH sensitivity is achieved with values approaching close to the Nernstian limit due to its high dielectric constant and buffer capacity.