Functionalizing Graphene Field-Effect Transistors for Sensor Applications

Graphene's unique electrical properties make it a strong candidate for field-effect transistors (FETs) used in sensing applications. However, such as charge inhomogeneity and accidental doping can affect performance, especially in chemical vapor deposition (CVD) graphene. This work investigates how sodium octyl sulfate (SOS), a surfactant, functionalization impacts graphene-based FETs. After functionalization, a shift in the charge neutrality point (CNP) toward lower gates was observed, suggesting reduced doping effects. The narrowing of the resistivity peak indicated improved charge uniformity, while both hole and electron mobilities increased significantly, reaching <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$2934 \text{cm}^{2} / \text{Vs}$</tex> and <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$3499 \text{cm}^{2} / \text{Vs}$</tex>, respectively. These improvements are likely due to the surfactant neutralizing charge puddles and removing residual contaminants. Our findings show that SOS functionalization enhances graphene's electronic properties, making it more effective for sensing applications.