Enhanced Ionic Sensitivity in Solution‐Gated Graphene‐Hexagonal Boron Nitride Heterostructure Field‐Effect Transistors

Abstract The charge transport in solution‐gated graphene devices is affected by the impurities and disorder of the underlying dielectric interface and its interaction with the solution. Advancement in field‐effect ion sensing by fabricating a dielectric isomorph, hexagonal boron nitride between graphene and silicon dioxide of a solution‐gated graphene field‐effect transistor is being reported. Ionic sensitivity of Dirac voltage as high as −198 mV per decade for K⁺ and −110 mV per decade for Ca²⁺ is recorded. Increased transconductance due to increased charge carrier mobility is accompanied with larger ionic sensitivity of the transconductance due to larger ionic sensitivity of the charge carrier mobility. These findings define a standard to construct future graphene devices for biosensing and bioelectronics applications.