Effects of pH and Ion Concentration in a Phosphate Buffer Solution on the Sensitivity of Silicon Nanowire BioFETs

Abstract

We have developed an in-house simulator based on the self-consistent solution of the three-dimensional (3D) Poisson-Boltzmann arid 3D drift-diffusion equations to examine the effects of pH arid ion concentration in a phosphate buffer solution on the sensitivity of a biologically-sensitive silicon nanowire field-effect transistors (BioFETs). We have analyzed the simulation results for the pH arid the ion concentration in the phosphate buffer solution by using the concept of the Debye length. We have found that the Debye length is decreased by increasing the ion concentration and decreasing the pH in the phosphate buffer solution. A short Debye length and large probe molecule charges are found to affect the sensitivity of the BioFETs.