Optimization of pH sensing using silicon nanowire field effect transistors withHfO2 as the sensing surface

Abstract

Silicon nanowire field effect transistor sensors withSiO2/HfO2 as the gate dielectric sensing surface are fabricated using a top down approach. Thesesensors are optimized for pH sensing with two key characteristics. First, the pH sensitivityis shown to be independent of buffer concentration. Second, the observed pHsensitivity is enhanced and is equal to the Nernst maximum sensitivity limit of59 mV/pH with a corresponding subthreshold drain current change of ∼ 650%/pH. These two enhanced pH sensing characteristics are attributed to the use ofHfO2 as the sensing surface and an optimized fabrication process compatible with siliconprocessing technology.