Anion detection using ultrathin InN ion selective field effect transistors

Ultrathin (similar to 10 nm) InN ion selective field effect transistors (ISFETs) have been demonstrated to perform ion sensing in aqueous solutions with a sensitivity of 5 mu A/decade and a response time smaller than 10 s. The positively charged surface states on InN surfaces selectively adsorb anions, building Helmholtz voltages in solutions and modulating the drain-source current of the ISFETs. The ISFET performance is greatly enhanced by depleting carriers in the ultrathin InN channel where the film thickness is close to depth of surface electron accumulation. (c) 2008 American Institute of Physics.