摘要
AlGaNGaN high electron mobility transistors (HEMTs) with an AgAgCl gate exhibit significant changes in channel conductance upon exposing the gate region to various concentrations of chloride (Cl-) ion. The AgAgCl gate electrode, prepared by potentiostatic anodization, changes electrical potential when it encounters Cl- ions. This gate potential changes lead to a change of surface charge in the gate region of the HEMT, inducing a higher positive charge on the AlGaN surface, and increasing the piezoinduced charge density in the HEMT channel. These anions create an image positive charge on the Ag gate metal for the required neutrality, thus increasing the drain current of the HEMT. The HEMT source-drain current was highly dependent on Cl- ion concentration. The limit of detection achieved was 1× 10-8 M using a 20×50 μ m2 gate sensing area. © 2008 American Institute of Physics.