CHARACTERIZATION, MODELING, AND CORRECTION OF DRIFT IN COMPLEMENTARY pH ISFET'S

摘要

A physical model for drift in pH-sensitive ISFET's is briefly reviewed and its implications as far as correction of device instability is concerned are discussed. According to this model, the origin of drift is associated with the relatively slow chemical modification of the gate insulator surface as a result of exposure to the electrolyte. The modeled-versus-measured fits for the drift characteristics of Si_3N_4-gate and Al_2O_3-gate pH ISFET's are presented. Furthermore, the drift behavior of complementary (n-channel versus p-channel) pH ISFET's are compared based on the proposed model, and the feasibility of a circuit technique for correction of drift using complementary ISFET's is discussed.