Thin insulator films chemically sensibilized by ion implantation for use in ISFETs : studies on the drift effect in NAS membranes

Abstract Drift effects in sodium aluminosilicate films (NAS) prepared by ion implantation were studied using the EIS condensator structure (electrolyte-insulator-semiconductor). Under d.c. bias a polarization was observed leading to a drift of the flat-band voltage and to non-idealities in the ion-sensing response. Mechanisms are discussed that can account for the observed results, and measuring conditions for stable potentiometric signals with such films were derived.