Influence of the gate insulator on gas measurements with suspended gate FETs

Abstract

An attempt is made to separate the relative contributions to the threshold voltage shift of the layers composing a suspended gate FET (SGFET). For that purpose the insulators silicon nitride and diamondlike (a-C:H) films, as well as the sputtered SnO/sub 2/ and Ti/W, active layers have been investigated. The gas-surface interaction has been characterized by carrying out simultaneous measurements of mass changes (quartz crystal microbalance) and work function shifts (Kelvin probe). It is shown that the threshold voltage shift of SGFETs, composed of various insulator/active layer combinations, is a superposition of the independently measured work function shifts.<>