MOS Device Chemical Response to Acceptor Stimuli

Abstract

Gap gate MOS capacitors exhibit changes in their state of charge, monitored by positive voltage shifts of the photocurrent induced by pulsed illumination under constant D.C. bias, proportionally to SO2 or NO2 concentration in air. Chemically induced charges are negative and their surface densities are twice as high for SO2 as those obtained for NO2, consistently with doubly charged anions; dynamic range is correspondingly halved. Both responses are mediated by associative chemisorption with oxygen.