Bias dependent response reversal in chemically sensitive metal oxide semiconductor capacitors

Abstract

Conditions for reversal of the voltage shift in chemically sensitive metal oxide semiconductor capacitors are surveyed with the pulsed illumination technique in Si∕SiO2∕Me0 capacitors, with annular Pd and Au gates under controlled H2 in N2 and NO2 in synthetic air stimuli, respectively. The polarity of the response is bias dependent. Above the threshold voltage, negative voltage shifts ensue from positive charges accumulated on the gate-dielectric interface for donor stimuli such as H2, whereas positive shifts indicate negative charge accumulation for acceptors such as NO2. Below the threshold voltage, the necessary charge compensation can be satisfied by proportional changes in the semiconductor-gate interface state population, which induce chemical shifts of opposite polarity.