Influence of adsorbed oxygen concentration on characteristics of carbon-doped indium oxide thin-film transistors under bias stress

Abstract

To clarify a factor on the reliability, we investigated the characteristics of carbon-doped indium oxide (InO1.16C0.04) thin-film transistors by varying the O2 concentration from 0.001% to 100% at atmospheric pressure under negative bias stress (NBS) and positive bias stress (PBS). A positive threshold voltage (V th) shift was observed when the bias stress was changed from NBS to PBS. The positive V th shift increased with increasing bias voltage irrespective of the O2 concentration. This behavior was attributed to the reaction between adsorbed O2 molecules on the back side of the InO1.16C0.04 channel and the electrons in the channel being strongly enhanced under PBS. We have found the magnitude and direction of the bias stress play an important role in the positive V th shift under environments included O2 at concentrations as low as 0.001%.