Bias stress in organic thin-film transistors and logic gates

Threshold voltage instabilities of all-organic thin-film transistors are in vestigated as a function of stress time and stress bias. The dominant effec t is a positive threshold shift for negative gate bias stress which is expl ained by mobile ions drifting in the insulator when a gate field is applied . Trapping of charge carriers at the semiconductor-insulator interface play s only a minor role. Furthermore, we investigate the stress behavior of a b asic logic element, an inverter. In comparison to a single transistor, we o bserve improved stability which arises from partial compensation of the par ametric shifts during operation. (C) 2001 American Institute of Physics.