Origin of the bias stress instability in single-crystal organic field-effect transistors

We report a systematic study of the bias stress effect at semiconductor-dielectric interfaces using single-crystal organic field-effect transistors as a test bed. A combination of electrical transport and ultraviolet photoelectron spectroscopy suggests that this instability is due to a ground-state (i.e., occurring in the dark) charge transfer of holes from the accumulation channel of the semiconductor to localized states of a disordered insulator. The proposed model is not semiconductor specific and therefore provides a general analytical description of this instability in a variety of organic and inorganic band semiconductors interfaced with amorphous insulators.