Influence of carrier mobility and contact barrier height on the electrical characteristics of organic transistors

We have investigated the electrical properties of organic thin-film transistors by way of two-dimensional drift-diffusion simulations. The dependence of the electrical characteristics on the mobility model and on the Schottky barrier height of the contacts is analyzed. We found that both the field dependence of the carrier mobility and the barrier height of the contacts are responsible for the nonlinearity of the output characteristics in the low bias region. We have then extracted the mobility from the simulated characteristics using standard metal-oxide-semiconductor analytic relations and compared to the mobility used in the simulation. The discrepancy found between the two mobilities is mainly induced by the presence of the contact barrier. (C) 2002 American Institute of Physics.