Mechanism of off-leakage current in InGaZnO thin-film transistors

We investigate the mechanism of off-leakage current in InGaZnO thin-film transistors using a two dimensional device simulator. In order to reproduce the magnitude of experimental data, deep donor-like trap states probably originating from the oxygen vacancies are introduced in IGZO channel, which significantly affect the off-leakage current. It is shown that the pinning effect of the channel potential causes the plateau behavior of I_d-V_g characteristics in off-state region, depending on the amount and depth of the deep states.